摘要:

THE J O U R N A L OF C H EM1 GAL S 0 C IE TY. TRANSACTIONS. H. E. ARMSTRONG, Ph.D., F.R.S. J. DEWAR, LL.D., F.R.S. WPNDHAM R. DUNSTAN, M.A., F.R.S. A. VERNON HARCOURT, &LA., F.R.S. R. MELDOLA, F.R.S. W. RAMSAY, Ph.D., F.R.S. W. J. RUSSELL, Ph.D., F.R.S. J. MILLAR THOMSON, F.R.S. T. E. THORPE, LL.D., F.R.S. 137. A. TILDEN, D.Sc., F.R.S. W. P. WYNNE, D.Sc., F.R.S. (E bit or : C. E. GROVES, F.R.F. %ub-&bifo.u : A. J. GREERAWAY. 1897. Vol. LXXI. LONDON: GURNEY & JACKSON, 1, PATERNOSTER ROW. 1897RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNQAY.C O N T E N T S. PAPERS READ BEFORE THE CHEMICAL SOCIETY. PAGE I.-Sulphocamphoric Acid and other Derivatives of Camphorsul- By ARTHUR LAPWORTH, D.Sc., and FREDERIC 11.-The Explosion of Acetylene with less than its Own Volume of Oxygen.By WILLIAM ARTHUR BONE and JOHN CANNELL CAIN . . 26 111.-The Direct Union of Carbon and Hydrogen. By WILLIAM ARTHUR BONE and DAVID SMILES JERDBN . . 41 1V.-Electrical Conductivity of Diethylammonium Chloride in Aqueous Alcohol. By JAMES WALKER, Ph.D., D.Sc., and FRED. J. HAMBLY, F.I.C. . . 61 V.-Experimental Methods employed in the Examination of the Products of Starch-hydrolysis by Diastase. By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and J. H. MILLAR . . 72 By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and J. H. MILLAR . . 109 VK-The Relation of the Specific Rotatory and Cupric-reducing Powers of the Products of Starch-hydrolysis by Diastase. By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and J. H. MILLAR . . 115 VIII.-Synthesis of Pentacarbon Rings.Part I. Anhydracet- onebenzil and its Homologues. By FRANCIS ROBERT JAPP, F.R.S., and GEORGE DRUCE LANDER, B.Sc. . . 123 IX.-Synthesis of Pentacarbon Rings. Part I S , Condensation of Benzil with Acetonodicarboxylic Acid. By FRANCIS ROBERT JAPP, F.R.S., and GEORGE DRUCE LANDER, B.Sc. . 139 X.-Synthesis of Pentacarbon Rings. Part 111. Condensation of B e n d with Lzvulic Acid By FRANCIS ROBERT JAPP, F.R.S., and THOMAS SMITH MURRAY, D.Sc. . . 144 XI.-Reduction of Yesyleneacetic Acid, and the Constitution of Zinin’s Pyroamaric Acid. By FRANCIS ROBERT JAPP, F.R.S., and GEORGE DRUCE LANDER, B.Sc. . . 154 phonic Acid. STANLEY KIPPING, Ph.D., D.Sc. . . I V1.-Specific Rotation of Maltose and of Soluble-Starch.iv CONTEXTS. XI1.-The Reduction of Xylic Acid, of Paraxylic Acid, and of Methylterephthalic Acid, and the preparation of Methyl- terephthalic Acid and of Methylisophthalic Acid.By WILLIAM HENRY BENTLEY and WILLIAM HENRY PERKIN, Jun. XIK-Observations on the Oxidation of Nitrogen Gas. By LORD RAYLEIGH . . XIV. -Derivatives of Msclurin. Part 11. By ARTHUR GEQRGE PERKIN, F.R.S.E. . XV.-Camphoroxime. Part I. Conversion of Camphoroxi me into Methylcamphorimine and into Camphenylnitramine. By MARTIN 0. FORSTER, Ph.D. . XBI. -Formation of Substituted Oxytriazoles from Phenyl- semicarbazide. By GEORGE YOUNG, Ph.D., and HENRY ANNABLE, Firth College, Sheffield. . XVI1.-Researches in the Stilbene Series. I. By JOHN J. SUDBOROUGH, Ph.D., D. Sc. XVII1.-Diortho-substituted Benzoic Acids. Part 111.Hydro- lysis of Substituted Benzamides. By JOHN J. SUDBOROUGH, PERCY G. JACKSON, and LORENZO L. LLOYD XIX. -The Refraction Constants of Crystalline Salts. By ALFRED EDWIN TUTTON . XX.-Derivatives of a-Hydrindone. By CECIL REVIS, Assoc. C.G.T., and FREDERIC STANLEY KIPPING, Ph.D., D.Sc. . XXL-The Amy1 (Secondary Butyl Methyl) Derivatives of Gly- ceric, Diacetylglyceric, and Dibenzoylglyceric Acids, Active and Inactive. By PERCY FRANKLAND, Ph.D., B.Sc., F.R.S., and THOMAS SLATER PRICE, B.Sc., late Priestley Scholar in Mason College, Birmingham . XXII-The Solution-density and Cupric-reducing Power of Dex- trose, Levulose, and Invert-Sugar. By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and JAMES HILL MILLAR XXII1.-Researches on the Terpenes, VII. Halogen Derivatives of Camphor and their Reactions.By JAMES ERNEST MARSH and JOHN ADDYMAN GARDNER . XX1V.-Supposed Condensation of Benzil with Ethylic Alcohol. A Correction. By FRANCIS ROBERT JAPP, F.R.S. . XXV. --Presence of Gold in Natural Saline Deposits and Marine Plants. By ARCHIBALD LIVERSIDGE, LL.D., F.R.S., Professor of Chemistry in the University of Sydney . XXV1.-Production of Pyridine Derivatives from Ethylic P-Ami- docrotonate. By JOHN NORMAN COLLIE, Ph.D., F.R.S. . XXVII. -Oxidation of Phenylstyrenyloxytriazole. By GEORGE YOUNG, Ph.l>., Firth College, Sheffield XXVII1.-Formation of Dithionic Acid by the Oxidation of Sul- phurous Acid with Potassium Permanganate. By THOMAS S. DYMOND and FRANK HUGHES . . PAGE 157 181 186 191 200 218 229 235 238 253 275 285 297 298 299 31 1 314CONTENTS XX1X.-Apparatus for ‘‘ Steam Distillation.” By FRANCIS EDWARD MATTHEWS .XXX.-Contributions t o the Knowledge of the P-Ketonic Acids. Part 111. By SIEGFRIED RUHEMANN, Ph.D., M.A. . XXX1.- Contributions t o the Knowledge of the p-Ketonic Acids. Part IV. By SIEGFRIED RUHEMANN, Ph.D., M.A., and A. S. HEMNY, B.A., M.Sc., Hutchinson Student of St. John’s College . XXXI1.-Contributions t o the Knowledge of the P-Ketonic Scids. Part V. By SIEGFRIED RUHEMANN, Ph.D., M.A., and A. S. HEMXY, B.A., M.Sc. . XXXIIL-The Nitrites of Mercury and the Varying Conditions under which they are formed. By P. C. RBY, D.Sc. (Edin.). XXX1V.-Crystallography of the Monhydrated Mercurous Nitrite. By THOMAS H. HOLLAND, A.R.C.S., F.G.S., Deputy-Superintendent, Geological Survey of India .XXXV.-Mercury Hyponitrites. XXXV1.-Contributions to our Knowledge of the Aconite Alka- loids. Part X1V.-On Pseudaconitine. By WYNDHAM R. DUNSTAN, M.A., F.R.S., and FRANCIS H. CARB, A.I.C., Salters’ Company’s Research Fellow in the Laboratories of the Scientific Department of the Imperial Institute . XXXVI1.-The Viscosity of Mixtures of Miscible Liquids. By THOS. EDWARD THORPE, LL.D., F.€LS., and JAS. WYLL~E RODGER, Asaoc. R.C.S. , XXXVII1.-A New Synthesis in the Sugar Group. By HENRY J. HORSTMAN FENTON, &LA. . XXX1X.-The Freezing Points of Alloys containing Zinc and another Metal. By CHARLES THOMAS HEYCOCK and FRANCIS HENRY NEVILLE . XL.-The Di-nitrosamines of Ethyleneaniline, the Ethylene- toluidines, and their Derivatives. By FRANCIS E.FRANCIS, Ph.D., B.Sc., Lecturer in Chemistry, University College, Bristol . XLI .-Dissociat ion-pressure of Alkylammonium Hydrosulphides. By JAMES WALKER, D.Sc., Ph.D., and JOHR S. LUMSDEN, B.Sc., Ph.D. . XLII. -Some Hydrocarbons from American Petroleum. I. Normal and Iso-pentane. By SYDNEY YOUNG, D.Sc., F.R.S., and GEORGE L. THOMAS, B,Sc., University College, Bristol. . XLIII. -The Vapour Pressures, Specific Volumes, and Critical Constants of Normal Pentnne, with a Note on the Critical Point. By SYDNEY YOUNG, D.Sc., F.R.S., University College, Bristol By P. C. R,~Y, D.Sc. (Edin.) V PAGE 318 323 329 334 337 346 345 350 360 3 75 383 422 428 440 446vi CONTENTS. XL1V.-A Synthesis of Citric Acid. By WILLTAN TREVOR XLV.-Sodsmide and some of its Substitution Derivatives.By XLV1.-Rubidamide. By ARTHUR TYV. TITHERLEY, BJ.Sc. , Ph. D. XLVI1.-Observations on the Properties of some Highly Puri- fied Substances, By WILLIAM ASHWELL SHENSTONE, Lecturer on Chemistry in Clifton College . . XLV1II.-Velocity of Urea Formation in Aqueous Alcohol. By JAMES WALKER, Ph.D., D.Sc., and SYDNEY A. KAY, B.Sc. XL1X.-Action of Diastase on Starch. Third Notice. By ARTHUR R. LING and JULIAN L. BAKER . L.-Studies on the Chemistry of Nitrogen. Enantioinorphous forms of Ethylpropylpiperidonium Iodide. By CLARE DE BRERETON EVANS . L1.-Magnesium Nitride as a Reagent. By H. LLOYD SNAPE, D.Sc., Ph.D. . LIL-Laurent’s Amarone. By H. LLOYD SNAPE, D.Sc., Ph.D., and ARTHUR BROOKE, Ph.D. . LI1I.-The Wide Dissemination of some of the Rarer Elements, and the Mode of their Association in Common Ores and Minerals. By WALTER NOEL HARTLEY, F.R.S., and HUGH RAMAGE, A.R.C.S.I., F.I.C.. L1V.-On the Spectrographic Analysis of some Commercial samples of Metals, of Chemical Preparations, and Minerals from the Stassfurth Potash Beds. By W. N. HARTLEY, F.R.S., and HUGH RAMAGE, F.I.C., A.R.C.Sci.I., Royal College of Science, Dublin . LV.-The Atomic Weight of Carbon. By ALEXANDER SCOTT, M.A., D.Sc. . LV1.-A New Series of Mixed Sulphates of the Vitriol Group. By ALEXANDER SCOTT, M.A., D.Sc. LVI1.-Solution and Pseudo-solution. Part 111. The Electrical Convection of certain Dissolved Substances. By HAROLD PICTON and S. ERNEST LINDER LVIIL-Action of Alkyl Haloids on Aldoximes and Ketoximes. By WYNDHAM R. DUNSTAN, F.R S., and ERNEST GOULDING, Assistant Chemist in the Laboratories of the Scientific De- partment of the Imperial Institute L1X.-Note on Wechsler’s Method for the Separation of Fatty Acids.By ARTHUR W. CROSSLEY, M.Sc., Ph.D. LX.-Researches on the Oxides of Cobalt. Cobalt Dioxide or Cobaltous Anhydride, Cobaltous Acid and Cobaltites. By ARTHUR H. MCCONNELL and E D G ~ R s. HANES . LAWRENCE, B.A., Ph.D. . ARTHUR W. TITHERLEY, M.Sc., Ph.D. . . . , PAGE 457 460 469 471 489 508 522 526 528 533 547 550 564 568 573 580 584CONTENTS. vii 1 Annual General Meeting . LX1.-Explosion of Chlorine Peroxide with Carbonic Oxide. By HAROLD BAILY DIXON, M.A., F.R.S., and EDWARD JOHN RUSSELL, B.Sc. . By F. D. CHATTA- WAY, M.A., Christ Church, and K. P. STEVENS, B.A., St. John’s College, Oxford .LXII1.-Monochlorodiparaconic Acid. By HENRY C. MYERS LX1V.-Halogen-substituted Acidic Thiocarbimides, and their Derivatives ; a Contribution t o the Chemistry of the Thiohydantoins. By AUGUSTUS EDWARDIXON, M.D. . LXV. -On the Circumstances which Affect the Rate of Solution of Zinc in Dilute Acids, with Especial Reference t o the Influence of Dissolved Metallic Salts. By JOHN BALL, Ph.D., A.R.S.M. . LXV1.-The Composition of Cooked Fish. By Miss KATHARINE I. WILLIAMS, Associate of University College, Bristol . LXVI1.-Oxidation Products of ay-Dimethyl-a’-chloropyridine. By Miss EMILY ASTON, B.Sc., and J. NORMAN COLLIE, Ph.D., F.R.S. . LXVII1.-Corydaline. Part V. By JAMES JOHNSTON DOBBIE, M.A., D.Sc., and FRED. MARSDEN, Ph.D., M.Sc. . LX1X.-The Reactions between Lead and the Oxides of Sulphur.By HENRY C. JENKINS and ERNEST A. SMITH, Metallurgical Department, Royal College of Science, London . LXX.-The Action of Bromodiphenylmethane on Ethylic Sodio- acetoacetate. By GEORGE GERALD HENDERSON, D.Sc., M. A., and MATTHEW ARCHIBALD PARKER, B.Sc. LXX1.-Some New Gold Salts of Hyoscine, Hyoscyamine, and Atropine. By HOOPER ALBERT DICKINSON JOWETT, D.Sc. Pasteur Memorial Lecture. By PERCY FRANKLAND, Ph.D., B.Sc., F.R.S., Professor of Chemistry in Mason College, LXXI1.-Dalton’s Law in Solutions (Molecular Depression of Mixtures of Two Non-electrolytes). By MEYER WILDERMAN, Ph.D.. . . . . . . . . . . . LXXII1.-Thermal Phenomena attending the Change in Rotatory Power of freshly prepared Solutions of certain Carbohydrates, with some Remarks on the Cause of Multi- rotation.By HORACE T. BROWN, F.R.S., and SPENCER U. PICKERINB, F.R.S. . . . . . . . . . LXX1V.-Thermo-chemistry of Carbohydrate Hydrolysis. By HORACE T. BROWN, F.R.S., and SPENCER U. PICHERING, F.R.S. . . . . . . . . . . . . LXI1.-Hydrolysis of Perthiocyanic Acid. . Birmingham . . . . . . . . . . ’AGE 591 605 607 614 617 641 649 653 65 7 666 676 679 683 743 756 783... V l l l CONTENTS. PAGE LXXV.-Experimental Verification of Van’ t Hoff’s Constant in very Dilute Solution (Law of Molecular Depression). By MEYER WILDERYAN, PhD. . . . . . . . 796 LXXV1.- Apiin and Apigenin. By ARTHUR GEORGE PERKIN, F.R.S.E. . . . . . . . . . . . 805 LXXVI1.-Rhamnazin. By ARTHUR G. PERKIN, F.R.S.E., and H. W. MARTIN . . . . . . . . . . 818 LXXVII1.-The Molecular Refraction of Dissolved Salts and Acids.Part 11. By DR. JOHN HALL GLADSTONE, F.R.S., and WALTER HIBBERT, F.I.C. . . . . . . . By F. D. CHATTA- WAY, M.A., Christ Church, and H. P. STEVENS, B.A., St. John’s College, Oxford . . . . . . . . 833 LXXX.-Production of some Nitro- and Amido-hydroxypico- lines. By A. LAPWORTH, D.Sc., and J. NORMAN COLLIE, Ph.D.,F.R.S. . . . . . . . . . . 838 LXXX1.-Connection between the Crystallographical Charac- ters of Isomorphous Salts and the Atomic Weight of the Metals contained. A Cohparative Crystallographical Study of tbeNormalSelenatesof Potassium, Rubidium, and Csesium. By ALFRED EDWIN TUTTON, Assoc. R.C.S. . 846 LXXXI1.-The so-called Hydrates of Isopropylic Alcohol. By LXXXI1I.-The Theory of Osmotic Pressure and the Hypo- thesis of Electrolytic Dissociation.By HOLLAND CROMPTON 925 LXXX1V.-Molecnlar Rotations of Optically Active Salts. By HOLLAND CROMPTON . 946 LXXXV.-Heats of Neutralisation of Acids and Bases in Dilute Aqueous Solution. By HOLLAND CROMPTON . , 951 LXXXVL -Optical Inversion of Camphor, By FREDERIC STANLEY KIPPING, Ph.D., D.Sc., and WILLIAM JACKSON POPE . . 956 LXXXV1T.-Derivatives of Camphoric Acid. Part 11. Opti- cally Inactive Derivatives. By FREDERIC STANLEY KIPPING, LXXXVII1.-Racemism and Pseudorscemism . By FREDERIC STANLEY KIPPING, Ph.D., D.Sc., and WILLTAM JACKSON POPE LXXX1X.-The Carbohydrates of the Cereal Straws. By C. F. XC.-On the Properties of Nitrobenzene. By RICHARD J. XC1.-A Space Formula for Benzene. By J. NORMAN COLLIE, XC)II.-The Isomeric Dibromethylenes.By THOMAS GRAY, B.Sc. 1023 822 LXX1X.-Reduction of Perthiocyanic Acid. THOS. EDWARD THORPE, LL.D., F.R.S. . . 9 2 0 Ph.D., D.Sc., and WILLIAM JACKSON POPE . . . . 962 989 CROSS, E. J. BEVAN, and CLAUDE SMITH . . . . 1001 FRIS WELL . . . . . . . . . . . 101 0 Ph,D.,F.R.S. . . . . . . . . . . 1013CONTENTS. ix PAGE XCII1.-Camphoroxime. Part 11. The Ethers of Camphor- XC1V.-The Action of Nitrogen Trioxide and Tetroxide on Alcohols. Part I. By JULIUS BEREND COHEN, Ph.D., and HARRY THORNTON CALVERT, B.Sc., The Yorkshire College . XCV.-The Action of Nitrogen Tetroxide on Ortho- and Para- nitrobenzylic Alcohols. By JULITJS BEREND COHEN, Ph.D., and WILLIAM HUDSON HARRISON, B. Sc., The Yorkshire XCV1.-The Action of Aromatic Amines on Diacetyltartaric Anhydride.By JULIUS BEREND COHEN, Ph.D., and WILLIAM HUDSON HARRISON, B.Sc., The Yorkshire College . . 1060 XCVI1.-Interaction of Ethylenic Chloride, Ethylic Malonate, and Sodium Ethoxide. By BEVAN LEAN, D.Sc., B.A., and FREDERIC H. LEES . . . . . . . . . 1062 XCVII1.-Studies on Citrazinic Acid. Part V. By WILLIAM JAMES SELL, &LA., F.I.C., and FREDERICK WILLIAM DOOTSON, B.A. . . . . . . . . . . . . 1068 XC1X.-The Condensation of Chloral with Resorcinol. (Second Communication.) By JOHN THEODORE HEWITT, M.A., D.Sc., Ph.D., and FRANK G. POPE . . . . . . 1084 G-On P-Oxycellulose. By BENJAMIN SAMUEL BULL, M. A,, B.Sc., Ph.D., A.I.C. . . . . . . . . 1090 C1.-On the Action of Sodium Hyponitrite on Mercuric Solu- tions. By PRAFULLA CHANDRA RAY, D.Sc. (Edin.), Pro- fessor of Chemistry, Presidency College, Calcutta .. 1097 (211.-On a New Method of Preparing Mercuric Hyponitrite. By PRAFULLA CHANDRA RAY, D.Sc. (Edin.), Professor of Chemistry, Presidency College, Calcutta . . . . 1105 CII1.-A New Synthesis of Phloroglucinol. By DAVID SMILES JERDAN, B.Sc. . . . . . . . . . . 1106 C1V.-Phenanthrone. By FRANCIS R. JAPP, F.R.S., and ALEXANDER FINDLAY, M.A., B.Sc. . . . . . 1115 CV.-The Crystalline Structure of Gold and Platinum Nuggets and Gold Ingots. By A. LIVERSIDGE, LL.D., F.R.S. . . 1125 CVL-The Yellow Golouring Principles of various Tannin Matters. By A. G. PERKIN, F.R.B.E. . . . . . 1131 C VI1.-Ammonia and Phenylhydraeine Derivatives of aP-Di- benzoylcinnamene (An hydracetophenonebenzil). By FRANCIS R. JAPP, F.R.S., and ALFRED TINGLE, B.Sc. . . . . 1138 CVIIL-Derivatives of Cotoin and Phloretin. By ARTHUR GEORGE PERKIN and H. W. MARTIN . . . . . 11 49 CIX.-Azobenzene Derivatives of Phloroglucinol. By ARTHUR GEORGE PERKIN . . . . . . . . . . 1154 oxime. By MARTIN ONSLOW FORSTER, Ph.D. . . . 1030 1050 College . . . . . . . . . . . 1057X CONTENTS. PAGE CX.-Action of Phosphorus Pentachloride on Fenchone. By JOHN ADDYMAN GARDNER, M.A., and GEORGE BERTRAM COCKBURN, B . A . . . . . . . , . . . 1156 (2x1,-Ketolactonic Acid and its Homologues. By CHARLES H. G. SPRANKLING, B.Sc. Lond. . . . . . . 1159 CXI1.-Synthesis of i-Camphoronic Acid. By WILLIAM HENRY PERKIN, jun., and JOCELYN FIELD THORPE . . , . 116 9 CXII1.-Yellow Colouring Matters obtained from Elms rhodan- the?na, Rerbes-is oetnensis, and Runtex obtusiyoolius. By ARTHUR GEORGE PERKIN, F.R.S.E. . . . , , 1194 CX1V.-Naphthylcarbamides. By GEORGE YOUXG, Ph.D., and ERNEST CLARK , . . . , . . . . , 1200 Obituary Notices . . . . . . . . . . 1204

ISSN:0368-1645    

DOI:10.1039/CT89771FP001

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

26 BONE AND CAIN: THE EXPLOSION OF ACETYLENE II.-Tlze Explosion of Acetylme with less than its own volume of Oxygen. By WILLIAM ARTHUR BONE and JOHN CANNELL CAIN. IN TRO D u CT 10 N. DURING the past three years, the authors have carefully studied the gaseous products formed when acetylene is exploded with less than its own volume of oxygen, a subject which up to the present has received very little attention. In 1892, Lean and Bone showed that when ethylene is exploded with less than its own volume of oxygen, the greater part of the hydrocarbon undergoes a partial combustion in accordance with the following equation C,H, + 0, = 2CO + 2H, whilst some of the excess of ethylene is decomposed at the high tem- perature of the explosion, forming methane and acetylene, together with a deposition of carbon, It seemed interesting t o compare the explosion of acetylene with that of ethylene under similar conditions, in the first place because acetylene is a characteristic endothermic compound, and is readily decomposed by shock into its elements, with the evolution of much heat ; secondly because this hydrocarbon has played a prominent part in recent discussions on the subject of the luminosity of flame; and finally because acetylene may now be pre- pared on a commercial scale from calcium carbide, and will probably be extensively used as an illuminant.Acetylene differs from methane and ethylene by the readiness with which it explodes when mixed with comparatively small volumes of oxygen. Methane will not detonate unless it is fired with nearly its own volume of oxygen; Lean and Bone showed that ethylene must be mixed with about 65 per cent.of its own volume of oxygen before itWITH LESS THAN ITS OWN VOLUME OF OXYGEN. 27 can be fired under ordinary conditions, On the other hand, a mixture of acetylene with from one-fifth to one-fourth its own volume of oxygen forms a mixture which when sparked explodes with the utmost violence; consequently the authors have been able to study the explosion of acetylene with from about 25 to 100 per cent. of its own volume of oxygen. The mixtures were exploded in a long leaden coil, at the atmospheric pressure, in a manner to be described in detail later; the chemical changes occurring were, therefore, those of the explosion wave. The results of our work may be briefly stated as follows.1. When acetylene is exploded with less than its own volume of oxygen, carbon monoxide and hydrogen are finally obtained owing to the partial combustion of the acetylene in accordance with the equation C,H, + 0, = 2 0 0 + H, the cooled products of the explosion in the coil being under consider- able pressure. 2. The excess of acetylene is for the greater part resolved into its elements by the shock of the explosion wave. A small quantity of acetylene (as much as 1 per cent. in some cases) is, however, found in the products of explosion. This may be due to acetylene which has escaped decomposition altogether, or possibly to a recombination of carbon and hydrogen in the rear of the explosion wave. The authors have not been able to detect the presence of any other unsaturated hydrocarbon in the products of explosion.3. Methane does not appear to be formed when acetylene is exploded with less than its own volume of oxygen, a t any rate not in any appreci- able amount. The authors have very carefully investigated this point, and although some of their earlier experiments led them to suspect the presence of a small quantity of methane (some 0.5 per cent.) in the products of explosion, a more rigid examination has left no doubt in their minds that methane is absent. This is particularly interesting, seeing that when ethylene is ex- ploded with less than its own volume of oxygen, methane is produced, in certain cases to the extent, of 6 per cent. of the whole products. The difference in the two cases is probably due to the fact that acety- lene is readily resolved into its elements by shock, whilst in the case of ethylene the excess of hydrocarbon which escapes combustion is subjected to a ‘‘ roasting ” process, and thereby decomposed into carbon and methane.4. Small amounts of a gas absorbable by solid potassium hydroxide were invariably found in the products of explosion. This was in part, if not altogether, due to the presence of carbon dioxide, for when28 BONE AND CAIN: THE EXPLOSION OF ACETYLENE the products of explosion were aspirated through a clear solution of baryta, a white precipitate of barium carbonate was formed. This was shown by firing a small volume of each mixture in a short eudiometer made of very stout glass. I n the case of mixtures containing acetylene mixed with less than three- quarters of its own volume of oxygen, a thick deposit of carbon formed, but where mixtures contained a larger proportion of oxygen much less carbon separated.EXPERIMENTAL. Pvepcwutiom of the ikixtwes. Pq*epm*cctioln of Acetylene.-The acetylene used in these experiments was prepared by the decomposition of ethylene dibromide by an alcoholic solution of sodium ethoxide, as follows.* 50 grams of sodium were dissolved in about 500 grams of alcohol (methylated spirits rectified by distillation over quicklime answers the purpose very well), and the solution introduced into the round- bottomed flask A (Fig. 1) (capacity = 1 litre) which was immersed in 5. Carbon was deposited. €3 C * This method for the preparation of acetylene was devised by V.Meyer and F. Marsden (Marsden, Imnug. Dissert., Heidelberg, 1892).WITH LESS THAN ITS OWN VOLUME OF OXYGEN. 29 a water bath, and fitted with a long reversed condenser B and a tap funnel C. As soon as the contents of A were boiling vigorously, the ethylene dibromide was allowed to drop in gradually from C ; it was then readily decomposed by the sodium ethoxide in A, acetylene and vinylic bromide being evolved, The volatile products of decomposition passed off through the condenser B, kept cool by a rapid stream of water, a considerable quantity of the vinylic bromide condensing and running back into A. The gas then passed through two cylindrical wash-bottles, D, each containing about 30 C.C. of alcohol, and surrounded by a mixture of ice and salt ; here a further quantity of vinylic bromide condensed.After leaving D, the gas passed into two Winchester pint bottles, E.E, about three-quarters filled with a freshly-prepared am- moniacal solution of cuprous chloride, where the acetylene was rapidly absorbed. At the conclusion of the experiment, the copper acetylide was allowed to settle, the supernatant ammoniacal liquor was poured off as completely as possible, and the copper compound washed by decan- tation with cold water ; it was finally filtered and washed a t the pump, and preserved for future use in a moist condition. The mixtures of acetylene and oxygen were made in a glass gas holder over mercury in the following manner. A quantity of moist copper acetylide capable of yielding about 1; to 2 litres of acetylene was introduced into a strong round-bottomed flask A, Fig 2.Dilute hydrochloric acid was then dropped on t o FIG. 2. the paste from the tap funnel, B, and on gently warming the flask, a steady current of acetylene was evolved. The gas passed through the washing cylinder, C, two-thirds full of a concentrated solution of potas- sium hydroxide, and then through a three-way tap, D, into t,he atmo-30 BONE AND CAIN: THE EXPLOSION OF ACETYLENE sphere outside the laboratory. As soon as all air had been expelled from the apparatus, the gas was sent into the graduated glass gas holder, E (capacity = 1,800 c.c.), previously filled with mercury from the reservoir, F. The latter was so arranged that it could be gradually raised or lowered a t will, so that the gas might be collected in E at as nearly as possible atmospheric pressure.When about a litre of acetylene had been collected, the tap, a, leading into the reservoir was shut, and the rest of the gas sent through D into the atmosphere. After about an hour, the levels of the mercury in E and F were equalised, and the volume of bhe gas in E read. Oxygen generated by heating pure potassium chlorate in a hard glass tube, and passing the gas evolved through a layer of cotton wool and then through a wash-bottle containing a strong solution of potas- sium hydroxide, was now added to the acetylene in E until a mixture of the desired composition was produced. The gases were allowed to stand for several hours in order that they might thoroughly mix, and then samples for analysis were collected over mercury.Explosiocn of the Mixtuws.-As mixtures of acetylene and oxygen explode with great violence, it was necessary to carry out the opera- tion in a leaden coil. The coil A, Fig. 3,s metres long and of an internal diameter of 13 mm. (capacity about 700 c.c.) was immersed in a bucket of cold water, a stout glass firing piece, B, being attached to the coil by means of Faraday cement. Each end of the coil was closed by d FIG. 3. C strong steel taps,a, 6, and communication was made through b and a glass tail-tap, c, with ct mercury manometer, C; the latter served to indicate, as will be afterwards shown, the presmre in the coil after anWITH LESS THAN ITS OWN VOLUME OF OXYGEN. 31 explosion, By means of the tail-tap, c, a direct connection could be made with the outside atmosphere instead of with the manometer, so that the products of explosion could be readily drawn off for analysis.Before making an experiment, the coil was thoroughly tested to see if all the joints were tight, by exploding a mixture of coal gas and air in it. The inside of the coil was then thoroughly dried by boiling the water in the bucket, and blowing a good current of dried air through the coil for several hours. The water in A was then allowed to cool, or was syphoned off and replaced by cold water from the mains, the air current through the coil being maintained meanwhile. The mixture of acetylene and oxygen mas introduced into the coil by attaching the gas holder to the end a and raising the mercury reservoir; then on opening the taps b and c the air was expelled from the coil.After about a litre of the mixture had been passed into the coil, the exit gases from c were found to be highly explosive, but another half-litre of gas was sent through the coil in order that there might be no doubtas t o its being filled with a gaseous mixture of the same composition as that originally made in the gas holder; the tapcc was then closed, and a few moments later the tap b. Thus the coil was filled with gas at the ordinary atmospheric pressure. The tap c was then turned so as to bring the coil in connection with the manometer, and the mixture was fired by an electric spark a t B. I f the various joints had successfulIy resisted the shock of the explosion, the coil and its contents were allowed t o stand for a quarter of an hour in order that they might cool down to the temperature of the surrounding water, and then, by opening the tap b, connection with the manometer, C, was made, and the pressure of the gases in the coil read off; in every case, a considerabIe i n c r e m e in pressure was observed.Finally samples of the products were drawn off through c and collected in tubes over mercury ; these samples were subsequently carefully analysed. The rest of the products were displaced by a current of air and sent through an ammoniacal solution of silver chloride. I n every case a precipitate of silver acetylide, identified by the usual method, mas obtained, showing that the products of explosion contained free acetylene.Ancilysis of the Gases.-The apparatus at our disposal for this part of our work was a modified form of the McLeod apparatus (described in Phil. T r a n s . , 1884, Part 11.). This consists of a eudiometer connected at its base by means of a gun-metal three-way tap with a barometer on the one hand, and a mercury reservoir on the other, the latter being so arranged that it could be raised or lowered as occasion required. Both eudiometer and barometer are water-jacketed, and by keeping a good stream of cold water direct from the mains running32 BONE AND CAIN: THE EXPLOSION OF ACETYLENE through the jackets, the temperature in the apparatus could be kept quite constant throughout an analysis. The upper end of the eudio- meter is connected by means of a glass capillary tube with a laboratory vessel, standing in a trough over mercury, into which the gases are sent for purposes of absorption.Both eudiometer and laboratory vessel are closed by glass taps, and careful experiments showed that the amount of gas left in the capillary tube between these two taps after each absorption was sufficient to appreciably affect the result of an analysis. The authors, therefore, at the outset of their work carefully determined the amount of gas left in the capillary for varying amounts of gas treated in the laboratory vessel, and from their results were able to draw up a table of corrections to be applied in any case. This correction amounted to about 0.1 volume for every 50 volumes of gas treated in the labora- tory vessel, and the various numbers given in the sequel are readings so “ corrected.’’ Before each analysis, the eudiometer was washed out, first with dilute sulphuric acid, and then several times with distilled water.The readings were made by artificial light, using a telescope fitted with cross-wires, and placed at a distance of 1.6 metres from the apparatus. T?ie O~igincd Mixtures.-After trying several methods for the analysis of a mixture of acetylene and oxygen, the authors finally adopted the following as by far the most satisfactory. A measured volume of the mixture under investigation was thoroughly mixed in the McLeod apparatus with from 10 to 12 times its own volume of air, previously freed from carbon dioxide by standing over solid pot,assium hydroxide. The mixture was then exploded, when, if a large excess of air had been added, a thin pale flame travelled down the eudiometer without causing any appreciable shock, and was not accompanied by any liberation of carbon. The advantage of this method is that the percentage of acetylene present in the original mixture may be determined from two data, namely, (1.) from the contraction, C, in volume which occurs on explosion (due to the water formed). (2) From t h e absorption, A, which occurs when the products of explosion are treated in the laboratory vessel with a solution of potassium hydroxide, as is readily seen from the equation C,H, + 240, - - 2C0, + H,O Y-’ 3+ volumes on cooling become 2 volumes.L- _-u Thus the acetylene = -2 C or -; A. The residual gases were then allowed to stand over an alkaline solution of pyrogallol in the laboratory vessel for one hour, in orderWITH LESS THAN ITS OWN VOLUME OF OXYGEN.33 that the excess of oxygen might be removed ; the residual nitrogen was then measured. Subtracting the amount of nitrogen present in the air added in the earlier part of the analysis, the amount of nitrogen in the original mixture could be determined. Having thus estimated the acetylene and nitrogen, the oxygen was determined by difference. The Pyoclucts of Explosion.-The products of explosion always con- tained small amounts of carbon dioxide, and of acetylene, possibly also some other unsaturated hydrocarbon *-the main constituents were, however, carbon monoxide and hydrogen. In order to determine the amounts of carbon dioxide and of acety- lene present in the products, a large measured volume of the gases was brought into contact with a ball of solid potassium hydroxide in the laboratory vessel of the McLeod apparatus, After the volume had been again measured, the gases were exposed in the laboratory vessel to a layer of pyrosulphuric acid for half an hour, in order athat all acetylene or other unsaturated hydrocarbon might be removed, then washed with a potassium hydroxide solution, and remeasured.For the further analysis of the products of explosion, a small measured volume of the gases, from which the carbon dioxide and acetylene had been removed in the manner already described, was mixed with an excess of air free from carbon dioxide, and exploded in the eudiometer of the McLeod apparatus.The contraction in volume, C, was determined, after which the gases were treated with a solution of potassium hydroxide in the laboratory vessel, and the absorption, A, estimated. The residual gas was then left in contact with an alkaline solution of pyrogallol for upwards of an hour, after which the volume of the residual nitrogen was read. Mixture A . This contained 100 volumes of acetylene to 29 volumes of oxygen. On exploding the mixture in the leaden coil in the manner described, an increase in pressure of 260 mm. was observed, the barometer being at 754 mm., and temperature of the water in the bucket, 15". A large quantity of carbon was deposited during the explosion. Analysis of the Uyigiml Mixtuye. Volume of mixture taken ........................ 62.5 Volume of air added .............................790.9 * The authors wish to state that in the case of two mixtures the amount of acetylene present in the products was estimated by a gravimetric as well as by the usual volumetric method ; the results agreed well, and therefore the presence of another unsaturated hydrocarbon is rather a reniote possibility. vor,. LXXI. D34 BONE AND CAIN: THE EXPLOSION O F ACETYLENE Volume of gas taken , . , , . . Volume of air added ...... Percentage C ......... Percentage A ......... Percentage nitrogen found Cj ................................................ 71.3 A ................................................ 95.2 Residual uitrogen, after absorption of excess of oxygen by alkaline pyrogallol.. .... 626.9 Nitrogen present in air added ..................625.6 ... Nitrogen originally present in mixture ... 1.3 i.e., 2 Ool0 11 5.50 469'00 104'00 44.50 - ] BIean 47.57 Calculated from C, Acetylene = 71.3 x Q = 47.53 9 9 9 , A, ,, = 95.2 x 8 = 47.60 Taking the oxygen by difference we arrive at the following percentage composition of the mixture. Acetylene. Oxygen. Nitrogen. 76.0 22.0 2.0 Leaving the nitrogen out of the question, this corresponds to a mixture of 100 volumes of acetylene with, as nearly as possible, 29 volumes of oxygen. Analysis of the Products of Explosion. a. Determination of the cas.bon dioxide, ncetplene, &c. Volume of gas taken Absorption by solid KOH ........................ Absorption on treatment with pyrosulphuric Hence carbon dioxide = 0.25, and acetylene, &c.= 0-56 per cent. b. Analysis of the Residucd Gases a f t w mnzoval of cadon dioxide, acetylene, &c.-Three analyses were made, the first two with gas from the same sample tube, and the third with gas from a second tube ; the last gave a slightly different result from the other two. In the following table we shall state the volume of the gas taken for each analysis, but in order that the results of the three may be readily compared at a glance, we shall state the contraction in explosion, C, and the absorption by potassium hydroxide after explosion, A, in volumes per 100 volumes of the original gases-terming these numbers percentage contraction and absorption respectively. ........................... 323.2 0.8 acid and KOH ................................. 1.80 109'00 ' 104.60 4;;::; 1 437'20 104'31 104'88 43'80 1 '00 1-33 ~~ Mean._____ - - 104.40 44-27 1'16WITH LESS THAN ITS OWN VOLUME OF OXYGEN. 35 Calculating from the above results, we shall see that there is no sign of the presence of any saturated hydrocarbon, such as methane, for instance, in these gases. For if x = volume of hydrogen present, and 9 = volume of carbon monoxide, Then 3x/2 + y/2 = 104.40 and y = 44.27 Solving these equations we get x = 54.85. Hi!. co. N2. Total. 54.85 44.2 7 1.16 100*28. Now if methane or any other unsaturated hydrocarbon had been present in fair quantity, say 1 per cent,, and we had calculated from the above figures on the hypothesis that only hydrogen, carbon monoxide, and nitrogen were there, our figures would have totalled up to much more than 100.As a matter of fact they sum np to 100.28, and this excess of 0-28 is no doubt due to error of experiment, prob- ably in the estimation of the nitrogen, which is very apt to come a little high in an analysis of this kind. If we include now the whole of the resuIts for the analysis of the products of explosion we obtain the following numbers. Therefore the residual gases contain CO,. C2H2. H2* co. N,. Total. 0.25 0.56 54.42 43.90 1.15 100.28 Mixtum E. This contained 100 volumes of acetylene to 328 volumes of oxygen, so that the two gases were mixed in the ratio of nearly 3 : 1 by volume. On exploding the mixture in the leaden coil, a very slight leakage at one of the joints was observed, caused, no doubt, by the violence of the explosion, This leak was at once repaired, and as the manometer still indicated an increase in pressure of nearIy 150 m.m., the mishap did not vitiate the experiment so far as the analysis of the products of explosion was concerned.A large quantity of carbon was deposited during the explosion. Ancclysis of the Origirzccl Mixture. Volume of mixture taken ..................... Volume of air added ........................... 49.10 473-40 C ............................................ 54.50 A ............................................. 72-00 Residual nitrogen after absorption of ex- cess of oxygen by means of alkaline pyrogallol .................................... 375.6 0 236 BONE AhtD CAfN: THE EXPLOSION OF ACETYLENE Nitrogen present in air added ...............374.5 Nitrogen originally present in mixture . , . Calculated from C, Acetylene = 54.5 x - - 36*33} Mean 36.16 Calculated from A, Acetylene = 72.0 x 8 = 36.00 Taking the oxygen by difference, we get the following for the per- centage composition of the mixture. Acetylene. Oxygen. Nitrogen. 73.65 24.1 1 2.24 Leaving the nitrogen out of the question, this corresponds as nearlyas possible to a mixture of 100 volumes of acetylene with 329 volumes of oxygen. A?zcclysis of the €3-oducts of Explosion. Volume of gas taken ........................... 160.9 2.4 Absorption by pyrosulphuric acid and KOH.. 1 *5 1.1 0 = 2 -24 o / o a. Deternzination of carbon dioxide, cccetylene, &c. Absorption by solid KOH ............... .,. ... Thus carbon dioxide = 1.49 per cent., and acetylene = 0.93 per cent.b. Analysis of the Residual Gases aftel* vemovnl of carbon dioxide, acetylene. -Two analyses were made of these residual gases, with the following results, which agree very closely. I. IT. Mean. Volume of gas taken .... '73*70 103.35 - Volume of air added .... 296.80 349.05 - Percentage C ...... 99.04 99.47 99.26 Percentage A ...... 49-79 49-35 49.57 Percentage Nitrogen ... 1 -03 1.00 1.01 Calculating from these, if x = percentage of hydrogen and y = per- centage of carbon monoxide, we have 3x12 + 912 = 99.26 y = 49.57 from which x = 49.65 and y = 49.57. That is, the residual gas contains H,. co. N, . Total. 49.65 49.57 1.01 100.23 which shows that no methane or other hydrocarbon of the series C,H,,~, is present.From the foregoing analysis we have calculated the percentage composition of the products of explosion to be as follows. CO,. C,H,. H,, co. N,. Total. 1.49 0.93 48.45 48.83 0.98 100.23WITH LESS THAN ITS OWN VOLUME OF OXYGEN. 37 94.00 395.50 92'23 55.42 2.50 Mixtuve C. This contained 100 volumes of acetylene to 55 volumes of oxygen. After exploding the mixture in the leaden coil an increase in pressure of nearly 300 mm. was observed. The barometer stood 752 mm. and the temperature of the water surrounding the coil was 15". Analysis of the Original Mixture.-Two analyses were made with the following results. I. 11. Volume of gas taken ............ 62.20 59.00 Volume of air added ............ 702.95 719.30 C .............................. 58.45 55.20 A ..............................79.60 74-30 Percentage of nitrogen found ... - 3.00 109 *80 422.50 92.35 55-01 - From these numbers we get - I. IT. Mean. 62'40} 62-60 Percentage of acetylene from C... Percentage of acetylene from A . . . 62-38 62.95 62.65 Taking the oxygen by difference, we get the percentage composition of the mixture. Acetylene. Oxygen. Nitrogen. 62.60 34-40 3.00 This corresponds t o a mixture of 100 volumes of acetylene with nearly 55 volumes of oxygen. Analysis o f the Products of Explosion. a. Determimtiosa of carbon dioxide, ucetylene.-Two analyses were made with the following results. I. 11. Volume of gas taken ............ 175.9 175-8 Percentage of carbon dioxide ... 0.51 0.56 Percentage of acetylene ......... 1 -08 1.20 We may therefore my that the products of explosion contained as nearly as possible U.5 per cent.of carbon dioxide, and 1-15 per cent. of acetylene. b. Ancdysis of the Residuul Gnses clfter wmoval of cccdon dioxide and ucetyZene.-Three analyses were made with the following results, Volume of gas taken ..... Volume of air added ..... Percentage C . . ......... Percentage A.. ......... Percentage nitrogen found I. 1 1 1 . I 111. 120'25 426'30 92.08 55-13 2 *oo Mean. - 92-21 55.19 2-1538 BONE AND CAIN: THE EXPT,OSION OF ACETYLENE Calculating in the same manner as in previous experiments, we get for the percentage composition of the residual gases the following. H,. co. N,. Total. 43.07 55-19 2.15 100.41 and the percentage composition of the products of explosion CO,. C,H,. H,. co. N,.Total. 0.50 1.15 42.37 54.29 2.10 100.41 Mixtuye D. This contained 100 volumes of acetylene to 81.5 volumes of oxygen. On exploding the mixture in the coil, an increase in pressure of nearly 350 mm. mas observed, the barometer standing at 769 mm.; the temperature of the water surrounding the coil was 16". The mixture was analysed with the following results. Volume of mixture taken.. .... 62.9 Volume of air added ............ 692.1 c .............................. 51.1 A .............................. 67.8 Calculated from C, Acetylene 34.07 Calculated from A, Acetylene 33.90 Mean .................. 33.98 or 54.0 per cent. The nitrogen was determined in a separate experiment, and was Taking the oxygen by difference, we arrive found to be 2 per cent. at the following percentage composition of the mixture.Acetylene. Oxygen. K itrogen. 54.0 44.0 2.0 and leaving the nitrogen out of the calculation, this corresponds with 100 volumes acetylene to 81.5 volumes oxygen. Analysis of the Y~oducts of Explosion. a. Detew&nation of the ccwbon dioxide ccnd acetylene. Volume of gas taken ........................... Absorption by solid KOH ..................... 187.25 1 *65 0.20 Absorption by pyrosulphuric acid and KOH This gives us as nearly as possible 0.90 per cent. of carbon dioxide b. Ancdysis of the Residual Gases clfiei* 9.enaovcd of cicr6on dioxide and 0.1 per cent. of acetylene. C6nd acetylene.-Two analyses were made with the following results.WITH LESS THAN ITS OWN VOLUME OF OXYGEN. 39 I. I. 11. &lean. Volume of gas taken .........94.00 103.90 - Volume of air added ......... 349.00 408.00 - Percentage C ............ 80.85 80.27 $0.56 Percentage A ............ 67.10 67.19 67.14 Percentage of nitrogen found - 1-23 - Calculating from the above results, we obtain the following per CO,, C,H,. H,. CO. N,* Total. 0.90 0.10 31.01 66-47' 1.25 99.73 centage composition of the products of explosion. 11. I HI. Mixture E. This contained 100 volumes of acetylene to as nearly as possible 95 volumes of oxygen. On exploding this mixture in the coil, an increase in pressure of about 370 mm. mas observed, the barometer being a t 766 mm., and the temperature of the water in the bucket 12". Analysis of the 01.igincd itfixture. Volume of gas taken .......................... 75.5 Volume of air added ...........................670.4 C ............................................. 56.2 A ............................................. 76.4 5 3 1 -5 Residual nitrogen.. ............................... Acetylene { Nitrogen = 1.35 or 1.80 per cent. From these results, we obtain calculated from C 37.5 calculated from A 38.2 Taking oxygen by difference, we get Acetylene. Oxygen. Nitrogen. 50.00 48.20 1 .so Gas taken ....................................... Absorption by Pyrosulphuric Acid and Absorption by solid KOH .................. KOH. 310.7 308.0 322.0 1 '2 1 '1 1'2 0 '3 0.4 -40 BONE AND CAIN: THE EXPLOSION OF ACETYLENE. Volume of gas taken ...... Volume of air added ...... Percentage C ......... Percentage A ......... Percentage nitrogen found From these numbers we calculate that the gases contained 0.37 per cent. of carbon dioxide, and approximately 0.1 per cent. of acetylene. b. Analgsis of the Residud Gchses cifter ~eirzovcd of c a ~ b o ~ ~ dioxide ccnd ncet9lene.-Three analyses were made 2s follows. 134.6 - 110*00 119'75 415'45 441 -20 444'3 - 80.86 80.84 80'00 80'55 68'20 68'37 68.34 68'30 0.77 0-84 0 '85 0'82 1 I. I 11. I 111. I Mean. Ratio Acetylene : Oxygen in mixtnre exploded. 100 : 29 Calculating from the above results, we get the following per- centage composition of the products of explosion. CO,. C,H2. H,. co. N2. Total. 0.37 0.10 30.78 67.98 0.82 100.05 We may tabulate the results of our experiments as follows. LOO : 32'5 No. of bfjxture. 1 A . I 1:. I C. I D. 1 E. 100 : 55 100 : 81'5 350 mm. 100 : 95 370 mm. ........... 0.56 . . . . . . . . . 54.42 .......... 1-15 Increase in pressure on explo- sion. !60 mm. 1'49 0'93 48-46 48'38 0'98 0.50 1-15 42-36 54.28 2.10 0.90 0'10 31.01 66'47 1'25 0.37 0'10 20.78 67.98 0-52 Total .................... 100.29 Whilst it follows from the above results that the main reaction occurring when acetylene is exploded with less than its own volume of oxygen may be expressed by an equation such as one of the following, C,H, + 0, = 2 0 + H, 2C,H, + 0, = 2CO + 2H, -+ 2C 3C,H, + @, = 2CO + 3H, + 4C, it must be admitted that some steam is also produced ; this is 100'24 300.39 99.73 100'05BONE AND JERDAK : DIRECT UNION O F CAREON AND HYDROGEN. 41 evident from the fact that the rat'io of the hydrogen to the carbon monoxide in the products is always less than the above equations require. 1Sloreover, it mould be very difficult to account for t h e presence of carbon dioxide in the products, were no steam produced. OWENS COLLEGE, l$ANOHESTER.

ISSN:0368-1645    

DOI:10.1039/CT8977100026

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

BONE AND JERDAK : DIRECT UNION O F CAREON AND HYDROGEN. 41 By WILLIAM ARTHUR BONE and DAVID SMILES JERDAN. IN T RO D u c T ION. ABOUT thirty years ago, Berthelot investigated the action of hydrogen on carbon a t high temperatures, and, as is well known, obtained acetylene by the direct union of its elements a t the temperature of the electric arc. His experiments may be briefly summarised as follows. (1) He heated retort carbon, contained in a porcelain tube, in a current of hydrogen to such a temperature that the tube softened; (2) he passed a series of electric sparks between carbon poles in an atmosphere of hydrogen; and (3) he formed the electric arc in an atmosphere of hydrogen between carbon terminals. The first two experiments, according to Berthetot, gave no positive result, whilst in the third experiment acetylene was formed.Berthelot, however, seems only to have examined the products of the action of hydrogen on carbon in the foregoing experiments quulita- tively ; moreover, he did not look for any other hydrocarbon except acety- lene, for a reason which he himself expresses as follows :-‘‘ Quant A I’hydrogbne, toutes ses combinaisons avec le carbon, extraites jusque 18 de produits organiques se detruisaient prhiskment sous l’influence d’une temperature rouge ; il semblnit dbs lors chimkrique de chercher Ales former diredement ” (Ann. China. Phys., 1863, [3], f37, 52). During the past two years, the authors have reinvestigated the whole question, and at an early period in their work satisfied themselves that Berthelot’s brilliant, pioneering researches leave much to be still worked out.The authors’ experiments may be conveniently divided int,o two series, as foIIows :-(1) In which a current of hydrogen was passed over carefully purified sugar-charcoal contained in a porcelain tube heated to about 1200” in a Fletcher furnace, in such a way that it was completely protected from the furnace gases. An examination of the exit gas showed that whereas it contained no acetylene or other un-42 BONE AND JERDAN : saturated hydrocarbon, about 1 per cent. of a saturated hydrocarbon, most probably methane, was invariably present. (2) I n which the electric arc was passed between terminals of purified carbon in an atmosphere of hydrogen, the apparatus being so arranged that samples of the gas could be drawn off for analysis a t regular intervals.The products were found to contain both methane and acetylene. Experi- ments in which the arc was active f o r about two hours, and in which samples of the gas were drawn off from time to time and analysed, indicat>ed a somewhat rapid formation of methane and acetylene during the first half hour, after which, however, the amounts of the gases seemed gradually to approach a limit, which was found to vary slightly with the voltage at the terminals, and possibly with other conditions. The establishment of this equilibrium between hydrogen, acetylene and methane is of considerable interest, and the authors were led to form the arc under similar conditions in an atmosphere of methane or acetylene. It was expected, from the results obtained with hydrogen, that the greater part of the methane or acetylene would be readily resolved into its elements, but that, on the continued passage of the arc, an equilibrium between hydrogen, methane, and acetylene, similar to that obtained in the experiment with hydrogen, would be established ; this expectation was fully borne out by the experimental results.Eerthelot (Compt. Tend., 1868,6’7) does indeed mention the establish- ment of a similar equilibrium when electric sparks are passed through methane, but he calls it an equilibrium between acetylene, hydrogen, and carbon vapour, and expressly states that no other hydrocarbon, except perhaps the polymerides of acetylene, takes part in the equilibrium. The results of the present investigation may be briefly stated as follows, 1.At a temperature of 1200°, or thereabouts, carbon unites directly with hydrogen to form methane, no acetylene or other unsaturated hydrocarbon being formed a t this temperature, 2. When the electric arc is passed between carbon terminals in an atmosphere of hydrogen, methane and acetylene are both formed; on continuing the passage of the arc, a state of equilibrium between hydrogen, methane, and acetylene is finally established. 3. The same state of equilibrium is produced when the electric arc is passed in an atmosphere of either methane or acetylene under similar conditions. It may be stated that all gas analyses in connection with this work were carried out by means of a modified form of McLeod’s gas-analysis apparatus, kindly placed a t our disposal by Professor Dixon.THE DIRECT UNION O F CARBON AND HYDROGEN. 43 PART I.EXPERIMENTS ON THE COMBINATION OF CARBON AND HYDROGEN AT A TEMPERATURE OF ABOUT 1200". In the first series of their experiments., the authors passed a current of hydrogen over purified carbon enclosed in a porcelain tube, and heated to bright redness in a Fletcher injector furnace by means of a coal-gas air blowpipe. Expe&izeizts O I L the D~fusion of Gases tlwough Porcekc&a at I h i g J ~ Before making the actual experiments with carbon, the authors thought it necessary to find to what extent the porcelain tubes to be used were permeable to the furnace gases a t the high temperatures of the subsequent experiments. A tube of the best Berlin porcelain, glazed wiOhin and without, having an internal diameter of 12 mm.and an external diameter of 16 mm., was placed in the Fletcher furnace in a manner to be described later, A glass tap was fitted into each end of the tube by means of a rubber stopper, the tube itself being of such a length that it pro- jected a sufficient distance on either side of the furnace to prevent the rubber stopper being appreciably heated during the course of an experiment. Bxpes-i?nent I.--A slow current of air which had been passed through a concentrated solution of potassium hydroxide and after- wards through sulphuric acid, in order to remove carbon dioxide and water vapour respectively, was sent through the porcelain tube heated tobright redness in the Fletcher furnace,and samples of the issuing gases were collected over mercury.Since any carbon compound diffusing through the walls of the tube would be converted into carbon dioxide under the conditions of experiment, if indeed it had not entered as such, it was only necessary to estimate the cofitraction which occurred when a measured volume of the exit gases was treated with a solution of potassium hydroxide in the McLeod apparatus, in order to determine the amount of such diffusion in terms of carbon dioxide ; in this way it was found that 334 volumes of the issuing gases underwent a contraction of 0.3 volume. This result pointed to a slight diffusion of furnace gases through the heated porcelain. I n order to confirm this conclusion, the authors repeated the experiment with the difference that the air was enclosed and heated in the porcelain tube for an hour, and was then expelled and collected over mercnry.703 volumes of this a i r gave an nbsorp- tion of 3.5 volumes, (reinpemtui*e. This was done as follows.44 BONE AND JERDAN: Expei*iment II.-A slow current of hydrogen, free from all gaseous carbon compounds, was dried by sulphuric acid and was then passed through the porcelain tube. After the air in the tube had been expelled, the furnace was gradually heated to bright redness, and as soon as t,he maximum temperature was attained the tap at each end of the tube was shut, and the hydrogen thus enclosed was kept a t a bright red heat for 54 hours. The gas mas finally expelled by a current of the same hydrogen, and collected over mercury.102.1 volumes of this gas were mixed in the McLeod apparatus with 385.2 volumes of air free from carbon dioxide, and exploded; when 336.8 volumes of gas remained, which on treatment with potassium hydroxide solution were further reduced to 336.5 volumes. Thus after explosion 0.3 volume of carbon dioxide was found in the residual gas. Since the original hydrogen on being exploded with a large excess of air free from carbon dioxide was not reduced in volume after treatment with potassium hydroxide solution, it is evident that carbon com- pounds had diffused through the walls of the tube during the heating. Experinzant III.-A supply of nitrogen was made by Harcourt's ammonia-air method and stored over water in a gas-holder. A slow current of this gas was passed successively through concentrated potas- sium hydroxide solution, over a heated copper spiral, through sulphuric acid, and finally through the porcelain tube heated to redness; by these means, any carbon dioxide, oxygen, or water vapour present in the gas would be removed before it entered the tube.After the current had been passed long enough to expel all the air from the tube, the taps were shut and the enclosed nitrogen was heated for an hour; finally the gas was expelled by a current of nitrogen and collected over mercury. 380.0 volumes of this nitrogen on standing in the McLeod apparatus over potassium hydroxide solution were reduced to 379 *4 volumes. The residual gas was further treated with a solution of cuprous chloride in hydrochloric acid t o absorb carbon monoxide, and was then washed with potassium hydroxide solution, but no further reduction in volume was observed.This result confirms those of the previous experiments, and further shows that the gaseous carbon compounds diffusing through the tube consist chiefly of carbon dioxide. Experiment IK-The amount of water vapour from the furnace gases diffusing through the porcelain tube was estimated as follows. A slow current of air was passed successively through potassium hydroxide solution and sulphuric acid, and over a layer of calcium chloride, so as to remove carbon dioxide and water, and then through the porcelain tube heated to bright redness, The issuing gases wereTHE DIRECT UNION OF CARBON AND HYDROGEN. 45 passed through a weighed calcium chloride tube, protected from the outer atmosphere by a wash-bottle containing sulphuric acid.The current of air was passed through the heated tube a t a constant rate of 2 litres per hour, and a t the end of 1; hours the calcium chloride tube had increased in weight by 7 milligrams. The calcium chloride tube was again attached, and after 3 hours, during which 5 litres of air were passed through the apparatus, it had increased in weight by 10.5 milligrams. The authors have calculated from the above results that the percentage of water vapoiir in the issuing air was 0.30 per cent. in the first case, and 0.26 per cent. in the second. As it was thus evident that the porcelain tubes to be used in the experiments were to a certain extent porous to the furnace gases at a bright red heat, it was decided to avoid heating the tubes in direct contact with the furnace gases.This was accomplished, as will be more fully described later, by surrounding the tube containing the carbon by a. wide porcelain tube, and passing a current of dry hydrogen through the annular space thus formed between the two tubes, an arrangement which proved to be thoroughly satisfactory. Prepnmtion and Purijcation of the Curbon, Pure cane sugar was carbonised by heating it it in a nickel crucible over a Bunsen flame. The residue was transferred t o a platinum crucible and strongly ignited over a blowpipe, the charcoal thus obtained being then placed in a combustion tube and heated to redness in a furnace, while a current of dry chlorine was passed over it for 7 hours. The charcoal was next washed with hot distilled water to remove the greater part of the chlorine, drained by means of the filter pump, and dried at 100". It was then heated in a combustion tube in a current of dry hydrogen for about 40 hours, until no more hydro- gen chloride was evolved, and was afterwards transferred to a short hard glass tube, one end of which had been sealed off. The other end of this tube was drawn out, and attached t o a Sprengel pump, the air thoroughly exhausted, and the tube then strongly heated in a small furnace for several hours, the exhaustion being continued meanwhile.The carbon thus prepared was kept in an exhausted desiccator over phosphoric anhydride for several months, and was afterwards used as required.PT-epcwu tion of the Wyclyoge9a. The hydrogen used in these experiments was prepared by the action of pure dilute sulphuric acid on redistilled zinc free from arsenic. The gas evolved, after being passed first through a solution of lead acetate, and then though t w o Erlenmeyer flasks containing a strongly46 BONE AND JERDAN: Hydrogen, C x 8 ...... 98'6 99'2 98.8 98.9 99.4 99.7 98.5 98.7 99.1 Absorption byKOH,A. 0.2 nil. nil. nil. 0.1 nil. nil. 0'2 nil. Nitrogen( by difference)" - 0.8 1.2 1.1 - 0.3 1'5 - 0'9 98'9 99'4 99.5 nil. 0.2 0.1 1'1 - + FIG. 1. N * Nitrogen is only taken by difference when no carbon compounds are present.THE DIRECT UNION OF CARBON AND HYDROGEN. 47 porcelain, glazed within and without, and was drawn out at either end as shown a t C.The total length of A was 60 cm., its internal diameter was 12 mm., and its external diameter 16 mm. This tube was fitted within a wider tube, B, also of glazed porcelain. The total length of B was 48 cm., its internal diameter 20 mm., and its external diameter 26 mm. The tubes were kept in position by two brass joints, one of which is shown in section in Fig. 2, in such a may that the two tubes had a common axis. D is a brass ferrule provided with two stuffing-boxes, EE and FF, Fig. 2, corresponding in diameter to the tubes B and A respectively. The stuffing-boxes were packed with a FIG. 2. C A \-I composition of asbestos and lime moistened with a strong solution of sodium silicate, which, when the collars were placed in position and the caps screwed down, gradually became solid, and made a good gas- tight joint.The ferrule, D, was bored at the point G, so as to admit of the insertion of the brass side piece, H, which served for the passage of the hydrogen through the jacket. The furnace, Fig. 4 (next page), employed for heating the porcelain tubes was rectangular in shape, and was made of fire-clay. Its length was 30.6 cm., breadth 24 cm., and depth 7 cm. The furnace was bored a t each side for the insertion of the porcelain tubes, and also in front for the introduction of the blowpipe. The furnace had a circular fireclay cover, bored obliquely so as to allow the furnace gases to escape. I n setting up the apparatus, the inner porcelain tube, A, was wrapped round spirally with asbestos string, so that each turn of the string was about 2 cm.apart from the previous turn, and was then inserted into the wider tube, B. I n this way the two tubes could be accurately centred, and kept apart when subsequently heated, while at the same48 BONE AND JERDAN : time a current of gas could be passed without diEculty through the annular space between them. The two tubes were then placed in position in the furnace, after which the brass joints were fitted on and packed with the composition of asbestos, lime, and sodium silicate as already described. A current of dry air was then passed through the jacket between the tubes for about two da,ys, in order that the joints might be thoroughly dried. I n this way a perfectly gas-tight joint was obtained. This arrangement of two concentric porcelain tubes was adopted in order to avoid heating the tube containing the carbon, in direct contact with the furnace gases, by surrounding it with a jacket of hydrogen.FIG. 3. To this intent the current of hydrogen, purified as already described (p. 45), was divided into two a t K, Fig. 1, one part passing through the tap L, and the other joint M into the inner tube, A, and the other part passing by the branch N, through the jacket between the tubes, FIG. 4. --. I - _. $1 and making its exit through H' whence, after passing through a wash- bottle containing sulphuric acid, it escaped into the atmosphere. ThoTHE DIRECT UNION OF CARBON AND HYDROGEN. 49 other end of the inner tube was connected by means of a joint, P, with a U-tube terminating in a tap, Q, by means of which connection could be made with a Schiff’s nitrometer containing mercury, which served to collect the gases from the inner tube.The tap, L, was a three-way tail-tap, so that samples of the hydrogen entering the inner tube could be conveniently drawn off during tlie course of an experiment. The connections, M and P, were made by sliding a short length of wider glass tubing over the ends of the porcelain and glass tubes to be connected, and securing the joint by means of thick rubber pump-tubing, Fig. 3, I n this way, the hydrogen was prevented from coming in contact with a rubber surface in the near neighbourhood of the furnace. The complete arrangement of furnace and tubes is shown in Fig. 4. Descmption of the Expe&nents. Blunk Experiment.-The first experiment performed with the ap- paratus just described mas intended to test whether or not any diffusion into the inner tube was now possible.A current of purified dry hydrogen was passed through the tubes for 6 hours in order to displace all the air. The furnace was then lighted, and the tubes gradually raised to a bright red heat. The taps, L and Q, were closed and the hydrogen thus shut up in the inner tube, A, was maintained at this temperature for about 3 hours, during which time a current of the same hydrogen was passed through the jacket between A and B. The hydrogen in the inner tube was then drawn off and collected in the nitrometer for analysis. I n the meantime, a sample of the hydrogen entering the tube had been collected through the tail-tap, L, and the two samples were then analysed by the methccl described on page 46.The gas which was drawn off at L, after explosion in the eudiometer with excess of air free from carbon dioxide, gave an absorption of 0.10 per cent on treatment with potassium hydroxide solution ; whilst the gas which had been heated f o r three hours in the inner tube, when treated in the same way, gave an absorption of 0-15 per cent. Thus the arrangement of the tubes prevents any appreciable diffusion of furnace gases into the inner tube even on prolonged heating. Actual Experiments.-Many experiments in which the purified carbon WRS heated in the tube A in a current of hydrogen were performed, the method of procedure being as follows. The purified carbon, which had been kept in a desiccator in a vacuum over phosphoric anhydride, was as rapidly as possible trans- VOL.LXXI. E On repeating this experiment a similar result was obtained.50 BONE AND JERDAN : ferred to the inner tube, A. The apparatus was then put together and a current of dry hydrogen passed through the whole for several days in order to sweep out all the air; the tubes were then gradually heated to bright redness, the current of hydrogen through A and through the jacket between A and B being maintained meanwhile. The heating wascontinued for 6 to 8 hours, after which samples of the exit gas from A were collected for analysis ; samples of the gas entering the tube were also collected a t L. The same carbon was used for several experiments, and was not changed until it became necessary to take the apparatus to pieces and refit it.The authors generally found that the gases which had passed over the heated carbon contained small amounts of carbon monoxide. A t first they were inclined to attribute this to a small inleakage of air ; but on investigating the matter they found the suspicion to be ground- less, because the gas entering the tube was found to be free from oxygen, and contained practically the same proportion of nitrogen as the exit gas. The authors finally concluded that the carbon monoxide was due in part to small amounts of oxygen or moisture occluded in the pores of the carbon used, and in part also to a possible slight reduction of the glaze of the inner porcelain tube in the presence of hydrogen and carbon at a high temperature. The latter supposition was based on the appearance of the inner tube after it had been used for a long series of experiments ; although the outer surface of that part of the inner tube which had been strongly heated was coloured black the glaze appeared intact, whilst on the inner surface of the tube the glaze appeared to have been considerably disintegrated.The analysis of the gases obtained in these experiments was performed as follows. I n cz few of the early experiments, the gaseous products mere specially tested for carbon dioxide, and unsaturated hydrocarbons generally, by exposing a measured volume of the gas in the McLeod apparatus to the action of potassium hydroxide solution, and fuming sulphuric acid respectively. As in no case did any absorption occur, these gases were not looked for in later experiments.Acetylene was also specially tested for by passing the gases issuing from the inner tube through an ammoniacal solution of silver chloride, but it was never detected. I n all the experiments, the following method of analysis was adoptbd. About 200 volumes of the sample were introduced into the McLeod apparatus and treated for 15 minutes with a hydrochloric acid solution of cuprous chloride (prepared according to instructions given in Hempel’s Gas Analysis, and then with a dilute solution ofTHE DIRECT UNION OF CARBON AND HYDROGEN. 51 Hydrogen, C x 8 .................. Nitrogen (by difference) ......... Absorption by KOH, A ......... potassium hydroxide, so as to remove any carbon monoxide.About 100 volumes of the residual gas were mixed with some 400 volumes of air free from carbon dioxide and exploded; after explosion, the gas was treated with potassium hydroxide solution, and the absorption measured. There was always an absorption, and this points to the presence of a saturated hydrocarbon in the gas analysed ; most probably this hydrocarbon was methane. The original hydrogen was analysed in the usual mauner. The following table shows the results obtained in six separate ex- periments. Artic Zysis of the Gases. I 98'9 98.9 99'4 99'4 - 98.9 - 0.0 0.0 0.2 0.2 0.0 0.0 I 0.0 1.1 1.1 - - - 1'1 - Experiment. Volume of gas tsken ............ Volume after treatment with Cu,CI, and KOH ............... Volume of residual gas taken ... Volume of air added ...............Volume after explosion ......... Volume after treatment with KOH ............................. Absorption ........................... - I. 184.9 184.7 107.0 460.1 409-5 408.5 1 -0 - - 11. 159.7 169'1 105.5 423% 374'9 374'2 0.7 - 111." 251'6 250.8 102.7 421 '2 370 '2 368'8 1.4 - 189.4 188.8 105'7 425.1 373'2 371.9 1 '3 - - IT. 214.1 212.2 107.7 451.3 399.1 397 9 1.2 - - v. 207'1 205'1 92.2 389.9 345'1 344'3 0'8 - - VI. 169-8 167'9 96.8 376.5 329'3 328.0 1.3 - Keckoning the saturated hydrocarbon present as methane, the following table gives the percentage composition of the issuing gases. Percentage Conapositiolz- of issuing Gases. Experiment. 1 1'. I IT. 1 IIT. 1 IV. I TT. I VI. Carbon monoxide .................. Hydrogen ..........................Methane ............................ Nitrogen (by difference) ......... 0 '1 9 i . 2 0'9 1 *a 0 '4 96'6 0.7 2.3 0.3 97.7 1.4 0 '6 0-3 97'5 1 *3 0.9 0 '9 96.7 1 *1 1 '3 1 .o 97 '2 0.9 0 9 1 '1 96-2 1 *3 1'3 The composition of the original hydrogen in these experiments is shown in the following table. Pewentccge Cornposit i o n of 0s.igincd Hyclyogen. Experiment.52 BONE AND JERDAN : Action of Carbon Monoxide on Hydpogen at High Temperatures. In the experiments just described, the authors had great difficulty in preventing the formation of small quantities of carbon monoxide. Thus, in three of the experiments quoted, nenrly.1 per cent. of carbon monoxide was present in the issuing gases, whilst in the first only of the six experiments was the amount of carbon monoxide in- appreciable.Although the amount of methane formed did not seem t,o depend at all on the percentage of carbon monoxide in the issuing gas, it seemed conceivable that the methane produced in the experi- ments might be due in part to the action of carbon monoxide on hydrogen a t the high temperature employed. To ascertain whether this were so or not, the authors passed a mixture of carbon monoxide and hydrogen, containing 20 per cent. of carbon monoxide, through the porcelain tubes heated t o bright redness in the furnace. The inner tube in this experiment was a new one and contained no carbon. The issuing gases were collected and analysed, but no methane was found, so that it appears that the formation of carbon monoxide in the foregoing experiments cannot affect the result so far as the methane is concerned.PART 11. EXPERIMENTS ON THE COMBINATION OF HYDROGEN AND CARBON AT THE TEXI'ERATURE OF THE ELECTRIC ARC. The authors investigated the effect of passing the electric arc between poles of purified gas-carbon in an atmosphere of dry hydrogen enclosed in a glass globe standing over mercury. Description of the Apparatus. Figure 5 represents the apparatus used in this series of experiments, and may be described as follows. A is a glass globe terminating below in a cylindrical portion B, and drawn out conically a t the top. This drawn out portion is bent a t right angles and sealed on to a three-wa.y tail-tap, C. The dimensions of this part of the apparatus are the following :-Total height, 42 cm. ; diameter of A, 17 cm.; diameter of B, 6 cm. ; length of B, 12 cm. ; total capacity, 3 litres. The globe stands in a mercury trough, D, and is supported on two rubber plates, one of which is shown a t E. By means of the three- way tap, C, communication is made through a tap, F, with a Schiff's nitrometer, G, filled with mercury, which served for the collection of the products and their transference to sample tubes at L. Each of the carbon terminals, HH, is attached t o a stout copper wire which is fixed by a plug of asbestos into a piece of narrow glass tubing, KK,THE DIRECT UNION OF CARBON AND HYDROGEN. 53 bent as in the figure and filled with mercury. The limb of the tube bearing the carbon is thrust into the globe from below the surface of the mercury in the trough.The other limb of each tube terminates in FIG. 5. G E a thistle funnel, filled with mercury, into which dips a stout copper wire leading from a dynamo. This limb is held in position by a clamp fixed to a retort stand and can be moved backwards and forwards as occasion requires for the making and adjustment of the arc. Prepamtion of the Cccrbon Terminals. The terminals were of gas carbon 3.5 cm. long and 1 cm. in diameter ; before being used, they were placed in a combustion tube sealed at one end, and connected at the other end with a Sprengel pump. The tube was thoroughly exhausted, and then strongly heated in a furnace for about 2g hours, the pump acting the whole time. The tube was allowed to cool, and the carbons were transferred to54 BONE AND JERDAN : another similar combustion tube and the treatment was repeated.carbons mere afterwards mounted in the apparatus as described. The Description of the Expei*ime?hts. The globe was completely filled with mercury by attaching an air- pump to the tap, C, and exhausting the air. Purified dry hydrogen, prepared as described on p. 45, was then introduced either from below the surface of the mercury in the trough or through the tap, C, until the globe was about three-fourths full. The electric arc was then formed between the carbon terminals, and continued for 15 minutes. The globe was again exhausted until the mercury completely filled it. I n this way any oxygen occluded in the pores of the carbon terminals would be removed. The globe was once more filled with the dry hydrogen as before.The arc was again formed and the current passed for a period of time varying from 30 minutes to 2 hours, and a t the end of 5,15, 30,45, &c., minutes, samples of the gas were drawn off into the nitrometer and transferred to sample tubes for analysis. Throughout these experiments, an alternating current from a dynamo was employed; the voltage a t the terminals of the dynamo in two of the experiments was taken between 40 and 60, whilst in the third it was about 160. Analysis of the Qc&ses. The gases obtained on passage of the arc in hydrogen were examined qualitatively, and were found to contain considerable quantities of acety- lene. Traces of carbon monoxide might also be present, owing to traces of moisture in the apparatus, and also small amounts of hydrogen cyanide due t o the presence of a small percentage of nitrogen in the hydrogen employed.After these constituents, and possible traces of other unsaturated hydrocarbons, had been removed, analysis showed that methane had been formed, to the extent of between 2 and 3 per cent., in the experiments in which the arc had been passed for half an hour or more. The complete analysis of the gases was carried out as follows. A large volume of the gas was treated, successively, in the McLeod apparatus, with (1) solid potassium hydroxide ; (2) fuming sulphuric acid ; (3) an acid solution of cuprous chloride, and (4) a dilute solution of potassium hydroxide. The gas was remeasured after absorptions 1 and 4. In this way, the hydrogen cyanide and acetylene (together with traces of unsaturated hydrocarbons and of carbon monoxide) were removed and estimated.In some of the later analyses, the gases were treated with an ammoniacal solution of ccryrous chloride in addition toTHE DIRECT UNION OF CARBON AND HYDROGEN. 55 5 mins. the other reagents, but this was not found to affect the final result. A known volume of the residual gas was then mixed with a measured excess of air free from carbon dioxide, and the mixture exploded in the eudiorneter ; after cooling, the gas was remeasured, allowed to stand over a strong solution of potassium hydroxide in the laboratory vessel, and then the volume was read again. In this way the contraction, C, was determined, and also the absorption by potassium hydroxide solution, A, which corresponds with the amount of methane in the gas.The hydrogen used in the experiment contained no gaseous carbon compound. The arc was passed for 45 minutes, and samples of the gases were collected a t the end of 5, 15, 30, and 45 minutes. The following tables show the results of the analyses of these samples. Experiment 1.-(voltage 40 t o 60). 15 mins. 30 mins. 45 mins. Samples collected at the end of 0 -1 2.1 0.6 96.4 0.8 Volume of gas taken ................. Volume after treatment with solid KOH .................................... Volume after treatment w i t h fuming sulphuric acid, acid cuproiie chloride, and K OH solution ...... 0 '2 5 '0 1'4 92 '0 1 -4 5 inins. 268.2 267.9 262'2 Volunie of residual gas taken ...... Volume of air added ..................c .................................... A .................................... 92.0 394.2 137.3 0'6 15 mins. 248 -1 217'6 235 *5 82.7 339'9 123.1 1 . 2 30 mins. 244'8 244.5 228.8 94 '9 373'8 140.6 2.3 45 mins. 247'7 247.1 227.1 85.2 126.6 2 . 1 338.5 The above numbers give the following as the percentage composi- tions of the samples. Hydrogen cyanide ..................... Acetylene ................................ Methane ................................ Hydrogen .............................. Nitrogen (by difference). ............ 0 '1 6-4 2.3 89'2 2'0 0 -2 8 . 1 2.3 87.8 1.656 BONE AND JERDAN : 288'4 288'4 274'3 Experiment 11.-(voltage 40 to 60, rising towards the end of the experiment).-The arc was passed for 2 hours, and samples were col- lected after 5, 15, 30, 60, 90, and 120 minutes.The following tables show the results of the analyses of these samples. 342.6 300.5 342.3 298-9 321.3 278.4 Volume of gas taken ............ Volume after treatment wit11 solid KOH ........................ Volume after treatment with fuming sulphuric acid, acid cuprous chloride, and KOH ... I Volume of residual gas taken ... Volume of air added .............. c ................................. A ................................. I I I 5 milis. I 312.7 312.7 306'1 ~- 89.7 377.9 131.8 0'9 - Samples collected a t the end of 15 1 30 1 60 mins. mins. mins. U 87-7 114.5 95.5 379'0 425.1 412'0 129'9 169'0 141.1 1.5 I 2.9 1 2.S 90 ni ins. 248'9 246'4 230'4 90'5 365.6 134.5 2 -1 100 mins. 206'1 205'3 189-7 91 -5 376.3 136.0 2.6 The following are the percentage compositions calculated from the above figures.Samples collected at the end of 5 niins. Hydrogen cyanide ................ Hydrogen ........................... Nitrogen (by difference) ......... Acetylene .......................... Methane ............................ iiil. 2 -1 1'0 94 -3 2-6 15 60 mins. 1 11:;s. 1 mins. 90 mills. 120 mins. 1 .o 6.4 2.1 88.8 1 *7 0 '4 7 *6 2 '6 87'7 3 *7 Expeviment III.-(voltage-l60).-The arc was passed for 1 hour, and samples of the gas were collected at the end of 5, 15, 30, and 60 minutes. The following tables shorn the results of the analyses.THE DIRECT UNION OF CARBON AND HYDROGEN. 57 Hydrogen cyanide ........................... Acetylene ................................... Methane ......................................Hydrogen .................................... Nitrogen (by difference) .................... Samples collected a t the end of nil. nil. 2'5 2 5 1'1 0.8 92.9 92.5 3.5 4'2 5 inins. * 0.2 6'1 2.1 2 . 2 89.4 I 1.0 7.7 3.8 2'9 84.6 Volume of gas taken ........................ 205-3 Volume after treatment with solid KOH 205.3 Volnnie after treatment with fuming sulphuric acid, ammoniacal cuprons chloride, acid cuprous chloride, and KOH .......................................... 200.1 I Volume of residual gas take11 .............. 90.5 Volume of air added ....................... 365'1 C ............................................. 131.3 A . . . .......................................... 1-0 146'4 146.4 142.7 106.1 436-8 152'6 0'9 15 30 mins.niins. 149'7 132.8 149'4 131.5 140'3 121.2 85'4 99'5 340'0 408.0 125'3 146% 1'9 4-2 60 mine. 335'4 334.2 308.9 100.4 415.2 148'1 4.2 - The following are the percentage compositions of the samples cal- culated from the above figures. Samples collected a t the end of l 5 mins. mins. miiis. I5 I 30 60 mins. 0 '4 7 -5 3 '8 85-5 2 -8 From the foregoing experiments it will be seen that, when the electric arc is passed between carbon terminals in an atmosphere of hydrogen, acetylene and methane are both produced. The nature of the results is best seen from the accompanying diagrams, Fig. 6 (p. 58), in which the abscissze represent time in minutes, and the ordinates the percentage of acetylene or methane in the products. The curves thus obtained for experiments B and C, in which the arc was continued for an hour or upwards, show how the rate of formation of the gases varies with the voltage employed, the rate being greater with the higher voltage used in experiment C as regards both acetylene and methane.The curves for both gases alike rise rapidly from the origin, but gradually become less steep, and both, after passing the * Two analyses were made of this sample.58 BONE AND JERDAN : ordinate 30, become practically horizontal. I n the curves derived from experiment B, the slight deviation from the horizontal is due t o a con- siderable rise in the voltage, which has been already noticed. Thus it FIG. 6. ' t A appears that for every voltage there exists a certain state of equilibrium between hydrogen, acetylene, and methane, and that the higher the voltage used, the greater the proportion of acetylene and methane FIG.7. 1 t B- e....- Time in minutes present in the final products after the passage of the arc for a sufficient length of time. The authors propose at some future time to investigate more care- fully the relations existing between the voltage employed and the corresponding state of equilibrium between the gases.THE DIRECT UNION OF CARBON AND HYDROGEN. 59 PART 111. EXPERIMENTS ON THE ACTION OF THE XLECTRIC ARC ON METHANE AND ACETYLENE. The experiments described in Part 11. show that when the electric arc is passed between carbon poles in an atmosphere of hydrogen, both acetylene and methane are formed, but that these two gases do not accumulate beyond a definite limit, which, however, varies with the conditions of the experiment. It therefore seemed probable that, if methane or acetylene were subjected t o the action of the arc, they would be to a large extent resolved into their elements, but that the decomposition products would contain acetylene and methane in approximately the same proportions in which they occurred in the products of the action of the arc on hydrogen.The authors, therefore, decided to study the action of the arc on methane and acetylene respectively, and considering the difficulty of maintaining exactly the same conditions in the three series of experiments, their results bear out in a remarkable way the theoretical conclusions. The experiments which follow show that methane and acetylene are to a great extent easily resolved into their elements by the electric arc, and that the gases drawn off after the arc has been passed for about an hour contain both acetylene and methane in nearly the same proportions as had been obtained in the experiments with hydrogen.Experitment with Net?tane. Methane was prepared by the method of Gladstone and Tribe, that is, by the decomposition of a solution of methylic iodide in methylic alcohol by the zinc-copper couple ; the gas was washed with alcoholic potash, and then collected in a gas-holder over water. From the gas- holder, the methane was bubbled through sulphuric acid, and thence into the large globe of the arc apparatus, arranged as described in Part 11. When the globe was three-quarters filled with the gas, the arc was formed.It soon became evident that the methane was being decomposed; large flakes of carbon formed in the neighbourhood of the terminals and fell on to the surface of the mercury below ; and a hard deposit of carbon adhered to the carbon terminals, closely resembling bunches of iron filings attached to the poles of a magnet, whilst the whole interior surface of the globe was covered with a dense black film. A large increase of the volume of the contained gas also occurred, which could not be accounted for by the mere expansion of the gas by heat. These signrj of decomposition continued for about ten minutes, after which the volume of the gas remained fairly constant, and during60 BONE AND JERDAN : the remainder of the experiment the arc did not differ in appearance from that obtained in the hydrogen experiments.The arc was main- tained for an hour, and afterwards samples of the gas were drawn off for analysis. Some of the remaining gas was passed through an am- moniacal solution of silver chloride, when a copious precipitate of silver acetylide was produced. The gas was analysed in the McLeod apparatus in the same way as the gas drawn off from the globe in the experiments with hydrogen, except that after the preliminary absorp- tions some of the residual gas was exploded with oxygen instead of air. The result of the analysis was as follows. Volume of gas taken ............................ Volume after treatment with solid KOH.. .. Volume after treatment with ammoniacal cuprous chloride, fuming sulphuric acid, acid cuprous chloride, and KOH ............ 270.4 268.1 241-5 '39.4 396.6 c ................................................ 148.5 A ................................................ 2.S Volume of residual gas taken .................. Volume of oxygen added ........................ From these numbers, the percentage composition of the samples has been calculated (nitrogen by difference). HCN. C,H2. H2. CH,. N,. 0.8 9 *s 85.6 2 -5 1.3 Experiment with Acetylene. The globe was filled with acetylene prepared by the action of water on the purest obtainable calcium carbide, and dried by exposure to potassium hydroxide. The arc (voltage-160) was made, and at once brought about rapid decomposition ; dense clouds of carbon rose from the terminals, and a large deposit of carbon rapidly formed on them ; a luminous smoky flame rose also for some time from the terminals, and much heat mas evolved. After 7 minutes, the 'action of the arc became quieter, and during the remainder of the experiment, which lasted for an hour, resembled the action of the arc in hydrogen. A t the close of the experiment, samples of the gas were collected, 2nd analysed in the McLeod apparatus as before. The following is an account of the analysis. Volume of gas taken .............................. Volume after treatment with solid KOH.. .. Volume after treatment with ammoniacal cuprous chloride, fuming sulphuric acid, acid cuprous chloride, and KOH ............ 238.9 238.5 214.9ELECTRICAL CONDUCTIVITY OF DIETHYLAMMONIUM CHLORIDE 61 Volume of residual gas taken ................... Volume of air added .............................. 93% 402.9 C .............................................. 140.2 A . . . ............................................. 3.4 Prom these numbers the percentage composition of the gas has been calculated as follows. HCN. C,H,. HP CH,. N2. 0.2 9.9 85.3 3.2 1.4 9 minute quantity of naphthalene was formed in this experiment, as was apparent from the smell of the products. An experiment was also made with acetylene prepared by the decomposition of cuprous acetylide by hydrochloric acid. The products contained 2-5 per cent. of methane and approximately 10 per cent. of acetylene. THE OWENS COLLEGE, MANCHESTEB.

ISSN:0368-1645    

DOI:10.1039/CT8977100041

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

ELECTRICAL CONDUCTIVITY OF DIETHYLAMMONIUM CHLORIDE 61 IV.-Elect rical Conductivity of Diethylammonium Chloride i ? ~ Aqueous Alcohol. By JAMES WALKER, Ph.D., D.Sc., and FRED. J. HAMBLY, E.1.C. IN the course of some experiments on urea formation in aqueous alcohol, we found it necessary to ascertain the effect produced on the electrical conductivity of a salt solution, as successive portions of the water used as solvent were replaced by ethylic alcohol. It was desired in particular to determine the part played by the alcohol in reducing the degree of dissociation of the salt as well as in reducing the speed of the ions, The salt selected as most suitable for our purpose was diethylam- monium chloride, which is readily soluble in ethylic alcohol. It was prepared by evaporating a mixture of diethylamine with a slight excess of hydrochloric acid t o dryness on a water bath, small quantities of water being afterwards added and the evaporation repeated.After remaining for a few days in an exhausted desiccator, the substance hardened to a dry cake, which was then powdered and kept in a desic- cator over caustic potash in order that it might lose any traces of hydro- chloric acid which still clung to it. From the chloride thus obtained62 WALKER AND HAMBLY : ELECTRICAL CONDUCTIVITY a normal aqueous solution was prepared, and this was used in all the subsequent experiments. The alcohol employed was '' absolute " alcohol treated with sodium and distilled. The apparatus in which the distillation was effected resembled that used in the operation of distilling with steam.An intermediate distilling flask was introduced between the flask con- taining the alcohol and the condenser, so that the vapour was washed in the liquid which condensed in the intermediate flask. Spirting was in this way effectually prevented. A glass condenser was used, and the connections were made with indiarubber which had previously been boiled with soda and thoroughly steamed. The specific conductivity of the alcohol thus obtained was 0-36 x in reciprocal Siemens units at 25". To obtain water of a suitable conductivity, ordinary distilled water was allowed to remain overnight after being treated with a little barium hydroxide and sodium hypobromite solution. The distilling apparatus was similar to that used in the preparation of the alcohol, the condenser-tube, however, being in this case of block tin, bent down- wards and backwards into the beak of a retort which served as the intermediate vessel.The water collected had on the averitge a conductivity of 1.5 x The conductivity of the salt in each mixture of alcohol and water was determined a t eight different dilutions, the strongest solution being decinormal. The mixture used as diluent was prepared by mixing the purified alcohol and water in certain proportions by volume, the actual composition of the mixture being then ascertained by an accurate determination of its specific gravity, To prepare the decinormal solu- tion, purified alcohol and normal diethylammonium chloride solution were mixed in the same proportions as were used in preparing the diluent, the solution thus obtained being then heated to 25.0", the temperature of experiment, and made up with the warmed diluent to 10 times the volume of the normal solution employed.This method assumes that the normal diethylammonium chloride solution contains its own volume of water, which is, strictly speaking, not thecase. The error in the conductivity introduced from this source is, however, small, and has in what follows been neglected. The mixtures used as diluents contained the following proportions of alcohol by weight corresponding to the proportions by volume at 15.5" at 25". 8.1 25.3 41.8 64.6 86.0 per cent. 10.1 30.7 49.2 72.0 90.3 per cent. An incomplete series mas also made with alcohol containing 98.3 perOF DIETHYLAMMONIUM CHLORIDE IN AQUEOUS ALCOHOL 63 cent.by weight, or 99.0 per cent. by volume. I n this case the deci- normal solution was made by dissolving a weighed quantity of the chloride in the appropriate volume of alcohol. The method adopted for the determination of the resistance of the solutions was Kohlrausch’s with induction coil and telephone. The apparatus was fitted up as described in Ostwald’s Physico-clwnical Measurements, p. 222 et seq., ,attention being given, however, to the more recent precautions and improvements suggested by Kohlrausch , (Ann. Phys. Chenz., 1893,49,225). With these precautions, the method gave excellent results even a t the greatest dilutions employed, and we are convinced that the source of any errors affecting our results is not to be sought for in the method of electrical measurement, but in the effect of small quantities of impurity, inaccuracies in the dilution, &c.The cell was of the type described by Arrhenius, the hole in the ebonite cover being closed by an indiarubber plug to prevent evaporation of the alcohol. The electrodes were well platinised several times during the course of the experiments. It is well known that after platinisa- tion it is almost impossible to mash the electrodes free from con- ducting material, a week perhaps elapsing before they are suitable for use in liquids of high resistance. We find that this difficulty may be got over very simply by dipping the electrodes after platinisation into a solution of sodium acetate, which is electrolysed in precisely the same way as the platinum chloride solution, the current being reversed several times.A few washings with water are then sufficient to render the electrodes fit for use. The measuring wire was carefully calibrated before and after the whole series of experiments, and the cell-constant was taken frequently during the progress of the measurements. The resistances in the box employed were compared against each other and found to have a negligible relative error. The temperature of experiment was 25*0°, the resistance-cell being immersed in the water contained in a thermostat of the form described by Ostwald, Zoc. cit., p. 59. I n performing the dilutions we experienced unexpected difficulty, and i t speedily became apparent that volumetric apparatus which worked quite satisfactorily with aqueous solutions gave untrustworthy results when mixtures of alcohol and water were employed as solvents, the irregularities being chiefly due t o unequal draining and the formation of “tears ” on the walls of the pipettes, &c.The plan of work finally adopted was as follows. Two 10 C.C. pipettes were taken, one of which was used for removing the solution from the cell and the other for delivering the diluent. On the stem of the delivery pipette a milli- metre scale was etched, and for each particular diluent the place on the stem was noted for which the volume delivered was equal to the64 WALKER AND HAMBLY : ELECTRfCAL CONDUCTIVITY v. A x 105. p. 100117. 10 847 84.7 78.8 20 448 89% 83'3 40 234-5 93.8 87'3 80 121'9 97'5 90.7 volume removed by the other pipette.By means of these pipettes the dilution was increased by successive doublings from w = 10 to v = 320, a reading of the conductivity being taken a t each fresh dilution. A direct dilution in one operation from v = 10 to v = 320 was then made by weight in the following manner. A tared measuring flask of 100 C.C. capacity was filled to the mark with the diluent and weighed, after which it was emptied and dried. A quantity of decinormal chloride solution equal in weight to of the quantity of the diluerit that the flask contained was then introduced, and the solution made up to the mark with the diluent. The error caused by the difference in the specific gravity of the diluent and the decinormal solution was found to be small compared with errors from other sources, and was consequently neglected. The differences between the conductivities of the solutions obtained by successive and by direct dilution were under 1 per cent.In all cases, the direct dilution was assumed to be correct, the appropriate correction being applied to lower dilu- tions when necessary. A dilution was then made by weight in the manner above indicated, from w = 320 to v = 1600, and then another in the same way from v = 1600 to v = 8000. The conductivity of the diluent was finally ascertained, and the correction applied in the manner proposed by Arrhenius. At the dilution 2r = 8000 this correc- tion assumes relatively large proportions, amounting occasionally to as much as 12 per cent. of the total conductivity. The results for that dilution are therefore probably much less accurate than those for lower dilutions, but we think that even here the total error is less than 2 per cent.of the whole value, for in several cases duplicate determiria- tions made with diluents prepared and mixed at different times showed an agreement well within that limit. I n the following tables of our results, v represents the number of litres in which one gram-molecule of the chloride is dissolved, X is the specific conductivity in reciprocal Siemens units, p the molecular con - ductivity and rn the ratio pv/p,, so that l O O r n represents the percent- age dissociation. The solvent employed is placed a t the head of each table. Water.. 2'. A x 10". p. 100n.L. ~~~~ 160 62-5 100'0 93.0 320 32-0 102'3 95.2 1600 6'60 105'6 98.2 8000 1'34 107.0 99.5 107.5 100 cc: -OF DIETHYLAMMONIUM CHLORIDE IN AQUEOUS ALCOHOL.65 33.1 34'6 36 '8 38 '7 10.1 per cent. alcohol by volume. 84.0 87 '8 93 '4 98.2 A x 105. I p. 17.0 20.0 23.3 26.7 100nz. 43.E 51.5 60'1 65.8 21. A x 105. 1001n. V. Pa 77.5 79-1 81'3 82.9 83.5 77.8 82.8 86'8 90 '3 92.8 94.7 97 '4 99 3 100 649 345'5 181.3 94 '2 64.9 69 *1 72.5 75 *4 10 20 40 80 160 320 1600 8000 a 48.4 24 -7 5 -08 1 -04 - ~~~ ~~~~~~ 30.7 per cent. alcohol by volnme. A x 105. 2'. 1 A x 105. i 'u. 10 20 40 80 405 218 114.5 59.5 40 -5 43 -6 45 '8 47'6 75.1 80.9 85 -0 88.3 160 320 1600 8OOC cc 30.7 15.7 3.21 0'665 - 49 *i 50.2 51 *3 53 '2 53.9 91.1 93 52 95 '2 98.7 100 49'2 per cent. alcohol hy volume. 10011a. I v. I A x 105. j p. 100172. A x 105.P. 160 320 1500 8000 tc 300 161.5 86.5 45 -5 23 -9 38.2 12.25 ~ 39.2 2 5 5 40.8 0'527 42'2 - 1 42.9 I 10 20 40 80 30'0 32.3 34 -6 36 '4 69 '9 75.3 80.6 84'9 I 89 *O 91 -4 95.1 98.3 100 72.0 per cent. alcohol by volume. A x 105. 100m. 100?12. pv I 29. A x 105. 9. I- 239 131.5 72 *5 38 *9 23 '9 26 -3 29'0 31 -1 160 320 1600 8000 a 20.7 10 '8 2 *30 0-484 - 60 *7 66.8 73% 78 -9 10 20 40 80 90.3 per cent. alcohol by volume. h x 105. 10 O?it. V. I- 160 320 1600 8000 tc 18 '4 10 -1 2'26 0.476 - 29 '5 32.4 36'2 38 *1 38 '8 76 0 83.5 93.3 95.2 100 10 20 40 ao 170 100 58 '3 33 '4 YOL. LS XI. F66 WALKER AND HAMBLY : ELECTRICAL CONDUCTIVITY v. 10 20 40 99.0 per cent. alcohol by volume. A x 105. p. 100??2. PIL__(-- 131 13-1 34.0 78 15'6 40.5 47'3 18'9 49.1 I-l-I- 28.2 22.6 1 58.7 16.8 26'9 j 69'9 320 9.7 31-0 80.5 cc - 38.5 1 100 The relations between the numbers obtained by us are rendered most evident by means of curves. We have therefore constructed diagrams to show the influence of dilution and of addition of alcohol on the molecular conductivity and on the degree of dissociation of the diethylammonium chloride in solution.In Fig. 1 the molecular conductivities have been plotted as ordinates ; and for abscissa we have taken v * instead of v in accordance with FIG. 1. previous practice. The curves all slope gently upwards towards the right, the total'ascent being greater in the case of pure water and of 99 per cent. alcohol than with the intermediate solvents. The distances between the various curves show that as increasirgOF DIETHYLAMMONIUM CHLORIDE IN AQUEOUS ALCOHOL.6 7 quantities of alcohol are added the effect of each increment on the conductivity decreases, especially a t the higher dilutions, In Fig. 2 we have as ordinates the percentage dissociation as measured by the ratio 1OOpL,/p,. Here also the curves all slope PIG. 2. upwards to the right, indicating an increase of dissociation with increased dilution; but in this case it will be noticed that the in- fluence of the first quantities of alcohol is comparatively trivial. So much is this the case that the curve for 10 per cent. alcohol had to be omitted, as it could scarcely be shown distinct from that of pure water on the scale of the diagram. The replacement of 10 per cent. of the solvent water by ethylic alcohol is therefore practically without effect on the degree of dissociation of the dissolved salt, the diminution being less than 1 per cent.Arrhenius (Zed. physikd. Chem., 1892, 9, 499) estimated the effect of 10 per cent. of a non-conductor such as alcohol on the degree of dissociation of a good electrolyte in strong solutions to be not greater than 1 per cent., a conclusion in accordance with our direct measurement. The slope of the curves becomes greater as more and more alcohol is added ; that is, between the limits of dilution given (v = 10 to v = 320), there is a much greater change in the dissociation with strongly alcoholic than with aqueous solutions. Results have not been given for dilutions greater than 320 Z., as the diagrams to contain them would have been inconveniently extended and as the curves at the high dilutions approach each other very closely, theoreti- cally to meet on the ordinate 100 when the dilution becomes infinitely s 268 WALKER AED HAIDIBLE’ : ELECTRICAL CONDUCTIVITY great.It should be observed that a t the dilution 320 1. the salt is more than 80 per cent. dissociated even in 99 per cent. alcohol. There is, it is true, a slight uncertainty in fixing the molecular conductivity a t infinite dilution from which the degree of dissociation is calculated, but the error from this source cannot be of great magnitude. Kohlrausch has investigated for aqueous solutions, and Vollmer for alcoholic solutions (compare Ostwald’s Lehhuch, vol. ii, part 1, section ii), the conductivity of a large number of binary salts at dilutions beyond = 8000, and from their results and the general character of our own curves we were able t o conclude with certainty that a very small addition to the molecular conductivity a t SO00 1.mould give the molecular conductivity for v = a. The addenda we used were 0.5 for water, 0.6 for 10 per cent. alcohol, and 0.7 for the other solvents, the relative effect of the addition being greater as the water is replaced by alcohol. Fig. 3 exhibits the effect on the degree of dissociation of substituting alcohol for water. The abscissze (23) are the percentages of alcohol by FIG, 3, volume in the solvent, and the ordinates represent the degree of dissociation. At infinite dilution, the effect is nil, for then the salt is wholly dissociated even in absolute alcohol.At 320 1. the effect is still comparatively small, the dissociation only falling from 95 to 80 per cent. as the solvent changes from water t o alcohol. I n the solutions of greater concentration, the influence is much more marked,O F DIETHY LAMMOXIUM CHLORIDE IS AQUEOCS ALCOHOI,. 69 the fall for 2) = 10 being from '79 to 34; that is, the dissociation is reduced to less than half. The character of each curve shows that the last additions of alcohol have a much greater effect than the first. For example, it is seen from the curve for v = 20 that 80 per cent. of the water must be replaced by alcohol before half the total fall is produced; and so it is also with the other curves. This is especially noteworthy on account of the light it throws on the curves of Fig.4, where molecular conductivities, p, are the ordinates and percentages of alcohol, p the abscissa The molecular conductivity of a substance in solution depends on70 WALKER AND HAMBLY : ELECTRICAL CONDUCTIVITY two variables-the proportion of ions in the solution, and their speed. Now we have seen from Fig. 3 that the degree of dissociation at a given dilution (that is, the proportion of ions present) is diminished as the water is replaced by alcohol. The molecular conductivity mill therefore fall owing to this cause. But the speed of the ions is also reduced by the substitution of alcohol for water, and consequently for this reason also the molecular conductivity will be diminished, This second mode of action of the alcohol is exhibited in the uppermost curve of Fig.4, which represents the molecular conductivity at infinite dilution. Change in the degree of dissociation is here eliminated, for the dissociation is throughout complete. From the shape of the curve, it is evident that the retardation of the ions is practically at an end when the solvent contains 60 per cent. of alcohol. For greater amounts of alcohol, the curve runs in what is approximately a straight line only very slightly inclined to the p-axis." The curves for finite dilutions bear a general resemblance to the curve for infinite dilution, so that we may attribute the chief effect of the alcohol in diminishing the molecular conductivity to the retardation of the ions. Up to p = 60 the curves very closely resemble the curve for v = =, but beyond that point the similarity in great measure ceases.This is owing to the appearance of the second factor -the diminution in the degree of dissociation. From Fig. 3, it may be seen that up to p = 60 the diminution is small, but it then becomes very marked, especially at the smaller dilutions. The consequence is that whilst the substitution of alcohol beyond 60 per cent. scarcely affects the speed of the ions, it now exercises a great effect in diminishing their number, and that the more as the dilution diminishes, with the result that the curves for the smaller dilutions in Fig. 4 bend away from the curve for infinite dilution and become more and more inclined to the p-axis. The curves for the molecular conductivity therefore exhibit contrary flexure : at first they are convex to the p-axis, but at the end they become concave towards it.As we have already stated, the curve for infinite dilution in Fig. 4 gives us a measure of the influence of the alcohol in diminishing the speed of the ions. A general expression which indicates the influence of the alcohol in diminishing the degree of dissociation may be found in the formula of Rudolphi (Zeits. physihcl. Ckm., 1895,17,385). Rudolphi found that for highly dissociated binary electrolytes the expression exhibited satisfactory constancy, the relation between the dilution and degree of dissociation being thus expressed with a single m2 (1 -m) JJU * This is not all brought out in the figure.OF DIETHYLAMMONIUM CHLORIDE IN AQUEOUS ALCOHOL. 71 1 constant.the various solvents and give our results in the following table. We have calculated the value of Rudolphi's expression for 2; = 10 20 40 80 160 320 Mean 0.93 0'93 0.95 0 '99 0 '98 1.06 0.86 0'89 0'90 0'94 0.95 0'94 0.97 0.91 30.7. 0 -72 0.77 0.76 0.74 0-74 0'72 49 '2. 0.51 0-51 0.53 0 -53 0 5 7 0.54 0'74 j 0-53 72.0. 0 *30 0 -30 0 '32 0 *33 0 -35 0'35 0 -33 For p = 90 the values of the expression increase very rapidly with the dilution, for which reason they have not been included in the table. For smaller values of p , the expression is fairly constant, and a mean has in each case been calculated. The divergences from the mean are not greater in the solutions containing alcohol than they are in the pure aqueous solution, and are on the whole of the same order as those given by Rudolphi.An error in the determination of m, when WE = 0.9, is magnified twelvefold in Rudolphi's constant, so that strict constancy cannot be expected. As will be seen, the value of the constant falls as alcohol takes the place of water in the solvent, indicating that the concentration a t which the salt is dissociated t o a given extent falls in like manner. I n alcoholicsolutions, there is not the same close resemblance in the behaviour of electrolytes that we find in aqueous solutions, and no doubt the results that we have obtained for diethylammonium chloride are not representative of the effect of alcohol on all binary electrolytes. Acids and bases diverge very widely in particular cases, so that no conclusions can be drawn as to their behaviour in alcoholic solutions from the known properties of their solutions in water.Salts present less irregular phenomena. We venture, therefore, to think that the curves we have given may be of use in indicating broadly the influence of alcohol on solutions of binary salts with univalent ions, whatever divergences may be found in details. Lenz (cited in Ostwald, Lehrbuch, vol. ii, part 1, 708) observed that in strong solutions of potassium iodide (v = 2 to v = 8) the influ- ence exerted by alcohol on the conductivity was independent of the dilution. In the following table we have calculated the conductivity of our alcoholic solutions in terms of the corresponding aqueous solutions, and so tabulated the results that if the regularity found by72 Lenz applied to the case in hand, the numbers in all the horizontal rows would have the same value. BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE 100 7 7 49 85 29 22 17 p = o 10'1 30 -7 49.2 72.0 90'3 99.0 100 77 49 37 31 25 20 ?_r = 10. 100 77 48 35 28 20 15 20. 1 40. I s 0. 100 77 49 37 32 27 23 320. 100 77 49 38 34 32 30 For small quantities of alcohol, the relativa diminution of the conductivity does indeed appear to be independent of the degree of dilution, but i t is obvious that this regularity does not extend over the whole table. The case of potassium iodide is probably an isolated one, the influence of the different factors in the range of dilution studied being of such a nature as to bring about the observed appearance of uniformity in the action of the alcohol. UNIVERSITY COLLEGE, DUXDEE.

ISSN:0368-1645    

DOI:10.1039/CT8977100061

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

72 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE V. -Experiment ccl ilfet h ocls employed in the Exarmhution of the Products of iS'tcc?.c72-hydi.olysis by Diastase. EY HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and J. H. MILLAR. Section I.- Estinzcction of Solids from Solution-density. Sect ion II,--Dete~w??2,incction of Specijc Koti6tos.y Power. Section III.-Fhe s.elcction of [ ~ ] j to [a],,. Section IV.-Detemzincitioz of Cujwic-~*educing Power. Section V.--Linzits of Accu;l*c~cy of the Nethods. As we hope to lay before the Society a series of papers embodying the results of our recent work on starch-hydrolysis, we have considered it desirable to preface these communications with a detailed and critical account of the methods we have employed in the examination of the products of change.A review of this branch of the subject is the more desirable as chemists are still not agreed on a common method of obtaining or expressing their results, and a considerable amount ofPRODUCTS OF STARCH-HYDROLYSIS EY DIASTASE. 73 misunderstanding has a t times arisen from individual workers not taking sufficient pains to master the systems of notation adopted by others. I n this preliminary Faper, we have endeavoured as far as possible t o remove some of the causes of misunderstanding, and to show t,he true relations existiiig between the different systems of notation, and the degree of accuracy which may be reasonably expected of the analytical methods. Ir, such an enquiry, there are many pitfalls which can only be avoided by great care and circumspection.I.-Estimation of Sol ids from Solution-deiasity. For a correct determination of the specific rotatory and reducing powers of the products of starch-hydrolysis, it is essential to know the concentrcbtion of the solution, that is, the weight of dry solids contained in a unit volume of the solution. To obtain the amount of solids by evaporation of the solution is a laborious operation, and a task of no small difficulty, as some of the carbohydrates retain water with great obstinacy and have to be submitted to very special processes in order to expel the last traces of moisture. This was a difficulty which was fully recognised and appreciated Ly O’Sullivan more than 20 years ago, and he turned the position by using the density of the solution as a guide to the total solids present.This principle has been very much employed since that time, although it has met with an occasional protest on the score of want of accuracy. We have no hesitation, however, in stating that when proper pre- cautions are taken the estimation of solids from solution-density is capable of as great, or in most cases of greater, accuracy than a determination based on evaporation and drying, unless the latter method is carried out with such refinements as are practically impossible when a large number of determinations have to be made. In his earliest papers, O’Sullivan assumed that, within certain limits of dilution, a solution of starch-products a t 15.6” increases in specifk gravit,y by equal increments of 3.85 for every gram of dry solids in 100 C.C.of the solution, water being taken at 1000 a t 15.5”. A solu- tion of either maltose or dextrin containing 10 grams of dry substance in 100 C.C. at 15.5” is stated to have a sp. gr. of 1038.5, “hence the number of grams in 100 C.C. of a solution of any specific gravity can be determined by dividing the weight above water by 3-85, For example, a solution of sp. gr. 1003.85 contains one gram; one of sp. gr. 1007.7 two grams per 100 c.c., and so on.” (O’Sullivan, Trans., 1876, ii, 130). O’Sullivan used this constant divisor of 3.S5 throughout all his74 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE researches prior to 1879, but he particularly states that he only regards it as approximately accurate. In the paper by one of us and Heron of 1879 (Trans., 1879, 35, 596), the uniform divisor of 3.86 was used in the same manner, and we have retained this factor throughout our subsequent papers, except where specially stated to the contrary, and have indicated its use in the value denoting the specific rotation and reduction by appending the number 3.86 to the respective symbols ; thus [~]j,.~~ 162*, K 3 - g ~ 48.This divisor 3-86 for the determination of solids from solution- density was adopted after a careful determination of the density of cccne-augur solutions of varying concentrations. In the above mentioned paper, the results for cane-sugar were plotted in the form of a curve in such a manner as to indicate the particular divisor t o be employed in order to determine from the solution-density the grams of dry sugar per 100 C.C.This curve, along with those of other carbohydrates, is reproduced in Plate I. (p. SO). It will be seen how the divisor varies with the concentration, and that whilst it is exactly 3-86 at a solution-density of 1055, it rises to 3.868 for a density of 1020. We were quite aware, even at that time, that the true divisors for maltose, and for mixtures of maltose and dextrin, by no means corre- spond with the divisors for cane-sugar. Thus in the case of perfectly anhydrous maltose, for a concentration of 5.0655 grams per 100 C.C. the divisor was found to be 3.9314 (Trans., 1879, 35, 602). Since, how- ever, the solution-densities of the products of starch-hydrolysis had not a t that time been determined for varying concentration, it was decided to use the constant divisor 3.86, with the full knowledge that when the true divisors were determined the values could readily be reduced.I n a footnote to the paper of 1879, attention was drawn to the fact that the analytical results, so far as percentages of constituerlzts go, were really not affected by the divisor employed differing from the true divisor. This is apparent when we consider that the values taken for the plpecific rotatory powers of maltose and of dextrin, into terms of which all the results were calculated, were based also on this same 3.86 divisor. Where mere pementuges of a mixture of carbohydrates are required, we might, in fact, assume a divisor for the mixed solids which might depart considerably from the true divisor and yet give a correct percentage composition, provided always the cabdation i s based on the specific rotatory and reducing vulues of the constituents correspond- ing to the particular divisor taken.Thus in working out the apparent composition of the mixed products of a starch transformation, and expressing them as percentages of maltose and dextrin, we might take a divisor of 3*86,3*95, or in fact any number we like, the only requisite condition being that we should use specific rotatory and cupric-reducingPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 75 values for maltose and dextrin, respectively, which correspond to the particular divisor we may decide to employ. The truth of this is obvious if we bear in mind that the values representing specific rotation and reduction, whatever notation is used, vary directly as the specific gravity divisor employed.Thus if 150" be the specific rotation of maltose for (that is, on the basis of the 3.86 divisor), the specific rotation where a divisor of 3.93 is used must be taken as "O" 3'93 = 152T0, and so on. Again, if a dextrin 3.86 on the basis of the 3.86 divisor has a specific rotation of 216O, on that of the 3.95 divisor it must be taken, for purposes of calculation, at 221". All that we have to take care of is that we employ optical and reducing constants bearing their proper relation to the divisor used, and that we do not vary the divisor in the same experiment." It may be considered that in the above remarks we have dwelt un- necessarily on what is evident to any one who has paid any attention to the subject, but these elementary facts have unfortunately often been misunderstood and misinterpreted by recent workers on the Con- tinent, who have failed to apprehend the true numerical relations of the constants we have employed.Quite recently, for instance, Ost (Cheenz. Zed., 1895, 19, 1501) raises serious objections to our expression of the law of relation of rotation and reduction on the ground that we have estimated the amount of substance indirectly from the solution- density by means of the constant factor 3.86. This he pronounces as 4' allowable for approximate determinations but not for the deduction of important laws." He overlooks the fact that the numerical rela- tions of the two properties are not in any way influenced by the greater or less accuracy of the divisor, and that the law in question snly deals with these relations.Where density of the solution is used for the determination of the solids, it is much to be desired that chemists would append an indica- tion of the divisor used to the symbols denoting specific rotation and reduction. Such a practice would enable us to readily reduce the results where required for purposes of comparison, and it would much * For purposes of strict comparison, the analyses must all be made in solutions of approximately the same density, and the above remarks are only strictly correct if the constituents of the mixture possess identically the same divisor. The larger the difference between the divisors of the constituents, the greater will be the error introduced from this source.We now know that the divisor for the dextrin or amylin portion of starch-conversion products is sensibly greater than that of the maltose constituent (see later in this paper), but the error introduced from this canse is but small, and does not in the least vitiate our former work, or the conclusions based thereon.76 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE diminish the risk of misunderstanding in a subject which is in it'self sufficiently difficult and complex. If, as frequently happens, a knowledge of the percentage composi- tion of the solids is insufficient, and we require to know the nctucd weight of these pel* unit of volume of solution, this must be determined either by the evaporation and drying of the residue from a given amount of solution, or it must be deduced from the density of the solution after the density constants of each constituent have been accurately determined.We have already referred to the great difficulty experienced in driving off the last traces of moisture from many of the carbo- hydrates. This is especially the case with those derived from the hydrolysis of starch, which are most difficult to obtain in a perfectly anhydrous state without decomposition. After many trials, we have finally adopted a form of apparatus essentially similar t o the one recommended by Lobry de Bruyn and Van Leent (Rec. Tmv. Chim., 1894, 13, 218.) Two small flasks are united by a tube furnished with a stop-cock and a side-tube leading to a good air pump, The substance to be dried is introduced into one of the flasks, the other being partially filled with phosphoric anhydride.After exhausting the apparatus, the flask containing the substance is immersed in a water, salt-water, or oil-bath, according to the final temperature required, and is slowly heated up to a point at which it ceases to lose weight. Crystallised hydrated maltose may in this manner be rendered com- pletely anhydrous in a few hours at 105-106" without any signs of fusing or of discolouration. Hydrated dextrose is still more easily rendered anhydrous in this manner, and crystallised levulose com- pletely loses all traces of adherent moisture below its fusing point. The dextrins, maltodextrins, and the mixed starch-transformation products, on the other hand, require much longer drying in this apparatus, and temperatures as high as 120-130", before losing the whole of their water.With the aid of this convenient apparatus we have determined, with every possible precaution, the density in solution, a t rarying concentrations, of maltose, dextrose, levulose, soluble-starch, and the mixed products of starch hydrolysis with diastase, carried to various points, and of definite and known composition. I n tabulating the results, we have put them in such a form as to ndicate the divisor to be used a t the various concentrations, in order to determine the grams per 100 C.C. of solution. For any given concentration, the proper divisor can be found either by inspection of the curves given in Plate L(p. 80), or by employing the equation ofPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE.77 the curves given, in each case, in the text after the experimental numbers. It will be seen that whilst the various carbohydrates examined differ considerably in solution-density at similar concentrations, they all show that the volume occupied in solution by a unit of weight of the substance is lees a t lower than a t higher concentrations, hence dilution must in all cases be attended with a contraction of volume. The specific gravities given were all taken at 15.5", and are referred to water a t the same temperature, Strictly speaking, the values given are not exactly grams per 100 c.c., but the weight of substance (weighed in air) contained in a volume of the solution equal to that occupied by 100 grams of water at 15.5", weighed in air against brass weights.I n order to convert the :results into true grams per 100 c.c., where great accuracy is required, a p , for instance, in determining specific rotatory constants, they must be multiplied by the factor 0.99802, thus reducing them by about 0.2 per cent.* In the following tabulated results, Column ( a ) gives the weight of dry substance taken. Column ( b ) gives the total weight of solution. Column (c) gives the specific gravity of the solution at 15.5', Column (cl) gives grams of maltose per 100 C.C. (reputed). Column ( e ) gives the divisor for the determination of grams per 100 C.C. (reputed) from the specific gravity. The greatest possible care was taken to ensure the purity of the referred to water at 15.5".various substances. TABLE I.-Solution Density of Maltose (anhydvous). 1 2 3 4 5 6 7 s 9 10 11 12 a. 1.0071 1-9783 1'4515 1.9595 4'9596 3'7107 5'8320 6 3222 7.0812 9'3267 10'3720 10.7029 6. 39,6425 40.8331 29.8000 40.1240 52'1081 38 '1672 4 1 -8 1 37 33.6245 33.9980 42 '3482 38'7564 34 0471 c. 1010.11 1019'43 101 9 *55 1019.59 1038 -8 3 1039.67 1057.77 1079.1 4 1088 -28 1093.81 1115.84 1138-39 * This factor is arrived a t in the following manner. d. 2.566 4-939 4.966 4.979 9.886 10.107 14.753 20.291 22.666 24'090 29.865 35'784 C. 3 '939 3.933 3.936 3.934 3-927 3,925 3.915 3 '900 3'893 3.894 3.879 3-867 The weight of the volume of water at 15.5" to which all the densities are referred is 100 grams, weighed in air. Reduced to a vacuum, this will weigh 100'106 grams, and as the density of water a t78 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE The above results are expressed in the maltose curve of Plate I , p.80 and the equation" for calculating the divisor for any given gravity is, in which D = the required divisor, and G = the specific gravity of the solution, TABLE 11.-Sohtiom Bemsity of Dextvose (ccd~yd~*ous). D = 3.9435 - 0°00044 (G - 1000) - 0.000001 (G - 1000)2, 1 2 3 4 5 6 7 I --- 1.2988 1'6324 3,2659 3.2751 8.3380 6'4414 9.0925 d. 1.1105 2.2691 3'9640 4-6645 2.9110 6. e. 3.998 4.000 4'028 4.019 4.012 49'8518 30.5690 51.2638 31 -1712 53.7774 36'5604 39,9196 ~~ _________ c. 1010 -12 1020.95 1025.07 1041.94 1062.93 1072.03 1094'66 d. 2.6317 5'4516 6.5306 10.9470 16-4800 18 '8870 24.9330 c. 3'845 3942 3'839 3.831 3.818 3'813 3 796 These results are shown in the dextrose curve (Plate I), the equation for which is, D F 3.848 - 0*00028 (G - 1000) - 0.0000028 (G - 1000).2 TABLE 111.-Solution Density of Soluble Stccrclz.1 2 3 4 5 - 15'5" is I b. a. 0-5606 1'1380 2.2063 2.3166 1.6118 50 -7 0 22 50.5957 56.5394 50 *5954 56.0157 c. 1004'44 1009'08 101 5 -95 1018'75 1011'68 0.99908 as compared with that of water a t 4", the true volume of the 100*106 "reputed" 100 C.C. a t 15.5" will be This represents the volume in true cubic centinietres of 100 grams of water weighed in air. The reciprocal of this 0'99802 is consequently the factor t o be employed for reducing the above experimental numbers to grams per 100 true cubic centimetres. TITe niuch require a convenient term to express the volume occupied at 15.5" by a definite number of grams of water: weighed in air.This value of the cubic centinietre, which is the one employed in the graduation of most of the flasks and pipettes used in the laboratories of this country, is manifestly not identical with the true cubic centimetre. We have ventured to append the term '' reputed " to the value in question. 100 "reputed" cubic centimetres are equal t o 100*198 true cubic centirnetres, and the ratio of a true to a '' reputed " cubic centimetre is 1 : 0.99802. * We are indebted to Dr. A. Lapworth for kindly calculating this and the following equations. +99908 = 100*198 C.C.PRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 79 1 2 3 4 Nos. 1 to 4 give the results obtained with a specimen of C.J. Lintner's soluble-starch prepared by the action of dilute acid, in the cold, on ungelatinised potato-starch. No. 5 was a specimen of C. J. Lintner's '' amylodextrin," prepared with malt-extract according to his directions. This is the first product of the liquefaction of starch-paste, and gives a deep blue reaction with iodine. It is the '' soluble-starch " of O'Sullivan and others. Owing to the comparative insolubility of these preparations of soluble-starch, the range of concentration in these experiments is necessarily small, and they do not admit, on this account, of quite the same degree of accuracy as the other carbohydrates, 1.2733 51-0694 1010*14 1 2.518 4.026 1 '7032 30 -371 4 1023.05 5'737 4.017 5.6768 52'4770 1045'30 11.311 4-005 6'0568 41 -4603 1061 *96 15'514 3.933 Solution Densities of the Mixed Pqqoducts of Stamh-lzyds.oZysis.The conversions were in these cases made with as small an amount of diastase as possible, consistent with the proper stage of conversion being reached. The mixed products, after analysis, were in the first place concentrated on the water bath, and were then transferred to the vacuum-apparatus, the temperature being slowly raised as the last traces of moisture were expelled. A final temperature of 110" is generally sufficient, but when the solution contains much soluble- starch it may be necessary to finish at 130". Xevies 8.-The solution-density and corresponding divisors here given are the experimental numbers obtained with the mixed products of hydrolysis when the conversion was arrested soon after complete limpidity of the starch-paste was attained. The products had the following optical and reducing properties.[a]j3.8s 203.6" { [a], 188.6") K3.86 11.8 [R 20.21 The letters at the heads of the columns have the same significance as in the foregoing tables. TABLE IV. The variation of the divisor with the concentration is shown in the curve of the '' High Transformation " of Plate I., the equation for which is, D = 4.032 - 0*0006 (G - 1000).80 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE Xew'es B.-In this case the solution-density of the mixed products of a somewhat more advanced conversion mere determined, the products of hydrolysis having a specific rotation and reducing power of TABLE V. a. 1.0552 2.7575 3.6031 3'6317 7'5073 7.9600 b.44.9101 53.3388 51.9826 34.1428 54-0266 43.4377 c. 100 9 -5 1 1021'31 1028.51 1044'32 1058'62 1078'58 d. 2.3719 5-2791 7.1286 11 -1080 14 9'110 19.7640 C. 4'009 4.002 3.999 3 '989 3.984 3'975 These results are denoted graphically by the curve of Plate I. for the Medium Conversion." The equation for finding the divisor is- Xevies C.-Here are given the results obtained with a low starch- conversion, that is, one in which the hydrolysis was carried almost to the lowest point, and in which the maltose is in a readily fermentable and diffusible condition. The optical and reducing properties of the D = 4.012 - 0*00044 (G - 1000) - 0.000001 (G - 1000)2. mixture were as follows. [ C t ] j 3 . 8 8 162.2" { [a], 149*7") K3.86 49.2 [R 82.8.1 TABLE VI. 1 2 3 4 5 6 7 8 - a. 0.8470 1.9545 2'2602 4'4225 4 -1 633 4'6694 7'6485 10 521 2 b.35 5237 39'1675 31.3523 45'3500 41 *6143 33.9971 47'4471 51.3166 C. 1009.55 1020'23 1029'39 1040.16 1041.23 1057.35 10 67 -82 1087'67 I 1 d. ~ 2'407 5.091 7'424 I 10'143 1 10.417 ' 14'522 17.214 I 22'300 I e. 3.967 3'973 3.960 3 '959 3'955 3.949 3.940 3.931 The results are given graphically in the Curve for "Low Conver- sionY7' Plate I, the equation corresponding to which is, I) = 3.9742 - 0.000403 (G - 1000) - 0*0000014 (G - 1000)2.PRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 81 When we regard the curves denoting the variation in the divisors for the mixed products of the hydrolysis of starch proceeding from the different grades of transformation, the important fact comes out that for equal concentrations the divisor to be applied for the deter- mination of dry solids per 100 C.C. increases with the specific rotatory power of the mixture, and decreases with the rise in cupric reduction ; in other words, the divisor varies in some inverse ratio t o the apparent maltose present.If we consider the mixed products of hydrolysis as composed of maltose and dextrin, and assume that the maltose constituent has the same solution-density per unit weight, and therefore the same divisor as ordinary maltose, then from the experimental data given we can determine the divisor for the dextrin or amylin constitutent. Let us, for example, take the medium transformation of Table V, in which the specific rotatory power is [ C L ] ~ ~ . ~ ~ 186.6" { [.ID 173*9"), and the apparent maltose is 45.4 per cent.[R = 45-41. For the mixed products of hydrolysis, we find by the experimental curve that the divisor a t a density of 1020 is 4.003. The divisor for maltose which goes to make up this density is 3.939, that is, the divisor corresponding to 45.4 per cent. of the density 1020 = 1009.1. The divisor due to the dextrin or amylin constituent will consequently be This, of course, is not the amylin divisor for a density of 1020, but for a density of 54.6 per cent. of this, L e . , sp. gr. 1010.9. Working in this manner with the results of the high transformation given in the curve, we find the following series of divisors for the amylin constituent at different densities. Density. Divisor. 1016.24 4.038 1032.48 4.023 1048.72 4.010 1064.9 6 3-996 These when plotted in the usual manner give the " Amylin " Curve of Plate I., shown by a dotted line.It will be noted that this curve is much steeper than any of the others. It may be urged that we are attaching too much importance to this calculated amylin curve expressing the variation in solution-density of the non-maltose constituent of starch transformations, and that we can adduce no certain proof that the reducing constituent or con- stituents of different grades OF transformation are comparable in this respect with pure maltose. VOL. LXXI. G82 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE This is perfectly true, and, moreover, knowing as we do that the maltose constituents of low-grade transformations exist in a readily fermentable and readily diffusible condition, whilst those of higher grade transformations exist to a great extent in some sort of combina- tion as maltodextrins, amyloyns or reducing dextrins (according to the point of view from which we regard them), it certainly did seem im- probable that the solution-densities of crystallisable maltose would be applicable to the reducing constituents throughout the whole range of starch-transformation products.As a matter of undoubted fact, how- ever, we find that when a series of dextrin or amylin divisors is deduced from the products of a single starch-transformation in the way we have indicated, then these divisors are applicable to ccll otlies- stcc~ccl~-tru~zsfo~.)?tcitions of very different grades. This goes very far to show that in starch-transformations of very different stages of hydrolysis the divisor for the reducing portion is identical for the same concentration ; and it necessarily follows as a corollary that there is the same constancy in the divisor of tho amylin or non-re- ducing portion of the products of hydrolysis.Be that as it may, however, there can be no doubt that by making use of the calculated dextrin curve given, and that of maltose, we can a t all times determine within certain limits of concentration, and with a close approximation to accuracy, the divisor (and of course if required the density in solution) of any mixed products of the hydrolysis of starch prepared with diastase, provided always we know the apparent per- centage of maltose, either through the specific rotation or the cupric reducing power.I n proof of this proposition, me have given below the calculated and observed divisors respectively of the mixed products of starch- hydrolysis for three transformations determined by the evaporation method. These are transformations occupying very different positions in the range between soluble starch and maltose, and are those of which the curves are given in the Table. The calculations are made for four different specific gravities of solution. TABLE VIL- The observed und calculated divisors of three stui*ch-ti*ans formations. Sp. gr. 1020. Sp. gr. 1040. sp. gr. 1060. sp. gr. 1080.PRODUCTS OF STARCII-HYDROLYSIS BY DIASTASE. 83 The following general formula is applicable for the determination of the divisor for the mixed products of the hydrolysis of starch whea the value of R (apparent percentage of maltose) is known.- -__ ~ D = S in which S = the specific gravity of the solution of the mixed products of the hydrolysis of starch at 15.5" after deducting 1000 (water a t 15.5" - 1000). R = the apparent percentage of maltose. RS S-RS S is made up of - +-- 100 100 RS d' = the divisor for maltose at a concentration of __ 100' This value is obtained from the maltose curve on Plate I. tration of '5' 100 ' curve shown by the broken line on Plate I. hydrolysis. d" = the divisor for the dextrin or amylin constituents at a concen- This value is obtained from the amylin or dextrin I) = the required divisor for the mixed products of starch- For practical use in the examination of starch-transformations, we havecalculated, by means of the above formula, the divisors of the mixed products of starch- hydrolysis for specific gravities of 1010, 1020, 1030, and 1040, and for increments of 5R between R=O and R: 100.If the specific gravity of any mixture of starch-transforma- tion products has been determined within these limits of concentration and the approximate value of R (which may, if desired, be obtained by the 3.86 divisor), we can a t once, by reference t o thisTable (p. 84), find the appropriate divisor for the determination of the grams of solid matter per 100 C.C.84 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE TABLE VIII.-The diviso~s for the mixed py*oclucts of the h y d ~ o l y ~ i s OJ stnrch cowesponding to R nnd [a],.a,. lib. 8 195.6 192.4 189'2 ia6.0 182 -8 179'6 176.4 173.2 170-0 166.8 163'6 160'4 157-2 1 5 4 4 150.8 147-6 144'4 141.2 138'0 R. 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 85 90 95 100 ao sp. gr. 1010 4.038 4'033 4 '029 4.024 4.019 4.014 4.009 4 004 3'999 3.994 3.989 3'984 3'Y79 3'973 3.968 3,962 3.957 3.951 3.945 3 '939 3p. gr. 1020. 4.031 4'027 4'023 4'019 4.014 4'011 4'005 4-001 3'996 3.991 3.986 3.980 3'975 3'970 3'964 3-958 3.952 3'946 3-940 3'934 Sp. gr. 1030. 4-023 4 -020 4.017 4'013 4,010 4.008 4.002 3'997 3'992 3.987 3'983 3 9 i 7 3.972 3'966 3-961 3.955 3.948 3.942 3.935 3-929 3p. gr. 1040. 4.015 4.013 4.010 4.008 4.005 4.001 3-997 3'993 3.989 3-985 3.919 3.974 3.969 3-963 3 957 3'951 3.945 3-938 3.931 3,924 II.-The Betewr~ination of Xpec;Jic Rotcbtoi-y Powey.The photogyric properties of a substance in solution, that is, the properties in virtue of which the substance is capable of rotating the plane of a linear polarised ray of light, are referred, for purposes of comparison, to a standard concentration and a standard length of column of the solution. The specific rotatory power of a n optically active substance in solution may be defined as the angle through which a linear polarised ray of light of definite refrangibility is rotated by a column, 1000 iiiillimetres in length, of a solution containing 10 grams of the sub- stance in 100 C.C. For the determination of specific rotatory power we must know, CL. The observed angle of rotation for a ray of definite refrangi- bility ; c. the concentration of the solution expressed in grams per 100 C.C.; L. the length of the column of the solution in millimetres. The specific rotation [a] is then expressed by the formula 1 0 4 ~ ~ [a] = -. L x cBROWN, MDRRIS, AYO MILLAR. Flate 1 DIYISORS FOR CARBOHYDRATES AT VARIOUS DENSITIES m I080PRODUCTS OF STARCH-HYDKOIJY SIS BY DIASTASE. 85 It will be convenient in the first place to consider the value of c in the above formula. Where absolute accuracy is required, as, for instance, in the determination of the specific rotation of a pure sub- stance and its variation under different degrees of concentration in a given solvent, we must substitute for c the number of grams of substance contained in 100 true C.C. of the solution. If we denote the density of the solution at 15.5", referred to water at 15*5", by d 15.5"/155", and the percentage weight of the substance in solution by p , then d 15*5"/15.5" x p equals the number of grams of substance in 100 vepzcted C.C.a t 15.5" : that is, in a volume of the solution equal to that occupied by 100 grams of water a t 15*5", weighed in air. This is, of course, as we have already seen, not exactIy the same thing as grams per 100 true C.C. I n order to convert '' reputed " into true C.C. we must ascertain the density of the solution at 15%" referred to water at 4", with due correction for air displace- ment. I f we express this by d 15-5"/4" the concentration will then be expressed by c = d 15.5" /4" x p . A near approach to acciiracy will be attained, as we saw in the last section, by multiplying the grams in 100 reputed C.C.at 15.5" by the fact or 0.9 9 8 02. The following formula, as given by Landolt, is of general application for determining the value of d t0/4", where to represents the temperature at which the density of the solution has been determined with reference to water at the same temperatnre. F W t0/4" = - (& - 8) + 8 where W = the weight of water; F = the weight of an equal volume of the solution ; Q = the density of water a t f, that of water at 4" being taken 8 = the weight of 1 C.C. of air in grams. as unity; For 6 the value of 0*00119 may be taken for temperatures between 10" and 25", and a t barometric pressures between 720 and 770 mm. The value of a varies with the refrangibility of the linear polarised ray, and it is therefore necessary in expressing [a] to specify the position in the spectrum of the particular ray employed in the determination.In one the value of [a] is referred to the ray D of the solar spectrum, the specific rotation being then expressed by [a]=; whilst in the other There are two systems of notation in use at the present time.86 BROWN, MORRIS, AND MILLAR: EXAMINATION O F THE notation the photogyric properties of the substance are referred to t.he so-called ‘I medium yellow ray,” the complement of Biot’s teinte sensible or ‘( transition tint,” in which case the specific rotation is expressed by [u]j. I n the determinations of [.ID, the sodium light is used in a Mitscherlich, Wild, JellettGornu, or Laurent instrument, and the angular rotation produced by the solution is determined in degrees of arc.The scale is conseqiiently a natural one, and differences of rotatory dispersion in the substances examined do not interfere with the comparison of results. The determinations of [a]j are made by’the aid of neutral-tint or half-shade polarimeters, such as the older instruments of Soleil, or their more recent modifications by Ventzke and Scheibler. The scale divisions of these instruments are of an arbitrary character, and hare to be converted into angular values before specific rotations can be calculated, It cannot be too clearly borne in mind that the readings given by all such instruments are based on the rotation value of a gzccwtx plate, cut perpendicular to its optic axis, and that no matter what the arbitrary scale employed may be, the readings must in the first place necessarily be in terms of the rotation of quartz for a plate of definite thickness.These instruments have also the disadvantage that, without proper reduction of the readings, they cannot be used for the comparison of the rotation values of different substances which happen to have a sensibly different power of rotatory dispersion from that of quartz. This fact was fully recognised in the early days of the original Solail instruments, and is very clearly expressed in the writings of Biot, on whose discoveries the saccharimeter of Soleil was based. In his earlier work, O’Sullivan used a Soleil-Duboscq instrument for the determination of [ c x ] ~ , in which 100 divisions of the scale corre- sponded to 24” of arc, this being the angular rotation experienced by Biot’s ‘ I medium yellow ” or j c m n e moyen ray (as determined by the transition tint) in traversing a quartz plate of 1 mm.in thickness, cut perpendicular to the optic axis. In the Soleil-Duboscq instrument as improved by Ventzke and Scheibler, the direcli dependence of the graduation on quartz values was somewhat obscured, 100 scale-divisions being made to correspond to the amount of rotation experienced by the medium yellow” in passing through a column of a solution of pure cane-sugar 200 mm. in length, containing 26.048 grams of cane-sugar per 100 C.C. at 17.-5”. Such a solution has a specific gravity of almost exactly 1100 (water at 17.5” = 1000). The readings for cane-sugar in these instruments con- sequently correspond closely to the specific gravity of the solution less 1000.There is no special advantage for general purposes in thisPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 87 change of graduation, and it has been rather an unfortunate one, as tending to obscure the fundamental fact underlying the construction of such instruments, that observat'ions made with them are in reality all referred t o the photogyric properties of a definite thickness of ~ U C L Y ~ X . I n the old Soleil-Duboscq instrument, as we have already said, each scale-division was equal to the rotation experienced by the '' medium yellow " or jccune ,?noyen of Biot in passing through &th of a millimetre of quartz,* that is, to a rotation of 0.24" of arc. In the case of the later instruments which we have described as being standardised by a solution of cane-sugar of definite strength, the arbitrary scale-divisions, in order to be converted into degrees of arc, have also to be translated into quartz values, which can be effected by making use of the known relations of the rotatory power of quartz and cane sugar established by Biot for his neutral or transition tint.When the millimetre-quartz value of 24" is taken for the transition tint, the speci6c rotatory power of cane-sugar for medium concent'ra- tions (5 to 15 grams per 100 c.c.) is found to be 73.8", and from this number the value of each scale-division can of coursa be estimated. In the instrument we are now using, a half-shade Schmidt and Haensch, we find that 100 divisions of the scale correspond to 38.43" o€ arc, taking the photogyric value of 1 mm.of quartz for the transition tint rtt 24". A considerable amount of confusion has arisen of late years with regard to the use of the expression "medium yellow" as applied to the position in the spectrum of the particular ray used in the deter- mination of [.]+ As this has led t o very contradictory statements on the relations existing between [a],j and [a],, we must refer somewhat in detail to the history of the subject in order to show how this serious misunderstanding arose. When a quartz plate cut perpendicular to its optical axis is placed between two Nicol prisms the "transition tint " or t e i n t e sensible is observed when the principal plane of the snalysing Nicol is parallel t o the plane of polarisation of the jcbune moyen ray of Biot.I n this relative position of the polariser and analyser, the jaum moyen ray is ext i q u i s h e d , the rays which collectively form the complementary transition tint being alone transmitted. This may be seen by passing the light, as it emerges from the analyser, through a spectroscope, when it will be found that the spectrum is crossed by a dark band corresponding to the missing ray. The rotation which this ray ex- periences in passing through a quartz plate was determined by Biot and found to be 90" for a thickness of plate of 3.75 mm. or 24" for * In speaking of the rotatory values of quartz plates throughout this paper, it is understood that such plates are all cut perpendicular t o the optic axis of the crystal.S8 BROWN, MOlIRIS, AND MILLAR: EXAMINATION O F THE a thickness of 1 mm.From this rotation, we can determine the refrangibility of the jccune moyen ray expressed in wavelengths, by employing the following dispersion formula of Boltzmann, which is approximately accurate for rays of any refrangibility. where a = the angle of rotation whicb a given ray experiences in passing through a quartz-plate 1 mm. in thickness; whilst X is the wave-length of the ray expressed in millimetres. If we substitute 24 for a in the above formula, we find that the jaune nzoyen ray of Biot, as determined by its complement, the transi- tion tint, has a wave-length of X 0*0005608. The yellow of the solar spectrum extends according to Thalen from h 0.000535 to X 0.000586, so that the true mean yellow has a refrangibility corresponding with h 0.000560, which is identical with that of Biot’sjuurze moyerz.Up t o about the year 1874, amongst those chemists who had a clear idea of the meaning of [ u J ~ , as distinguished from [a],,, there seems to have been no difference of opinion as to the particular ray to which Lct’lj was referred ; it was always the jccune moyen of Biot, which is rotated through 24” by 1 mm. of quartz, and which, as we have seen above, is identical in refrangibility with the true mean yellow of the solar spectrum. I n or about 1874, the innovation was made which has resulted in so much confusion,,and which has practically introduced a totally different set of values for [a]j, It has not hitherto been recognised that we have a t the present time two different ways of expressing specific rotation as [a]j, and that these two systems, in which exactly the same symbol is used, are not even referred to the same ray of the spectrum, and that consequently they bear quite different relations to [aID, even for substances of exactly similar rotatory dispersion.As far as we have been able to ascertain, it was Montgolfier who was in the first instance responsible for this serious confusion. I n a paper published in 1874 entitled “Pouvoirs Rotatoires du camphre, et de quelques autres corps” (Bull. Chim., SOC. 22, 487), after justly calling attention to the confusion which a t that time still existed amongst certain authors as to the expressions [ a ] j and [a],, he proceeds to discuss the relative robation, for the same substance, of the D ray on the one hand, and of the juune moyen of Biot on the other.It is not at all clear from the description how the comparison was made, but for the determinations of the rotation of the D ray he appears to have used a Cornu instrument. A t the commencement of the table in which the results of hisPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 89 experiments on sugar and camphor are given, he correctly states that the rotation of the D ray in passing through a quartz plate 1 mm. thick is 21-61", but he gives the rotation of the jaune naoyen of Biot, deter- termined by the transition tint, as 24.5" for the same thickness of quartz, instead of 24" as determined by Biot himself. I n the column headed '' Rapport des deviations " he gives 1 : 1,048, with Broch's name attached to it, whilst the relations of the two rotations for a series of by no means concordant experiments with cane-sugar vary from 1,1167 to 1.1350.The important point, however, to bear in mind is that we here have for the first time a reference of the rotation of Biot's j a u n e '~)20yen, not to the millimetre-quartz value of 24", as originally determined, but to cc yay of decidedly higher refyungibility with cc rnillimetre-puccrtx yotcition of 246". It is the exact arithmetical mean of the rotation experienced by the D ray and the E ray of the solar spectrum in passing through 1 mm. of quartz; the rotation of D being 21*67", and of E 27.4" under these conditions, and to this ray the term '' medium yellow " was improperly applied as a synonym for Biot's jnune moyen, although it is a ray of quite a different refrangibility.Unfortunately Landolt, in his book on the Polariscope, adopted the same ray as Montgolfier had done for the '' medium yellow," objecting to the '' transition tint " as corresponding to no sharply-defined ray, but he fails to draw attention to the important fact that if values of [a]j are referred to this new ray they cannot be directly compared with determinations made on the basis of Biot's j c c u n e moyen. For instance, the specific rotatory power of cane-sugar for a certain medium concentration is [a]j 73.8" if we refer it to the true medium yellow of Biot; but if the specific rotation is to be referred to Montgolfier and Landolt's " medium yellow " the value becomes It is not difficult to see how this value of 24.5" was arrived at.~ 24'5 x 73.8" = 75*3O, a very serious difference. 24 The value of each scale division of the Ventzke-Scheibler or any similar instrument when expressed in degrees of arc will also be materially influenced by the particular medium yellow " we chose t o refer to. I f one scale division, as on 0111- instrument, is equal t o 94.5 0.3843" for Biot'sray,it will correspond to -I x 0,3843" = 0.3923" for 24 the so-called "medium yellow" of Montgolfier and Landolt." It is * These facts must be carefully borne in mind when reading Landolt's book on the polariscope, as he altogether omits calling attention to the importaut results which follow from a selection of a "mediiini yellow " of clifferent refrangibility from Biot's original ray.90 BROWN, MORRIS, AND MICLAR: EXAMINATION OF THE most important to remember these facts when the ratio of [a]j to [.I,, is discussed, as we shall have occasion to see later on.We have already stated that some objection has beenmade to the employment of Biot's jccune n-2oyen ray on the ground that it is not a ray of very definite refrangibility. This is, however, by no means a valid objection, since the wave-length admits, as we have seen, of being calculated from the known rotation for a given thickness of quartz, This original ray of Biot has, in fact, as great a title t o definite refrangibility as the substituted ray of Montgolfier, and has the extra advantage of really being what its name implies, the tq*ue medium yellow of the solc~r spectrum, that is, a ray with a wave-length of 0*0005608, which is almost exactly intermediate between the value of X for the sodium and thallium .lines.Montgolfier, on the other hand, and more recently Landolt and others, have, €or [a]j determina- tions, made use of a ray having certain relations to the lines D and E, which bound a portion of the spectrum somewhat more extended than the yellow as defined by Thalen. They have not, however, chosen the ray intermediate in wccve-length between D and E, but have taken the one which undergoes ccn intemxecliccte or ccbout cc.n intermediate amount of yotcction o n pccssing tlurouglc 1 TIWL of qucwtx. The wave-length of this empirically chosen ray, which, unlike the D ray, or the jchu?Le nzoyem of Biot, corresponds with no ray employed in any existing instrument, can o€ course be calculated with the aid of Boltzmann's dispersion formula from its millimetre-quartz rotation value of 24.5". We find it to be h 0*0005553, so that the Montgolfier ray for [a]j lies considerably on the green or more refrangible side of the true medium yellow, whilst the Biot ray, on the other hand, as determined by the transition tint, corresponds very closely with the true medium yellow.111. I % e Relation of [~]j to [a],. It will be evident from the remarks in the foregoing section, that in speaking of [a]j and the relations which exist between this and [a],, we shall in future have to specify to what particular ray in the yellow the [a]j value is referred, whether on the one hand to the true medium yellow orjaune mo?/en of Biot?with a wave-length of 0*0005608, and a millimetre-quartz rotation of 24", or on the other to the so-called medium yellow of Montgolfier and Landolt, with a wave-length of 0*0005553, and a millimetrequartz rotation of 24.5". Where there is any chance of confusion we shall refer to the former as [a]j Biot, and to the latter as [a]j Montgolfier.As the determinations of both values of [a]j are dependent either directly or indirectly on quartz values, it is manifest that there canPRODUCTS O F STARCH-HYDROLYSIS BY DIASTASE. 91 be no constant factor applicable to the reduction of [a]j to [a], in the case of substances whose .r*otcbtoiy dispersion sensibly d@em from that of qua./.tx. There will be a constant factor for each separate substance under these circumstances, but it will not be applicable to a series of substances unless they are of equal rotatory dispersive power.With the exception of cane-sugar, there are but few of the carbo- hydrates which have had their rotatory dispersive powers compared. The specific rotation of cane-sugar for rays of different refrangibility was investigated by Arndsten (Ann. Chz'm. Phys., 1858, [3], 54, 403) and by Stefan (Sitx. Ber. cl. Wiener Akud., 52, ii, 486), who used Broch's spectroscopic method. Their results show the almost abso- lute identity of the rotatory dispersion of cane-sugar and quartz throughout the whole visible spectrum. Quite recently the subject has been further investigated by Landolt (Bey., 1894, 27, 2872), who employed a new method based on the direct determination of the angular deviation of rays of definite refrangibility obtained by passing white light through a series of coloured screens.Landolt has in this way been able to still further confirm the exact correspondence of quartz and aqueous solutions of cane-sugar as regards rotatory dispersion. A comparative determination of the specific rotatory power of dextrose for different rays was made by Hoppe-Seyler in 1866 (Zeits. c~nccl. Chern., 1866, 412). His results indicate that the rotatory disper- sion of dextrose, whilst closely approximating to that of quartz, and consequently of cane-sugar, is really very slightly greater. Bearing in mind the identity of the rotatory dispersions of cane- sugar and quartz, it is evident that the factor necessary to convert [a]j Biot into [a],, in the case of cane-sugar will be identical with the ratio of the rotations experienced by the D ray and jaune moyen ray respectively in passing through quartz plates of equal thickness.The D ray in passing through a quartz plate 1 mm. thick is rotated, according to Broch, Stefan, and to Wild, through 21-67", whilst the jaune moyen, according to Biot, is rotated through 24" under the same conditions. The ratio of these numbers is 1 . 1.1075, and the latter number is the factor to be applied in converting values of [a]j Biot into [a]. in the case of all substances having an equal rotatory disper- sion to that of quartz or cane-sugar. The factor for the conversion of [a]j Montgolfier into [a].with the same limitations as regards dispersion will of course be It will be seen that there is suficient difference in these two factors to cause grave errors in the conversion of one notation into the other if the facts we have stated are not kept constantly in mind. It is, for 24*5/21*67 = 1.130.92 BROWN, MORRIS, AND MILLAB : EXAMINATION OF THE instance, by no means an unusual thing to find papers published within the last ten or fifteen years in which the factor applicable only to [ ~ ] j Montgolfier has been used for the conversion of [ u J ~ Biot into [a],. I n considering how far the factors 1.1075 and 1.130 are applicable to the carbohydrates with which we have most to do in this particular investigation, we have in the first place to satisfy ourselves as to whether the carbohydrates produced during starch-hydrolysis differ sensibly from cane-sugar in ~otc~tory dispemion.Unfortunately, we have very few published data from which any conclusions can be drawn. It occurred to us, however, that if the carbohydrates of starch-hydrolysis differ in rotatory dispersion from cane-sugar to a sufficient extent to be of any practical moment, this oixght to become evident by a direct comparison of the various solutions in a Ventzke- Scheibler quartz instrument, and in a sodium-light instrument such as the Jellett-Cornu or Laurent. If we are dealing with a series of substances which do not differ i n t w se in rotatoq dispemiorz, then, no matter what the actual differ- ences may be in the specific rotatory powers, the number of scale- divisions of the Ventzke-Scheibler instrument (in which we measure the rotation of thejcmne moyen ray) corresponding to a degree of arc of the sodium-light instrument ought always to be the same.If there is not this correspondence, it can only be due to the fact that the rotntovy dispes-sions of the different substances are not identical. This method of comparison will also give us the factor to be used for each substance in converting [aJj into [.ID or vice versa. Through the kindness of Dr. Ai,mstrong, who put his fine Jellett- Cornu polarimeter a t our disposal, we have been able to make careful comparisons of this kind with solutions of (1) cane-sugar, (2) dextrose, (3) maltose, and (4) the mixed products of starch-hydrolysis apparently containing 80 per cent.of maltose and 20 per cent. of dextrin. The last-mentioned solution had a specific rotation of [a-jj3.86 162O.O. Numerous closely concordant readings of each solution were taken in each polarimeter successively, using a 200 mm. tube, which was interchangeable with the two instruments. The circle-readings of the Jellett-Cornu were taken in two parts of the scale 180" apart, in order to correct for any irregularities in the calc-spar prisms, and all care was taken to make the comparisons as rigorous as possible. It is unnecessary to give the details of the observations, which are summarised beelow. Column A gives for each separate solution the result of dividing the scale reading of the V.3. instrument by the circle reading of the Jellett-Cornu polarimeter : it consequently represents the number ofPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 93 Cane-sugar ...............Maltose ..................... Dextrose .................. ~ , .................... ,, ................ Starch-products ........ 9 , ), ........ V. -S. scale divisions corresponding to 1 O of the sodium-light instru- ment. Column B gives the value of a scale division of the V.-S. instru- ment expressed in terms of ray D. Column C gives for each solution the ratio of [a]j Biot to [a]Da As cane-sugar and quartz have exactly the same rotatory dispersion, the ratio in this case is 24/21-67=1*107, and on this basis the other figures in this column are made proportional to those of column A. These ratios of column C can also be obtained by dividing the results of column B into 0.3843, which gives the angular value of eech scale division of the V.-S.instrument expressed in terms of Biot's jaune mo gem. Column D gives the ratio of [u]j Montgolfier to [a]D in each case. 10 p. C . 10 P.C. 5 p.c. 10 p. c. 5 p c . 10 p.c. 5 P.". TABLE IX. A . 2'882 2.899 2'892 2.904 2'894 2.891 2.895 12. 0.3469 0.3449 0.3457 0'3442 0.3454 0.3458 0.3454 C. 1.107 1'113 1.111 1.115 1.111 1.111 1.111 D. 1'130 1.136 1'134 1.138 1.134 1.134 1.134 It will be observed that there are slight but sensible differences between cane-sugar and the other carbohydrates examined, and these can only be explained by assuming that cccne-sugcw is slightly less clispeysive than the othey substances. The factor 1.107 for the conver- sion of [u]j Biot into [.ID is only strictly correct for cane-sugar, and is slightly too low for the other carbohydrates examined, for which the factor 1-111 is more nearly correct.This is the value we have adopted for the translation of [a]j Biot of starch-products into [.ID, whilst 1.134 represents the ratio of [a]j Montgolfier to [a],, for starch- products somewhat more accurately than does the cane-sugar factor 1.130. It was only after planning and completing the above experiments that our attention was directed to a paper by Landolt published in 1888 (Ber., 21, 191) in which he mentions that he has applied the same process of comparison to cane-sugar, milk-sugar, dextrose, invert- sugar, cholesterin, and turpentine oil, using a half-shadow V.-s.quartz instrument by Schmidt and Kaensch, and two polaristrobo- meters of Laurent and Lippich. The results are given only in the94 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE form of the values of one division of the V.-8. instrument in degrees of the sodium-light instruments, and are comparable with column B of the above table. He obtains for cane-sugar the value 0.3465, and for dextrose the value 0,3448, numbers remarkably close to our own, and indicative of the same want of exact correspondence of the rotatory dispersion of these two carbohydrates. We have still to consider the relation of the [a]j values to those of [a], in cases where the former value has been determined on the solids deduced from a divisor which differs sensibly from the true divisor.I n order to convert values of for instance, into [a],, it is not sufficient merely t o know the above-mentioned optical relations of [u]j to [a],, but we must know also the true divisor for the solids at the particular concentration at which the determination is made. The true value of [a]j is then obtained by raising the [a]j3.s6 value in the proportion of 3.86 to the true divisor, and [a]D is deducible directly from the result by applying the optical rela- tions of [u]j to [.ID given above. This will be evident from the following example. The specific rotatory power of maltose, in a 5 per cent. solution, when calculated on the basis of the 3.86 divisor for the solids, is [a]j,.86 150.5". On reference to the maltose curve of Plate I, we find the true divisor for maltose at this concentration is 3.934, and as the optical relations of [a]j to [a], for a substance of the dispersive power of maltose are as 1-111 : 1 the Value of [a], for maltose Calculated in this manner will be 3.934 3-86 150.5 x ---+1*111 = 138.05 The following general formula is applicable to the products of starch- hydrolysis for the conversion of Biot into [a],.where D, which is obtained by inspection of Table VIII., p. 84, is the true divisor for the part,icular grade of transformation, and for the particular concentration of the solution. IV. TTL~ Determination of the Cupic-~ecluciizg Powei.. I n determining the important factor of the cupric-reducing power of the products of starch-hydrolysis, we have hitherto adopted. a modification of the gravimetric method, described by C.O'Sullivan in 1876 (Trans., 1876, ii, 130), and provided the conditions under which i t is carried out are exactly defined and followed, it is one which isPRODUCTS OF STARCH-HPDROLY STS BY DIASTASE. 95 capable of yielding very consistent and concordant results. Careful attention must, however, be paid to the following points. (1). The exact composition of the Fehling’s solution, especially as regards the nature and amount of the alkali it co ntains. (2). The degree of dilution of the Fehling’s solution. (3). The restriction of the amount of copper reduced within certain prescribed limits. (4). The mode of heating the solution and the time occupied in reduction.* When all these conditions have been definitely fixed for any par- ticular reducing sugar, and the amount of Cu or CuO corresponding to 1 gram of the sugar under these conditions has been determined, there must be no deviation from them in any analytical process, If for any reason a deviation becomes necessary, the reducing power of the sugar in question must be again determined under the altered con- ditions.The following are the normal conditions under which all our deter- minations are made. 1. Composition of the Fehling’s solution, in grams per litre.? * An extremely important paper on the action of alkaline copper solutions on the sugars has recently been published by J. Kjeldahl (Rt%tone’ dz.4 Compte-rendi.4 des travat~x du laborntoire de Carlsberq, 4me vol., Ire livr. 1895), in which the influence of varying conditions on the amount of copper redticed is very fully discussed.It is shown that the amount of copper reduced by any given amonnt of sugar is appreciably decreased as the surface of liquid exposed to the air is increased ; that within certain wide limits the amount of soda has little influence on the reducing power of dextrose, but with maltose and lactose a different proportion of .soda exercises a considerable effect on the amount of copper reduced ; that the longer the liquid is heated the greater the amount of reduction, this being apparently due to spontaneous reduction ; that the extent to which spontaneous reduction takes place depends on the dilution of the Fehling’s solution; that the amount of copper reduced by a given weight of sugar is greatly influenced by the state of dilution of the Fehling’s solution : the greater the dilution, the smaller the reduction. Kjeldahl also gives an elaborate series of tables showing the amount of co1)pcr reduced by different weights of dextrose, levulose, invert-sugar, galactose, lactose and maltose under varying conditions.In making the determinations, Fehling’s solution of the same composition as that used by us was taken, but the heating was continued for 20 minutes, and all the reductions were made in hydrogen, the result being that Kjeldahl’s values for maltose are about 6 per cent. higher than those obtained by our method. We shall refer more fully to this work of Kjeldahl in a subsequent paper. .t. As Fehling’s solution is very prone to undergo change, it is essential that it should either be freshly prepared for each series of experiments, or be stored in two solutions and mixed when required.In the latter case, the shove quantity of copper sulphate is dissolved in 500 C.C. of water, and the Rochelle salt and alkali in a similar volume ; the two solutions are then mixed i n equal volumes immediately before each determination is made.96 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE Recrystallised copper sulphate.. . . . . . . . Rochelle salt ......... ... ... ... ... ... .., . . 173.0 ,, Anhydrous sodium hydroxide . . , . . . . , . 65.0 ,, 34.6 grams. As the oxidising power of the solution is very sensitive to small changes in the amount of alkali present, great care must be taken to ensure accuracy in the above weight of sodium hydroxide.* The influence of varying amounts of alkali will be more fully referred to later.2. The degree of dilution of the copper solution, after taking into account the volume of the sugar solution added, is one part of Fehling’s solution to one part of water; 50 C.C. of the undiluted Pehling being used in each experiment, and made up to 100 C.C. 3. An amount of the reducing sugar is taken which will give a weight of CuO lying within the limits of 0.15 to 0.35 gram. 4. The diluted Pehling’s solution is heated in a small beaker,? in R boiling water bath until the temperature is constant, and then the weighed or accurately measured volume of liquid containing the reducing substance is added, and the heating in the water bath continued for exactly 12 minutes, the beaker being covered with a clock glass during the whole period of heating.The filtration is per- formed as rapidly as possible through a Soxhlet’s tube under reduced pressure, and the cuprous oxide is either oxidised to CuO in a stream of oxygen, or is weighed as Cu after reduction in hydrogen. As the most carefully prepared Fehling’s solution always gives a very slight precipitate of cuprous oxide on heating, due to spontaneous reduction, it is necessary that this should be determined for every fresh batch of the solution, and be allowed for in the final result of each determination. This spontaneous reduction usually amounts to from 0.002 to 0.003 gram of CLIO per 50 C.C. of Fehling’s solution em- ployed. In order to conveniently compare the reducing power of various substances, it has been usual to refer the results to some definite standard, which is either that of dextrose or of maltose.C. O’Sullivan adopted dextrose as his standard, and referred the reducing powers of * The nature of the alkali in the Fehling’s solution is also important in dealing with the cupric-reduction of maltose and the starch-transformation products. This has recently been well shown by Glendinning (Trans., 1895, 67, 999-1002), who obtained considerably higher results when potassium hydroxide was substituted for the sodium compound. J t is necessary to bear this in mind, as in some analytical works the formula for Fehling’s solution contains potash in place of soda. .f. I t is important that the beaker used should always be of the same size and shape.In all our experiments the surface of the liquid had an area of 44 square centimetres.PRODUCTS OF STAKCH-HPDROLYSlS BY DIASTASE. 97 all substances to it, He took its specific reducing power as 100, and then a substance which had half the reducing power of dextrose, weight for weight, was said to have a specific reducing power of 50, whilst a substance having, say, one-tenth the reducing power of dextrose had a specific reduction of 10, and so on. O’Sullivan used the symbol K to express the specific reducing power so found, and in our previous papers we have used the symbol K to express the same value. When the solid matter, on which the reductions were calculated, was found by the 3.86 divisor, we have expressed this fact, just as we have done in the case of the specific rotatory power, by appending the figures 3.86 to the symbol.Thus K ~ . ~ ~ = 25 means that the reducing power of the substance is one-quarter that of dextrose when the solid matter is determined by the 3.86 divisor. I n referring the reducing power of the sugars to dextrose, O’Sullivan stated that, under the particular conditions he employed, one gram of dextrose reduced exactly 2.205 grams of QUO.* We find, however, that this value is only obtained if we employ conditions of reduction differing materially from those laid down above as our st,andard con- ditions for the estimation of the reducing power of starch-transforma- tion products. Thus, the commonly accepted value of 2.205 grams of CuO per gram of dextrose is only correct when the Fehling’s solution is diluted with considerably more water than that given above, when nearly the whole of the copper present is reduced, and when the amount of alkali in the Fehling’s solution is less than 65 grams per litre.Under our conditions, the amount of CuO reduced by one gram of dextrose varies between 2.558 and 2.321 grams, the exact amount depending on the extent to which reduction takes place. We shall refer more fully to this in a subsequent paper. Notwithstanding the fact that the ratio of 2.205 : 1 does not represent the true relation of CuO reduced to dextrose oxidised when working under our standard conditions of reduction, yet this does not in the least stultify the values of K or K, which have been given by O’Sullivan and ourselves in previous papers.It is only necessary to remember the basis to which the values are referred, and then there is no reason why this basis should not be a purely arbitrary one. As we shall presently show, one gram of maltose, estimated by the 3-86 factor, reduces under our standard conditions almost exactly 1.345 gram of CuO, and so long as this value is constant it is immaterial on what basis it is expressed, provided, of course, that all results are referred to the same basis, and that this is clearly stated. Thus, on the 2,205 basis the cupric-reducing power of maltose is ++ Since the above mas written, C. O’SulIivan and A. L. Stern have shown (Trans., 1896, 69, 1691) that under their standard conditions 1 gram of dextrose reduces about 2‘306 grams of UuO.VOL. LXXI. H98 BROWN, MORRIS, AND MILLAR: EXAMINATION O F THE 1.345 x'100 - 61 'o, - 2.205 and we have, therefore, hitherto always taken the K ~ . ~ ~ of maltose as 61.0. In order to convert the K 3 . s ~ values for maltose into absolute values, it is only necessary to raise the former in the relation of the true divisor for maltose for the solution employed (which may be obtained from the maltose curve of Plate I, p. 80) to 3.86. Thus if ill be the true divisor, then K& = K absolute. 3-86 Under the conditions which give us K3.86 = 61.0, we find that the value of K expressed on the true weight of anhydrous ma.ltose is 62.1. Another mode of stating the specific reducing power has been adopted, among others, by C. J. Lintner. It is one which is certainly very convenient in the case of starch-conversion products, although not applicable to all reducing substances.It consists in expressing the amount of Cu or CuO reduced by 1 gram of anhydrous maltose as 100, and calculating all other quantities of Cu or CuO as a percent- age on this amount. The symbol R is adopted for this value, and the specific reducing power of pure maltose is then R = 100, whilst a sub- stance 1 gram of which reduces half the amount of copper reduced by 1 gram of maltose has R = 50, and so on. The conversion of K or K into R is very simple when we have to do with the absolute value for the former, since by calculating the percentage of maltose we also get R, thus 5x100 = R (or the percent- 62.1 age of maltose). When we have to deal with K3.86, however, the conversion is not quite so simple, since we have to take into account the true divisor for the strength of the solution used.The calculation is then expressed by the following equation, where M stands for the true divisor for maltose- K3.86 x 15 x 100 = R. ____-__ 3.86 x 62.1 The foregoing considerations apply particularly to solutions of maltose, but when we have to deal with starch-conversion products the problem becomes more complicated, owing to the solution-densities of the individual constituents differing considerably from each other, as has been shown in a previous section. I n this case, when we require to convert K~~~ ifit0 R, it is necessary t o multiply the apparent percentage of maltose, deduced from K ~ . ~ , by the ratio of the true divisor for the starch-products to the true divisor for maltose.These factors can be obtained from the maltose curve and the table given on page 84,PRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 99 and then, if S be the divisor for the mixed starch-products and iM the frue divisor for maltose, the equation becomes K3.86- x 100 x s 61.OxM =R' In the following table, we give some results obtained by reducing Fehling's solution with maltose under our standard conditions, The determinations were made exactly as previously described : 50 C.C. of Fehling's solution were diluted to 100 C.C. with the sugar solution and water, and the heating was continued for 1 2 minutes. The quantity of sugar added was so arranged that the amount of copper weighed varied from 0*080 t o 0.315 gram.The final results are expressed as K3.86, K absolute, and R. TABLE X.-Cupi+ic-recluction f Maltose. - CuO cor- respond- ing to 1 gram of 3 *86 maltose. - CuO cor- respond- ing to gram oj absolute maltose. 1'377 1-389 1'412 1 *413 1'347 1'349 1'366 1-396 1.365 1'410 1'381 1-37] 1'376 1'373 1 *378 1.375 1.377 1 '383 Maltose by 3'86 divisor. Maltose absolute. cu. weighed. B, 99'3 100.1 101.8 101'8 97 '1 97'3 98'5 100'6 98'4 101 '6 100'4 99.7 100'1 99 '8 100.3 100-0 100.1 100'6 Kabsolute. 62.4 63 -0 64'0 64 *1 61 -1 61 -2 62'0 63.3 61 '9 63 *9 62-6 62 '2 62 '4 62 '3 62 5 62-3 62-4 62.7 62-2 62.3 61 *9 61.8 62.0 62 2 61 '8 0.0716 0.0728 0,0721 0 *0732 0.0750 0'0726 0.0709 0,0741 0.0707 0'0703 0.0787 0.0807 0-0812 0-0825 0.0806 0.0782 0.0773 0.0826 0.0770 0.0791 61'4 61 '9 63 *O 63.0 60-0 60 *1 60 *9 62'2 60.8 62 '8 0'0728 0.0740 0'0733 0'0744 0.0762 0.0738 0.0721 0.0754 0,0720 0.0716 0.1458 0.1475 0'1456 0.1471 0.1451 0.1465 0.1524 0.1457 1.354 1.366 1.389 1.390 1.325 1.327 1 '344 1.373 1.341 1.385 1.359 1 *349 1.354 1.350 1 -356 1 *3 52 1.355 1 *361 0.1434 0.1481 0.1432 0,1447 0.1460 0.1441 0.1499 0.1433 0.1581 0.1588 0'1573 0.1585 0.1606 0-1 581 0.1647 0'1582 61.6 61'1 61-4 61'2 61 *5 61 -3 61.4 61'7 0.2221 0.2185 0 '221 8 0.2428 0,2397 0-2411 99.9 100.2 99 '4 0.2262 0'2225 0'2259 0.2928 0'2913 0'2932 0.2931 1-371 1.373 1-365 1 -363 1.367 1'371 1 '363 1 '348 1.351 1.341 1 -340 1 -343 1 -348 1 *340 - 61.1 61-2 60 *7 60 '6 60 '8 61 -1 60.6 - 0,2880 0.2865 0.2884 0.2883 0'3124 0.3116 0-3152 0.3125 - 99.3 99 -5 100~0 99 '3100 BROWN, MORRIS, AND MILLAR : EXAMINATION OF THE It will be seen that with an increasing weight of Cu, there is a slight decrease of CuO corresponding t o 1 gram of maltose, but it may be taken that between the limits of 0.150 and 0.300 gram of copper the amount of CuO reduced by 1 gram of the sugar is practi- cally the same, the mean values between these limits being K3.86= 61.14, K absolute= 62.24, and R= 99-9.From the above experimental data, we have constructed the follow- ing table for the reducing power of absolute maltose. The table commences with 70 mgms. of the sugar, and rises by increments of 5 mgms. to 300 mgms., giving the amount of Cu and CuO reduced by each weight, and the amounts of Cu and CuO respectively reduced by I gram of the sugar when the respective quantities of copper or copper oxide are weighed.TABLE XI.--Reducing vcdues of vaying qucmtities of Mcdtose zcnderr* Xtc~nclcwd Conditions. 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 1E5 160 165 170 175 180 185 - *0772 '0826 '0880 '0934 .0988 '1042 *lo97 -1151 -1205 -1259 -1313 1367 '1422 '1476 13YU 01584 01634 *1692 '1747 '1801 -1855 *1909 *1963 '2017 *.I I..,. - - 5 % .A BCi zi *0966 '1034 *1102 -1169 *1237 '1305 -1373 '1441 -1509 *1576 -1644 -1712 ,1779 '1848 '1916 *1983 '2051 '2119 *2186 -2254 -2323 '2490 -2458 -2526 - 1.1029 1.1026 1'1023 1'1020 1.1017 1.1013 1~1010 1 *lo07 1.1004 1'1001 1.0997 1 -0994 1-0991 1 -0988 1.0985 1'0981 1-0978 1-0975 1.0972 1.0969 1 *0965 1.0962 1.0959 1.0956 1*3800 1'3796 1'3792 1'3788 1.3784 1'3780 1'3777 1'3773 1'3769 1-3765 1'3761 1'3757 1'3754 1.3750 1'3746 1.3742 1.3738 1.3734 1 -3731 1'3727 1.3723 1'3719 1-3715 1'3711 - 190 195 200 205 210 215 22 0 225 230 235 240 245 250 255 260 265 27 0 275 280 285 290 295 300 305 - ,2072 '2126 '2180 '223 4 '2288 '2342 '2397 '24 5 1 '2505 '2559 '2613 '2667 '2722 '2776 '2330 '2884 '2938 '2992 '3047 '3101 '31 5 5 '3209 '3264 '3318 - *2593 '2661 '2729 -27 97 '2865 2933 '3000 '3068 '3136 '3203 '3272 '3340 '3407 '3475 '3543 '3610 '3678 '3747 '3814 '3882 '3950 '4017 '4085 '4154 - sz 1'0953 1'0949 1 *0946 1.0943 1'0940 1.0937 1.0933 1.0930 1,0927 1,0924 1,0921 1,0917 1.0914 1*0911 1.0908 1.0905 1 *0901 1.0898 1.0895 1,0892 1,0889 1.0885 1,0882 1 *ON9 1'3708 1'3704 1'3700 1'3696 1.3692 1.3688 1 -3685 1.3681 1.3677 1.3673 1.3669 1.3665 1'3662 1.3658 1.3654 1 *3650 1.3646 1.3642 1 *3639 1'3635 1-3631 1 *3627 1.3623 1.3619PRODUCTS OF STARCH-HYDROLTSIS BY DIASTASE.101 With the aid of the foregoing table we can easily calculate the reducing power, R, of any starch-conversion product. The necessary quantity of the solution of the substance is accurately measured or weighed, and the amount of solid matter corresponding to this measure or weight is ascertained from the specific gravity and true divisor for the solution. The latter is obtained from the table given on p. 84, section I. The amount of copper or copper oxide given by this amount of substance is converted into maltose by means of the above table, and this is then calculated as a percentage on the amount of solid matter taken.The result is the reducing power, expressed as R. An example will perhaps make this clearer. 11.846 C.C. of a solution of specific gravity 1020.37 gave 0.1934 gram of metallic copper. The true divisor for a solution of this sp. gr. is 4.01, therefore 100 c,c. (reputed) contains 5.0798 grams of solid matter, and 11 $46 c.c., the quantity taken for the determination, 0*6016 gram. But on reference to the above table me find that 0,1934 gram of copper corresponds t o 0.1765 gram of maltose, Theref ore The reducing power may also be determined by calculating the weight of copper or copper oxide into grams per 100 c.c., and then using the gram equivalent, corresponding to the copper precipitated. Supposing in the above instance the copper had been weighed as CuO, the quantity per 100 C.C.would then be 2.047 grams. From the above table the amount of CuO corresponding to 1 gram of maltose, when the reduction is carried to the point of this experiment, is 1.3717. Then We have already referred to the necessity, especially when dealing with maltose and starch-conversion products, of keeping the amount of sodium hydroxide constant in the Fehling's solution I n some formulze for this solution, the amount of alkali used is 52 grams, and the folIowing results show the influence of this decreased amount of sodium hydroxide. The solution was made up as before, with the exception that 52 grams, instead of 65 grams, of anhydrous soda were used. The determinations were carried out in exactly the same manner as those given in the previous table, and the results are expressed in the same way.The quantities of copper weighed fall practically within the same limits as in the previous series of experi- ments.102 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE TABLE XI1 .- Cupric- yeduct i o n of Jfc& ose with Fehling's fl07ution contcuhing 52 g.l.nms of Xoclcc ye31 litye. Maltose by 3'86 divisor. 0.0715 0'0682 0.0689 0.0700 0.1398 0.1407 0.1362 0.1375 0'1484 0'1434 0'2800 0.2766 Maltose absolute. 0*070l 0'066 S 0.0676 0.0687 0.1375 0.1384 0.1339 0.1352 0'1456 0'1407 0-2753 0.2720 c u weighed. ~I 0'0814 0.0770 0-0788 0'0798 0.1567 0'1568 0'1541 0'1 541 0.1676 0'1618 0'3168 0.3105 CuO cor- respond- ing to 1 gram of 3.86 maltose. 1 *426 1.414 1 -433 1-427 1 *405 1 -397 1 *418 1.405 1-416 1'415 1.418 1.407 CuO cor- respond- ing to 1 gram of absolute maltose.1 *453 1 '44 1 1 -460 1,455 1.429 1 *420 1'442 1 *428 1'443 1 *441 1'442 1'431 - K3.86. 64.7 64 *1 65'0 64.8 63.7 63'3 64 -3 63 *7 64 '2 64'2 - Ktabsolute. 65 -9 65-4 66-2 66.0 64-8 64'4 65.4 64.8 65.5 65.4 65'4 64.9 - - R. 104.9 104.0 105'3 104.9 103.8 103'2 104.8 103 -8 104.9 104.8 105'3 .104-5 It will be seen from the above that the specific reducing power of maltose throughout the series is appreciably higher than when the normal amount of alkali is used, and from this it also follows that the amount of CuO reduced by 1 gram of maltose is also greater. If we bear this in mind, however, results obtained with Fehling's solution of the composition used in the above experiments can be converted with equal ease into R (the percentage of maltose).All that is necessary is that the mean values from the above table be substituted for the values given in the preceding equations, which then become K3.86 X M X 100 K3.86 x 100 x s 64-0 x M =R' = R. and 3.86 x 65.4 I n comparing our results with those of continental workers, there is still an important point to be considered, namely, the manner in which the determinations are made. We have already described the method adopted by us, and generally by English workers, but the majority of the continental chemists, who employ a gravimetric method, adopt an entirely different procedure for the determination of the cupric-reduction of starch-conversion products. This is known as Wein's method, and it appeared very desirable t o make a compari-PRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE.103 son, using identical reducing solutions, between this method and the one in use by ourselves. Wein’s method is described in a little book published by him in 1888, entitled ‘‘ Tabellen zur quantitativen Bestimmung der Zucker- arten.” This contains tables for obtaining the sugar values of varying quantities of copper for the majority of the reducing carbohydrates, but it is only with maltose that we are concerned at present. Wein makes up his Fehling’s solution in two solutions, which are prepared as follows. ( a ) Copper solution, 69,278 grams of carefully re-crystallised copper sulphate are dissolved in 1 litre of water, (b) Soda solution, 173 grams of Rochelle salt are dissolved in 400 C.C.of water, and mixed with 100 C.C. of a solution containing 516 grams of sodium hydroxide per litre. These two solutions are then mixed in equal volumes immediately before use. The undiluted Fehling’s solution thus contains 51 -6 grams of sodium hydroxide per litre. In carrying out the determinations, the quantity of Fehling’s solu- tion required for the sugar under examination (usually 50 C.C. are taken) is placed in a porcelain dish and heated to boiling over a naked flame. The necessary amount of the sugar solution is then run into the vigorously boiling liquid from a pipette, and boiling continued for a certain number of minutes, the exact time depending on the sugar under examination. After boiling for the requisite time, the precipi- tated cuprous oxide is quickly filtered off through a Soxhlet tube, and after reduction in a current of hydrogen weighed as metallic copper.For maltose the precise conditions are- 25 C.C. of copper solution, 25 C.C. of Rochelle salt-soda solution, and 25 C.C. of sugar solution, containing not more than 1 per and the boiling is continued for 4 minutes after addition of the sugar solution. In the following table we give the results obtained by us with the two methods when the =me solution of maltose was employed. We also extended the comparison to solutions of starch-conversions of different types. In column (1) is given the volume of reducing solution used ; in (2) the weight of solid matter corresponding to this volume; in (3) the amount of copper weighed, (a) when the determination was made according to Wein’s method, and (b) when made according to our method; in (4) the amount of maltose corresponding to (3), (u‘) calcu- cent.of maltose,104 BROWN, MORRIS, AND MILLAR : EXAMINATION OF THE 19'0 19.1 18.6 19'2 lated from Wein's tables, (b') calculated from the table given on p. 100; and in (5) the value of R, calculated on (2) (cc'') from Wein's results, (b") from the results by our method. TABLE XIII. 19'9 19.7 19'6 19.3 Pure Maltose. 2 3 4 I 5 1 Volume of solution taksn. Cu obtained. Weight of substance x. ____ 0.2422 , Y J J 0.d669 $ 7 J Y 9 9 Wein's method. a. By J\7ein's tables. a'. 0.2290 0'2298 0.2309 0 -2298 0.0919 0.0911 0.0902 0-0914 Own method. b. 0'2648 0'2650 - - 0.1081 0*1076 - I 6_' = b".2 100'04 100'1 - - 101.1 100.7 - - 25 C.C. f 9 Y , Y 9 10 C.C.) 9 ) 9 1 J Y 0.2591 0.2600 0'2612 0.2600 0-1060 0.1051 0.1041 0'1055 94'5 94 *9 95.3 94'9 94 9 94'0 93'1 94.3 0.2423 0'2425 - 0.0980 0-0976 Low Conversion, [ u ] j ~ 163.1 ; [U]D 149.7. 20 C.C. 10 C.C. 5 C.C. J Y 9 9 Y > 0'3410 O.ifO5 0 4 5 2 Y J 0'3C47 0.3058 0.1542 om^ 0.0781 I 0'0792 0.2697 0.2707 0.1352 0'1348 0.0672 0.0682 0.2825 0.2819 0.1397 0.0711 0.0702 - 79 *1 79.4 79.3 79 -1 78 '9 80.0 82.8 82 *7 81.9 83'4 82 '4 - 0.3085 0.3080 0.1533 0,0787 0.0778 - Medium Conversion, [u]js.sfi 186.5 ; [Q]D 173.9. 0.2472 0'2474 0.2492 0-0996 0.0997 0.0994 0 '2480 0'2513 0'0986 0*0990 - 0.2183 0'2185 0.2201 0.0863 0.0864 0.0861 0-2268 0.2299 0.0894 0.0895 - - 43*1 43.1 43 '4 42-5 42'6 42-4 44'8 45 '4 44 -1 44 '1 - - 25 C.C.2 , 9 , 1c C.C. Y ? 9 9 High Conversion, [ U ] j $ . s f i 203.6 ; [U]D 183%. 0'2231 0.2209 0*1107 0.1110 0.0550 0.0567 0.2235 0.2231 0'1 111 0'1098 0.0552 0'0544 0.1967 0.1948 0.0962 0'0964 0'0470 0,0483 0.2043 02039 0.1009 0,0997 0.0495 0.0488 20 C.C. 10 C.C. 5 C.C. 9 ) >, ,Y * Where less than 25 C.C. of the solntion of reducing substance was taken, it was made up to this volume with distilled water, so that the dilution was the same in all the experiments.PRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE. 105 VoIurne of solution taken. TABLE XIII-( continued). ~ Weight of substance x. Fractionated product, [a],3.sc; 194.0 ; [ u ] ~ 181.0. ~~ 3 I 4 1 5 Cu obtained. 1- Maltose found. R. 10 C.C. 11 7 ' 5 C.C. 7 ' 9 9 f. 0'5900 0*&50 1 9 9' 9 ' 0.2089 0-2090 0.2094 0.1059 0'1057 0.1043 0.2120 0'2101 0.2119 0-1072 0'1061 0.1038 0-1841 0'1841 0.1545 0'0919 0.0915 0.0903 0.1937 0.1920 0.1936 0'0973 0'0963 0.0943 31 '2 31 '2 31.2 31.2 31'0 30.6 32 -8 32'5 32.8 33'0 32-6 31 *9 From the above results, it is evident that any given weight of maltose or starch-conversion product, when oxidised under the con- ditions described in an earlier part of this section, reduces consider- ably more copper oxide than it does when oxidised under the condi- tions of Wein's method.This, however, would be immaterial in comparing the reducing power, R, of maltose or of a starch-conversion product,, arrived at by the two methods, if the table drawn up by Wein t3ruly represented the anhydrous maltose value of the copper reduced, Unfortunately, this does not appear to be the case, as when the maltose found by the Wein method and table is calculated as a percentage on the actual weight of maltose taken, the result, expressed as R, is almost exactly 5 per cent.lower than it should be; in other words, the R of pure maltose is 95 instead of 100 when determined according to W7ein. This difference is also found in the reductions made with conversions of different types, in all of which the reducing power comes out approximately 5 per cent. of R lower when determined by Wein's method and table than it does by our method and table. Thus with the medium conversion, Wein's method gives a mean R of 42.8, whilst R by our method is 44-6, the difference between the two being somewhat above 4 per cent,.; and the reductions with the other con- versions show a corresponding percentage difference. lyhat the reason of this is, we are not prepared to say, as in the book above referred to, Wein does not give any explanation of the way in which he obtained the experimental data on which the table is founded, and we have been unable, up to the present, to obtain a copy of the original paper (Allge. Brr*auei* u. Hopfesz Zeitung, 1885) in which the method was first described. It is, however, very important to remember that the reducing powers, given by workers who use Wein's106 BROWN, MORRIS, AND MILLAR: EXAMINATION OF THE table, are about 5 per cent. lower than the actual values, that is, they require t o be raised by about 5 per cent. of R in order to bring them into line with R as determined by our method and table.I n considering the experimental errors in the determination of the cupric-reducing power of maltose and starch-conversion products, we have to regard them from two standpoints. In the first place, there are the errors introduced by varying the conditions laid down for any given method of determination. These have been already touched on, and, moreover, in the paper by Ejeldahl previously referred to, the influence of such variations are so exhaustively treated that i t is unnecessary to further discuss them here. It suffices t o say that the precise condi- tions laid down for any particular method, must be rigidly adhered to, and, in case any slight deviation from the conditions is made, each worker must determine for himself the effect of this deviation on the final result.I n the second place, there are the experimental errors incidental to any particular method, when the conditions of that method are rigidly adhered to. Very extended experience has shown us that within the limits of CuO, mentioned on p. 96 (0.15 to 0-35 gram), the error amounts to 0.001 gram on the amount of copper weighed. This error is fairly constant within the above limits; it is therefore obvious that it represents a greater percentage error on the reducing power when the amount of copper weighed approaches the lower limit, than it does when the larger quantity of copper is reduced. Thus, with 0.15 gram the error amounts to 0.7 per cent. R, whilst with 0.35 gram the error is only 0.3 per cent.R. When smaller quantities of copper than 0.15 are weighed, the error appreciably increases, for not only is the percentage greater, but there also appears to be less stability in the reaction. We therefore consider that 0.15 gram is the lowest permissible amount of copper oxide which should be reduced, and we prefer that the amount should fall between 0.25 and 0.30 gram. When the experiment is so arranged that the amount of copper oxide reduced falls within the last-mentioned limits, we regard the maximum experimental error as falling within 0.5 per cent. of R. V. On the Limits of Accumcy of the Methods EmpZo?jed. I n the determination of specific rotatory power, the value of [u] in the formula [u] = LXC will be most influenced by (1) actual errors of instrumental reading, which are included in cc, and (2) by the greater or less exactness of the factor c, which represents the concentration or the weight of substance in a given volume of the solvent. The error int,roduced by any want of accuracy in the length of the 1 O"aPRODUCTS OF STARCH-HYDROLYSIS BY DIASTASE.107 column of liquid can, of course, always be allowed for if necessary, but in our case no correction was made for this as the 200 mm. and 100 mm. tubes used were found to have a length of 199.99 mm. and 99.99 mm. respectively, a t a temperature of 18".* Provided the polarimetric readings are taken at approximately the same temperature as that at which the density is determined (in our Case 15*5"), there is no appreciable error introduced in the readings of solutions of the products of starch-hydrolysis ; where, however, it is a question of establishing constants for the pure carbohydrates, the readings must be made at an exactly known temperature.As regards (l), the actual error of reading in our Ventzke-Scheibler half-shade instrument is certainly not more than kO.05 of a scale- division o n mazy single obsesvation, which represents +, -01 9 degree of arc for Biot's juur/ze n20ye.12 ray, or f *017 degree for sodium light. On a series of readings, the error is much less, and we are over-stating it a t +, 0.009 of a degree for the jnwze moyen, and +, 0408" for sodium light. This probable error is, of course, const,ant for large or small readings alike, and the extent to which i t will affect the specific rotatory power depends on the magnitude of the total reading as conditioned by the concentration of the solution, the length of column, and the specific rotatory power of the substance or mixture of substances we are dealing with.A solution of cane-sugar of sp. gr. 1036.54 (about 9.4 grams per 100 c.c.) gave a reading in the 200 mm. tube of 32.88 scale-divisions for sodium light. The probable error on a series of observations, as we have already seen, does not exceed 0.025 scale-division, which is 0.076 per cent. of the total reading in this case. As the specific rotatory power of cane- sugar a t the above concentration is [.ID 66.45", the error of reading will not affect this value more than +_0.05". For a concentration of half the amount., that is, about 5 grams of sugar per 100 c.c., errors in readings in the 200 mm. tube will be liable to affect the specific rotatory power & 0-10". In working on the products of starch-transformation, we generally have to deal with solutions varying in concentrations between 4 and 10 grams per 100 c.c., and with substances varying in specific rotatory power between [ a ] D 202*Oo and [a], 138". It can readily be shown, as in the case of the cane-sugar example given above, that a 0.025 error This is shown by the following concrete example. in the scale reading will influence the specific rotatory powers from [a], 0.04" to [a], 0*10". -With regardto (2), the possible error in the value of c, this is the product d x p , that is, the density of the solution by the percentage * We are indebted to Mr. W. Watson, of the Royal College of Science, for these measurements.10s BROWN, MORRIS, AND MILLAR : weight. If the weight of substance in a given volume is already accurately known, a small error in d will make very little difference in the value of [a]. If, however, as is usually the case in experiments on the products of starch-hydrolysis, the percentage weight 23 has to be determined from the demity of the solution, then this density has to be determined with the greatest accuracy attainable. The error in our determinations of the specific gravity of the liquid by means of the pyknometer or the Sprengel-tube is not more than 0.01 when water is taken a t 1000. The influence of this source of error has to be considered from two points of view, (A) as an error in the actual determinat,ion of the density of the solution under experiment, and (B) as an error in the previous determination of the divisor which has to be applied for the determination of the true weight of solids. If we confine ourselves to the products of starch-hydrolysis of a concentration of from 4 to 10 per cent. or thereabouts, that is, to solutions having a density of from about 1015 to 1040, and varying in specific rotatory power from [a], 202" to [.ID 138", it can readily be shown that the experimental errors due to A will fall between [a]D 0.03" and [a], 0.14" ; and as the determinations of the divisors are subject t o the same errors which will equally affect the specific rotations, we arrive a t the conclusion that even if the errors of A and B are curnu- lative, that is, are both plus, or both minus, their sum must lie be- tween [a], 0*06", as a minimum, and [a], 0.28" as a maximum, that is, a mean error of [a],, 0.17". When the calculations of the specific rotatory powers are not referred to water at 4", that is, to t m e cubic centimetres, and the correction for air displacement is not made, the values of [ a ] , as we have seen in a previous section, will be about 0.2 per cent. below their true value. The limits of accuracy of the cupric-reducing methods have already been referred to in Section IV, p. 106. A word still remains to be said on the corrections to be applied to starch-transformation products when the hydrolysis has been conducted with malt-extract, or with a diastase solution where solids bear any sensible proportion to the amount of the products of starch-hydrolysis formed. The precautions to be taken in such cases have been SO fully described in a previous paper (Brown and Heron, Trans., 1879, 35, p. 601) that it is only necessary to allude to them very briefly. As the properties of malt-extract undergo slight changes under the action of heat, it is a matter of importance to determine the specific gravity, optical activity, and cupric-reducing power of the transforming agent after it has been heated up to the point at which the transformation is t o be carried out, and for the same length of time as is occupied by the hydrolysis. An accurate correct'ion can then be made for the amount of transforming agent used.

ISSN:0368-1645    

DOI:10.1039/CT8977100072

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

SPECIFIC ROTATION OF MALTOSE AND OF SOLUBLE-STARCH. 109 No. 3 2 3 4 5 6 7 8 9 VI.--Spec$c Rotation o j Mccltose ccncl of Soluble- sta.l'ch. By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., AND J. H. MILLAR. XTeight. per cent. P. 4.95 9.70 18'65 18-67 19.68 19'91 33'e6 34-72 34.95 FOR a successful investigation of the laws which regulate the hydro- lysis of atarch by diastase, it is essential to determine with the greatest possible accuracy the specific rotation of soZubZe-stu~*c7~, the first sub- stance formed on the liquefaction of the starch-paste, and of maZtose, the final product of the reaction. The specific rotation of maltose has of late years been investigated by Meissl (J. p. Chem., 1880, [a], 21, 274) and by Ost (Chenz. Zeit., 1895, 19, 1501) with special reference to the influence of varying con- centration and temperature.Meissl found that the value of [.ID diminished as the concentration and temperature increased. The following table gives the summary of his results. TABLE I.-S~3eciJic Rotictioiz of Mcdtose according to Meissl. 15". 138 -67" 138'79 138'56 138'68 138'70 138.50 138.35 138'26 133.34 138.46" 138.54 138.33 138.40 138'30 138.39 138'12 138.00 138'11 137'97" 137'84 137'57 137'68 137-59 137'55 137.33 137.29 137'40 137.08" 136.95 136.75 136.79 136.66 136.61 136-38 136.37 336.48 From these data, Meissl deduces the following general formula for the calculation of the specific rotatory power of maltose for all concen- trations between 5 and 35 per cent., and for temperatures between 15" and 35"- [.ID= 140.375 - 0.01837 P - 0.095 T, where P represents the per- centage of anhydrous maltose in the solution, and T the temperature in degrees Centigrade.The experiments were made with carefully purified, cystallised,11 0 BROWN, MORRIS, AND MILLAR : SPECIFIC ROTATION hydrated maltose, in a portion of which the water was previously determined by drying in a vacuum at 100". Ost, on the other hand (Zoc. cit.), denies that the concentration of the solution has any influence on the specific rotation between 2 and 21 per cent., and states that at 20" the value within these limits is The previous determinations by one of us and Heron (Trans., 1879, 35, 619), of the specific rotation of maltose, for concentrations lying between 5 and 10 per cent., pointed to the value 150.4" ; this, when reduced in the manner described in our previous paper (this vol., p.94), is found to be [a], 137.7" or [u]jBiot 153.1". This value lies between Meissl's and Ost's numbers, and agrees very closely with the specific rotation originally ascribed to maltose by O'Sullivan, whose mean result mas [ ~ I j 3 . 8 5 150.2", corresponding We have now made a further investigation of this subject, using maltose which had been purified with the greatest possible care. As it was not our object to determine the influence of temperature, but only that of Concentration, the readings in the polariscope were all taken at the same temperature of 15.5". [.ID 137.04". to [ u ] j 153*5", and to [.ID 138.1". TABLE II.--X'cij$c Rotation of Xcdtose at 15 5" in vcc~ying concentmtions.I Grams of anhydrous Maltose. 2.4574 2-5183 4.9352 5.7716 5.8530 9.8420 11.251 12-801 15'577 20 830 21.695 25'899 3i.840 Density of solution a. 15'50/15.5e. 1 *00968 1.00992 1.01942 1.02870 1 '02302 1.03863 1 '0441 3 1'05017 1.06097 1'08128 1.08457 1 -1 0072 1'14595 - 111 Density of solution d. 15'5°/4.~o. 1.00873 1 -00897 1'01845 1,02173 1 -02204 1'03762 1.04311 1.04914 1'05992 1-08018 1 *08347 1.09959 1-14472 - IV Percent- age of Maltose P. 2,4339 2.4935 4.8411 5.6435 5.7213 9.4759 10'775 12.189 14'679 19'264 20.004 23'529 33.020 - V Degrees of rotation for Na light. 6.7796 6.9422 13'6077 15 -89 7 5 16 -1 327 27.0770 30.9753 35.2541 21.4521 28'6751 29 -847 7 3 5 '5931 103-8166 VI E ah. 138.06" 137'96 137.99 137'85 137.94 137.99 137'94 137.99 138.03 137'80 137.71 137.57 137.36 VII 1 VIII 153'39 153.27 153'31 153.15 153.25 153.30 153'25 153.30 153'35 153-09 152-99 152.84 152'60 150.30 150.20 150'42 150.34 150.44 ~ 180.77 150 -82 150'99 151.27 151.51 151-46 151.69 152.71OF MALTOSE AND OF SOLUBLE STARCH. 111 The determinations were made on pure hydrated maltose, and the solutions were allowed to stand sufficiently long for the effects of bi-rotation to disappear. The weight of anhydrous maltose in a definite volume or weight of the solution, given in column I, was determined from the specific gravity by means of the divisor-curve for maltose given in the preceding paper.This is a method which we find t o be quite as exact as that of rendering the hydrated maltose anhydrous in a vacuum over phosphoric anhydride, and very much more accurate than the method employed by Ost, and referred to later on, of weighing the hydrated substance, and calculating the corresponding amount of anhydrous maltose. The divisor-curve referred to was constructed from a large number of careful and concordant deterrnina- tions, the maltose being rendered anhydrous by heating in a vacuum over phosphoric anhydride.As we have already referred to these points very fully in our previous paper, and to the limits of error of the method, it is unnecessary to dwell further on them here. We give, however, one or two examples showing that the specific gravity method gives results quite comparable with those obtained by direct weighing. Hydrated maltose was dried in the vacuum apparatus in the usual way until eonstant in weight, the temperature being gradually raised from 50" to 108".The dry product, weighing 10.4928 grams, mas dissolved in about 35 C.C. of water. The weight of the solution mas 41.8967 grams, and its sp. gr. a t 15.5" mas 1107.S4 (water a t 15.5"= 1000). This gives a concentration of 27.745 grams per 100 C.C. (reputed).* If we calculate the anhydrous maltose present in the solution by means of the divisor for the sp. gr. 1107.84, as deduced from the curve for maltose, we find the weight of sugar to be 10.4976 grams, against 10.4928 grams actually weighed in the anhydrous state. This difference of 0-0048 gram, equal to 0.04 per cent., will only affect the specific rotation t o the extent of 0.05". I n the following Table, the specific rotatory power was based upon actually weighed quantities of the dried anhydrous maltose.It will be noticed that the values correspond with those for similar concentrations, as given in Table 11, where the weight of substance was deduced from specific gravity. * For t h e meaning of this term, see preceding paper (p. 77).112 BROWN, MORRIS, AND MILLAR : SPECIFIC ROTATION 138.05" 138'04 TABLE 111. 153.38 153.37 I I-;- -- 4'9596 1 1.03883 1 1'03782 ~ 9.5179 3,7107 1 1.03967 , 1.03866 9'7220 I v Degrees of rotation for Na light. 27.274" 2; *880 VI 1 VII 150%8" 150.67 The density given in column I1 of both of the previous tables is taken a t 15.5" and referred to water a t 15.5". I n column 111, the density a t 15.5" is referred to water at 4", as is usual in such calcu- lations.(See preceding paper, p. 85). Our experiments indicate that there is practically no difference in the specific rotation of maltose in concentrations lying between 2 and 20 per cent.? Between 20 and 30 per cent., there is a very small decrease in specific rotation as the concentration increases, but it is much less than accords with the formula of MeissI, whose numbers are all sensibly greater than ours. So far, our general results agree with those of Ost,, but the actual values which we obtain are sensibly greater than his after reducing the results to a uniform temperature. Our average value at 15.5" between 2 and 20 per cent. solutions, as shown in Table I, is [ a JD 137.93, whereas Ost gives, for a temperature of 20", [aID 137*04", within the same limits, If we apply Meissl's correction for temperature to Ost's number, we obtain the following comparison.[a],, of Mdtose C L ~ 15.5", ccnd in concentmtions between 2 and 20 pep* cent. Ost .................................... 137.46" Our determinations ............... 137.93" It is not difficult t o see how this small discrepancy has arisen. + Although the values of [a]D and [a]j are remarkably constant within theabove- mentioned limits of concentration, it will be noticed that there is a slight increase in the values of [ a]j3. This is, of course, due to the fact that these values are calculated on a constant divisor of 3'86, instead of on a divisor gradually decreasing as the coilcentration increases. This is a fault inherent t o this mode of expressing specific rotatory powers, but the difference is so small in the lower stages of concentration, within which the products of starch-hydrolysis are generally examined, that it does not vitiate any of the older analyses, or the con- clusions drawn from them, where a uniform value for maltose has been taken at [ a ] ~ ~ .~ ~ 150'0" with increasing concentration.OF MALTOSE AND OF SOLUBLE STARCH. 113 The determinations of Ost mere all made on weighed quantities of hydrated maltose, which had been dried in a desiccator over sulphuric acid until constant in weight. The anhydrous maltose was then cal- culated on the assumption that a substance of the composition Cl2Hz2Ol1,H20, and containing, therefore, exactly 5 per cent. of water of crystallisation, was being dealt with.We have always found that hydrated maltose, although readily acquiring a constant weight when dried in the desiccator in this manner, invariably contains, even after several weeks' drying, an amount of water greater than that corresponding to 1 molecule. This is shown by the loss in weight which the hydrate subsequently under- goes when dried carefully in a vacuum over phosphoric anhydride in the Lobry de Bruyn apparatus, and in such a manner as to preclude the possibility of any decomposition taking place. The specimens I and I11 had been crystallised from alcohol of 80 per cent. ; whilst I1 was crystallised from water. The following experiments illustrate this point. Aoss of weight 0 t h complete d+ng of hydrated maltose wlhich had been previously di-iecl iw, the desiccator over sulphuric acid.Percentage of H,O lost i n vacuo over P205. Hydrate in desiccator. on heating I 5 days .............................. 5.40 I1 10 days .............................. 5.43 111 45 days ............................. 5-56 The average amount of water retained by the hydrate is 0.46 per cent. in excess of that corresponding with the 1 molecule, conse- quently the specific rotatory powers of anhydrous maltose, based on weighings of the hydrate, as in Ost's experiments, will be about one- half per cent. too low. Ost's values must, in fact, be raised in the proportion 94.54 : 95.00 in order to give true values. We can now make a final comparison between our number and that of Ost, after this correction has been applied. Spci& rotato?-y power of anhydrous maltose at 15*5", ccnd at concentra- tions between 2 and 20 per cent.Ost (corrected) ................................. [a],, 138 -1 2" Brown, Morris and Millar .................. ,, 137.93" These values are in very close accordance with each other, and it is clear that within the limits of concentration mentioned above we may VOL. LXXI. T114 BROWN, MORRIS, AND MILTIAR : safely take the specific rotatory power of anhydrous maltose as fa], 138.0". For the determination of the optical properties of soZubZe-sta!wh, we have found it convenient to use the soluble-starch prepared by C. J. Lintner's method, rather than the first product of the liquefaction of starch-paste with diastase, with which it is undoubtedly identical. Lintner's substance is prepared by the limited action of 7.5 per cent.HCl on purified, ungelatinised potato-starch in the cold. Its properties have been fully discussed in a previous paper, On the Amylodextrin of W. Nageli and its Relation to Soluble-Starch " (Brown and Morris, Trans., 1889, 55, 449). When quite pure, it is devoid of any cupric-reducing power, but in order to obtain it in this state, it is necessary to limit the action of the acid to a few hours, until the starch-granules, after being freed from acid, dissolve in hot water without the formation of a viscid solution, The following are some of the experimental numbers obtained €rom an examination of various specimens. Column A gives the specific rotatory power calculated as [ u ] j on the basis of the 3-86 divisor ; column B gives the cupric-reducing power in terms of dextrose ; and in column C we have given the specific rotatory power, on the 3-86 basis, of the amylin constituent, on the assumption that the small reducing power of I1 and I11 is maltose. A B C K386 0 11 215.1" 1-16 2 16.3" I11 216.0" 0.56 216.0" The results point to a value of [ a]j3.R6 2 16" as being very close to the true specific rotation of soluble-starch, and this value coincides with all previous determinations. As we have given in the preceding paper (this vol. p. 78) the determinations of the solution density of soluble-starch, it is easy t o convert the above number on the 3.86 basis to true values of [ u ] j and [ a]D respectively. The mean divisor for soluble-starch for concentrations of from 2.5 to 4.5 per cent. is 4.012 ; [ u ] j will, therefore, be expressed by raising 216 in the proportion of 3.86 to 4.012, and the value of [.ID will be obtained from the formula given in this vol. p. 94, substituting 4.012 for D. On the three methods of notation, me then have the following expressions for the specific rotatory power of soluble-starch. [U]j3.s6 216.0". [ U ] j ~ p , ~ ~ l ~ & 224.4". [a], 202.0".

ISSN:0368-1645    

DOI:10.1039/CT8977100109

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

RELATION O F SPECIFIC ROTATORY POWER, ETC. 115 VI1.-The Relation of the SpeciJic Rotatory and Cupric- reducing Powem o f the Pyoducts of Staych- ilydl.olysis by Diastwse. By HORACE T. BROWN, F.R.S., G. HARRIS MORRIS, Ph.D., and J. H. MILLAR. IT is a fact familiar t o all who have given even the most passing attention to the phenomena of starch-hydrolysis by diastase, that in the progressive stages of the reaction the power of the solution to rotate a ray of plane polarised light gradually diminishes, whilst there is a corresponding increase in its capacity to reduce cupric salts. That the two functions of the hydrolysed products, namely, specific rotatory power and cupric-reducing power, stand in some very intimate relation to each other, followed, as a matter of course, from the con- clusions drawn by O’Sullivan in 1876, and described in his epoch- making paper, ‘( On the Action of Malt-extract on Starch ” (Trans.1876, ii, 125). Four years prior to this, O’Sullivan had shown that the end-product of the action of malt-extract on starch-paste was the sugar maltose, and that if the action were arrested before the conversion of the starch into sugar were complete, it was possible to isolate two dex- trins, a and p, which have the same action on polarised light as soluble-starch. Although he never succeeded in obtaining either of these dextrins absolutely devoid of reducing power, yet such a close approximation to this was attained that he felt justified in concluding that, in a perfectly pure state, they would exert no action on cupric salts.I n the section of his 1876 paper devoted to the proof that maltose and dextrin are the only products of the reaction, O’Sullivan, for the first time, clearly showed that there is a definite relation between the rotatory power and reducing power of the products of transformation. He found this relation to be of such a nature tbat if he calculated the reducing power of the mixed products as maltose, and assumed the difference in weight between this and the total solids to be dextyin with optical properties identical with those of the dextrins he had previously described, then, on re-calculating the specific rotatory power of such a mixture of maltose and dextrin, the value he obtained was in very close agreement with the observed specific rotatory power.O’Sullivan’s subaequent work (Trans., 1879’35, 770) fully confirmed this relation, as also did the work of one of us and Heron, published in the same year (Trans. 1879, 35,596). I 2116 BROWN, MORRIS, AND MILLAR : RELATION OF THE In 1885 (Brown and Morris, Trans., 1885, 47, 527)) we subjected the non-crystallisable products of starch-hydrolysis to a more rigorous examination, and although we were able to show that there exist substances of definite composition intermediate between soluble-starch, on the one hand, and its penultimate products of hydrolysis, the dextrin of the so-called " No. 8 equation " and maltose, on the other, yet the previously-expressed relations of rotatory and reducing power still held good, even for these intermediate products : that, in fact, the composition of the mixed starch-transformation products, at any stage of the yeaction, or the composition of arty jkcctionchted portion of these poducts, could always be consistently expressed in terms of nzcdtose, and of a non-reducing d e x t ~ i n having a rotatory power of [a]j3.ss 216".From this, it naturally followed that if one of the two functions, rotation or reducing power, were known, the other could always be calculated. In view of the large amount of experimental proof of this relation which has been accumulated by workers in this country during the last twenty years, i t is remarkable that this most fundamental principle has not been recognised by some Continental chemists, whose work on starch during the last five years has attracted much attention.C. J. Lintner, for instance, in a recent contribution to the subject (2eitsclw.f. d. ges. Brauwesen, 1895, 255), sums up his opinion by asserting that the law of definite relation of the optical and reducing powers of starch-products is an artificially constructed one, which in no way corresponds t o the actual conditions, and that it depends on the unproved and unprovable assumption of the existence of a non- reducing achroo-dextrin. Still more recently, we find Ost stating (Chem. Zeit., 1895,19, 1510) that he has been unable t o substantiate the relation between opticity and reducing power of starch-products which is said to exist by English chemists. It is evident that both these observers have entirely failed to under- stand the terms in which this law of relation has hitherto been expressed, and, so far from their own observations disproving the existence of such a relation, they are strikingly confirmatory of it, as we shall see later on.The evidence so far accumulated that, at a certain stage of the reaction, the products of hydrolysis consist of maltose and a compara- tively stable dextrin, which has no reducing power and is very resistant to further hydrolysis, appears to us to be unmistakable, and, hitherto, for convenience' sake, we have preferred to express the law of relation in terms of these two products. The expression of the rela- tion is, however, capable of being put in a much more abstract form,SPECIFIC ROTATORY AND CUPRIC-REDUCING POWERS, ETC. 11 7 and that without pre-judging in the slight'est degree the true nature of the products of hydrolysis; in fact, if we knew absolutely nothing of the true chemical changes attending stmch-transformation, the relation between rotation and reduction would be just as readily expressed, and with one property known, it wouId be possible to predict the other.In the following table, we have given, in columns I, 11, V and VI, the experimental numbers obtained in the examination of a large number of starch-transformations, the reaction having been arrested at various stages of the hydrolysis. Besides the analyses of the total mixed products of starch-hydrolysis, we have included a considerable number of examinations of fractionated products, obtained by precipi- tating the mixed products with alcohol of various strengths.These are distinguished in the table by the letter F being appended to them. The reducing powers and specific rotatory values have been worked out according t o the two methods most generally in use. Columns I and I1 give the values, deduced from the 3.S6 divisor, of K and [ a ] j , the reducing power K being referred to an empirical dextrose reduction, as explained in our previous paper. Columns V and VI, on the other hand, give the absolute values for R (maltose = 100) an3 [a],, on actual weights of starch-products, as deduced from their proper divisor according t o Table VIII of a previous paper (p. 84). TABLE I.-The optical and ?*educing yopes.ties of stai.c~-ti.ccnsformationa of vn~ious yvacles. I - - F. F. F. F. F. F. F. F. F. F.F. I K3.86 (Experi- mental). 1 -2 4.8 4 *8 5.5 5.0 5 *5 4.9 4.9 10.1 10'1 10.1 10-5 10'5 13 2 13'2 12'4 11.7 13'6 [ a J j 3 . 8 ~ (Experi. mental). 215.1 21 1 *2 209.9 209.3 209.3 209.3 209.1 209.1 205 '6 204.6 204'6 204.3 204'3 202'4 202.4 202'2 202'2 201.5 I11 [ a I j 3'86 :alculatec from K3'86. 214'7 210'8 210.8 210'0 210% 210.0 210.7 210.7 205'1 205.1 205'1 204.6 204% 201 -7 201.7 202'6 203.3 201.3 1V liffereiici +0'4 + 0-4 - 0.9 - 0.7 - 1.3 - 0.7 - 1 . 6 - 1'6 +O-5 - 0.5 - 0.5 - 0.3 - 0.3 + 0.7 4- 0.7 - 0.4 - 1.1 + 0.2 v R :Experi iiental) --__ 9 q-j 7 9 i . 9 9 '1 8.3 9 '1 8 '1 8'1 16.7 16.7 16.7 17'4 17'4 21 '9 21 '9 20.5 19-4 22 '5 TI ~ [ a ] , (Experi- mental). ~- 201 '4 197.6 196.4 195.9 195.9 195.9 195.7 195.i 1922 191-3 191-3 191 -0 191.0 189.1 189.1 188.9 188'9 188'2 - v1 I [alp :alcularec from R.. _ _ _ 200.7 186.9 196.9 196-1 196'6 196'1 196'8 196.8 191.3 191.3 191'3 190.8 190.8 188.0 188.0 188'8 189.5 187'6 TTI I T Iifference __ ~~ +0.7 + 0.7 - 0.5 - 0-2 - 0.7 - 0.2 - 1.1 - 1.1 + 0.9 0-0 0 '0 t- 0.2 + 0.2 +l+l f l . 1 + 0.1 - 0.6 f 0 - 6118 BROWN, MORRIS, AKD MIILLAR: RELATION OF THE TABLE I. (continued )-Fh optical und ?*educing p o p w t i e s oJ starch- trcmxformations of various grudes. - - F. F. F. F. F. F. F. F. F. F. F. F, F, F, F F F F F F 9 F E E I - I W E 6 Experi- iental). 13.9 13.4 13'0 14.1 15.5 14.5 14'4 15.9 18 -6 18.7 18'8 18'9 19.6 20 *1 20 *7 22 *o 23-2 25.2 24 *8 26 *6 26 -4 30.4 30.5 34'4 36.6 39-2 40'7 44.5 46'6 45'8 49.5 48-8 49 -5 49.4 49 '3 49'6 49 *3 49 -1 49.7 49.2 51 '1 5 2 5 54 '4 55.7 55-9 56 '0 56.2 56 '2 56.5 56 *7 57 6 57.8 - I1 : a1 j 3 .8 ~ Expen- iental). 201.2 201.0 200'6 200'4 199-5 199'1 198.7 198.2 196.4 195-4 195'1 195.0 194.4 194.2 193.6 192'4 190.3 188'7 188'1 187'6 186.7 184'6 182.1 177.7 176.1 173.9 173.0 168% 167.2 165.8 163% 163-3 162.9 162.7 162.4 162.3 162.3 162.1 162.1 162.0 160'3 160.3 157'6 156-9 156.4 156.2 155.5 155'5 154.7 154.2 154.1 153.0 201'0 201.5 201.9 200.7 199.2 200.3 200 '4 198-8 195.9 195.8 195.7 195.6 194.8 194-3 193.6 192.1 190*9 188.7 189-2 187-2 187.4 183.1 183 0 178.8 176'4 173.6 172.0 167.8 165% 165.6 162'4 163.2 1624 162.5 162 -7 162.3 162.7 162'9 162.2 162.8 160.7 159.2 157'1 155.7 155.5 155.4 155.2 155-2 154.9 154.6 153'7 153-3 - + 0'2 - 0.5 - 1.3 - 0.3 +O-3 - 1.2 -1.7 - 0.6 + 0 5 - 0.4 - 0.6 - 0.6 - 0.4 -- 0.1 0.0 + 0 * 3 - 0.6 0 .o - 1.1 $0-4 - 0.7 +1.5 - 0.9 - 1.1 - 0.3 +0*3 +1'0 +0*8 +1'6 $ 0 ' 2 3.1'2 $ 0 1 +0*5 + 0'2 - 0.3 0'0 - 0'4 - 0'8 - 0.1 - 0'8 - 0'4 +1'1 +0'5 +1-2 +0'9 3-0'8 + 0 ' 3 +0*3 - 0 '2 - 0'4 +0-4 - 0'3 23.0 22.2 21 -5 23-3 25 *7 24 .O 23 -9 26 *3 30.8 30.9 31 -0 31.1 32-4 33 *3 34.2 36.4 38 -4 41.7 41 -0 44.0 43.6 50 *2 50 -3 56.7 60 -3 64 -5 67.0 73 *1 76 -5 75.2 81.2 80 .o 81 *2 81 '1 81 *o 81'3 81 *O 80.8 81 '4 80 '9 83 -7 86'0 89'0 91 '1 91 '4 91 *5 91 -9 91 '9 92-4 92.7 94'1 94'4 TI c .ID Experi- iental.) ~ _ _ 187'9 187 *8 i87-4 187.2 186.3 185-9 185.5 185.0 183.2 182.3 182 .O 181.9 181 *3 181.0 180.4 179.2 177.4 175.6 175.1 174.5 173.7 171.5 169.2 164.8 163-1 160 *9 160.0 155.6 154.2 152.9 150 *6 150'4 150.0 149.8 149 '6 149.5 149.5 149'3 149'3 149'2 147'5 147'5 144 *7 144.0 1435 143'4 142.7 142'7 141.9 141.5 141'2 140 '2 1-11 [alp lculated from R.187.3 187 -7 188'2 187.0 185 5 186'6 186.7 185.1 182.3 182'2 182.1 182.0 181.2 180.7 180.1 178'7 177'4 175.3 17'5'7 173'8 174'1 169'8 169'8 165.7 163'4 160.7 159'1 155'2 153-0 153.7 160 *o 150'8 150'0 150.1 150'1 149 '9 150'1 150.2 149'8 150.2 148 -4 146.9 145'0 143'7 143'5 143'4 143.1 143'1 142.8 142% 141-7 141'5 VIII ff eren c e __- -- +O% + 0'1 - 0'8 + 0.2 -1-0.8 - 0.7 - 1.2 - 0.1 + 0.9 +0.1 - 0.1 - 0.1 -0.1 +0*3 f 0 . 3 + 0.5 0 *o +0.3 +O% +0*7 + 1.7 - 0.6 - 0.9 - 0.3 f 0 ' 2 + 0 '9 + 0.4 + 1 -2 - 0.8 + 0% - 0'4 0-0 - 0.3 - 0.5 - 0.4 - 0% - 0'9 - 0.5 - 1 .o - 0.9 + 0.6 - 0.3 +0*3 0 *o 0 *o - 0.4 - 0'4 - 0.9 - 1'1 - 0.5 -1'3 - 0.4SPECIFIC ROTATION & C U Q R I C - R E D U C I N G POWER O F STARCH CONVERSION PRODUCTS OF TABLE J 20 40 6r7 8U IUUZSPECIFIC ROTATORY AND CUPRIC-REDUCING POWERS, ETC.II 9 If we plot the experimental numbers of columns I and 11, or of V and VI, of the above table on a system of rectangular co-ordinates, the degrees of specific rotation bet ween soluble-starch and maltose being represented on the line of ordinates, and the cupric-reducing powers from soluble-starch to maltose on the line of abscissz, we at once see that the experimental values ull f u l l practically on a siPc6ight line, joining the points of intersection of the co-os.dinutes corvesponding to the optical and ?*educing poperties of soluble-stccrch and of maltose respective ly.This is shown on the Plate, for R and [a], of columns V and VI, and exactly the same result would, of course, be obtained by plotting the values of K ~ . ~ ~ and [a]js.sG of columns 1 and 11.” The fall of specific rotation is strictly proportional to the rise in cupric-reduction at all stages of the transformation between soluble- starch and maltose and for all fractionated products. If the properties of soluble-starch and of maltose are taken as given in the preceding paper (p. 114), namely Soluble-Starch R = 0 [a], = 202.0” Maltose R = 100 [a],= 138.0” then the relation of specific rotation [a],,, and cupric-reduction R for any mixture or fractionation of the products of starch-hydrolysis will be expressed by the equation 202 - 13BR [a], = 202 - 100 .*. [a], = 202 - 0.64R.If the experimental numbers have been expressed in terms of K ~ . ~ ~ and [ C C ] ~ ~ . ~ ~ then the equation becomes By the aid of one or other of these formulz, or by mere inspection where the graphic method is employed, we are able to determine, within reasonable limits of error, either the specific rotation of starch- conversion products from their cupric-reduction, or, conversely, the cupric-reduction from the optical properties. In columns I11 and VII of Table I, we have given the specific ro- tatory powers calculated in this manner from the cupric-reducing powers, and in columns 1V and VIII, respectively, are shown the differences * The whole of the tabulated fesults cannot be shown on the Plate, as many of the val ues coincide.120 BROWN, MORRIS, AND MILLAR : RELATIOX OF THE between these calculated and experimental results ; it will be noted that the differences are for the most part very small, and this is still further shown on the Plate (see p.118) by the close approximation of the experimental results, shown by the dots, to the theoretical straight line. It cannot be too strongly emphasised that this relation of optical t o reducing properties is, in the first place, solely based o n expemhent, and is quite independent of any theoretical views which may be held on the nature and constitution of the products of hydrolysis, but this empirical law is on such a sound experimental basis that, when we do not find the proper numerical relation holding good, we are justified in assuming either that some analytical error has been made, or that the products of the hydrolysis of starch are contaminated with some other substance or substances.In the few cases of discrepancy which have occas- sionally arisen, further investigation has always confirmed this. We have, in this ‘I law of relation,” the most valuable and useful criterion of purity which can be applied to starch-transformation products. Both C. J. Lintner and Ost (Zoc. cit.) have strenuously denied the existence of any relation of optical and reducing properties, and we have now to enquire how far their own results justify them in assuming this position. In the earlier work of C. J. Lintner and Dull (Zeit.f. ccngewan,dte Chenz., 1892, 263), the large number of fractions of starch- transformation products were characterised only by their optical, and not by their reducing, properties.I n the paper of 1893 by the same authors (Be?*., 1893, 26, 2533), the reducing powers of the various dextrins are given as well as their specific rotations, and in a later paper still (Rev,, 1895, 38, 152S), they have given both properties oE a considerable number of fractions precipitated with alcohol from the products of the limited action of dilute oxalic acid on starch. As the whole of the dextyose had been carefully eliminated from the fractions before analysis, it might be expected that their properties would fall under the same law of relation as those of the products of the hydrolysis of starch prepared with diastase. I n their examination of the sub- stances, Lintner and Dull deduced the amount of solids in solution from the specific gravity, the weight-constants being determined by drying 2 to 3 grams of a 10 per cent.solution at looo, or sometimes only at 60°, until the weight of the residue was constant. We have already seen that it is impossible to expel the last traces of moisture from the products of starch-hydrolysis in this manner, as nothing short of heating in a vacuum over phosphoric anhydride and considerably abore 100” is effective, and i t follows that both the values of [a], and R as given by Lintner and Dull must be somewhat too low for the perfectlydrysubstance. If we had before us the densities of the solutions analysed, and the actual weight of solids found onSPECIFIC ROTATORY AND CUPRIC-REDUCING POWERS, ETC.121 drying at looo, we could make the necessary correction of the results. We shall not be far wrong, however, in assuming that Lintner and Dull's fractions for the most part contained 2 per cent. of water. There is some internal evidence of this in the numbers given, and this is also about the difference we find between the products of starch- hydrolysis dried at looo, and the same products dried completely in a vacuum over phosphoric anhydride as previously described. I n Table 11, we have brought together all the available analyses given by Lintner and Dull in their papers. In columns I and I1 are the values of R and [alD as given by the authors. Columns I11 and I V show the same values corrected for dry weight, on the assumption that Lintner and Dull's products contained 2 per cent.of moisture. Column v gives the value of [ a ] D as calculated from 11 by the formula [:a], = 202 - 0.64 R, and column VI gives the difference between the observed and calculated specific rotatory powers. TABLE 11.-Lintner and Dull's Fmctions. - NO. ~ 1 2 3 4 5 6 7 8 9 10 11 12 1 3 14 - - I R. 0 1 *o 10.1 26.6 30.0 12'8 13'2 8.5 3 -0 8.0 30.0 25-0 20 .o 82.4 - 196 '3" 196.0 192.0 183.0 178.0 190,o 190 -0 194.0 196-0 194.0 182.0 184 0 188 0 140.0 - 1x1 R sected. (Cor- 0 1 .o 10.3 27 *1 30.6 13.0 13.4 8.6 3.0 8.1 30.6 25 5 20.4 84 .O - IV [ a ID. (Cor- *ected. -_ 200.1' 200 '0 195.8 186% 181.4 193'8 193.8 197.8 199'8 197'8 184'6 187 % 191'6 142.8 - - v la],. Calc. 202.0" 201.3 195.4 184.7 182.4 193.7 193'5 196.7 200.1 196.8 182.4 185.7 169.0 148-3 - - VI Differ- ence.~- + 1 .go + 1 -3 - 0'4 - 1.9 + 1.0 - 0'1 - 0.3 - 1.1 + O 3 - 1.0 - 2'2 - 1 ' 9 - 2-6 + 5.5 - " Amylodextrin " (Lintner). Erythrodextrin 7 , Achroodextrin I ,, Achroodextrin I1 ,, Fractions from conversions I with dilute oxalic acid after separation of the dextrose. " 1son:altose" (Lintner). We see that in Lintner and Dull's fractionated starch-products there is for the most part a very fair accord in the relation between the calculated and observed values of [ a ] D , and doubtless this accord would have been even closer if we had possessed the requisite data for exactly correcting in each case for the retained moisture. There is one con- siderable exception, however, in No. 14 of the series, which is the so-called '' isomaltose." As we have recently dealt very fully with122 BROWN, MORRIS, AND MILLAR: RELATION OF, ETC.this substance (see Trans., 1895, S7, 709), and have shown what its true nature is, it will be unnecessary to say more about it here. Even if it could be shown that such a substance as isomaltose existed amongst the products of starch-hydrolysis, it is impossible that it should possess the optical and reducing properties assigned to it by C. J. Lintner. The substance described cannot be either a pure product of the hydrolysis of starch or a mixture of such products, its wide departure from the law of relation " clearly indicating either the presence of some impurity, or errors in the determination of its optical and reducing properties. We have still to consider the properties of the fractionated products of starch-transformations described by Ost in his Studien uber die Xtarke (Zoc.cit.). As all his fractions were finally dried at 130°, it may be assumed that they were quite free from moisture when examined, and the general agreement of their optical and reducing properties indicates that such was the case. We have given the results in Table 111, and in column 111 have appended the specific rotation as calcu- lated from R, by the usual equation [a], = 202 - 0.64 R. The differences between the calculated and observed values are given in columnIV. The reference numbers are those given by Ost. TABLE 111.-Ost's F ~ a c t i o n s . I Ia I1 IIa (1 and 2) b I11 IIIa IV 30 *6 27 '4 31.5 28.2 37 -7 41.5 32 5 38 -0 183.5" 182.4 181 '1 183'0 380.5 178'0 180.1 176.7 182*4O 184.5 181.9 184.0 180.0 175.7 181'2 177.7 - 1'1 +2'1 +0*8 + 1 -0 - 0.6 - 2.3 +1'1 + 1.0 Out of these eight fractionated products obtained by Ost, six con- form closely to the "law of relation," whilst the other two do not depart widely from it.We see, therefore, that even the results of 0. J. Lintner and of Ost, who have both been active in denying the existence of any relation between! the optical activity and reducing power of the products ofJAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS. 123 starch-hydrolysis are, for the most part, strongly confirmatory of there being such a relation. The small amount of real advance made in our knowledge of starch- hydrolysis of late years, an advance altogether disproportionate to the amount of work done, is in no small measure due to the neglect of this important principle, which lies at the root of the whole question.Any serious attempt to explain the complicated changes which starch undergoes when acted on by diastase must take into account first of all this law of relation ” ; the crux of the whole question, in fact, lies in it, and when the true meaning of the law is understood we shall know all about starch-hydrolysis. Addendum.-Since this paper was written, there has appeared an important communication bearing on the subject : ‘( An Analytical Investigation of the Hydrolysis of Starch by Acid,” by Rolfe and Defren ( h ~ r n . Amsr. Chern. Xoc., 1896, 18, 869). The authors find, when starch is hydrolysed by dilute mineral acids, that, notwithstanding the fact that dextrose is produced along with the other products of hy- drolysis similar to those produced by the action of diastase, the cupric- reduction of the total products at any stage of the reaction bears a constant relation to the specific rotatory power, even when the starch is hydrolysed under very varying conditions ; that, in fact, the specific ‘rotatory power during the reaction is an exact guide to the composition of the products of hydrolysis, and that there is a “law of relation ” for acid just as there is for diastase conversions. It is manifest, however, that the law cannot be as simple in the former case as in the latter, as maltose is, of course, being converted into dextrose simul- faneously with the breaking down of the starch and higher dextrins. This law of relation for acid conversions laid down by the authors does nbt apply to mixtures of different transformations as it does in the simpler case of the transformations by diastase; and it would also follow from the authors’ statements, although they do not draw the conclusion themselves, that the relation they find in the case of acid conversions will not hold good for fractionations by alcohol or by dialysis.

ISSN:0368-1645    

DOI:10.1039/CT8977100115

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

JAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS. 123 VIII. -Synthesis of Pentacarbon R.iugs. Pa9-t I. Anhydracetonebenzil and its Homologues. By FRANCIS ROBERT JAPP, F.R.S., and GEORGE DRUCE LANDER, B.Sc. ONE of the chief objects of the systematic study of the condensations of certain a-diketones (benzil and phenanthraquinone), and of a keto- alcohol (benzo’in), which has occupied one of us, along with various1% JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS. collaborators, more or less continuously from the year 1880 down t o the present time, has been the synthesis of cycloids. The various “ condensations in the ortho series ” which, shortly before this work was begun, had been studied by various investigators, especially by Ladenburg and von Baeyer, indicated a possibility of the occurrence of similar condensations in the case of aliphatic chains containing two ketonic or alcoholic functions in the a-position. I n passing, we may point out that the analogy of the a-position in aliphatic compounds to the ortho-position in the benzene series was not quite so obvious then as it is now.A t that time, Ladenburg’s ‘‘ prism ’’ formula could still be seriously put forward as a satisfactory expression of the reactions of benzene ; and in this formula the ortho-carbon atoms are not directly united. Every condensation, therefore, which bore out the foregoing analogy was a fresh argument against the ‘‘ prism ” formula. Indeed, it is cumulative evidence of this character, rather than any definite disproof, that has caused the ‘‘ prism ” formula to be withdrawn from discussion.The a-diketones and the a- keto-alcohol just mentioned were selected for study, in the first instance, on account of the ease with which they could be obtained. A further advantage was that the products of the various reactions were crystalline solids and, consequently, easy to purify. The phenyl and phenylene groups, to the presence of which in the molecule the latter advantage was largely due, took no direct part in the reactions ; so that, in reality, the problem resolved itself into the relatively simple one of ascertaining the nature of the condensations of the groups -CO*CO- and -CHOH* GO- with various compounds. Against these advantages must be set the deterrent effect which the somewhat formidable-looking formulae of the resulting compounds probably exercised on the majority of readers.That this object of the synthesis of cycloids has been amply realised may be seen from the following list of the various classes of compounds obtained in these reactions : 0xaxoles.-1. By the interaction of a-diketones with aldehydes and ammonia (Trans., 1880, 3’7, 669 ; 1881, 39, 225).-2. From benzo‘in and nitriles (ibid., 1893, 63, 469). From a-diketones, aldehydes, and ammonia (ibid., 1882, 41, 146, 157, and 323; 1886, 49, 464 ; 1887, 51, 552 and 5 5 9 - b . Te.r.tiary lmidaxoles and Quc6te.r.- nary Imidaxolium Compounds. From a-diketones and primary amines of the formula R*CH,*NH, (ibid., 1895, 67, 32). PurfurarLs.--By the action of hydriodic acid on the condensation pro- ducts of a-diketones with ketones (ibid., 1890, 5’7, 662).fifidoles. -By the condensation of benzoi’n with primary benzenoid amines (ibid., 1894, 65, 889). Iinidaxoles.-a. Ordinary (secondary) Inaidazoles.JAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS. 125 Axines.-By the action of ammonia ( 2 ) on benzoin and (2) on U- diketones (ibid., 1886, 49, 528; 1887, 51, 98). To the foregoing list might have been added : Zcctones and pywho- Zones. A pyw4oZe has also been obtained in an investigation the results of which will be published shortly. I n some of the foregoing condensations, a union of carbon with carbon occurs, but only a t one point: the closing of the chain is effected by some other element -nitrogen or oxygen. I n the present and the two following communications, condensations are described in which t,he union of carbon to carbon takes place a t two points, both carbonyl groups of an a-diketone attaching them- selves to carbon atoms of an aliphatic chain and in this way leading to the formation of cycloids containing only carbon in the ring.These compounds are formed by the condensation of benzil with ketones or ketonic acids of the formula RCH,*CO*CH,R’, in which R’ may be hydrogen, or alkyl, or carboxyl, or *CH,*COOH. The condensation of benzil with acetone was first studied by Japp and Miller (Trans., 1885, 47, 21). Acting on these substances with a small quantity of potassium hydroxide, they found that the aldol C,H,* ~(O.H).CH,*CO CH, C,H,*CO condensation compound, acetonebenzil, , was formed. When treated with an excess of the alkali, this compound parted with a molecule of water, yielding anhydracetonebenzil C17H,,0,. From a study of the oxidation of anhydracetonebenzil, they concluded that a closed chain of carbon atoms had been formed during the condensation, and they inclined to ascribe to the compound the constitution C H 5~ *C<gEt>CO C,H,* GO Y They were led to adopt this view by observing that the compound, oxidation with chromium trioxide in acetic acid solution, yielded on an acid, C1,Hl,O3, to which they assigned the formula of a P-benzoyl- hydrocinnamic (desylacetic) acid.Desylacetic acid has, however, since been prepared 5y Victor Meyer and Oelkers, and we find that the two substances are quite distinct. The argument put forward in favour of the above formula must therefore be withdrawn, although the con- siderations which led Japp and Miller to reject an open chain formula for the compound are still valid.Japp and Burton pointed out (Trans., 1887, 51, 420) that the closed chain might equally well consist of five carbon atoms. They suggested that the first step in the transformation of acetonebenzil into anhydr- acetonebend was $he occurrence of an aldol condensation with the126 JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS. second methyl group of the acetone, yielding the hypothetical inter- mediate compound which would then part with water, forming anhydracetonebenzil. The results of the present investigation lead us to conclude that, in this dehydration, a hydroxyl group is eliminated along with hydro- gen from an adjacent carbon atom, and that anhydracetonebenzil is a diphenylcyclopentenono Z of the formula C',H,*C----- CH I >GO.C,H,* C(OH).CH, The only points in the behaviour of the compound which are not in entire accordance with this formula are that it yields neither an acetyl derivative nor an additive dibromide. The inability to form an acetyl derivative is, however, due t o the circumstance that acetic anhydride has a dehydrating action on anhydracetonebenzil, con- verting it into the compound C,,H,,O,, which was obtained by Japp and Burton (Zoc. cit.), by boiling anhydracetonebenzil with dilute sul- phuric acid. And as regards the non-formation of a dibromide, the merely negative evidence of this fact is outweighed by the positive evidence of the oxidation with sodium hypobromite.Treated with this reagent, anhydracetonebenzil gives, as we find, an almost quanti- t ative yield of Japp and Davidson's desyleneacetic acid, C6H5* C:CH* COOH C,H,* CO I 9 thus proving the presence of double bonds in the molecule of the compound. . This result may also be taken as indicating that desylene- H- C- COOH C,H,* C* COB C,H, acetic acid has the configuration il We do not lose sight of the fact that the formation of desylene- acetic acid could be even more simply explained by assigning to C H *C:CH*CO*CH, ; C,H5*C0 anhydracetonebenzil the open-chain formula I but this formula is excluded by various considerations. Thus anhy- dracetonebenzil yields no acetic acid when oxidised by a mixture of potassium dichromate and dilute sulphuric acid, whereas acetonebenzil readily yields acetic acid under these conditioris (Japp and Miller, ZOC.cit.). But the strongest evidence against the open-chain formula is afforded by the experiments which we are about t o describe. As already mentioned, Japp and Miller, by oxidising anhydrace-JAPP AND LANDER: SYXTHESIS OF PENTACARBON RINGS. 127 tonebenzil by heating it with chromium trioxide in acetic solution, obtained an acid of the formula C,,H,,O,. We find, however, that this acid is not the primary product of oxidation : when the process is conducted in the cold, simultaneous oxidation and hydration occur, C,H,*y( OH) CH, COOH C,;H,* C(OH).COOH 3 is formed. and dipheny Zdihydroxpglutm-ic acid, " I . On heating this acid for some time it decomposes, parting with carbon dioxide and water, and yielding Japp and Miller's acid, which has the C H *C:CH, I C,H,* C(OH)*COOH * formula of an isocinnc~meny~?~~andelic cccid, When boiled with fuming hydriodic acid, or wvth fuming hydro- chloric acid, diphenyldihy droxyglutaric acid also parts with carbon dioxide and water ; but the carbon dioxide is, in this case, furnished by C,H, *aH* CH, COOH, C,H;CO the other carboxyl group, and desylacetic acid, is formed, together with a small quantity of its dehydration C R *C-CH, diphenylcrotolmtone, 11 I The mechanism of the C,H,*C CO \/ product, two pro- 0 cesses may be represented as follows........................................... C~,H,*C(OH)~*CH,*jCOOH~ P c&,* 5: : CH, I ............. ............... ! -3 C,H,.C(OH)-COOH C,H,* C(0H) COOH Action of heat. C,H,* V*CH,-COOH C,H,* CH* CH,* COOE, + I C6H5* C*OH C6H,* co Action of hydracids. a portion of the desylacetic acid, while still in the enolic form, elimi- nating water, and yielding diphenylcrotolactone. The necessit'y of accounting for the formation of desylacetic acid C,H5mCH.CH(OH)--COOH C,H,*C( OH)*cOOH excludes the other possible formula, I , for diphenyldihydroxyglutaric acid. But, quite apart from the question of the exact constitution of this acid (dthough we regard this as settled), the oxidation of anhydracetonebenzil to a dibasic acid containing the same number of carbon atoms as this compound itself is a process that can be explained only on the assumption that a closed carbon128 JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS.chain, which was formed in the original condensation, has been opened during the oxidation, Isocinnamenylmandelic acid yields an acetyl derivative. When heated above its melting point, this acid parts with 1 mol. of water, forming a compound ClGHlZO,. By partial redaction by boiling it for a few minutes with fuming hydriodic acid, it is converted into isopJLenethyl- naundeZic acid, I C H *CH*CH, C, H5*C(OH) *COOH' By the partial reduction of anhydracetonebenzil with hydriodic acid, Japp and Burton obtained a compound, C17H140, melting a t 110", which yielded a hydrazone, and therefore contained the original car- bony1 group of the anhydracetonebenzil. We find that this compound C H -C.CH, C,H,- C-CH, has the constitution of a dip~henylcyclopentenone, 11 >co.That the foregoing change in the position of the double bonds has faken place during the reduction, is shown by the fact that the com- pound yields, on oxidation with sodium hypobromite, diphenylmaleic acid, which, when liberated from its salts, changes into the very - C,H,*C.CO C,H;C:CO characteristic anhydride, 11 >o. The hydrocarbon, C17H18-(m. p. 47"), obtained by Japp and Burton by the complete reduction of anhydracetonebenzil with hydriodic acid and amorphous phosphorus, is a diphen?/ZcycZo~ntane, C,H,*YH*CH, C,H,* C H* CH, >CH,. The various compounds obtained by Japp and Burton (Trans., 1887, 51, 431) by the condensation of benzil with homologues of acetone of the general formulae CH,R'*CO*CH, and CH,R*CO*CH,R must be regarded as homologues of anhydracetonebenzil.The constitution of those members of this class which are formed from symmetrical homo- logues of acetone follows, as a matter of course, from that of anhy- dracetonebenzil it'self ; thus the condensation product of benzil with diethyl ketone (Zoc. cit., p. 438) is di~zethylccnhydrcccetonebenxil, C H 5~ -C= "("H3)>,0. C,H,- C(0H) CH(CH,) But in the case of the compounds obtained from unsymmetrical ketones there are two possibilities ; thus, in nzethyZanh?/dracetonebenxiZ (formed from b e n d and methyl ethyl ketone), the methyl group may replace hydrogen either in the methylene or in the methenyl group of anhy- dracetonebenzil, lending respectively to the formulsJAPP AND LANDER: SYNTHESIS O F PENTACARBON RINGS.129 The following considerations appear to us to decide in favour of Formula I. Von Baeyer's well-known test for non-saturation in organic com- pounds-namely, the rapid change of the colour of permanganate to brown when a drop of permanganate solution is added to a cold solution of the substance in presence of excess of sodium carbonate (Annalen, 245, 146), is not applicable to compounds in which an ethylene group has no hydrogen attached to it, as in this case the action of per- manganate on the substance in the cold is very slow. Von Baeyer mentions, as examples of this limitation, dimethylmaleic acid and A1 tetrahydrophthalic acid (Annulen, 1889, 252, 207); and we find that the same holds good of diphenylmaleic acid, desylenemalonic acid, and dibenzoylstilbene, all of which are stable towards permanganate in the cold.I n this way, it is possible to decide between two competing formulae for an unsaturated compound, one of which contains hydrogen attached to the ethylene group and the other not. Thus, in the case under discussion, if methylanhydracetonebenzil has the constitution represented by Formula I, it should be as easily attacked by per- manganate as anhydracetonebenzil itself; if, on the other hand, its constitution corresponds with Formula 11, it should be as stable towards permanganate as dimethylanhydracet80nebenzil. Experiment showed that the former was the case." The times required for the complete reduction of the permanganate were : with anhydracetone- benzil, 30 seconds ; with methylanhydracetonebenzil, 30 seconds ; with dimethylanhydracetonebenzil, 5 minutes.Amylanhydracetonebenzil, which was also tested, required 18 minutes, the somewhat more slug- gish action being due to the larger molecule, although the compound obviously belongs to the same category as methylanhydracetonebenzil. We had not a specimen of ethylanhydracetonebenzil; but it would doubtless behave like the other two monnlkyl derivatives. The monalkyl derivatives of anhydracetonebenzil prepared by Japp and Burton would therefore be formulated as follows. C,H,* C CH i >GO C H .C-- CH C,H,* C(0H) CH(CJ3,) >" Met h y lanhy drace tonebenzil. (m. p. 179"). 5~ C,H,* C(OH)*CH(C,H,) E th ylanh ydrace tonebenzil. (m. p. 156"). * The experiments were carried out in the way recommended by von Baeyer for testing non-acid substances (Annulen, 252, 286) ; to a solution of the compound in pure alcohol, a little of an aqueous solution of sodium carbonate was added, and then a drop of the permanganate solution.VOL. LXXI. K130 JAPP AND LANDER : SYNTHESIS O F PENTACARBON KIhGS. ">co C H *C-- - C,H,* C(OH)-CH(C,Hll) Amylanh ydracetonebenzil. (m. p. 150.5"). 5~ E X P E RIME N T A L . Prepration of An~Lydracetonebenxil---The following mode of prepara- tion differs from that originally employed by Japp and Miller only in the fact that the ingredients are heated during the reaction. I n this way, a great saving of time is effected, whilst the yield is not diminished. Two hundred grams of finely-powdered benzil, 125 grams of pure acetone (Kahlbaum's acetone (( from the bisulphite compound " was used), and 3 C.C.of a 33 per cent. solution of caustic potash were introduced into a flask, and constantly shaken until the benzil had all dissolved. The liquid became slightly warm during this process, owing to t.he formation of the aldol condensation compound, acetone- benzil. Fifty grams more of the caustic potash solution were then added, and the liquid was gently warmed for about half-an-hour on the water bath, shaking it from time to time. Hot water was then added to remove the potash, and the organic substance was washed with hot water. When cold, the solidified product was ground in a mortar, washed with a small quantity of ether to remove dark-coloured impuri- ties, and recrystallised from benzene. The substance thus obtained is yellow, but is pure enough for the study of its reactions, and even for analysis, so that it is not necessary to subject it to the troublesome and wasteful process required to obtain it in a colourless state (cJ: Japp and Miller, Zoc.cit., p. 27). Cryoscopic determinations of the molecular weight, using benzene as a solvent, gave the following results. The yield was 150 grams. Weight of Weight of Mol. substance. solvent. Depression. weight. I ............... 0.1255 22.49 0.105O 260 I1 ............... 0.3050 21-75 0.245 280 C,7Hl,0, = 250. Action of Acetic Anhydride on Anl~ydraceto.lzebenziZ.--Ten grams of the substance were boiled with 30 grams of acetic anhydride and 5 grams of fused sodium acetate for 4 hours, the latter addition being made because Japp and Miller had obtained no definite result with acetic anhydride alone.The only product, however, was the compound C34H2402, prepared by Ja pp and Burton by boiling anhydracetonebenzil with dilute sulphuric acid. It was deposited from benzene in forms indistinguishable from those of the compound C34H2402, and, like theJAPP AND LANDER: SYNTHESIS OF PEXTACARBON RINGS. 131 latter, melted a t 195-200°, evolving gas. It is formed according t G the equation 2C1iH,,0, - 2H,O = C,,H2,02, and the double molecular weight was assigned to it to account for the fact that, when heated, it parts with 1 mol. of carbon monoxide, yielding the compound C33H240* (Trans., 1887, 51, 426). Our cryoscopic determinations, made with a benzene solution, confirm this conclusion.Weight of Weight of Mol. substance. solvent. Depression. weight. I ............... 0.1995 32.46 I1 ............... 0.2715 21.65 C,,H,,O, = 464. Prepccmtion of Diphenylcyclopentenon~, compound was obtained by Japp and Burton 0*065O 463 0.130 4'73 C,H,* f*UH, C,H5* C*UH, >CO.-This " - by boiling anhydracetone- beniil for a few minutes with excess of fuming hydriodic acid. The following method is more economical and gives a better, although by no means satisfactory, yield. Forty grams of anhydracetonebenzil were boiled with 160 grams of glacial acetic acid, 9 grams of amorphous phosphorus, and 4-5 C.C. of fuming hydriodic acid (sp. gr. 1-96} for 4 hours, using a reflux condenser, and adding a few drops of water from time to time, whenever vapours of iodine appeared in the flask.The liquid was filtered hot and diluted with water. The semi-solid mass which separated was dissolved in ether ; the solution was shaken first with aqueous sulphur dioxide and then with sodium carbonate, dried with calcium chloride, after which the ether was expelled and the residue distilled under reduced pressure. It passed over at 250-260' under a pressure of 18-20 mm. The solidified distillate was recrystallised from alcohol. It formed pale yellow needles, melting at 110', as described by Japp and Burton. The yield of pure substance was only 12 grams. C,H,* CH*CH, C,H,* CHGH, Preparation of Diphenylc yc lopentane, I >CH,.-This compound was obtained by Japp and Burton by heating anhydracetone- benzil with hydriodic acid and amorphous phosphorus in a sealed tube.We find, however, that the reduction may be equally well effected by boiling these substances in a flask fitted with a reflux condenser, Ten grams of anhydracetonebenzil, 150 grams of hydriodic acid (sp. gr. 1 T), * Japp and Burton state that the substance, C,,H,,O, crystallired from benzene, melts, after expelling the benzene of crystallisation, at 162-163". This melting point is too low ; probably the benzene was not entirely expelled. The substance is deposited from alcohol in lustrous crystals, containing no solvent of crystallisation and melting a t 175". K e132 JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS. and 20 grams of amorphous phosphorus were employed, and the boiling was continued for 5 hours. The product was purified by distillation under reduced pressure and subsequent recrystallisation from alcohol (cf.Trans., 1887, 51, 423). The yield was small : from the foregoing quantity of anhydracetonebenzil only 1-8 grams of pure recrystallised hydrocarbon melting a t 47' were obtained. Cryoscopic determinations of the molecular weight, using benzene as a solvent, gave the following results. Weight of Weight of MoI. subs trtnce. solvent. Depression. weight. I. ......... 0.1475 15.34 0,225" 209 I1 ....... , . 0.1025 18.05 0.1 35 206 C17Hl, = 222. This 1 : 2-diphenylcyclopentane ought to exist in two modifications, cis and tyans, but we failed to detect, among the products of the reduction, any form other than the foregoing. Oxidation of Dip~nyZc/cZopentenone with Sodium Hypobrornite.Formation of Bipihen y lrna Zeic A cid. -Twelve grams of fine1 y-powdered diphenylcyclopentenone, the first reduction product of anhydracetone- benzil, were mixed with a solution of 36 grams of bromine in excess of strong caustic soda, and the mixture was stirred by means of a mechanical stirrer for 72 hours; the unchanged substance, which was separated by filtration, weighed 9 grams. The alkaline filtrate was saturated with sulphur dioxide, acidified with dilute sul- phuric acid, and extracted with ether. Aqueous sodium carbonate removed no organic acid from the ether, which was then shaken with sodium hydroxide solution; the latter, on acidifying, gave a yellow precipitate ; this, on recrystallisation from benzene, was deposited in thick, yellow needles, with a slight greenish fluorescence, and melted at 156-157'.These are the properties of diphenylmaleic anhydride, into which diphenylmaleic acid spontaneously changes on liberation from its salts. Analysis gave figures agreeing with the expected formula C,,H,,O,. Found : C = 76.50 ; H = 4.11. Calculated : C = 76.80 ; H = 4.00 per cent. From the 3 grams of diphenylcyclopentenone used up in the oxidation, 2 grams of pure anhydride were obtained. Allowing for unavoidable loss in purification, this may be regarded as a quantitative yield. Oxidation of Anhydracetonebenxil with Sodium Hypobrornite. Formation of De Zeneacetic Acid.-Ten grams of finely-powdered anhy- dracetonebenzil were shaken with a solution of 20 grams of brominein an excess of a 15 per cent.solution of After remaining for about an hour in the cold, with frequent shaking, the liquid was almost filled with a colourlese, crystalline substance which sodium hydroxide.JAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS, 133 enclosed particles of unaltered anhydracetonebenzil. On adding a little water and warming to about 40°, the substance dissolved. The liquid was filtered, saturated with sulphur dioxide, and acidified with dilute sulphuric acid, which produced a microcrystalline precipitate of an organic acid. This acid was extracted with ether and the ethereal solution shaken with a solution of sodium carbonate. After this treat- ment, the ether left practically no residue on evaporation. The organic acid, reprecipitated from the Carbonate solution, and purified by re- crystallisation from benzene, melted at 168 O; recrystallised, it melted at 1 4 2 O , and, after resolidification, again at 168'.It was indistin- guishable from a specimen of desylenaacetic acid prepared by Japp and Davidson (Trans., 1895, 67, 138) by heating desylenemalonic acid, and, on analysis, gave figures agreeing with the formula of desyleneacetic acid. Found : C = '76.03 ; H = 4-87. Calculated for C,,H,,O, : C = '76.19; H: = 4.76 per cent. Japp and Davidson also observed two melting points for desylene- acetic acid-15O0 and 168O-but gave it as their opinion that the lower melting point was merely that of an unstable crystalline form of the substance, I n spite of this, it is stated, in the abstracts of the paper which appeared in the Bericlhte (Referute, 1895, 465) and in the Bulletin (Trccvaux ktrangers, 1895, 1039), that stereoisomerides were observed. It is clear, however, from the above changes in the melting points- from the lower to the higher on melting and resolidifying, and from the higher to the lower on recrystallising-that the phenomenon is due merely to dimorphism.The form of lower melting point does not contain benzene of crystallisation. An attempt to obtain a stereoiso- meride by heating the substance in a sealed tube with glacial acetic acid saturated with gaseous hydrogen chloride gave no result ; only unchanged substance was recovered. Oxidation of Anhydrucetonebenxil with Chromium Trioxide. Formation of Dipphenyldihydroxyglzctccric Acid.-The conditions essential to success in the following experiment were discovered only after considerable expenditure of time and material, and a very slight deviation from them suffices to reduce the yield-at no time good-to the vanishing point. Fifty grams of anhydracetonebenzil were dissolved with the aid of heat in 350 grams of glacial acetic acid and the solution cooled.The beaker containing it was kept immersed in cold water and the solution stirred by a mechanical stirrer, while a solution of '75 grams of chromium trioxide, in a sufficiency of glacial acetic acid, was added in small portions at a time, so as to avoid any appreciable rise of temperature. A slight separation of solid substance, which afterwards re-dissolved, occurred on the addition of the chromium trioxide. After the stirring134 JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS. had been continued for 24 hours, the beaker was removed from the water and the solution allowed to sta,nd a t the ordinary tempera- ture for 5 days, after which it was ponred into excess of water, which occasioned the separation of a flocculent substance; this was collected in a filter, washed with a little cold water, and dissolved in alcohol with the aid of a gentle heat.Alcoholic caustic soda and afterwards aqueous caustic soda were then added, until the liquid was distinctly alkaline; this caused a separtion of solid matter. Warm water was then added to dissolve the salts of organic acids, and the liquid was filtered from unaltered substance and chromium componnds. From the filtrate, dilute sulphuric acid precipitated an oily acid, which was extract,ed with ether, again removed from the ether with sodium carbonate solution, reprecipitated, and re-dissolved in ether.The ethereal solution wa,s evaporated to a small bulk and excess of benzene added; this occasioned the separation of the new acid in needle-shaped crystals grouped in rosettes. (Yield : 11-12 grams.) The substance thus obtained, although otherwise pure, contains benzene of crystallisation, which, apparently, cannot be entirely expelled by heat without a t the same time decomposing the substance. The crystals, freed as far as possible from benzene of crystallisation by long exposure t o the air, were therefore dissolved in ether, and t o the solu- tion light petroleum was carefully added. I n this way, the compound was obtained in crystals which, when rapidly heated, melted a t 120° with evolution of gas.On analysis they gave figures agreeing with the C,H,*~(OH) *CH, COOH C,H5* C(OH) *COOH formula of di~~en~Zdih~drox?/glzctaric acid, 0.1427 gave 0.3367 CO, and 0-0640 H,O. C = 64-35 ; H = 4.98. 0.2209 ,, 0.5219 CO, ,, 0.1007 H,O. C=64*43 ;H=5.07. Cl7Hl,O, requires C = 64-55 ; H = 5.06 per cent. The silverr. salt was obtained as a white precipitate by dissolving the It was dried in a acid in dilute ammonia and adding silver nitrate. vacuum desiccator. 0.3070 gave, on ignition, 0.1263 Ag. C17H,,06Ag2 requires Ag = 40.75 per cent. When the oxidation of anhydracetonebenzil is allowed to go on in the cold for a fortnight, instead of for 5 clays, or when the liquid is heated, isocinnamenylmandelic acid (m.p. 1 60°), the oxidation product obtained by Japp and Miller, is formed. This is not due to a further oxidation, but to a splitting off of carbon dioxide and water from diphenyldihy droxyglutaric acid (see following paragraph). Action of' Heat on D~p~n?/ld~~ydoxygZut~~~ic Acid. Formatioiz of Ag = 41-14.JAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS. 135 Isocinnamenylrnandelic Acid-Diphenyldihydroxyglutaric acid decom- poses when kept for some time a t looo, melting, with evolution of gas, and then resolidifying. The best yield of the product of transforma- tion by heat is obtained when air is excluded during the process, and the temperature is not allowed t o exceed 105'. The operation mas conducted as follows.Ten grams of diphenyldihydroxyglutaric acid were introduced into a tubulated flask and heated at 105" by means of a glycerol bath, the flask being attached to a filter-pump and exhausted during the entire process. The fusion, frothing, and resolidification of the substance proceeded gradually, from the outer portions inwards. The end of the reaction was shown by the rise of the mercury in the gauge of the pump. The product was dissolved in hot benzene, from which it separated in tufts of needles melting at 160' with evolution of gas. The total yield from 40 grams of diphenyldihydroxyglutaric acid, treated as above, was 18 grams of recrystallised substance. On analysis, it gave figures agreeing with the formula of isocinncmengl- C H *C:CH, C,H,- C( OH) *COOH ' mandelic acid, I Found : C = 75.56 ; H = 5.38.Clal- culated : C = 75.59; H = 5.51 per cent. An experiment, in which a weighed quantity of diphenyldihydroxy- glutaric acid was heated in a Sprengel vacuum, pumping off and mea- suring the carbon dioxide evolved, and determining the loss in weight of the heated substance, showed that the decomposition took place according to the equation C,7H,,06 = Cl6Hl,O, + CO, + H,O. Isocinnamenylrnandelic acid is identical with the acid obtained by Japp and Miller by the oxidation of anhydracetonebenzil (Trans., 1885, 47, 30), and regarded by them as /3-benzoylhydrocinnamic (desylacetic) acid. The lower melting point (152') which they found is accounted for by the fact that, in the method of preparation employed by them benzoic acid is simultaneously formed, and it is difficult to free the substance from it, except by repeated recrystallisation.A speci- men prepared by them, which we examined, contained a little benzoic acid, but was otherwise indistinguishable from that just described. Owing to the; circumstance that Japp and Miller erroneously as- cribed to this acid the const'itution of desylacetic acid, and that Victor Meyer and Oelkers, who afterwards prepared the true desylacetic acid, were apparently unaware of the existence of an acid for which this constitution had already been claimed, and therefore made no compa- rison of the two acids, the properties of both-often of a somewhat contradictory character-figure side by side in Beilstein's Hcindbuch(3rd ed., vol. ii, p.1713) as those of desylacetic acid. As it would be impossible for any one, without studying the original memoirs, to assign these properties to the compounds to which they belong, we append, in tabular form, a comparison of the two acids. 1. Crystallises from benzene in tufts of needles, melting a t 161". 2. The solution in sodium carbonate is instantaneously oxidised by per- manganate in the cold. 3. Not reduced by sodium amalgam in alkaline solution. 4. When boiled for a few minutes n-ith fuming hydriodic acid, is reduced t o isophenethylmandelic acid (v. infm). 5. Does not interact with phenyl- hydrazine or with hydroxylamine. 6. Yields, with acetic anhydride, a monacetyl derivative (v. infra). 7. Heated above its melting point, it parts with water yielding a compound C,,H,,O,, ni.p. 118-120" (v. Cnfm). Desylacetic Acid. CRH5* vH-CH,*COOH C6H5* co 1. Crystallises from benzene in lustrous 2. Sodium salt stable towards per- octahedra, melting at 162". nianganate in the cold. 3. Reduced to By-diphenyl-y-hydroxy- butyric acid, which when liberated from itssalts, formsthe lactoneC,H,*CH*CH, (To be described in a subsequent paper.) 4. Not reduced by this treatment. Longer boiling, however, reduces it to By-diphenylbutyric acid. (To be de- scribed in a subsequent paper.) 5. Yields, with phenylhydrazine, anilinodipheiiylpyrrholone (Klingemann). 6. Action not studied. 7. Yields diphenylcrotolactone, m. p. 151 -5" (Klingemann). The barium salt, (C16H130,),Ba,2H,0, given by Beilstein under desylacetic acid, was prepared by Japp and Miller, and is a salt of isocinnamenylmandelic acid.The fact that isocinnamenylmandelic acid is not reduced by sodium amalgam, shows that the unsaturated group, the presence of which is proved by the behaviour of the acid towards permanganate, is not in the up-position relatively to the carboxyl group. Action of Hydi-iodic Acid and of Hydrochloric Acid on Diphnyldihy- droxyylutaric Acid. Formation of Desylacetic Acid and Diphenylcroto- lactone.---Five grams of diphenyldihydroxyglutaric acid were boiled with excess of fuming hydriodic acid (sp. gr. 1.96) for 5 minutes. The ethereal solution of the product was shaken with aqueous sulphur dioxide, washed with water, and then treated with a solution of sodiumJAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS.137 carbonate, which extracted an organic acid, whilst a neutral substance remained, dissolved in the ether. The reprecipitated acid was purified by recrystallisation from benzene, from which it was deposited in the characteristic lustrous octahedra of desylacetic acid, melting a t 16 1". The yield was 0.7 gram. When dissolved in sodium carbonate and treated with a drop of permanganate in the cold, no action occurred, showing that it was free from the isomeric isocinnamenylmandelic acid. Analysis gave figures agreeing with the formula of desylacetic acid. Found : C = 75.54 ; H = 5-57, Calculated for C16H1403 : C = 75.59 ; H = 5.5 1 per cent. It was in every respect indistinguishable from a specimen of desylacetic acid prepared by Knoevenagel's method (from sodium deoxybenzoin and ethylic iodoacetate, hydrolysing the ethereal salt thus obtained).The ethereal solution which remained after the desylacetic acid had been removed by sodium carbonate, left on evaporation a neutral substance which crystallised from benzene in tufts of needles melting a t 150". It was identical with Klingemann's diphenylcrotolactone (m. p. 151*5"), which he obtained by the dehydrating action of heat on desylacetic acid (Anncden, 1892, 269, 134). A supersaturated solution of the substance in benzene crystallised immediately on adding a crystal of diphenylcrotolactone. A simultaneous formation of desylacetic acid and diphenylcrotolactone, by the action of hydriodic acid on desylene- malonic acid, was observed by Japp and Davidson (Trans., 1895, 67, 136).As the action of hydriodic acid on diphenyldihydroxyglutaric acid was thus not a reduction, but merely an elimination of carbon dioxide and water, it seemed probable that hydrochloric acid would have the Eame effect. This was found to be the case. Diphenyldihydroxyglutaric acid, boiled with fuming hydrochloric acid for 10 minutes, gave desylacetic acid, which, after purification, crystallised in the charac- teristic octahedra and melted a t 160". An acid melting at 185" was simultaneously formed, but in quantity too small for further examina- tion. Porma- tion of Isop?~enethylmccndelic Acid.--Five grams of isocinnamenyl- mandelic acidwere boiled with excessof fuming hydriodic acid (sp. gr. 1 *96) for 5 minutes. The product, dissolved in ether and freed from iodine by sulphurous acid, was separated by sodium carbonate into two substances : an acid and a neutral oil, the latter of which was not further examined.The acid crystallised from benzene in small, oblong plates, generally grouped together into rosettes, melting at 134-136'. The solution in sodium carbonate was stable towards permanganate in the cold, showing that the ethylene group of isocinnamenylmandelic acid had taken up Action of Hydriodic Acid on Isocinnamenylinccndelic Acid.138 JAPP AND LANDER : SYNTHESIS OF PENTACARBON RINGS. hydrogen during the reduction. those required for isop?~eneth?/ZmandeZ,ic cccid, Analysis gave figures agreeing with C,H,* YH*CH, C,H,* C(OH)*COOH 0.1214 gave 0.3339 CO, and 0.0688 H,O. 0.1306 gave 0.3592 CO, and 0.0749 H,O.We endeavoured, by carrying the reduction further, to convert this acid into up-diphenylbutyric acid, in order to compare it with the py-diphenylbutyric acid which we describe in a subsequent paper. For this purpose, 10 grams of isocinnamenylmandelic acid were boiled for 5 hours with hydriodic acid (sp. gr. 1.7) and amorphous phosphorus. A considerable quantity of neutral oil was formed, together with a mixture of acids. We could not succeed in separating the latter from one another, owing to the small quantity of substance a t our disposal. Porma- tion of the Monacetyl De~ivatiue.-One gram of isocinnarnenylmandelic acid was warmed with acetic anhydride a t 100" for 18 hours, the excess of anhydride was distilled off under reduced pressure, and the residue twice crystallised from benzene.The acetyl derivative was deposited in tufts of needles melting, without decomposition, a t 145-1 46". Analysis of the substance, dried at 90°, gave figures agreeing with the formula C=75*01; H=6*29. C =75 01 ; H=6*31. Cl,Hl,03 requires C = '75.00 ; H = 6.25 per cent. Action o j Acetic Anhyd?*ide on Isocinnarnen~lman&Zic A c i d ~l,Hl,O, ( %,H:3*)* 0.0856 gave 0.2292 GO, and 0.0445 H,O. C,,H,,O, requires C = 72.97 ; H = 5.41 per cent. Action of Heat o n Isoci.lznc~~~enylmccndelic Acid.-Three grams of isocinnamenylmandelic acid were introduced into a small distilling flask, which was exhausted by a Sprengel mercury pump and heated in a glycerol bath a t 160' until the evolution of gas had almost ceased. The gas, which was removed by the pump during the process, was collected and examined. It was found to be pure carbon dioxide, and its volume was 120 C.C. (standard-dry), or rather less than half of that which would have been evolved had the whole of the acid been decom- posed with elimination of this gas. The substance remaining in the flask was dissolved in ether and shaken with a solution of sodium carbonate, which extracted only a trace of an acid, but caused the separation of oily drops which remained suspended in the aqueous liquid ; addition of benzene readily removed these. The ether-benzene solution was evaporated to a small bulk and alcohol added ; this caused the separation of large, yellow, prismatic crystals. Recrystallised from hot alcohol, the substance was deposited in yellow needles, closely C=73*02; H=5*77.JAPP AND LANDER: SYNTHESIS O F PENTACARBON RINGS. 139 resembling benzil in appearance, but melting a t 118-120'. Further recrystallisation did not remove the colour or alter the melting point. Analysis gave figures pointing to the formula Cl6Rl2O2. 0,1602 gave 0.4769 CO, and 0.0746 H,O. The substance is formed from isocinnamenylmandelic acid according C=81*19; H=5*17. CI6H,,0, requires C = 81.35 ; H = 5.09 per cent. t o the equation and the evolution of carbon dioxide observed is due to another reaction, the product of which is probably the oily substance which remains after the removal of the foregoing crystals; but me could not succeed in isolating any definite compound from this. The compound Cl6Hl,O2 (m. p. 1 18--l2O0) is insoluble in aqueous caustic alkali; but if it is dissolved in alcoholic caustic soda, and the solution evaporated to dryness, the residue is soluble in water. On acidifying, an organic substance is precipitated ; but the quantity a t our disposal did not suffice for further examination. If the compound C,,H,,O, is a lactone, it cannot be formed from isocinnamenylmandelic acid except by an intramolecular change. C16Hl403 = C,6H,,O2 + w, CHEMICAL DEPARTNENT, UNIVERSITY OF ABERDEEN.

ISSN:0368-1645    

DOI:10.1039/CT8977100123

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

JAPP AND LANDER: SYNTHESIS O F PENTACARBON RINGS. 139 IX.-Synthesis o f Pentucurbon Rings. Part II. Con- densation of Benxil with Acetone Dicurboxylic Acid. By FRANCIS ROBERT JAPP, F.R.S., and GEORGE DRUCE LANDER, B.Sc. BENZIL and acetonedicarboxylic acid, when gently warmed with dilute alcoholic potash, condense according to the equation yielding anhydracetoneBenxi1cu~boxylic acid (melting at 167-1 68"). I n the preliminary note on this subject which we published (Proc., 1896, log), this acid was formulated as an analogue of isophenanthroxyl- C H *C=C COOH ene-acetoacetic acid l 6 I >CO (Japp and Klinge- C6H4' C(OH)* UH, mnnn, Trans., 1891, 59, 2). Further investigation, however, has shown140 JAPP AND LANDER : SYKTHESIS OF PENTACARBON RINGS. that this analogy does not hold.Thus, whilst isophenanthroxyleneaceto acetic acid, dissolved in sodium carbonate, is stable towards permangan- ate in the cold, anhydracetonebenzilcarboxylic acid is rapidly oxidised. This difference in behaviour is in keeping with the formulze here as- cribed to these acids, the oxidisable acid containing,and the stable acid not containing, hydrogen directly united to the ethylene group. The position of the carboxyl group in anhydracetonebenzilcarboxylic acid is thus identical with that of the alkyl group in the mon-alkyl derivatives of anhydracetonebenzil (see preceding paper), When anhydracetonebenzilcarboxylic acid is boiled for a few minutes with fuming hydriodic acid, it is reduced and at the same time deprived of carbon dioxide, yielding a di~~~enylcyclopent~none, C H *C*CH, II >CO (m.p. l l O o ) , identical with that obtained from C,H,* C-CH, anhydracetonebenzil itself (see preceding paper). By oxidation with sodium hypobromite, anhydracetonebenzilcarboxylic acid yields a mixture of diphenylmuleic and diphenylficrnaric acids, these two substances being produced in approximately equal quantity. A change in the position of the double bonds ta,kes place during this process. The corresponding change which occurs in the formation of diphenylcyclopentenme has been discussed in the preceding paper. When oxidised with chromium trioxide in acetic acid solution, it parts with 2 atoms of hydrogen, yielding an acid of the formula C118H220, (melting a t 205 -207", with decomposition). The primary product is a, yellow compound, apparently the hydrazone ; but this readily changes, especially on recrystallisation, into dark red needles of a substance melting indefinitely about 200") formed by elimination of 1 mol.of water from 2 mols. of the hydrazone, The action of phenylhydrazine is complex. EXPERIMENTAL Pyepumtion of Anhydrucetonebenxilcccrboxylic Acid .-Twent y-one grams of finely-powdered benzil and 15 grams of acetonedicarboxylic a,cid were introduced into a flask along with sufficient alcohol to dissolve the benzil in the subsequent process of warming. To this were added 17 grams of potassium hydroxide dissolved in 20 C.C. of wat.er and 100 C.C. of alcohol, after which the mixture was very gently warmed on the water bath until everything had dissolved. The flask was then re- moved from the water bath, and allowed t o stand.Too long heating, or too high a temperature, decomposes the acetonedicarboxylic acid, andJAPP AND LAXDER: SYNTHESIS OF PENTACARBON RINGS. 191 must therefore be avoided; and for the same reason, the benzil should be previously powdered, in order that it may the more readily dissolve. On standing, the liquid deposited a potassium salt, which was separated by filtration, washed with cold alcohol to remove adhering caustic potash, and then boiled with alcohol, in which it is only sparingly soluble ; it was thus freed from benzil and dark-coloured impurities. From the solution of this salt in water, the new acid was precipitated by dilute sulphuric acid. It was purified by dissolving it in hot glacial acetic acid and di- luting with hot water ; on standing, the liquid deposited crystals of the new acid. It may also be recrystallised from a large bulk of boiling water, From either of these solvents, it crystallises in two forms : (I) small, thickish, oblong plates, frequently grouped into rosettes ; this form is ailhydrous and melts at 167-168"; and (2) thin, very lustrous plates, or flat needles, containing 1H,O; these melt on the water bath, but the fused substance speedily re-solidifies in crystals of the first fonn, and then melts a t 167-168".With concentrated sulphuric acid, it gives an intense red coloration, resemblirig that produced by benzilic acid under the same circumstances. I t s sodium salt is rapidly oxidised by permanganate in the cold (von Baeyer's test for non-saturation). Analysis* of a specimen recrpstallised from a mixture of ethylic acetate and light petroleum gave figures agreeing with the formula Cl8H1404.0.2972 gave 0.7996 CO, and 0.1304 H,O. C = 73.37 ; H = 4.S7. 0.2084 ,, 0.5605 CO, ,, 0.0922 H,O. C = 73.35 ; H = 4.91. C18H1404 requires C = 73.47; H = 4.76 per cent. I n order to indicate its relationship to anhydracetonebenzil, we have 0-4585 of the lustrous plates, deposited from water, lost, on heating named it unhyd~.ucetonebenxilcurboxylic acid. a t loo", 0.0254. H,O = 5-54 per cent. Cl8H1,O4,H,O requires H,O = 5-76 per cent. The d v e r salt was obtained as a white precipitate by adding silver nitrate to a solution of the ammonium salt. 0.3756, dried at 80°, gave, on ignition, 0.1006 Ag = 26.78 per cent.C18H1,04Ag requires Ag = 26.93 per cent. Action of Concentrated Ifgdriodic Acid on An~gdracetonebenxiur- boxylic Acid. Formation of Diphenylcyclopentenone.-Ten grams of an- hydracetonebenzilcarboxylic acid were boiled with excess of concen- * The acid was prepared and analysed by Dr. J. Bishop Tingle, who began this research, jointly with one of us, in the Chemical Laboratory of tlie Royal College of Science, London, in 1890. The work was interrupted at the time by Dr. Tingle's departure from London.142 JAPP AND LANDER : SYNTHESIS O F PENTACARBON RINGS. trated hydriodic acid (sp. gr. 1.96) for 5 minutes. The solid mass left on cooling was washed with water, extracted with ether, and the ethereal solution freed from iodine in the usual way with sulphurous acid.It was difficult to purify, but as we could perceive that it was diphenylcyclopentenone, we recrystallised it, as recommended by Japp and Burton, from a large volume of boiling water and afterwards from alcohol. It was thus obtained in thin, yellowish prisms melting a t 1 lo", which is the melting point of diphenylcyclopentenone. Analysis gave figures agreeing with the expected formula C17H,,0. Found : C = 87.02 H = 6-24. Calcu- lated : C = 87-18 ; H= 5.98 per cent. The product of reduction was not an acid. It is formed according to the equation Cl8HI4O4 + H2 = C17H140 + CO, + H2O. Oxidation of Anhydraceto.r.Le6enxiEcar6oxylic Acid with #odium Hypo- twomite. ETormation of Dipheny Zmaleic and DiphenyZjunzaric Acids. - Twenty grams of anhydracetonebenzilcarboxylic acid were dissolved in caustic soda, a solution of 60 grams of bromine in excess of caustic soda was added, and the mixture allowed to stand at the ordinary tempera- ture for a fortnight, after which it was saturated with sulphur dioxide, precipitated with dilute sulphuric acid, and the precipitate taken up with ether.The ethereal solution was extracted, first with aqueous sodium carbonate, which removed an organic acid, and then with aqueous caustic soda, which took up a substance insoluble in the car- bonate. On acidifying the caustic soda solution, a yellowish precipitate was obtained; this was recrystallised from benzene, from which it was deposited in the characteristic, greenish-yellow, fluorescent crystals of diphenylmaleic anhgdvide, melting at 156".Found : C = 76.71 ; H = 4.05. Calculated for C16Hlo0,: C=76*80; H=4*00 per cent. The yield was 3 grams. The sodium carbonate extract gave, on acidification, a precipitate of an acid. This was deposited from ethylic acetate, on the addition of benzene, in colourless needles, melting, when rapidly heated, at 276" with evolution of gas (aqueous vapour). The yield was 3 grams. Analysis showed that the substance had the composition of diphernyl- fumaric acid. Calculated for C16H1204 : C = 71.64 ; H = 4.48 per cent. Reimer (Ber., 1882, 15, 1627) gives 260" as the melting point of this compound. It does melt a t that, temperature, if kept there long enough ; but, when rapidly heated, it melts as above at 276". The lower melting point is doubtless due to the slow conversion of the substance into diphenylmaleic anhydride and water.Owing to this discrepancy in the melting point, we thought it necessary Found : C = 71 -42 ; H = 4.50.JAPP AND LANDER: SYNTHESIS OF PENTACARBON RINGS 143 to identify the diphenylfumaric acid still further by transforming it into diphenylmaleic anhydride. For this purpose, a portion of it was heated in a Sprengel vacuum at 260O. Only water was given off, while a yellowish substance sublimed and collected in crystals in the upper part of the flask. The product was deposited from benzene in greenish- yellow, fluorescent prisms, melting a t 156", and was diphenylmuleic ccnhy d d e . Oxidation of An~?/drucetonebenxilcarbox~Zic Acid with Ch~omizcm B*ioxide.-Ten grams of anhydracetonebenzilcarboxylic acid were dis- solved in a little glacial acetic acid, and the solution was diluted with water, but not so as to cause precipitation. Eight grams of chromium trioxide dissolved in a little water were then added, and the liquid was warmed on the water bath until the oxidation appeared to becomplete, after which the dark green solution was poured into excess of water.The precipitate was collected, extracted with sodium carbonate, and the organic acid reprecipitated and purified by recrystallisation, first from benzene, and afterwards from ethylic acetate. It crystallised in minute needles, melting with evolution of gas at 205-2079 (The melting point 201O was erroneously given in our first note.) Analysis gave figures agreeing with the foi inula C,,H,,O,, showing that the new acid had been formed from anhydracetonebenzilcarboxylic acid by the withdrawal of two atoms of hydrogen.0.1194 gave 0.3241 CO, and 0.0463 H,O. C = 74.02 ; H=4.31. 0.1850 ,, 0.4994 CO, ,, 0.0682 H,O. C = 73.63 ; H = 4.09. C,,H,,O, requires C = 73.97 ; H = 4.1 1 per cent. The siEvev scclt was obtained as a white precipitate by adding silver nitrate to a solution of the ammonium salt. It was dried at 80'. 0,1691 gave 0.0457 Ag. Ag = 27-02. C,,H,,O,Ag requires Ag = 27.07 per cent. Action of Phenylhydmxine o n Anhydrcccetonebenxilcarboxylic Acid.- Five grams of anhydracetonebenzilcarboxylic acid were boiled with phenylhydrazine in alcoholic solution. Almost immediately, a crystal- line substance of a clear, yellow colour was deposited.This was separated by filtration and extracted with boiling benzene, in which it is only sparingly soluble. The yellow residue was then dissolved in boiling alcohol, which deposited it in dark red needles, the substance having undergone a change during recrystallisation. The benzene extract also yielded red needles. The melting point was very indefinite, as the substance decomposed in melting : the point of decomposition lay somewhat over 200°. Some specimens which had been purified by144 JAPP -4ND MURRAY : SYNTHESIS OF PENTACARBON RINGS. recrystallisation from a mixture of ethylic acetate and light petroleum, or acetone and light petroleum, melted lower than this (180-182'). I f acetic acid is used as a solvent in the preparation of the compound, the red substance is formed at once ; but too high a temperature must be avoided, otherwise the product is resinified. The substance separates from the acetic acid solution on dilution with water. Analyses of specimens prepared by both methods gave identical figures. 0.1756 gave 0.4947 CO, and 0.0832 H,O. C = 76.83 ; H = 5.26. 0.1838 ,, 12.20 C.C. moist nitrogen a t 15Oand 753 mm. N = 7.69. 0.1123 ,, 7.40 ,, ,? ,, ,, 16' ,, 750-5 mm.N = '7.58. C,,H,,N,O, requires C = 76.80 ; H = 5-07 ; N -- 7.47. 0.1134 ,, 0.3181 CO, ,? 0.0542 H,O. C=76.50; H=5*31. We have already pointed out that the formation of such a compound might be accounted for by supposing 2 mols. of the normal hydra- zone, C,,H,,N,O, (possibly represented by the yellow compound), to unite with elimination of 1 mol. of water. The unstable yellow compound was not analysed. CHEMICAL DEPARTMENT, UNIVERSITY OF ABERDEEN.

ISSN:0368-1645    

DOI:10.1039/CT8977100139

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

144 JAPP -4ND MURRAY : SYNTHESIS OF PENTACARBON RINGS. X.-Sy.nthesis of Pentacarbon Rings. Paiht 111. Condemation of Benzil with Lavulic Acid. By FRANCIS ROBERT JAPP, F.R.S., and THOMAS SMITH MURRAY, D.Sc. HUGO ERDMANN (Annwlen, 1889, 254, 187 ; 1890, 258, 129) has shown that, in the condensation of benzaldehyde with lsvulic acid, the benzal group attaches itself to the lsvulic acid chain either in the p- or in the &position, according to the nature of the condensing agent employed. Thus either /3-benzallsvulic acid, C6H,* CH:C<gg2:FdoH, or 6-benzal- laevulic acid, C6H,* CH:CH* CO*CH,* CH,* COOH, is formed, accord- ing as the dehydrant is fused sodium acetate or dilute caustic alkali. We find that, in the condensation of benzil with laevulic acid under the influence of caustic potash, both carbonyl groups of the benzil, and both the /3- and the &groups in the lmwlic acid chain, take part in the condensation.Two isomeric acids are obtained, the formation and constitution of which may be represented as follows.JAPP AND MURRAY: SYNTHESIS OF PENTACAREON RINGS. 145 C,H,* 70 + C H 3 > ~ ~ - H,O C,H,* CO CH, CH,*COOH >GO and C,H,* C=CH >GO I - C,H,* Y(OH)*CH, - C,H,*C L__ C CH,.COOH C,H,*C(OH)*CH CH,*COOH a-AnhydrobeiizillEvulic acid. &Anhydrobenzillfevulic acid (known only in its salts). the latter substance being formed in subordinate quantity. The condensation is analogous to that which occurs in the formation of anhydracetonebenzil and its homologues (see Part I. of this series of papers), the same cyclopentene group being formed in both cases.The relationship of the two anhydrobenzillaevulic acids to anhydracetone- b e n d might be indicated by naming them anhyd9*acetonebentxilethyZoic acids. The formation of the two acids might be accounted for by sup- posing the first stage of the reaction to consist in a di-aldol condensa- tion, leading to a hypothetical intermediate compound of the formula >CO C,H,* C(OH)*CH, I c,H,- C(OH)-CH CH,.COOH ' which might then part with a molecule of water in two different m a p , yielding the two anhydrobenzillsvulic acids. The sodium salt of the P-acid is instantaneously oxidised by perman- ganate in the cold, whilst that of the a-acid is only slowly oxidised. This behaviour is in accordance with the foregoing formulz, in which the P-acid contains, and the a-acid does not contain, hydrogen directly attached to the ethylene group.The a-acid is stable in the free state, the P-acid, when liberahed from its salts, spontaneously parts with water, changing into the lactone, (See Part I.) CGH5* C:CH I >GO C,H,* C CH 0-co ' X H , The action of the a-acid with hydroxylamine is abnormal, an addition of hydrogen, effected by the excess of hydroxylamine, accompanying the formation of the oxime : C,,H,,O, + NH,OH + H, = C19H180,(N* OH) + H,O. The action of the P-acid with hydroxylamine was not studied for want of material. Both the a-acid and the lactone, when boiled for a short time with fuming hydriodic acid, are converted into the same diphenylcyclopen- tenonethyloic acid, C6H5* !?cH2>co , a change in the position C,H,* C*CH * CH,* COOH VOL.LXXT. L146 JAPP AND MURRAY : SYNTHESIS OF PENTACARBON RINGS. of the double bonds accompanyin: the reduction. That this change occurs is shown by the formation of this compound both from the a-acid and from the lactone of the P-acid, and also by the fact that diphenyl- cyclopentenonethyloic acid yields, on oxidation with sodiuiii hypo- bromite, a mixture of cliphenn?/lmuleic and diphenyllfumuvic cccicls. We do not, however, lay much stress on this last argument, as anhydrace- tonebenzilcarboxylic acid, in which the double bonds are not in the position which they occupy in diphenylmaleic and diphenylf umaric acids, gives a mixture of these two acids on oxidation (see preceding paper). The formation of the fumaroid form in these cases is anomn- lous; one would expect that, in the opening out of the closed chain, only the malenoid form would be produced.Diphenylcyclopentenonethyloic acid yields an oxirne. I f a-anhydrobenzillaevulic acid is boiled with hydriodic acid and amorphous phosphorus for some hours, the diphenylcyclopentenonethy- loic acid, which is first formed, is further reduced and a t the same time parts with carbon dioxide, yielding methyldiphenylcycZo~)eiztane, 2>CH,, C,H,. CH* CH C,H,*CH*CH CH, I a homologue of the diphenylcyclopentane obtained from anhydracetone- benzil. Only one of the possible stereoisomeric forms of this hydro- carbon was observed. EXPERIMENT A L. Prepration of a- A?& y d ro bend Zevulic A cid ccnd j3- An hydro benxi Zlcevu Zo- lactorte.-One hundred and five grams of benzil are dissolved with the aid of heat in 300 C.C.of alcohol ; 58 grams of laevulic acid are added, and the mixture is cooled, shaking the flask all the time to prevent the benzil from separating in large crystals. To the magma thus obtained, a solution of 50 grams of caustic potash in 75 C.C. of water is added, and the whole is heated on the water bath to boiling for about 20 minutes, after which it is poured into water and the solution saturated with carbon dioxide, to prevent the excess of caustic alkali from exercising any decomposing action during the subsequent evaporation. The liquid is then evapo- rated until the whole of the alcohol is expelled; a large bulk of water is added, and the solution, after filtering, if necessary, is precipitated with dilute sulphuric acid, adding the acid gradually to the hot liquid, so as to prevent the simultaneous precipitation of salts.By stirring vigorously and heating on the water bath, the organic acids are obtained as a tarry mass, from which the supernatant liquid can be poured off. On standing for two or three days, this mass solidifies. It is then ground in a mortar and thoroughly extracted with boiling water, t oJAPP AND NURRAY: SYNTHESIS OF PENTACARBON RINGS. 147 remove salts and sulphuric acid, after which it is twice boiled with a solution of sodium carbonate ; this extracts the a-anhydrobenzillaevulic acid, leaving the P-anhydrobenzillaevulolactone as a brown powder, the treatment of which will be described later on.The solution of the sodium salt is then precipitated with diIute sulphuric acid, washing the organic acid thoroughly with water. It is dried, extracted with a small quantity of boiling benzene, which removes most of the brown colouring matter, dissolved in the smallest possible quantity of hot glacial acetic acid, and an equal bulk of benzene added. On standing, the solution deposits the acid in needles. It is sufficiently pure for the study of its reactions, but it was further purified for analysis by recrystallisation from a mix- ture of ethylic acetate and light petroleum. The yield of once c rystal lised substance from the above quantities, conducting the operation as described, ranges from 70 to 80 grams ; but more may be obtained from the mother liquor.a-AnhydrobenziZZ~vzcZ~c acid crystallises in colourless needles, melting with decomposition at 178-179O." It is readily soluble in alcohol, glacial acetic acid, and ethylic acetate; but only sparingly in benzene and ether. It is only very sparingly soluble in boiling water, but may be obtained pure by recrystallisation from a large bulk of this solvent. It gives a brown coloration with concentrated sulphuric acid. Analysis t gave figures agreeing with the formula C,,H160,. 0.3414 gave 0.9230 CO, and 0.1558 H,O. C = 73.73 ; H = 5.07. 0.2436 ,, 0.6602 CO, ,, 0.1114 H20. C = 73.91 ; H = 5.08. C19H1604 requires C = 74.02 ; H = 5.19 per cent. The sodium, potassium, and ammonium salts are sparingly soluble in cold, readily in hot, water. The barium salt, obtained by precipitation from the ammonium salt, crystallised from dilute alcohol and gave figures agreeing with the formula (C,,H,,0,),Ba,5H20. 0.2802 lost, at 150°, 0.0297, and the residue gave 0*0776 BaSO,.H,O = 10.6 ; Ba (in anhydrous salt) = 18.22 per cent. (CIgH,,0,),Ba,5H,0 requires H,O = 10.7 per cent. (C,,H,50,),Ba requires Ba = 18-27 per cent. The process of heating with dilute sulphuric acid to which the freshly-precipitated mixture of anhydrobenzillaevulic acids is subjected ensures that any P-acid which may be present is converted into lactone, ++ By an unfortunate transposition of the figures in writing the preliminary note which we published on this subject (Proceedings, 1896, 146), this melting point was erroneously given as 187-189". .F These analyses were made by Dr.J. Bishop Tingle, by whom the acid was first prepared. (See footnote to preceding paper.) L 2148 JAPP AND MURRAY: SYNTHESIS OF PENTACARBON RINGS. which remains undissolved when the a-acid is extracted with sodium carbonate. The brown powder thus obtained (u. supra) is washed wit11 ether, which removes much of the colouring matter, and is then mrgrstallised several times from benzene; it is thus obtained in well- defined, colourless, flat prisms, or plates, with bevelled edges, melting a t iI51-152O. It is moderately soluble in benzene and alcohol, sparingly in efher, and insoluble in light petroleum. It gives a pale yellow colora- hima, with concentrated sulphuric acid. The yield is small; only 8 grams of the lactone were obtained from 210 grams of b e n d Analysis gave figures agreeing with the formula of P-ccnhyd~o6enxil- hseclolactone, C,,H,,O,.0,1455 gave 0.4183 CO, and 0.0646 H,O. C = 78.40 ; H = 4.93. D.1501 ,, 0.4315 CO, ,, 0.0668 H,O. C = 78.40 ; H = 4.94. C1,H1403 requires C = 78.62 ; H = 4.83 per cent. A cryoscopic determination of the molecular weight, using benzene as a solvent, gave a result in accordance with the foregoing formula. Weight of Weight of Mol. substance. solvent. Depression. weight. 0.1070 23.435 0 . 0 8 O 280 ClgH140, = 290. /l-Anhydrobenzillzevulic acid, when freshly precipitated from solutions of its alkali salts, is soluble in sodium carbonate; but after standing for some time under the liquid, it no longer dissolves, and is found to have been transformed into the lactone. The silver 8aZt of /3-anhydrobenzillaevulic acid was, after several unsuccessful attempts to prepare it from the ammonium salt, obtained by the following method.The lactone was dissolved in alcohol, and alcoholic potash was added so as to leave the lactone in excess. This point could easily be observed, owing to the change in the colour of the solution, which occurred as soon as the potash was in excess, in which case it was necessary to add more lactone. The solution was then evaporated to dryness, the residue dissolved in water, and the liquid filtered from unattacked lactone. From the solution of the potassium salt, the silver salt was obtained as a white precipitate by adding excess of silver nitrate. It was dried in a vacuum and analysed. 0.7908 gave 0.2062 Ag.Ag=26*07 per cent, ClgH,50,Ag requires Ag = 26.02 per cent. Behaviow of a- and P-An?~yd~oEenxilZevzcZic Acids towavds Peiman- gnnate.-The sodium salts of the two acids were employed, that of the 8-acid being prepared from the lactone by the method just described inJAPP AND NURRAY: SYNTHESIS OF PEKTACARBON RINGS. 149 the case of the potassium salt, and recrgstallised several times to ensure purity. Solutions of the two d t s , of equal strength, were. mixed with sodium carbonate, and a drop of permanganate solution was added to each. The change to a brown colour was instantaneous in the case of the /?-salt, but required one or two minutes in the case of the a-salt. This, as has already been pointed out, is in keeping with t h e difference in the constitution of the two acids.Action of Hydroxyhrnine on a-A~hydi.obenxilZevu7/ic Acid.-Nine grams of the finely-powdered acid were suspended in about 100 C.C. of water, and 4.2 grams of hydroxylamine hydrochloride and 12 grams of caustic potash, each dissolved in water, were added. The mixture was allowed to remain, with occasional shaking, for 3 days, at the end of which time almost everything had dissolved. The liquid was filtered, and carbon dioxide was passed into the clear solution. The dense white, granular precipitate thus produced was filtered off, and washed with a little cold water. It was found to be the potassium salt of an oxime. It was soluble in much water, and apparently unaltered even by long boiling. The oxime mas obtained from this potassium salt by treating it with excess of cold, dilute sulphuric acid and extracting rapidly with ether ; the ethereal solution, after washing it with water and allowing it, t o evaporate spontaneously, left an oil, which was dried in a vacuum oveF sulphuric acid. By dissolving this oil in ethylic acetate and adding benzene, the oxime was deposited in tufts of white needles, which, when dried, had a matted appearance. The substance was several times recrystrallised from the same mixture.It melted, with decomposition. at 122-123O. The analytical figures appeared to point to the formula. which is that of a normal oximeplus 2 atoms of hydrogen. 0,1352 gave 0.3459 CO, and 0.0694 H,O. C=69.75 ; H=5*70. 0.1358 ,, 0.3475 CO, ,, 0.0690 H,O. C = 69.80 ; H=5.65. 0.1053 ,, 0.2693 CO, ,, 0.0550 H,O.C = 69.75 ; H= 5-80, 0.2384 ,, 8-02 C.C. moist nitrogen a t 14' and 760 mm. N = 3-96, 0.2058 ,, 7.04 C.C. ,, ,, ,, 11' ,, 759 mm. N=4.07, C,9H,9N0, requires C = 70.15 ; H = 5.85 ; N = 4-31. The oxime is sparingly soluble in water. Boiled with water, it dis- solves ; on further heating, carbon dioxide is evolved, and a yellowish substance separates, insoluble in alkalis. We were unable t o ohtain this substance in a crystallised state, and did not examine it further. The siher salt of the oxime was obtained as a white precipitate by150 JAPP AKD MURRAY: SYNTHESIS OF PEKTACARBON RINGS, adding silver nitrate to a solution of t,he potassium salt. i t was dried at 100". For analysis, 0.2660 gave 0.0669 Ag. Ag = 25-15, C19H18N0,Ag requires A g = 25.00 per cent.The foregoing sparingly soluble potassium salt was not analysed, but. was doubtless the monopotassium (carboxylic) salt corresponding with this silver salt. The solution in excess of caustic potash must have contained a soluble dipotassium (carboxylic and oximic) salt which was converted by carbon dioxide into the monopotassium salt. The same phenomenon is exhibited in the case of another oximino-carboxy-acid described later on. Reduction of a-Anl~~drobenxilZ~vzLlic Acid with Liydriodic Acid.--In the first experiment which we made t o reduce this acid by boiling it, mith hydriodic acid, great difficulty was found in obtaining the product in a crystallised form. As the substance was an acid, salts of it were prepared ; but these showed equally little disposition to crystnllise.At last it was found that in a specimen of the gummy reduced acid, which had been allowed to stand for some months covered with benzene, and protected from evaporation, a small rosette of prisms had formed. This was freed from the adhering gummy substance, and was used in starting subsequent crystallisations. It was also found that the product was more readily cry stallisable if the boiling with hydriodic acid was not continued longer than was absolutely necessary for the reduction. Forty grams of finely-powdered a-anhydrobenzillaevulic acid were heated to boiling with excess of fuming hydriodic acid (sp. gr. 2.0) for about a minute and a half, shaking the flask continually during the process. The substance melted. It was then poured into water and the liquid extracted twice with ether.The ethereal solution was decolorised with sulphurous acid, well washed with water, and dried with calcium chloride. On evaporation, it left a gum, which was dissolved in benzene, and the crystallisation was started by means of the crystalline substance already mentioned. A mass of hard crystals, embedded in the syrupy benzene solution, was thus obtained. The syrup was removed with the aid of the filter-pump, and the crystals, after washing with benzene, were redissolved in this solvent. The solution deposited 31 grams of almost pure substance, which gave practically no colour with concentrated sulphuric acid, showing the almost entire absence of unchanged a-anhydrobenzillEvulic acid. Recrystallised once more from benzene, it melted constantly a t 126- 127*, and now gave no coloration with sulphuric acid.It forms rosettes of prisms. It is slightly soluble in boiling water and separates The following process gave a good result.JAPP AND MURRAY: SYKTHESXS OF PENTACARBON RINGS. 151 again on cooling ; readily soluble iii ether, alcohol, or benzene; in- soluble in light petroleum. Analysis showed that the original acid had parted with an atom of oxygen during the reduction, yielding an acid of the formula C19H160,. 0.1281 gave 0.3674 00, and 0.0642 H,O. C = 78.22 ; H = 5.57. 0.1258 ,, 0.3601 CO, ,, 0.0635 H,O. C=78.07; H ~ 5 . 6 1 . C,,H,,O, requires C = 78-08 ; H = 5.48 per cent. We have already given reasons for regarding this compound as The silvey salt warns obtained by precipitating the ammonium salt di~~henylcyclopenteIIo~~ethyloic w i d .with silver nitrate. For analysis, it was dried at 100'. 0.8733 gave 0.0730 h g . Ag=26.71. C19Hl,0,Rg requires Ag = 27-07 per cent. Action of Hyd~*oxylc~rnine on D~p~~enylcyclo~enterw~ethyloic Acid .- 5.8 grams of acid, 5.5 grams of hydroxylamine hydrochloride, and 15 grams of caustic potash were dissolved in water, and allowed to stand in the cold for 3 days. Carbon dioxide was then passed into the solution, when a potassium salt of the oxime was precipitated ; this was washed with cold water, in which it was practically insoluble. A portion of it was dissolved in alcohol, and an alcoholic solution of silver nitrate was added. The gelatinous precipitate of silver salt thns obtained was washed first with alcohol and then with water, and finally dried in a vacuum desiccator for some days.0.4492 gave 0.1165 Ag. The free oxime was obtained by shaking the potassium salt with dilute sulphuric acid and ether, washing the ether with water, drying it with calcium chloride, allowing it to evaporate spontaneously, and, when it had reached a small bulk, adding light petroleum. The oxime separated in minute, white, crystalline warts, melting constantly a t 183--184O, with slight darkening, Analyses agreed with the formula Ag = 25.93. C,,H,,NO,Ag requires Ag = 26-09 per cent. C1,H160,(N0H)* 0.1558 gave 0.4224 CO, and 0-0791 H,O. C=73.94 ; H=5*64. 0.3165 ,, 12.3 C.C. moist nitrogen at 7" and 752 mm. N= 4.66. Cl,H17N0, requires C = 74-26 ; H = 5.54 ; N = 4.56 per cent.Oxidation of Diphenylcyclopentenonethyloic Acid with #odium Hypo- bromite.-As diphenylcyclopentenonethyloic acid had evidently the same relation to a-anhydrobenzillsvulic acid as diphenylcyclopentenone has t o anhydracetonebenzil, and as diphenylcyclopentenone yields, by152 JAPP AND MURRAY : SYNTHESIS OF PENTACARBON RINGS. oxidation with sodium hypobromite, diphenylmaleic acid (see Part I.), it was of interest to ascertain how diphenylcyclopentenonethyloic acid would behave towards this oxidising agent. 5.8 grams of the acid were dissolved in caustic soda, and a solution of 30 grams of bromine in excess of caustic soda was added. The mixture was allowed to stand for 3 days with frequent stirring, after which sulphur dioxide was passed in, the liquid acidified with dilute mlphuric acid, and the organic substance extracted with ether.The ethereal solution was extracted twice with sodium carbonate, and then with caustic soda. The united sodium carbonate extracts, on acidification, gave a pre- cipitate, which was taken up with ether and was left, on evaporating the ether, as a resinous mass containing crystals. After removing the resin with benzene, the crystals were dissolved in ethylic acetate, and benzene was added. A compound separated in needles and appeared to be diphenylfumaric acid, but the melting point was unsatisfactory. As the substance was suspected to contaio diphenyl- maleic anhydride, we treated it again with sodium carbonate. An undissolved residue was filtered off and the acid reprecipitated from the filtrate.It now crystallised from the mixture of ethylic acetate and benzene in small, white needles, melting at 271". The melting point of diphenylfumaric acid is given by Reimer at 260", and by Japp and Lander at 276" (see preceding paper). Much depends on the rate of heating, as the substance decomposes on melting. Analysis gave figures agreeing with the formula of diphnglfu;maric ncid. Calculated for C16H,,0, : C = 71.64; H = 4.48 per cent. The caustic soda solution gave, on acidification with dilute sulphuric acid, a yellow prccipitate, which was recrystallised twice from benzene, and was thus obtained in rosettes of yellow prisms, with a characteristic greenish fluorescence, and melting at 156.5'. These are the properties of diphnylmccleic nnhydride.Calcu- lated for C,,H,,O,: C = 76.80; H = 4.00 per cent. Reduction of a-An~yd~.obenxiIk~vulic Acid with Hydriodic Acid and Amo~phous Yhosphorus.-The fact that anhydracetonebenzil, which by boiling for a short time with hydriodic acid yields diphenylcyclopen- tenone, can, by more protracted reduction with hydriodic acid and amorphous phosphorus, be converted into the hydrocarbon diphenyl- cyclopentane, led us to try whether an analogous further reduction could also be effected in the case of a-anhydrobenzillEvulic acid. We expected in this way to obtain a diphenylcyclopentanetl~yloic acid. On trying the experiment, however, we found that carbon dioxide was eliminated and methyldiphenylcyclopentane was formed. Found : C = 71.70 ; H = 4.72. Found : C = 76.63; H = 3.93.JAPP AND MURRAY: SYNTHESIS OF PENTACARBON RINGS.153 Ten grams of a-anhydrobeiizillzvulic acid were boiled with 150 grams of hydriodic acid (sp. gr. 1.75) and 20 grams of amorphous phosphorus for 6 hours. Water was added, and et,her to dissolve the organic sub- stance, after which the excess of amorphous phosphorus was filtered off. The ethereal solution, after decolorising with sulphurous acid, was shaken with alkali, which, however, extracted practically nothing from it. On evaporating the ether, a yellow oil remained, which became crystalline on standing. By dissolving the crystalline mass in ether and adding methylic alcohol, the compound was obtained in rosettes of very slender, white needles, which, after repeating this process of crystal- lisation two or three times, melted constantly at 62-63'.The sub- stance is soluble in light petroleum, very soluble in benzene and ethylic acetate, less so in ethylic alcohol and methylic alcohol. Analysis agreed with the formula of metl~~lWip~~enyZcycZo~~e.1atccne. 0.1271 gave 0.4255 CO, and 0.0980 H,O. C = 91.30; H = S.5'7. 0.1243 ,, 0.4166 CO, ,, 0.0955 H,O. c1 = 91.40; H = 8.54. C,,H,, requires C = 91.52; H = 8.48. h'ecluctiorz of ~-~nhydrobenx~~kevu~o~ccctone with Hychiodic Acid.-- This experiment was performed in order to ascertain whether the pro- ducts of reduction of the a-and p-acids were the same or different. Two grams of the finely-powdered lactone were boiled for 2 minutes with excess of the strongest hydriodic acid, and the product of the action was treated exactly as in the preparation of diphenylcyclo- pentenonethyloic acid from a-anhydrobenzillaevulic acid, except that, in order to remove any unchanged lactone or other neutral substance, the ethereal solution of the reduction product was extracted with sodium carbonate and the acid reprecipitated from the carbonate solution. It was again taken up by ether and, on evaporation, remained as an oil, which, on touching it with a crystal of diphenylcyclopentenonethyloic acid, obtained by the reduction of the a-acid, at once began to crystal- lise. The crystals were freed from gummy matter by draining on a porous tile. After recrystallising five times from benzene, they melted at 124-126'. They were indistinguishable from those of diphenyl- cyclopentenonethyloic acid, except that the latter melted 1' higher. 0.1383 gave 0.3953 CO, and OW719 H,O. The a- and the P-acid thus both yield the same clil3JLe~Zylc~clo~ei~~~?~- The conclusions to be drawn from this C = 77.95 ; H = 5.77. C19H1,0, requires C = 78.08 ; H = 5.48. onethyloic acid on reduction. fact are discussed in the introduction. CHEMICAL DEPARTMENT, UNIVERSITY OF ARERDEEN.

ISSN:0368-1645    

DOI:10.1039/CT8977100144

出版商:RSC    

年代:1897

数据来源: RSC