摘要:

2098 GIBSON : SOME MOLECULAR COMPOUNDS OFCCIX-Some Molecdaq- Compounds of Styplmic andPic& Acids.By CHARLES STANLEY GIBSON.ALTHOUGH our knowledge of the molecular compounds formed bypicric acid with other aromqtic substances is fairly extensive, littlework has so far been done on similar compounds which may be formedby the analogous trinitroresorcinol, styphnic acid. Noelting and Salk(Bey., 1882, 15, 1863) prepared naphthalene styphnate, and Summererhas recently described (Diss., Zurich, 1907) cinnamaldehyde styphnate.The styphnic acid used was successfully prepared according t o hlerzand Zetter’s method (Ber., 1879, 12, 2037), and the followingcompounds have been prepared.A cen aph them St y p h a te, C , , H, ,, , C, H (OH), (N 02)3.When 3.1 grams of acenaphthene and 5 grams of styphnic acid itree x h dissolved in alcohol and the solutions mixed while still warmSTYPHNIC AND PICRIC ACIDS. 2099acenaphthene styphnate crystallises out in long needles on cooling.It is obtained pure by recrystallisation from alcohol :0.1510 gave 14.05 C.C. N, a t 16.7" and 754.5 min.: N = 10.88.ClsH,,OsN, requires N = 10.53 per cent.Acenuphthene styplmccte crystallises in long, orange-coloured, doubly-refracting prisms, which melt at 153-i54" to a red liquid. I t ismoderately soluble in cold alcohol, and is decomposed by a large excessof this solvent ; after several crystallisations, pure acenaphthene(m. p.=95') is obtained. I n acetone and ethyl acetate it is reaidilysoluble and stable, but in ether it is partly decomposed.Thecompound is decomposed by carbon disulphide, chloroform, carbontetrachloride, light petroleum or benzene.z'henanthene Styphnnte, C14H10, c6 H( OH),( NO,),.This compound is prepared by dissolving 3.6 grams of phenanthrenein alcohol, and adding the solution to 5 grams of styphnic acid, alsodissolved in alcohol. On cooling, the substance separates out, and iseasily purified by recrystallisation from alcohol :0.1806 gave 15.10 C.C. N, a t 18*5O and 763.3 mm. N= 9.83.C,,H,,O,N, requires N = 9.93 per cent.Phenanthrene styplinate crystallises in yellowish-red, doubly-re-fracting needles melting at 125-126'. It is readily soluble andstable in alcohol, acetone or ethyl acetate. In benzene it is readilysoluble, but the substance suffers decomposition.It is quicklydecomposed by carbon disulphide, ether, chloroform or carbontetrachloride in the cold, but more slowly by light petroleum.a-Bromonaphthnlene Styphnate, C,, H7Br,C6H(OH),( NO,),.On adding 4.2 grams of a-bromonaphthalene to a warm alcoholicsolution of 5 grams of styphnic acid, bromonaphthalene styphnate isobtained. The compound is recrgstallised from as little alcohol aspossible ; the pure substance possesses a distinct odour of bromo-naphthalene :0.1704 gave 13.6 C.C. N, at. 20.0° and 757-5 mm.C1,H,,,08N,Br requires N = 9.30 per cent.a-Bromonaphthalene styphnate melts a t 107-1 08", and crystallisesin small, bright yellow, dou5ly-refracting needles. It is solublein ether, acetone or ethyl acotate, and is stable in these solvents.When light petroleurn is added to the ethereal solution, styphnicacid is precipitated.The compound is soluble and fairly stable inalcohol, being decomposed by a large excess of the solvent.Bromonaphthalene styphnate is immediately decomposed by carbonN = 9.272100 MOLECULAR COMPOUNDS OF STYPHNIC AND PICRIC ACIDS.disulphide, chloroform, or carbon tetrachloride, Rtyphnic acid beingprecipitated in all casee. I n benzene the decomposition is not sorapid.m-NitroaniZirte St yphnate, N H,. C,H, *NO,, C,H( OH),(This substance is formed when warm alcoholic solutions of equi-molecular proportions of m-nitroaniline and styphnic acid aremixed and the solution allowed to evaporate spontaneously. Thecompound is very soluble in alcohol, and is best recrystallised fromhot benzene:0.1242 gave 19.6 C.C.N, at 16.0' and 757.0 mm.C,,H,O,,N, requires N = 18.28 per cent.m-Nitroaniline styphnate crystallises in pale yellow, dou bly-refract-i n g needles, which, like the corresponding picrate, tend to form inradiate masses. It melts at 1 3 7 O , and is soluble and stable inalcohol, ethyl acetate o r benzene. From its solutions in ether oracetone the compound does not crystallise well. It is decomposedby carbon disulphide, and to some extent by chloroForm or carbontetrachloride.N = 18.56.m-Nitroaniline Picrate, NH,*C,H4 'NO,,C,H,(OH)( NO,),.This compound has not been previously describe!. It is preparedin exactly the same wiiy as m-nitroaniline styphnate, and may bepurified by recrystallising from alcohol or benzene :0.072s gave 12.2 C.C.N, a t 21.0' and 761.2 mm.C,,H,O,N, requires N = 19.08 per cent.m- Nitroaniline piclaate crystallises in doubly-ref racting, radiatingneedles, which melt at 143'. The crystals are of a distinctlydeeper yellow colour than those of the styphuate, but the propertiesgenerally of the two substances show a very close resemblance.The crystals deposited from a benzene solution lose benzene ofcrystallisation very rapidly and become opaque. The compound isalso readily soluble and stable i n alcohol, ethyl acetate, ether oracetone, but it does not crystallise well from the latter solvent.m-Nitroaniline picrate is almost insoluble, and not so stable incarbon disulphide or carbon tetrachloride ; i n chloroform it is rathermore soluble. Even in hot water the compound suffers very littledecomposition. It is interesting to note in this connexisn thatVignon and Evieux, basing their evidence on the heat of solutionin benzene of o-nitroaniline amd of picric acid compa.red with thatof a preparation made by mixing picrio acid with fused o-nitro-aniline, and also on a cryoscopic: determination of the molecularN=19.48PRING: TEE FORMATION OF SOME CARBtDES 2101weight of the preparation, hzve quite recently (Compt. rend., 1908,147, 69) concluded that no combination between picric acid ando-nitroaniline takes place.I t is hoped to continue this investigation.I wish to express my thanks to Professor W. J. Pope, M.A.,F.R.S., who suggested this work and supplied me with the materialsem ploy ed.MUNICIPAL SCHOOL OF TECHNOLOUP,VICTORIA UNIVERSITY OF MANCHESTER

ISSN:0368-1645    

DOI:10.1039/CT9089302098

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

PRING: TEE FORMATION OF SOME CARBtDES 2101CCX. - The Formation of Some Carbides.By JOHN NORMAN PILING.ALTHOUGH a certain number of compounds between metals and theelement carbon has been known from quite early times, the composi-tion was, in almost all cases, ill-defined, and the chemistry of thesesubstances was first systematically investigated by Moissan, who, atthe high temperatures made available with the arc furnace, succeededin producing a whole series of new compounds.More recently the preparation of some of these carbides hasbeen brought about by " thermite " reactions, and in ordinary fuel-heated furnaces.In view of the fact that the carbide-forming elements are, in manycases, known to react with carbon monoxide and other carbon com-pounds, considerable discussion has recently been evoked as to whetherthese elements can combine directly to form carbides in the absence ofsuch gaseous impurities.Moissan showed that a t very high temperatures, where carbonappeared to occur in the state of vapour, direct union with the vapourof some elements, such as silicon, was possible, aud that at lowertemperatures the presence of metals, such as iron in a fused condition,facilitates the formation of carbides in the case of boron and silicon.Aloissan concludes that this is due to the metal acting as solventof these elements (The Electric Furnace, London, 1904, pp.264, 274).'l'he nature of the reaction which takes place at lower temperatures,namely, below 1200°, where carbon vapour can no longer be supposedto exist, has, however, been left an open question, and a n estimation ofthe temperatures at which carbon first combines directly with otherolemeuts hatb nut yet appareutly been carried out2102 PRING: THE FORMATION OF SOME CARBIDES.A clearing up of these points has, it is hoped, been accomplished inthe case of aluminium, silicon, and iron in the following work, whichalso includes some preliminary experiments with magnesium.The method used consisted in mixing intimately the purified elementaud very carefully purified carbon, obtained in a fine state of division,and heating a t a constant tempernture for specified periods of timeunder diminished pressure, which, in this work, was in some cases aslow as 0.01 mm.The apparatus used was of two types : (1) For experiments below900°, the mixture was placed in a porcelaiu boat, which was heated ina silica tube in a platinum-foil electric resistance furnace, a thermo-junction being arranged alongside the tube and opposite the boat forthe temperature readings.The ends of the silica tube were connectedby ground joints to glass tubes, on one side leading to a Topler pump,and on the other t o n tube containing charcoal, which could becooled by liquid air. I n this way, the substance could be heatedfor several hours st a temperature constant to within about loo, andas high as 900°, while the pressure remained below 0.03 mm. (2) Forexperiments above 900°, the mixture was placed in a graphite tubeabout 9 cm. long! 0.9 cm.external, and 0.6 cm. internal diameter,fitted in graphite end plugs, which were mounted in water-cooled brassholders in a tubular glass flask, the brass tubes being fitted into theside-tubes of the flask by means of wax. The graphite tubewas heated by the passage of a n electric current through it(compare Greenwood, Trans., 1908, 93, 1485). Exact temperaturereadings could be taken by means of the Wanner optical pyrometer.A constant temperature, which could be taken as high as3000°, was obtained in the middle part of the tube over a distance ofabout two-thirds of the total length, although the temperature a t theends was rather lower. The pressure could be kept a t about 0.05 mm.by means of a glass tube 7 inches long and la inches diameter, filledwith cocoanut charcoal, and immersed in liquid air.This tube wasusually attached to the neck of the flask by means of a ground joint.Several experiments were conducted without the use of the charcoaltube, exhausting by the Topler pump alone, whereby the pressureobtained was not so low. Measurement of the low pressures wasmade by means of a McLeod gauge, which was first carefullycalibrated.The carbon used for studying the formation of carbides was in theform of retort graphite, which was powdered in an agate mortar,sieved through cotton, and heated in a carbon tube resistance furnacefor about half an hour * at a temperature of 1800 -2OOOO in a current* Originally designed by Hutton aiid l'atterson ( l'mns. Paraday Soc.,1905, 1, 1)PRING : THE FOKMATlON OF SOME CARBIDES. 2103of chlorine and then for the same time in hydrogen.Before thistreatment, the carbon contained 0.38, and afterwards less than 0.01,per cent. of ash.Aluminium Cadride.Guntz and Masson (Compt. rend., 1897, 134, 187) showed thataluminium in presence of a trace of aluminium chloride reacts withcarbon monoxide and carbon dioxide to give aluminium carbideand alumina.Franck (Chem. Zeit., 1898, 22, 236) prepared a small quant,ity ofthis carbide by heating aluminium in carbon monoxide, and alsoby heating the metal with lampblack.I n the preparation of aluminium carbide in the Moissan arc furnace,starting with ingots of the metal, the author found that the reactiontook place chiefly by the fixation of the carbon monoxide present(Pring, Trans., 1905, 87, 1531).Weston and Ellis (Tvans.Furaday. Soc., 190S, 4, 60) preparedaluminium carbide by the interaction of aluminium powder andvarious varieties of carbon, heated in a muffle furnace, and obtained insome cases yields as high as 66 per cent. of the carbide.They conclude that the air played an important part in thereactions, chiefly by causing oxidation OF the aluminium powder andthereby raising the temperrtture of the mixture, and if air had beenrigorously excluded they consider that very little action would havetaken place.In the work described below, aluminium was used in the form of avery fine powder, carefully washed with alcohol and ether to removeany carbonaceous matter, and dried at 150".The metal, on analysis, wasfound to contain -41 = 98.91, Fe = 0.90, and Si c 0.04 per cent. Thiswas then intimately mixed with purified carbon in the proportiondemanded by the formula Al,C,, and heated in the porcelain boataccording to method 1, or in the graphite tube according t omethod 2.After each experiment a portion of the product was examined bycompletely decomposing with dilute hydrochloric acid, collecting theg rses evolved, and nnalysing in a Sodeau apparatus, which enabled themethane t o be estimated to within about 0.05 per cent.Precautions were taken t o avoid the formation of nitric acid duringexplosion of the hydrogen.The results of the experiments are expressed in tabular form onp. 2104.From these results, oiie can see that the reaction commences at asurprisingly low temperature, namely, 650O.It proceeds, however,somewhat slowly, and only at about 1400' is the combination completeVOL. XCIII. 7 2104 PRING: THE FORMATION OF SOME CARBIDES.Temp.1420"1250125011801090970870760650500600Duration ofexperiment.75 mins.30 9 930 >,30 9 ,30 I 930 8 ,50 > ? 2 hours2 ,,2 9 ,20 9 ,Pressure.PMaximum. Average.mm . mm .9'0 6-07.0 5 '50 -05 0'0415.0 9.06'0 5.08.0 7.01 '0 0.80'4 0.140.35 0'200.03 0.0080'12 0.015Percentageof Al,C, *in product.nearly all Al,C,39 '248 '440.720'79.44.46-41.3nilnil* Only some two-thirds of the mixture was exposed to the temperature hererecorded in the case of experiments carried out above 900" where the graphite tubewas used.in a short time, The product in all cases is the characteristic,brilliant yellow-coloured Al,C,, although, probably owing to its finestate of division, no crystalline structure was apparent when examinedunder a high power microscope.Silicon Carbide.The formation of this compound is stated by Moissan to take placewhen carbon and silicon are heated together in a wind furnace at atemperature of 1200-1400° (The Electric Furnace, 1904, p.264).Tucker (J. Amer. Chem. SOC., 1906, 28, 853) mtimated the tempera-ture of formation of silicon carbide in the electric carborundumfurnace to be 1700-15009Greenwood (Trans., 1908, 93, 1492') found that the reductian ofsilica by carbon takes place at 1460' under a pressure of 2-3 inni.,the product obtained being carborundum.Further investigation of the formation of this carbide was under-taken by the author in order to ascertain the precise temperature ofti10 direct union and to examine the possible effect of the presence ofsolid and gaseous impurities.Various kinds of silicon were takenfor this purpose, namely, that obtained by the Deville process withaluminium, commercial silicon prepared in the electric furnace, andthirdly, the same substance carefully purified by subsequent chemicaltreatment. This purification process consisted in grinding the siliconin an agate mortar and sieving through cotton, to obtain a very finepowder. This WRS then treated with hot aqua re@ until no furtheraction took place, filtered and washed, and then treated twice withhot hydrofluoric acid solution in a platinum dish and evaporated todrynessPRINGI: THE FORMATION OF SOME CARBIDES.2105Analyses of the different varieties gave the following results :Deville Commercial Purifiedsilicon. silicon. silicon.Si ........................... - - 99'70Fe ......................... 0.73 5.52 0.10Al ........................... 5'24 0.73 0'20SiO, and other impurities 2.62 - -All the experiment3 with silicon were conducted in the electricallyheated graphite tube inside the glass flask, and the product wasafterwards analysed by taking a known weight, treating with hotaqueous potassium hydroxide to remove the free silicon, and thenigniting at a red heat in air until no further loss in weight occurred,to estimate the carbon.With impure silicon, a further treatmentwith aqua regia followed, t o remove iron, etc.The product remaining consisted of the carbide, Sic, which hada crystalline appearance when examined under a microscope, andwas of a light grey colour when the purified silicon was used andgreenish-black with the impure varieties. The results are givenbelow in tabular form.I n experiment No. 9, electrolytic iron to the amount of 13 per cent.of the total mixture was added to the silicon and carbon to ascertainif any effect in lowering the temperature of combination wasproduced. The result showed that the presence of iron causes nodifference in this reaction.Pressure.Duration Fd-y PercentageExpt.of run, Nature of Maximum. Average, of Sic inNo. Temp. mins. silicon. mm. mm, product.1 1100" 12 Commercial 1-00 0.35 nil3 1200 40 0'14 0'10 5.55 1400 30 0 '02 0915 30'06 1200 35 Atmosphere of Co 1'27 1310 30 PUlYfiCd 0 *05 0.03 8.08 1400 30 0.07 0-05 30'09 1240 30 Purified:;l3x Fe 4'00 3.00 nil10 1340 30 Purified 5.00 4.00 8.02 1300 80 Y ? 0.15 0.10 28'04 1280 30 DeS.il le 0'02 0.02 2.1Y YIt is thus apparent that with highly purified silicon combinationoccur^ at temperatures as low as 1300", whilst already a t 1400" a cou-siderable proportion of tho inaterials have united to form carborundum.With the more impure varieties, the reaction commences a t somewhatlower temperatures.Iron Carbide.Moissan corisidered that the direct union of carbon, silicon, and boronwith iron at 1200' indicates that these elements exert a slight vapout.pressure at this temperature (The AZectric flumace, 1904, p.358).? 2106 PRTNG: TEE FORM.4TTON OF SOME CARBIDES.The union of carbon with iron in a vacuum has been investigated byW. C. Roberts-Austen (J. Iron and Steel Inst., 1890, Sl), whoheated together electrolytic iron and diamond dust, and found thatsome combination took place at a full red heat. No exact temperaturemeasurement was made, however, and no information regarding thecompleteness of the vacuum appears to be given. It was accordinglythought it mould be of some interest to carry out further experimentson this subject at various known temperatures, using the highestvacuum obtainable in the apparatus described above, and measuringthe pressure.Electrolytic iron in the form of fine powder was mixed with carefullypurified retort carbon (containing very little ash) in the proportiondemanded by Fe,C, placed in a porcelain boat, and heated according tomethod 1 described above.After each experiment, a small portion of the product was tested forcombined carbon by the colorimetric test, using 50 per cent.nitric acid,and comparing the colour with that given by a steel of known com-position, treated alongside in the same manner.Pressure. Percentagec of combinedTenip. of run. imi. mm . in product.Duration Maximum. Average. carbon870" 3 hours 0.05 0 -04 0.44850 3 Y Y 0 '06 0 -05 0 *32660 5 9 ) 0'08 0.05 nil750 6 $ 9 0 '04 0 '02 0'35Magnesium.The existence of a carbide of magnesium was first announced byBerthelot, who heated magnesium powder in a stream of acetyleneand obtained a product which evolved acetylene on treatment withwater.This carbide was found by Moissan to be completely decomposedat :t high temperature.By the reduction of magnesium oxide by carbon, Slade (Trans.,1908, 93, 327) showed the possibility of preparing metallic magnesiumby the use of a graphite retort. On conducting this reaction in acurrent of hydrogen, the metallic product was largely contaminatedwith n carbide which gave acetylene on treating with water. Sladeconsiders this carbide to have arisen by the interaction of acetyleneand magnesium.Weston and Ellis (Trans.Puraclay Soc., 1908, 4, 71) publish afootnote to a paper announcing that evidence of the direct combinationof magnesium and carbon has been obtained.I n the present work, it was thought that it might be possibleto effect decomposition of maguesium chloride vapour at a higPRINGC: THE FORMATION OF SOME CARBIDES. 2107temperature by means of hydrogen containing some acetylene orbenzene vapour hg an analogous reaction to that which was foundto take place between silicon chloride and acetylene, giving siliconcarbide.Some experiments were accordingly carried out * in a carbon tubefurnace placed horizontally, fitted in the centre with a vertical inlettube, and provided with a condensing tube a t the end.The carbontube was heated to the temperatiire a t which magnesium chloridevolatilisep, a current of hydrogen containing benzene vapour passedthrough, and magnesium chloride admitted by the vertical tube,It was, however, not found possible to effect any decomposition orobtain a product which gave any considerable evolution of gas ontreating with acid.The effect of heating pure magnesium powder with pure carbonin a high vacuum was next investigated, using method 1, describedabove. It was found in all cases that the metal practically alldistilled from the boat, leaving behind carbon, and condensing inthe cooler parts of the porcelain tube. The product was analysedby decomposing with hydrochloric acid, collecting the gas evolved,and estimating the hydrocarbon present.No trace of acetylenewas in any case noticeable. On treating with hot water, aslight evolution of gas was noticed with the product from experi-ment 4.Small amounts of a hydrocarbon, other than acetylene, appearedto be present in this gas, apparently showing a slight solubility ofcarbon in magnesium at these temperatures, with the formation oftraces of some carbide other than that obtained a t higher temperatures.Pressure.Duration Maximum. Average. ?f (Mg,C) ?Expt. No. Temp. of run. mm. mm. in product.1 650" 30 mins. 0.8 0.25 0.852 700 2 hours 0.2 0.10 0.63 1000 45 mins. 0 -20 0.15 0.44 600 3 hours 0.05 0.04 1'2c - PercentageXunrrnary and Concdusion .Silicon.-The direct union of pure silicon and carbon in R vacuumcommences between 1250' and 1300", the reaction proceeding rapidlyabove 1400'.Commercial silicon containing 5 per cent.of iron and 0.7 per cent.of aluminium reacts with carbon at all temperatures above 1200".The presence of iron does not apparently facilitate the reaction, nordoes carbon monoxide exert any infiuencc between the limits of* Conducted by W. Fielding2108 BALY AND MARSDEN : THE RELATION BETWEEN ABSORPTIONatmospheric pressure and 0.03 mm. ; hence already below its meltingpoint silicon is proved to combine with carbon.AZuminiu~n.--This element unites diimtly with pure carbon ina vacuum at its melting point (650°), forming alnminium carbide(A14C3), and the velocity of the reaction increases with the tempera-ture, proceeding rapidly above 1400'.Iron.-Direct union with carbon occurs at about 700' under apressure of about 0.05 mm.Magnesium.-Evidence is forthcoming t o indicate the formation toR limited extent of a new carbide below 600°, this compound givinghome saturated hydrocarbon (probably methane) on decompositionwith water or acids. A t higher temperatures the reaction apparentlyceases. This unstable compound is probably Mg,C, of an analogousnature to Al,C, ; the only carbide of magnesium, MgC,, hithertoknown corresponds with the carbides of the alkali and alkaline earthmetals.Finally, I wish t o thank Dr. R. S. Hutton for the kind interest hehas taken i n this work and for much valuable advice and assistance.ELECTKO.CHEMICAL LABORATORY,MANCHESTEI~ UNIVERSITY

ISSN:0368-1645    

DOI:10.1039/CT9089302101

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

2108 BALY AND MARSDEN : THE RELATION BETWEEN ABSORPTIONCCXI.-The Relation belween Absorption Spectra andChemical Constitution. P a r t X I I . Some Anzino-aldehydes and -kctones of the Aromatic Series.By EDWARD CRARLES CYRIL BALY and EFFIE GWENDOLINE MARSDEN.IN a previous paper (Baly and Collie, Trans., 1905, 87, 1333), t h eabsorption spectra of benzaldehyde and ncetophenone were described,and i t was shown t h a t both these compounds exhibit only a verysmall ahsorption band, the view being put forward that the motionsof the benzene ring were t o a very great extent restrained by thepresence of the ketOnic oxygen i n the @-position i n t h e side-chain. Wehave now invwtigated some of the amino-aldehydes and -ketones ofthe benzene series with the view of determining the influence of theamino-group.From a comparison of t h e absorption of aniline witht h a t of benzene, i t is evident that the intluence of the amino-group isdirectly opposite to t h a t of the ketonic oxygen i n the @-position, forthe very large' absorption band of aniline would suggest that thedynamic activity of this compound is even greater than that oSPECTRA AND CHEMICAL CONSTITUTION. PAKT X11. 2109benzene itself. This fact is, of course, in agreement with the resultsobtained by mngnetic rotation (Perkin, Trans., 1896, 79, 10%). In&lie amino-aldehydes and -ketones we have therefore two well-definedinfluences brought simultaneously to bear on the phenyl group,namely, first the ketonic oxygen in the P-position tending to restrainand lock up the motions of the phenyl group, and secondly, the amino-group with an influence of exactly the opposite nature.Inasmuch as the absorption curves of these compounds all showlarge absorption bands, it is evident that the restraining influence of theketonic or aldehydic group is more than counteracted by theamino-group .It is interesting, moreover, to note that in these compoundsgenerally the ortho-isomeride exhibits the greatest absorption bandand the para the least; the meaning of this is not at present clear.Itmay be pointed out that these substances are coloured yellow, owingto their absorption bands being situated in the visible region ofthe spectrum. I f to the solution of one of the aminoaldehydes orarninoketones in alcohol a small quantiby of alcoholic hydrogenchloride is added, the yellow colour of the solution is very muchintensified, and the absorption spectrum now shows a new absorptionband nearer to the red and at greater concentration than the originalband.In the presence therefore of very small quantities of hydrogenchloride, the alcoholic solution of amino-aldehydes and -ketones showstwo absorption bands, the principal band being unaltered by the smallamount of free mineral acid.The effect of the mineral acid is most pronounced in the para-isomeride and least in the case of the meta-compound. In Fig. 1 the fullcurve shows the absorption spectrum of o-aminobenzaldehyde, and thedot and dash curve that of the para-isomeride; the upper and lowerdotted curves show the absorption of the two compounds in presenceof 1/2 eqiiiv.and 1/10 equiv. of hydrogen chloride respectively, Thegreater effect produced in the case of the para-compound by 1/10equiv. of hydrogen chloride than by as much as 112 equiv. in the caseof the ortho-isomeride is very evident. The lower portions of bothcurves are not altered in any way by such small quantities of acid.Fig. 2 (full and dotted,curves) and Pig. 3 (dot and dash, dash and twodots curves) represent the absorption of p - and o-aminoacetophenone inneutral and slightly acid alcoholic solutions respectively. We giveonly the results obtained with the ortho- and para-compounds; theresults were quite similar with the meta-isomerides, but in a lessdegree than in the case of the ortho-derivative.The amount of acid necessary depends very much on the nature ofthe compound, and it appears that less acid is required with thealdehydes than with the ketones, and, moreover, as has alread2110 BALY AND MARSDEN : THE RELATION BETWEEN BBSORP1'IOKbeen pointed out, less is required with the para-compound than withthe two other isomerides.The most sensitive compound is p-amino-benzaldehyde, which develops a large and very pcrsislent absorptionband with only 1/10 equiv. of hydrogen chloride, and, since the bandFIG. 1.Oscillation frepuewcies.2000 20 40 60 80 3000 20 40 60 804000 20 4010,000$000$2500 280LOO0 z-2 d500E 250 g-5Y3100 ga*50225 2** uG10542'5Fill1 ciirve : o-Amisiobenznldeh~de.Upper dotted curve : o-Aminobenzdd~hyd~ + 112 eq.HC1.Dot and dash curve : p-A?irinobe?~~.xnldehyde.Dash and two dots cnrve : ,, Lnwer dotted curve : 2 9 ,, +1/10 eq. HC1. ,, +excess of a p e o z u HCl.is obtained with N/lOOO solution, so the concentration of the acidis only N/lO,OOO. The extreme sensitiveness of the reaction is thusmanifest. I f too much hydrogen chloride is added, the effect isdestroyed, owing t o the conversion of the compounds into the hydro-chlorides, which in every case are perfectly white compounds. ThSPECTRA AND CHEMtCAL CONSTITUTION. PART XII. 2111maximum amount allowable is of the order of 1/2 equiv. ; more than thisquantity causes the whole spectrum to tend towards that of the hydro-chloride.Indeed, in the curve of o-aminobenzaldehyde with 1/2 equiv.of hydrogen chloride (Fig. 1, upper dotted curve), it mill be noticedFIo. 2.Oscillation frequemie.9.2000 20 40 60 80 3000 20 40 60 80 400020 404442Ft' 2 40$ 3836N -08 2 3432f 30.f 283 5 26% 2422 s3 202$ 165'$ 14x-*.+ -% 188 121086Full curve : p-Aminoncelophenone.Upper dotted curve : p-Aminoacetophenone + 1/25 eq. HC1.Dash and three dots curve :Dash and dot curve : p- Dimethylaminobenzaldehyde.Dash and two dots curve : 4 : 4'- Tetramethyldiaminobenzophenone.,) in excess of apueoics IICl.Middle dotted ,, : 9 ) ,, + 2/5 eq. HCI.Lower dotted curve : J ) ) I + 1/2 eq. HC1.that it does not quite coincide with the curve of the compound inneutral solution; this is owing to the partial conversion into thehydrochloride.If the aminic hydrogen atoms be replaced by alkyl groups, the sam2112 BALP AND MARSDEN : THE RELATION BETWEEN ABSORPTIONresults are obtained, although in a less degree. This can be seenfrom the curves of 21-dimethylnrninobenzaldehyde (Fig.2, Jot and dasharid middle dotted curves) and of 4 : 4’-tetramethyldiaminobenzophenone(Fig. 2, dash and two dots and lower dotted curves).If the substances are dissolved in water or dilute alcohol, the aboveFIG. 3.Oscillation frcqucmies.2000 20 40 60 80 3000 20 40 60 80 4000 20 40- 250,000 -- 100,000- G50,000 20 25,000 03 - -0 810,000 2--r( -35000- c r-c: - 2500 .$7 3- 1000 23- p1500 5 ‘v _.G - 250-- 10050__- 40Full curve : o-nminobeiizalclo~inre.Dotted, ,, * +1/5 eq. HCI.Dot and dash’ curve : )d-Aminoaceto~he?LoIic.Dot arid two dash ,, : 9 9 +1/5 eq. HCI.effect is no longer produced on the addition of hydrochloric acid ; thespectrum merely tends towards that of the hydrochloride, a1 thoughthis latter spectrum is only finally reached in presence of consider-able excess of acid. The absorption of pamioobcnzaldehyde hydro-chloride and of p-aminoacetophenone hydrochloride is shown in Fig. SPECTRA AND CHEMICAL CONSTITU'I'ION. PART XII. 21 13(dash and two dots curve) and Fig. 2 (dash and throe dots curve)respectively.The effect of the addition of hydrogen chloride to these compoundsseems to be due undoubtedly to the amino-group.Some experimentsat present in progress on certain complex amino-compounds wouldsupport this view, for i t appears that the nature of the substituentgroup in the aniline residue is immaterial. For example, the amino-benzaldoximes exhibit the same phenomenon as can be seen fromthe full and dotted curves on Fig. 3, which show the absorptionof o-aminobenzaldoxime. It would appear that the addition of theacid produces an increase in the amount of the residual affinity of theamino-group ; in neutral solution the nitrogen atom is undoubtedlytervalent, and possibly the addition of the acid makes i t functionate asa quinquevalent atom, so that its residual affinity is increased inthe ratio of 5 t o 3. This increase in the residual affinity, beingas it were superadded to that of the neutral molecule, mould nodoubt account for the new absorption bands. The increase in theresidual afEinity produced by the addition of acid would account alsofor the catalytic action of mineral acid on the acetylation of amino-compounds.Conclusions.1.The amino-aldehydes and -ketones of the aromatic series inneutral alcoholic solution exhibit one broad absorption band.2. The addition of small quantities OC alcoholic hydrogen chlorideto the solution causes the development of a second absorption band,the first remaining unaltered, provided that insufficient acid has beenadded to produce the hydrochloride.3. This effect is most marked in the amino-aldehydes and further inthe para-isotneride.4. The phenomenon appears t o be due t o the amino-group ; it ispossible that the nitrogen atom is caused to functionate as a quinque-valent atom, so that the residual affinity is increased in the ratio of5 t o 3.5. The results throw considerable light on the catalytic actionof mineral acid in the acetylation of amines.It is not produced at all in aqueous solution.The authors wish to express their thanks to the Chemical Societyfor a grant in aid of this work.SPECTROSCOPIC LABORATORY,UNIVERSITY O F LOMDON,UNIVERSITY COLLEGE

ISSN:0368-1645    

DOI:10.1039/CT9089302108

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

21 14 VELEY : THE AFFINITY OF CERTAINCCXII .-The Afinity of Cwtaz'7.l Alkaloids forHydrochlo& A cid.By VICTOR HERBERT VELEY.IT has been observed for many years that certain alkaloids, such asthose of the cinchona and nux vomica groups and others, althoughcontaining two atomic proportions of nitrogen or two amino-residues,yet combine for the most part with only one molecular proportionof hydrogen chloride, their dihydrochlorides being obtained eitherwith difficulty under special conditions, or even under no conditions,in the solid form. It was thought that the methyl-orange methodcould be applied to determine the proportion of hydrochloric acidwhich will combine in solution with the monohydrochlorides of suchalkaloids, and hence some insight might be obtained into the relativeafinities of the two nitrogen atoms or amino-groups. I have at theoutset to express my obligations to Mr.David Howard for beautifulsamples of certain cinchona hydrochlorides, to Messrs. Burroughs,Wellcome and Co., and workers in their laboratories, for other samples,and to several friends who have also r ndered assistance.The Cinchona Gs*oup.It is well known that the salt formed directly from these alkaloidsand hydrochloric acid is the monohydrochloride, B,HCl, sometimescalled the normal salt, and that the hydrochloride, B,2HCl, sometimescalled the acid salt, can be obtained by evaporation, under specialconditions, of solutions of the alkaloid or mono-salt with excess ofconcentrated hydrochloric acid, or by passing the dried gas over themono-salt or other indirect methods.Hesse (Annulera, 1875, 176, 227) and Oudemans (ibid., 1876, 182,51) determined the specific rotatory powers, [.ID, of aqueous solutionsof these alkaloids with different molecular proportions of hydrochloricacid, but drew no conclusions as to any difference between theaffinity values of the two amino-groups.Colson and Dztrzens (Compt.rend., 1893, 118, 250) remarked that quinine contains a feeble basicfunction analogous to that of quinoline, and a stronger basic functionsimilar to that of the amines of the ethylic or piperidine series.Salamonsen (Ned. Tydsch. Pharm., 1895, 7, 195, 225) regardedquinine as a true dibasic alkaloid, and the combination of onemolecule of alkaloid with two molecules of hydrogen chloride as thenormal salt, on the ground that if the salt were truly of an acidcharacter it would not be neutral to methyl-orange, even although itis acid t o litmus.More precise information from the physicaALKALOIDS FOR HYDROCHLORIC ACID. 2115chemistry standpoint is afforded by the determinations of Berthelotand Gaudechon (Compt. rend., 1903, 136, 128) of the thermo-neutralityvalues of the cinchona alkaloids, which may be summarised as follows(+ =heat quantity in 100 gram calories),Q u i n i m und Quinidine.U + 2 mols. HCI. q = 208B + 1st mol. HC1. 9 = 119(Difference) B f 2nd niol. HCl. 9 = 89-Cinchonine and Cinchonidine.B -I. 2 mols. HCI. @ = 292.0B + 1st mol. HCI. $ = 131'5(Difference) B + 2nd mol.HCI, 9 = 70.5No values could be obtained for cinchonamine, owing to the sparingsolubility of its salts.The heats of neutraliaation of the former pair of bases with the firstmolecular proportion of hydrogen chloride are approximately equal tothat of dimethylamine (+= llS), and those of the second pair of basesare approximately equal to those of methylamine (+ = 131) or piperidine(+ = 135), whereas in the case of the second molecular proportion ofhydrogen chloride the values are rather higher than that OF quinoline(+ = 68). The difference in the affinity values of the two amino-groupsis very marked.If the formula of Konigs (AnnuZen, 1906, 347, 232) be adopted forquinine and quinidine (cinchinine), namely :CH \ CH (2-MeO*Cf"'CH CH, H,C,'&CH*CH:CH,HCI \----CI C H z C H 2 ' I 9/ \I/HC \!\P N OH Nand that of cinchonine and cinchonidine which differs from the aboveonly in containing a hydrogen atom in the place of the methoxylgroup, then all these four bases contain a piperidine and a quinoliueresidue, and consequently the afinity constanb of one amino-groupshould be of the order of piperidine, kb = 1.58 10-3, and the other of theorder of quiniline, kb = 3.4 10-9.It was first found that the monohydrochlorides of the five alkaloids,quinine, quinidine, cinchonine, cinchonidine, and cinchonamine, showedno indicntions of hydrolysis with N/30 or N/40 solutions (Ir= 4 x lo3and S x lo3), arid thus they rssemble piperidine hydrochloride in thattheir nfinity constants are beyond the limit which c m be detected b2116 VELEY : THE AFFINITY OF CERTAINY= 4 x 104.~ = 2 x 104.1.0 2 '01.9 4'03 -1 6-0the methyl-orange method, which is approximately OF the orderkb= 1 x lo-', but as these alkaloids are precipitated by ammoniafrom their salts, their affinity value is less than 1 xEach of the hydrochlorides was then dissolved in such a volumeof N/20 hydrochloric acid so as to form an N/20 or N/40 solution(according to solubility) of the dihydrochloride on the presumptionthat no hydrolysis of the latter salt took place. Such solutions werediluted after the lapse of two or three days in accordance with myusual plan of working, and hence the amount of such hydrolysis andthe affinity constants of the second aniino-group determined.Theresults are given as under :Y= 4 x 104. v=2 x 10'.4'9 8.26 -9 8'27.9 8-2v=4 x 104. v= 2 x 104.Temp. 11". Temp. 13".0.9 1 -91.8 3.8v= 4 x 104. Y= 2 x 104.Temp. 11". Temp. 13".3.4 7.64.5 9.5It appears that quinidiue is a slightly weaker base than quinine,but the difference is almost within the limit of experimental error.The results obtained with the dihydrochlorides of cinchonine,cinchonidine, and cinchonamine were practically identical with thoseobtained with the salt of quinine ; hence i t is not necessary to give thefigures ; the only difference was that all reaction sooner came to anend in the case of cinchonamine.The conclusion to be drawn from these experiments is that theaffinity constant of the second amino-group is rather less than that ofquinoline (see following paper), although it was to be expected thatthe constant would be rather greater, as the piperidine nucleus is inthe 4-position with respect to the nitrogen atom.B u t otherwise theresults are in general accordance with those of Colson and Darzensand of Berthelot and Gaudechon, but the statement of SalsmonsenALKALOIDS FOR HYDROCHLORIC ACID. 2117that an ~ U Q O U S solution of quinine dihydrochloride is neutral t omethyl-orange, appears to require modification ; it is probable that thelast author used a too concantrated solution of the indicator. So faras I am aware, no determinations have been made of the electric con-ductivity of the dihydrochlorides of these alkaloids which might serveas a further confirmation of the above results; Bredig (Zeitsch.yhysikcd.Chem., 1894, 13, 289) determined the conductivities ofquinine, quinidine, and cinchonine monohydrochlorides, from which i twas concluded that the velocity of t,he cinchona ion is of a relativelylow order. It may be added that Hiidrich (Zeitsch. physikal. Chem.,1893, 12, 476), by determinations of the specific rotatory power ofcertain salts of the cinchona group, arrived at the conclusion thationisation is complete at N/10 or 3/20 dilution. If, then, theseobservdtions, as also mine, that no hydrolysis could be detected atthe latter dilution, are well founded, then it would follow either thatRobertson’s view (J. Physical Chem., 1907, 11, 437) is correct, thataccurate hydrolysis values can only be obtained when the respectivefunctions of the base and hydrochloric scid are of a sufficient differentorder, or, what may come to the same thing, the velocity of thecinchona ion is so small that its detection by the methyl-orangemethod requires infinite time.Pilo car pine, C, H1602N2.The investigations of Jowett, published in a series of memoirs(Trans., 1900-1905), have shown that this alkaloid forms a stablemonohydrochloride, B,HCl, from which the base can be displaced by asolution of ammonia in excess (Trans., 1900, 77, 477), and also thatthe alkaloid and its isomeride, isopilocarpine, react with methyl iodideto form a methiodide, from which methylamine can be obtained, butno further methylation takes place (Trans., 1906, 89, 497, 854)even when heated with excess of methyl iodide.The coustitution ofthe alkaloid is probably represented by the formula :( 2)>CHEtyH* yH-CH,-fi:NMeCO-CH, HC-N \/ (1)0(Trans., 1905, 87, 797 ; compare Pinner and Schwarz, Ber., 1902, 35,2441), or, in other words, it is a methylglyoxaline with a lactonic,namely, the homopilopic, residue attached. From these considera-tions it would appear that pilocarpine contains one amino-group ofaffinity value lower than that of ammonia, kb= 1.7 probably theresidue marked ON:, whilst thitt of the other group, :NMe, would(1) (22118 VELEY : THE AFFINITY OF CERTAINY= 8 x 10.'. v= 4 x 104.1.0 2.12.1 4'23 '2 6.3?7=8 x lo4. v= 4 x 104.4 '1 8.35'2 8'36.3 8.3(2)4-MethyZgZyoxalirne, MeR*NH> CH.CH-N/(1)Having regard to the relationship of pilocarpine to the glyoxalineseries, i t was thought that a study of the affinity values of thenitrogen atoms or amino-groups of a glyoxaline might be a matter ofadditional interest. For this purpose, Dr. Jowett kindly supplied mewith a sample of the above compound. The material presented slightexperimental difticultiep, in that i t appeared to retain traces of wateror an oil, and as i t was volatile at a comparatively low temperature i tcould not be dried by any heating process, but by adopting suitableprecautions, it was believed that the necessary small quantities wereweighed out with only a slight error.First, i t was found that when an N/10 solution of hydrochloricacid mas added to an aqueous solution of a weighed quantity of thebase, the point of neutrality corresponded very approximately with theformation of the monohydrochloride when methyl-orange was used aALKALOIDS FOR HYDROCHLORIC ACID.2119an indicator according to the usual process of volumetric analysis,when the mass of reacting salt is very greatly in excess of that of themethyl-orange.Secondly, it was found that when the base was dissolved in thevolume of N/20 hydrochloric acid required to form an N/20 solutionof the monohydrochloride, B,HCI, such a solution showed no traceof hydrolysis by the methyl-orange method; hence the affinity valueof the grouping *N: is greater than 1 lo-', and is probably oE theorder of the aliphatic amines.Thirdly, the base mas dissolved in a volume of Nl.20 Iiydrochloricacid so as to form an N/20 solution of the dihydrochloride, B,SHCl,presuming that no hydrolysis took place; the solution mas verystrongly acidic towards methyl-orange, which would shorn that thesecond grouping, *NH*, was either acidic or that the dihydrochloridewas very largely hydrolysed, such as the cases of hydrazine or thediamines of the aromatic amines, for example.Mter standing forsome hours, the solution was diluted to N/103--N/400, and thesesolutions allowed to stand for about eighteen hours.(1)(7)The following results were obtained at a temperature of 18' :I. I I. 111.V=8 x 104. v=4 x 104. v=2 x 104.0.6 1.1 2'451 '2 2.3 4'91% 4 *7 7.352.3 5.9 9 -8I. 11.111.Y= 4 x 104.2 *3 7.0 11'32.3 8 -3 11'32.3 9.2 11'3Y= 8 x 104. v= 2 x 104.Values of k=O.6, 1.2, and 2.45, corrected 0.605, 1.21, and 2.42respectively ; hydrolysis value 37.8 ; kbtls) = 2.78 10-l". As the solu-tions gave results identical within the limits of experimental errorwith those obtained in the case of hydrazine hydrochloride, hydro-lysis value = 37.5 (Trans., 19OS, 93, 660), the N/20 original solutionwas heated for three hours a t 60' and diluted, as previously described,but the results obtained did not differ from those of the solution whichhad not been so treated, The general conclusion appears to be thatthe above metlhylglyoxaline behaves as a diamine ; unfortunately, therehave been no determinations of the heats of neutralisation of this basewith one and two molecular proportions of hydrogen chloride re-spectively, but it seems probable that the heat value for the firstmolecuh of hydrogen chloride would be about 100, and that for thesecond molecule would be less than 1.It would obviously have beenbetter for the purpose of comparison with pilocarpine to haveexamined a glyoxaline of the type RE:NMe>CH. HC-XVOL. XCIII. 7 2120 VELEY: THE AFFINITY OF CERTAINThe Nux Vomica Alkaloids : Strychni?be and Umcine.Both the above alkaloids form a crystalline hydrochloride, B,HCl,although containing two atomic proportions of nitrogen or two amino-groups. So far as investigations have gone, i t appears that theycontain (i) a hydropyridine residue, (ii) a grouping convertible intoquinoline (Hanssen, Be?.., 1886, 20, 451 ; Stocker, ibid., SlO), and(iii) a grouping -O<g(OH)-, transformable by an intramolecularco- rearrangement into -0GNH, in that the so-called methyl- andbenzyl-strychnines, for example, may be regarded as betaine derivativesof strychnic acid (Tafel, Anncden, 1891, 264, 33 ; Monfang andTafel, ibid., 1898, 309, 49).The thermochemical investigations ofBerthelot and Gaudechon (Compt. rend., 1905, 140, 715) show thatstrychnine and brucine may be regarded as monobasic, although thelatter mill under certain conditions take up as many as four molecularproportions of hydrochloric acid ; their neutrality values given are asBrucine + 1 mol. HCI. 9 = 112.0Strychnine -!- 1 mol.HCI. Q, = 70.3f 01 lows, :It is therefore evident that brucine is the stronger.It mas found that the hydrochlorides of brucine and strychnineshowed no hydrolysis by the methyl-orange method ; hence the affinityvalue of one amino-group in both is greater than 1 x lo-' ; as ithas been shown independently that ammonia in solution will displacestrychnine but not brucine from its salts, the affinity value of oneamino-group in brucine is greater, and in strychnine less, than1.7 loe5. The mothod of determining the affinity value of the secondamino-group in these alkaloids was precisely as described above, andthe following results were obtained.&rychnine.-Two solutions of the monohydrochloride, dissolved inthe required quantity of A720 hydrochloric acid to form a dihydro-chloride, were examined, and the following results obtained at 20' :v=a x 104. Y X 4 x 104.5'3 10 '96.2 13.01.0 2.22 -1 4-243 '1 6'4 j 7.4 13.04.2 8.6 8-6 13'0I Y=8 x 10.'.v=4 x 104.Values of k=1-05 and 2.15, corrected 1.06 and 2.13 respectively;hydrolysis value = 66-3, hence kb(zo) = 5-95 10-l1, a value of the orderof benzobetaine, 3.4 10-l1 (Curnming, Proc. Boy. Soc., 1906, 78, A ,139); this result appears to confirm the views of TafelALKALOIDS FOR HYDROCHLORIC ACID. 2121Bruciqa-The method of experiment mas precisely as that used forstrychnine, and the following results obtained at 20" :v= s x 104. Y= 4 x 104.1 -3 2.62.5 5 -13-7 7.8but it was observed that all reaction sooner came to an end.Values of k= 1-25 and 2.6, corrected 1.27 and 2.55; hydrolysisvalue = 79.4, hence kb(20) = 2-52 10-ll.The affinity value of the secondamino-group in brucine is approximately half the corresponding valueof strychnine ; thus the position of affairs is reversed as compared withthe first amino-group, a result which has been independently confirmedby another method. However, the data obtained by the methyl-orangemethod confirm the general conclusions which have been arrived a tregarding the constitution of these alkaloids.Gelsentine.The formula assigned by Cushny (Ber., 1893, 26, 1713) to thehydrochloride of this alkaloid is C4,H,,O,,N,,2HC1; although moreextended investigation may possibly lead to its revision, yet it is notprobable that the ratio of the atomic proportion of nitrogen tomolecular proportion of hydrogen chloride mould be reduced toequality, and therefore the alkaloid might come under the same categoryas those discussed above.An N/40 solution of the above salt showedno trace of hydrolysis by the methyl-orange method ; such a volume ofN/20 hydrochloric acid was then added to a given volume of thesolution so as to obtain an "40 solution of a possible salt, B,4HC1.But on dilution and subsequent examination in the usual way, itwas found that none of the hydrochloric acid thus added hadcombined with the alkaloid; thus proving that of the five atomicproportions of nitrogen, three possess a different function from theremaining two, presuming that Cushny's formula is substantiallycorrect.Summary.(1) Determinations are given of the affinity values of the nitrogenatoms or amino-groups of certain alkaloids which, although containingmore than one atomic proportion of nitrogen, yet form stable com-binations with one molecular proportion of hydrogen chloride only,the dihydrochloride being produced under special conditions, or, notas yet, obtained in the solid form.It is shown by the application ofthe methyl-orange method that in all cases these values are of awidely different order.(2) I n the case of the alkaloids of the cinchona group, the affinity7 ~ 2122 VELEY: THE AFFINITY CONSTANTS OF BASES ASvalue of one amino-group is less than that of a hydropyridine, whilstthat of the other is rather lower than that of quinoline. Theseresults are in conformity with the accepted constitution of thesealkaloids and the thermo-neutrality values for the first and secondmolecular proportion of hydrogen chloride added.(3) In the case of pilocarpine, the value of one group is intermediatebetween that of ammonia and the limit value of the methyl-orangemethod, whilst that of the other is equal to those of true amphotericelectrolytes. A methylglyoxaline was examined on account of therelationship of pilocarpine to these compounds ; the value of the t w onitrogen atoms or amino-groups and its general behaviour correspondedwith a diamino-base of the type of hydrazine.(4) Of the Nux vomica alkaloids, strychnine and brucine wereexamined; in both cases the affinity value of one amino-group wasbeyond the limit value of the methyl-orange method, but i t has beenshown independently that the value of the brucine group is greaterthan that of strychnine. The affinity value of the second amino-groupis of the order of value of the betaines, which accords with theconclusions arrived a t from chemical considerations ; but, here, thestate of affairs appears to be reversed, as the grouping in brucine hasa slightly lower value than that of strychnine.I have again to express my obligation to friends, and it is hopedto lay before the Society in the near future a method for furtherdifferentiating between the basic values of the alkaloids

ISSN:0368-1645    

DOI:10.1039/CT9089302114

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

2122 VELEY: THE AFFINITY CONSTANTS OF BASES ASCCXII1.-The Aflnity Constants of Bases asDetermined by the Aid of Methyl-Orange.By VICTOR HERBERT VELEY.Introduction.IN the present communication i t is proposed t o give an account ofresults obtained by the methyl-orange method for the hydrochloridesof nitrogenous bases derived from cyclic compounds. As some ofthem were antecedent to those contained in my previous publication(this vol., p. 652, et sep.), but deferred for the sake of convenience,there is nothing further to add as to variation of method or improve-ment in detail.Since my investigations were published, Salm (Zeitsch. physikalDETERMINED BY THE AID OF METHYL-ORANGE. 2123Chem., 1908, 63, 83, et seq.) has used various indicators, and amongthem methyl-orange, for determining the affinity constants of acids ;the process adopted by this chemist differs from mine in detail ratherthan in principle, in that he used the method commonly known asnesslerisation, namely a series of standard tints.My method appearsto possess the advantage that several determinations and not oneonly can be made with the same solution, and thus the chance OF errorreduced proportionally to the number of such observations, but, on theother hand, Salm’s method would have the advantage over mine whenthe hydrochloric acid, either as such or liberated from a chloride bythe process of hydrolysis, exceeds a certain amount, since experiencehas shown that a methyl-orange solution containing too mzny of thered ions (whatever their constitution) cannot be matched as regards tintby a length of solution containing the orange ions only.Or to statethe case in another form, observations by my method fail when theabsorption bands X=541, between B and F, and X=504, betweenb and F, characteristic of the reddened methyl-orange, become toopronounced.The values obtained for the affinity constants of bases by mymethod are more generally in accordance with those obtained by thecatalysis of methyl acetate or inversion of sucrose methods; this resultis to be expected, as in all three methods the constants are determinedinferentially by the amount of chemical change conditioned, whetherinstantly or after the lapse of time, by the hydrochloric acid liberatedby hydrolysis.Objections have been raised to this inferential methodof calculation by Robertson (J. Physical Chem., 1907, 11, 437) onthe ground that approximately accurate results can only be obtainedif the larger function, namely, that of the hydrochloric acid, issufficiently great as compared with the smaller function, that of the base.This criticism has been met by L u n d h (J. Biol. Chem., 1908, 4, 268)on mathematical considerations based on the degree of ionisation ofeach of the several constituents present in a solution of a hydrolysedhydrochloride. So far as my method is concerned, it mould appearthat there is a certain cogency in Robertson’s criticism, in that in thecase of bases with affinity constants of the order of kb = 1 x lo-* only afew observations could be obtained before a condition of equilibriumset in.The values obtained by my method are also in fair accordance withthose obtained by the electrolytic method, by which the affinity constantsare determined directly.The values obtained by Farmer and Warth(Trans., 1905, 85, 1713) by the extraction method in some casesaccord with, but in others differ widely from, those furnished by othermethods ; herein it may be remarked that results obtained by any ex-traction method are of the nature of a double convergent series, on th2124 VELEY: THE AFFINITY CONSTANTS OF BASES ASone hand, towards totality as regards the extracting liquid, and, on theother, towards nil as regards the extracted liquid." The final state ofaffairs may be reached in some cases after some minutes, and in othersafter some hours, according to the peculiar circumstances of eachcase.The experimental results are given in Section I, their mutualrelationships discussed in Section IT, and the temperature-coefficientsof certain functions deduced from my experiments and those of othersare dealt with in Section 111.Salts und Solutions used.Some of the salts were purchased directly from reliable firms andpurified by recrystallisation when necessary, and I have again toexpress my obligations to the Research Fund Committee of theChemical Society for a grant towards the expense.Other sampleswere presented by various kind donors, alluded t o in the sequel ; otherswere prepared by adding concentrated hydrochloric acid solution tobases, either purchased or presented, and recrystallising the hydro-chloride two or three times from water or alcohol.I n cases inwhich the salts could not be conveniently obtained in a crystallineform by these methods, a weighed amount of the base was dissolvedin an X / 2 0 hydrochloric acid solution so as to form an N/20 solutionof the hydrochloride, presuming that no bydrolysis occurred ; suchsolutions were kept for n few days before further dilution, so thatthe final state of equilibrium of salt- base-acid-water, or ions thereof,might be reached.EX PE R I M ENTA L.Section I.-Benxenoid Amines : (1) Xonoacidic bases.Aniline Hydrochloride.-Solut ions of three concentrations wereexamined, with the following results :I.11. 111.Temp. 15". Temp. 15". Temp. 12".1.0 2'2 3 *92.2 4'4 8-13.1 6-6 12'04 '1 8 -8 15.9v=4 x 104. v=2 x 104. v=2 x 104.I. 11. 111.Temp. 15". Temp. 15". Temp. 12".5.0 10.8 15.96.0 12.8 15'97.1 12-8 15'97.9 12.8 15.9v=4 x 104. v x 2 x 104. v=2 x 104.Values of k for I and 11 = 1 and 2.15, corrected 1-03 and 3.07;* The iise of chloroform, which has also been suggested as the extractive licliiid ininvestigations of this kind, appears to be peculiarly open to criticism on account of'the diEciilty of maintaining this liquid free from traces of hydrochloric acid, soreadily formed by exposure t o lightDETERMINED BY THE A1D OE' METHYL-ORANGE. 2125hydrolysis value = 32*2* ; for 111, k = 4 ; hydrolysis value = 31.2 ;k b = 2-6 at 1 2 O , 3.2 a t 15O.As the hydrolysis values obtained a t the several dilutions do notdiffer within the limits of experimental error, which may be taken asat one unit, it would appear that at a dilution of V = 1 x lo4,or thereabouts, either the process of hydrolysis commences to bereversed, or the increased mass of inactive water may act as matterin the way of the smaller mass of water, which may be regardedas active, a conclusion which would be in accordance with the resultsobtained in the study of the effect of water on certain chemicalchanges.But with the view of meeting an obvious criticism that themethyl-orange method is not of a sufficient order of accuracy todifferentiate between the amounts of hydrolysis at the severaldilutions, the following calculations may be adduced.I n the Arrhenius equationkb/k, = (1 - X ) V / z ? .. . . . . . . (1 >,the value of the function kb/k, for aniline from the results of themost trustworthy observers is (63 +_ 0*5)103 at 1 5 O ; substituting thevalues V=(1, 2, 4)104 respectively, and solving the equations forx, there are obtained numbers which multiplied by 100 aregiven in column I1 of the table below, and compared therewiththe values given in column 111, which are obtained by my methodwithout applying corrections even of the first order.I. 11. 111. v. 100 z (calc.). 100 II: (foiund).1 x 10' 32-7 a t 15" 32.2 a t 12"2 x 104 42.7 ,, 31'3 a t 154 x 10' 55.6 ,, 33.6 ,,It will be evident that the differences of the last two valuesin column I1 are ten to twenty times greater than the differencesof the uncorrected values in column 111, and such result appears to bea sufficient answer to the criticism.Derivatives of Aniline.Monomethylaniline Hydrochloride.-Two concentrations wereexamined, with the following results (temperature 18') :v= 4 x 10'.3.0 6.07.2 I 3.63.6 8.5 1 3-6 9'6I v=8x104*Y= 8 x 10'.v= 4 x 10'.0 '6 1-31 -2 2.51 -8 3 -72.4 4.9* As the methyl-orange solution used is the same as in my former work, the factorsgiven on p. 656 were used ; for each solution and individnal observer, such factorsmust be determined separately. It appears desirable to call attention to this point,as my method is now being applied for the quantitative determinatio;~ of ncitlsolutions which are beyond the limit of volumetric analysis2126 VELEY: THE AFFINITY CONSTANTS OF BASES ASv=4 x 104. Y= 2 x 104.0'9 1-751 '9 3.52'7 5 -25Values of k-0.6 and 1.2; hydrolysis value=37*5; value ofIt appears from this result that methylaniline is a weaker basethan aniline; Walker (Trans., 1898, 67, 576) arrived at an oppositeconclusion by the inversion of sucrose method at a temperatureof 60'.Dimethylcmiline Hydvochloride.-The examinat ion of this saltpresented certain experimental difficulties, owing to the readinesswith which the base separates out on exposure of the crystals toa i r ; Walker (Zoc. cit.) was anable to obtain any results for thisreason.Two samples were examined at different times with differentmethods of manipulation, but the results obtained were the samewithin the limits of experimental error; two series of observationsare given (temperature 18') :kb = 2.55 10-10.v= 4 x 104.v=2 x 104.3'6 5-254'4 5-25v= 4 x 1~4. v=2 x 104.1.2 2.22'4 4.53.6 6.6benzenoid amine examined by himDETERMINED BY THE AID OF METHYL-ORANGE. 2127Scrim 1. Series 11.V=8 x lo4. v=4 x 104.Temp. 13". Temp. 10".1.5 2.72'0 5.4The ChZoroaniEines.-Some years ago Beilstein and Kurbatoff(Annalen, 1875, 176, 27) stated that the salts of the ortho-base weremuch more readily hydrolysed a t a temperatnre of boiling water thanthose of the meta- and para-bases; the affinity constants of themeta- and para-bases have been determined by Farmer and Wartho-Chloromziline Hydrochloride.-Two dilutions were examined, butthe colour reactions were not so sharp as in other cases; after theaddition of three or four portions of the solution to the methyl-orangesolution, some secondary change appeared to ensue (temperature 19O) :(loc.cit.).Scries I. smies ir.V=8 x 10'. v= 4 x 104.Temp. 13". Temp. 10".5-7 10.i7-1 13'2t'= 8 x lo4. v= 4 x 104.1-45 2 . i 52'9 5.54 -35 8.25Values of k = 1.45 and 2.75, corrected 1.42 and 2.83 ; hydrolysism-C'hboyoaniline Hydrochloride.-Two dilutions were examined atvalue = 90.3 ; value of kb = 9.1 6 10-13.slightly different temperatures :Value of k in series I = 1.4 ; in I1 = 8.3 ; hydrolysis values 87.5 andp-Chloroaniline Hydrochloride.-The results obtained a t two dilutions83 ; value ofare as follows (temperature 10') := 7.65 1 0-I2, of kb(lo) = 6.58Y=S x 104.v=4 x 104. Y= 8 x lo4. Y= 4 x 104.9 -69 '69.61 -25 2 '42.7 4.83'9 7 . 2 8.65.1 9.6 I 9.9 9.6Values of k = 2-25 and 2 4 , corrected 1-23 and 2.46; value ofkb - 1 *24 10-11; the last number is less than that, 12.7 1 0-I1 (corrected),given by Farmer and Warth (Zoc. cit.) at a temperature of 25O, whichwould correspond with R value, 7.6 1O-I1, approximately, at a tempera-ture of 10"-BromoaniZines.-The salts of the metn- and para-bases were preparedin a crystalline form in the usual manner.m-Bronzocmilime 1iydrocidoride.-Two dilutions were examined, bu2128 VELEY: THE AFFINITY CONSTANTS OF BASES ASa difficulty similar to that noticed in the o-chloroaniline salt wasexperienced (temperature 19') :v= 8 x 104.v= 4 x 104.0-9 1.71'8 3.52.7 5.2V= 8 x lo4. v= 4 x 104.3 '7 6 *94'7 6.9Values of k=O.9 and 1.75, corrected 0.88 and 1.77; hydrolysisp-Bromoaniline Hydrochloride.-The results obtained (temperaturevalue = 56-9 ; kb(19) = 935 10-11.18') for two dilutions are as follows :Y=8 x lo4. v= 4 x 104.0.75 1 '41-5 3.92.3 4.4v = 8 x 104. v = 4 x 104.3.0 5.73 *7 5.7Values of k = 0.75 and 1.45, corrected 0.74 and 1.47 ; hydrolysisvalue = 46.1 ; kd")= 2.07 10 -10.Benzylamine and the Toluidines.Benzylnmine Hydrochloride.-The hydrolysis of the salt was toosmall for accurate measurement ; its behaviour, as to be expected,resembles that of the aliphatic amines, which have a thermoneutralityvalue equal to it, I find myself unable to follow the line of reasoningof Walker (Proc.Roy. Soc., 1906, 88, 141) with regard to anypeculiarity in the constant of the base.o-Toluidim Hydrochloride.-The results obtained with this saltwere given in my previous communication (pp. 657-658) as illustra-tive of the method; it is therefore unnecessary to repeat them.m-Toluidine Hydrochloride.-Three series of experiments wereconducted with solutions of this salt, the results of which are givenbelow :1. 11. 111.v=4 x 104. v = 2 x 104. v=i x 104.Temp. 13". Temp. 13". Temp. 14".0 '9 1.8 3-61 '9 3.6 7'22-8 5'4 10.73-6 7'0 14'2I. 11. 111.Temp. 13". Temp. 13". Temp. 14".4-6 7-0 14'25'4 7-0 14'26'2 7.0 14.2v=4 x 104.v=z x 104. v=i x 104.Values of k = 0.9, 1.8, 3.6 respectively ; hydrolysis value = 28.1 ;These last values are in accordance= 6.1 ; that obtainedp-Toluidine Hydrochloride.-Two concentrations were examined atklr(13, = 3.54 10-10,with that given by Bredig (Zoc. cit.), namely,by Farmer and Warth, kbc2a, = 8-49 1O-l1, is probably too lorn.= 3.9 10-10DETERMINED BY THE AID OF METHYL-ORANGE. 2129v=2 x 104. v=i x 104.0.7 1 -31.4 2.62.2 3 '9temperature = 1 5 O , but all reaction came sooner to an end than in thecase of the isomeric salts :v=2 x 104. Y= 1 x 104,3.6 3'94 -2 3.94.8 3 -9Y= 4 x 104. v=2 x 104. I ~ = 4 x 104. v= 2 x 104.1'0 1.8 3-8 3-62 '1 3% i 4-6 3.62.9 3-6Values of k = 0.9 and 1% respectively ; hydrolysis value = 28.1 ;kb!15,=4*5 this last number is more in accordance with thatgiven by Bredig (Zoc.cit.), kb{%) = 14 10-10, than that, kb(25) = 3.1obtained by Denison and Steele (Trans., 1906, 89, 999, 1386) bytheir ion migration method.Substituted ToZuidines.-The dimethyl-o- and ptoluidine hydro-chlorides, like the ethylanilines, cannot conveniently be obtained in acrystalline condition ; consequently, a similar method of procedure wasadopted.Bimeth y I-o-t o Zuidine Hy droch loridc. --T wo solutions were examined(temperature 15O) :v=1 x 10.'. v= 2 x 104.0'9 1.91-9 3.92.7 5.7Values of k=OT and 1-3, corrected 0.6s and 1-35; hydrolysisvalue = 8.4, kb(1,, = 6-36 10-9.The behaviour of the above substances resemble the substitutedanilines in that all reaction soon comes to an end; their affinityconstants have not been previously determined.Xylidines.The hydrochloxides of nt-4- and p-xylidine were prepared fromm - 4- Xp lid ine I f p d ~ o c hloride.--T mo solutions gave the f ol lowingtheir respective bases and examined.results (temperature 15") :I'=1 x 104.4.2 8'48 '4I 17=2x104-JIr=2 y 10'. 1'=1 x 10'.I 5 '41 '4 2.82% 5 2130 VELEY: THE AFFINITY CONSTANTS OF BASES ASValues of k = 1-4 and 2.8 respectively ; hydrolysis value = 21.9 ;p-Xylidine HydrocAloyide.--Two solutions were examined a t 20" := 6.34 lo-'('.Y= 2 x 104. Y= 1 x 10'. Y= 2 x 104. v = 1 x 104.3.2 6'4 8.6 9.4I4.9 9'41 *5 3'1 I 6.6 9.4IValues of k = 1.6 and 3.15 respectively ; hydrolysis value = 24.8 ;q-Cumidine Hydrochloride.-Two solutions were used (temperaturekb(20)= 9.63 lo-''.18') ; all reaction soon came to an end :v=2 x 104.Y= 1 x 104.0.7 1 '61 '4 2.81'4 4.2Values of k = 0.7 and 1.4 respectively ; hydrolysis value= 10.9 ;kb(ls,=4.8 10-9; this last is rather higher than that found, kbr25,=1.7 10-9, by Lowenherz (Zeitsch. physikal Chsn~, 1898, 25, 285) by thesolubility method.PhenyEhydvaxine Izydrochloride. -Examination of solutions of thissalt presented certain difficulties, owing to the separation of the baseor it.s hydrate, a fact previously noted by other observers ascharacteristic of substituted hydrazines. Two concentrations wereexamined, but all reaction soon came to an end (temperature 15') :Y= 3 x 104.Y=1 x 104.1 '0 1 '81 '9 3 62-8 3'6Values of k = 0.9 and 1.8 ; hydrolysis value = 14.8 ; kb(15) = 1.62-a result rather higher (having regard to difference of temperature)than that, kb(40) = 1.6 10-9, obtained by Allen (J. Arner. Chsrn. SOC.,1902, 25, 421) by the catalysis method, However, both results showthat phenylhydrazine behaves as aniline, in which hydrogen isreplaced by an amino-group (which causes an increase of basic value),rather than as hydrazine, in which hydrogen is replaced by a phenylgroup.The separation of base alluded to above prevented any satisfactoryresults in the case of p-bromophenylhydrazine hydrochlorideDETERMINED RY THE AID OF METHYL-ORANGE. 2131Aininopheizols mid their Derivatives.0- and p-Aminophenol Hydrochlorides.-The following results wereobtained for these salts under the conditions of concentration set outand at 159ortho-Salt.para- S a1 t .I. 11. 111. I v.Y= 4 x 104. v= 2 x 104. Y= 2 x 104. v=1 x 104.1.2 2.0 0.6 1 '12'4 4-2 1'1 2.13.4 4-2 1% 3.03 '4 4'2 2'1 3'0Values of L for I and I1 = 1.15 and 2-1, corrected 1.1 and 2.2respectively ; hydrolysis value = 34.4 ; kb(15) = 2.18 10-lO ; values of Efor 111 and IV=O-55 and 1.0, corrected 0-53 and 1.06 respectively;hydrolysis value = 8-3 ; kb(15) = 6 -6 1 O-y.0- and p-Anisidine Hydrochlorides.-The results obtained withsolutions of these salts, prepared from the respective bases and hydro-chloric acid, are given below :ortho-Salt (temp. 15").I.I I.1'2 2.72.5 5.23.5 7.75.2 7.76.4 7 -77-6 7.7Y= 4 x 104. v = 2 x 104.para-Salt (temp. 17").111. IV.0.5 1 *051.0 2.11% 3 '12-2 4'22'9 5.22.9 5-2v= 2 x 10'. v=1 x 10'.Values of k for I and 11= 1-25 and 8-55, corrected 1-26 and 2.53respectively ; hydrolysis value = 39.5 ; kb(,5) = 1.9 ; values of kfor I11 and IV-0.55 and 1.05; hydrolysis value=8*4; kb(,7,=0- and p-Yhenetidine Hydi*ochZorides.--The results obtained are given5.7 10-9.below :ortho-Salt (temp, 20"). para-Salt (temp. 15").I. 11. 111. I v.Y= 4 x 10'. Y= 2 x 104. v = 2 x 104. v=1 x 104.1'3 2-4 0 '8 1.82'2 4.3 1'8 3.53.1 6.5 2.8 3'54'1 8.5 2.8 3.5Values of k for I and 11= 1.05 and 2.2, corrected 1.07 and 2.15respectively ; hydrolysis value = 33.6 ; kblzo) = 4.64 10-16 ; values of ?cfor 111 and I V = 0.9 and 1.8 ; hydrolysis value = 14,2-15 10-92132 VELEY: THE AFFINITY CONSTANTS OF BASES AS11 miuobei ~ x o y I A ZcohoZs oj‘ the Q p e 0 Bz C Melt CH NMe,.These alcohols were originally prepared by Fourneau (Compt.rend.,1904, 138, 766) by the action of a secondary or tertiary amine onTiff eneau’s chlorohydrins, OH*CMeR*CH,Cl ; the hydrochlorides oftheir benzoyl derivatives crystnllise well. Such compounds belongrather to the aliphatic series, but, since the date of my last com-munication, MM. Poulenc Frhres, of Paris, have kindly presented mewith fine, crystalline samples for the purpose of investigation, and Itake this opportunity of tendering my thanks to this firm for theircourtesy and generosity.The most important of these compounds, (I) methylethyldimethyl-aminomethylcarbinol benzoate hydrochloride,OBz*CMeEt *C H,*NMe,,HCl,commercially known under the name of stovaine, is now largely usedinstead of cocaine for hypodermic injections to produce local anssthesiaand other purposes, as being less toxic and safer to administer.I t iswell known that the base is precipitated from aqueous solutions evenby very dilute solutions of borax, the soda liberated by hydrolysisbeing sufficient to upset the equilibrium between the base and hydro-chloric acid. Aqueous solutions are also decomposed when heated ina soda-glass vessel in an autoclave, the course of events being probablythat the water dissolves out sodium silicate, which consists largely, inaqueous solutions, of free soda and silicic acid (Kohlrausch, JPiecl.Ann.,1892, 47, 756), and then the former combines with the hydrochloricacid.Besides stovaine, the hydrochlorides of the following bases wereexamined.11. Dimethyldimethylaminomethylcarbinol benzoate,OBz*CMe,*CH,*NMe,.OBz*CMe(C,H,,)*CH,*NMe,.111. Meth ylisoamyldimethylaminome t hylcarbinol benzoate,IV. Phenylmethyldimethylaminomethylcarbinol benzoate,OBz-CMeP h*CH,*NMe,.All these salts in N/ZO or N/100 solution showed no trace ofhydrolysis by the methyl-orange method ; hence their basic constant isgreater than 1 x 10-7, which is rather remarkable having regard to thepresence of the benzoyl grouping.A description of the method adopted for differentiating between thebasic values of these several salts, and its applicability in other cases,is deferred to a subsequent communicationDETERBIIKED BY THE AID OF METHYL-ORANGE.2133( 9 ) Uincidic Buses.P~e?zyZe92edi~~i,2inne HydyochZorides.--These compounds have previouslybeen examined by Bredig (Zoc. cit.) by the electric conductivity method ;the writer pointed out that they all gave a strongly acid reaction withmethyl-orange, and arrived at the general conclusion that they werehydrolysed to a greater or less degree into the monohydrochloride andhydrochloric acid (as hydrazine hydrochloride). It was thought advis-able to make determinations, not only with the N/20 solutions diluteddirectly, but also with the same solutions heated in a thermostat forthree hours at 60°, and then subsequently diluted (series marked T).But although further information was obtained by the double method,yet the difficulty was experienced that, in the process of heating, thesolutions turned a yellow t o yellowish-red colour, the change being mostmarked in the para-derivative, less in the meta-, and inappreciable inthe ortho-derivative.The probable explanation is that traces of safra-nine compounds were formed (compare Witt, Ber., 1883, 16, 472, etc.),the conditions being favourable, namely, the presence of hydrochloricacid liberated by hydrolysis and of oxygen, whether dissolved in thesolution or absorbed from' the superincumbent atmosphere. The sameremarks also apply to the tolylenediamine hydrochlorides, consideredin the sequel.o-Phenylenediarnine Hydrochloride.-Three series of experiments wereconducted, with results as under :Series I.Series I 1 (T). Series III.V=I x 104. Y=S x lo-'. v=4 x 104.0.6 0'8 1 *31 '2 1 -5 2.82.0 2.3 4 '32.7 3.1 5.83.5 3.9 5 -8Series I. Series I I (T). Series I I I .V=8 x lo4. V=8 x 10'. J7=4 x lo4.4.2 4.9 5.85.0 5.6 5 '85.0 6'4 5.85-0 8.3 5.8Values of k for series I and III=O*'7 and 1.45, corrected 0.71and 1.42 ; hydrolysis value = 44.4 ; for series 111, k = 0.8 ; hydrolysisvalue =50*0.m-Phenylenediumine Hydrochloride.--Five series of experiments wereconducted, namely, three with one and two with another sampleof the salt, purchased a t a different time; the results of only threeare given, and the differences in values obtained with the two sampleswere within the limits of experimental error :Series I.Series 11. Series III.0'8 1 '4 1-61.5 2-6 2-92-3 4.0 4'43.0 5.5 6 *3V=8 x lo4. V=4 x lo4. V=4 x 104(T).Series I. Series II. Series IlI.3 -7 7.0 7.64'4 8.5 8.9Y = 8 x 1 O 4 . V=4x104. v=4x104(T).I 5.2 8.5 10.2134 VELEY: THE AFFINITY CONSTANTS OF BASES ASValues of k for series I and I1 = 0.75 and 1.40, corrected 0.72and 1.45 ; hydrolysis value = 45.3 ; for 111, k -- 1-55 ; hydrolysisvalue =48*4.p-Phenylenediccrnine N~clrochEoi.ide.--The results of three series ofexperiments are given below :Series I. Series 11. Sese.r.ies 111. I Series I. Series 11. Series 121.Y= 8 x 104. Y= 4 x 10'. Y= 4 x lo4( T).I Y= 8 x lo'. V = 4 x 10'. V=4 x lo4( 7').1 4.5 8 '4 7.65.1 9 '9 7 %0% 1 -3 1.55 *7 9.9 7.6 / 1.3 2-9 3'02'1 4-3 4.52 *8 5 '7 6.2 I , 6'4 9.9 7.63.7 7.0 7,% 8 -0 9.9 7.6IValues of i% for series I and I1 =0.7 and 1.4; hydrolysis value= 43.7 ; for series 111, k = 1.5 ; hydrolysis value = 47.0.I n all the above sets of experiments with the isomeric phenylene-diamine hydrochlorides a slight tendency for the differences, y' - y, toincrease was observed, due probably to a trace of hydrolysis of themonohydrochloride ; but as the point has frequently been alluded toit is unnecessary to dwell frirther on it. The results for hydrolysis arecompared in the following table :X. x (TI.p-Derivative ..................... 43.7 47'0o-Derivative., .....................44.4 50-0mDerivative .................... 45'3" 48.4It thus appears that the phenylenediamine hydrochlorides are, underthe conditions of the experiment, hydrolysed nearly completely intothe monohydrochloride and hydrochloric acid, thus :ClH,N*C,H,*NH,Cl + H,O = ClH,N*C,H,*NH,*OH + HCl,and that the order of affinity of bases is p > m > 0, the result marked *being an exception not readily explained; it was repeated with twodifferent samples a t two different times with concordant results.Diaminop Aeno I Hydroch I ovid e.As solutions of this substance commenced to turn yellow shortIyafter making up, the operations of dilution and examination wereconducted as quickly as possible ; the following results were obtainedin two series :Series I.Series II.Y= a x 104. V=4 x lo4.0.7 1'41.4 2.92'2 4'43'0 5'93'8 7.5Series I . Series 11.4.5 9'25.2 9'26.0 9-26% 9 '2v=a x 104. v= 4 x 104DETERMINED I1Y THE All3 01.' METHYL-ORANGE. 2135Iserics I. Serics II. Series III.Y= 8 x lo4. V= 8 x lo4 (T). V= 4 x lo4.0'6 0.7 1.51 '2 1-5 3.22.1 2-3 4 '82 *7 3'1 6.33.5 4.0 8.2Values of k for series I and I1 = 0.75 and 1.50 ; hydrolysis value =47.0.The introduction of the hydroxyl group into an o-diaminobenzeneappears to cause a slight increase in the hydrolysis value; otherwisethe above remarks are equally applicable.Phenylenetet,*amet?h ylcliarnine Hy&rochZoride. --Solu tions of this sub -stance were almost impossible to work with, owing to the rapidity withwhich they assumed a bluiah-violet Golour, doubtless from the formationof a trace of some induline derivative; the results of one series aregiven :Y= 8 x 10.'.Y= 8 x 10'.0.8 3 *11.5 3'92.2 3 -9k = 0.8 ; hydrolysis value = 50.0.Tolplenediamine I~yd~oc?~loricEes.--The.2 ; 4, 2 : 5-, and 3 ; 4-derivativeswere examined. The results are given below :b'erl'es I. Series 11. Sei-ies 111.V= 8 x lo4. V=S x lo4 ( 7'). V= 4 x lo4.4'4 4.9 9.75'2 5.7 11'46-0 6-13 11.46 *7 6.6 11'47% 6.6 11-4Scrics I. Series II.V= 8 x lo4. v= 4 x 10.'.0 -7 1.51-5 2.92 '1 4-32 Y3 5-73'6 7.2series I. Series 11.Y= 8 x lo4. v= 4 x 1 0 4 .4.2 8 *75.0 10'35.9 10'36.7 10.37'3 10.3Scrics I. ,Yeries II. Scries 111.0'8 0.8 1 '41-5 1% 2'72.3 2 '4 4-23 '1 3 *2 5 .6~ = 8 ~ 1 0 4 . v = s x i o y ~ ) . ~ = ~ ~ 1 0 4 .Scries 1. Series 11. Serics III.3'9 4 '1 7 *14 % 5'0 8.55 *4 5.9 10'2v = s x i 0 4 . v = 3 x 1 0 4 ( q . ~ = 4 ~ 1 0 4 2136 VELEY : THE AFFINITY CONSTANT8 OF BASES ASValues of k for series I and I11 = 0.75 and 1.40, corrected 0.72 and1.45 respectively ; hydrolysis value = 45.0 ; for series 111, k - 0.8 ;hydrolysis value = 50.0.It will be evident from the above results that the behaviour of thetoly lenediamines is completely analogous to that of the pheny lene-diamines, in that they are hydrolysed nearly completely into the mouo-hydrochloride and hydrochloric acid, and the change is complete if thesolutions are previously heated. Bredig (Zoc.cit.) examined the 2 : 4-derivative, and his results at dilution V=2048 point to a similarconclusion.Benzidine Hydrochlwide-Owing to the sparing solubility of this salt,the usual method of procedure mas slightly altered ; an N/40 insteadof an iV'/ZO original solution was prepared, and this was subsequentlydiluted. The results obtained are given below (temperature 16").v=a x 104. v=4 x 104. 1 v=sX104. v= 4 x 104.I 3-9 7'44-6 8.8 1 0 '8 1'41.7 2.82 -4 4 ' 4 4'6 10'43'1 6.0 1Values of k = 0.75 and 1.5 ; hydrolysis value = 46.6.The behaviour of benzidine hydrochloride is thus perfectly analogousto that of the diaminobenzenes; my results are not in this respect inaccordance with those of Bredig (Zoc. cit.), who concluded from hismeasurements that the salt was only slightly hydrolysed.Dibenxylamine and diphenylamine hydrochlorides were not sufficientlysoluble, or gave the insoluble base on hydrolysis ; the methyl orangemethod could not therefore be applied.Nc~pldiylamines.a- and p Naphthykcnzine Hydrochlorides.--My experience in oh tainingthese compounds in a sufficient state of purity for examination wassimilar to that noted by Lellmann (Annwlen, 1891, 263, 297), and itappeared that the impurities present, of whatever nature, were of anorder of value less than that deducible by a determination of thechlorine contents. The criterion of purity finally adopted was thatthe N/20 solutions of the recrystallised salts should withstand heatingfor three hours at 60° without becoming discoloured, or showing onlytraces of fluorescence.The values of kb obtained were in both caseshigher than those obtained by Farmer and Warth (Zoc. c i t . ) , who giveno details as to any special precautions adopted in the preparation ofthe salts examinedDE'I'ERMINED BY THE AID OF METHYL-ORANGE. 2137a-Salt (teinp. 15").I. 11.1'2 2 '02'2 4'03-1 6.04-3 8.15.4 10'46.7 10'48.0 10.49-2 10'410 *4 10.4Y=4 x 104. v=z x 104.&Salt (temp. 15").111. IV.1.1 1.92.1 3.63 *1 5 -54 '1 5.55.0 5 *55'0 5.55'0 5.55 -0 5 55.0 5.5Y= 4 x 104. v= 2 x 104.Values of k for I and 11= 1-15 and 2.0, corrected 1-08 and 2-05respectively ; hydrolysis value = 33.4 ; kbiI5) = 2.8 10'" (Farmer andWarth found kb(25) = 0.99 lo-'") ; values of k for I11 and I V = 1.0 and1.8, corrected 0.95 and 1.9 respectively ; hydrolysis value = 29.7,kb(ls) = 3 9 lo-'" (Farmer and Warth found kb(25) = 2.0 10-l0).Theresults obtained by these writers and myself concur in showing Bhatp-naphthylamine is a stronger base than a-naphthylamine.Pyridine Bases.Pyridine HydyoclJoride.-It mas found i n the case of this salt thatequilibrium of the system water-acid-base-salt was attained after alonger interval (two or three days) than in all other cases hithertoexamined. Three solutions were examined at 1 3 O , with the followingresults :Y= 4 x lo4. Y= 3 x lo4. Y= 2 x lo4. Y= 4 x 104. Y= 3 x 104. Y= 2 x 104.3.6 6-7 ;:; 1 ;:; 3.6 8.50.9 1-21.7 2'42.5 3.6 5.2Values of k=O*S5, 1.2, and 1.7, corrected 0.86, 1.18, and 1.73respectively ; hydrolysis value = 26.1 ; kb(15) (at V= 2 x lo4) = 1.06 1Lunddn (Meddel.K. Vetensk. Nobelinst., 1907, 1, No. 8et seq.) has determined the value of kb for pyridine a t differenttemperatures by the electric conductivities of the hydrochloride andacetate. The value given above is identical with that found by t h i sauthor at loo, but otherwise is more nearly concordant with it thanwith those obtained by Constam and White (Amer. Chem. J., 1903,29, 36) and Goldschmidt (Zeitsch. yhysikal. C l ~ m . , 1899, 29, 89).In this connexion I may be allowed to remark that my determinationswere made some months before Herr Lundbn was courteous enoughto send me his publications, from which I have derived considerableassistance ; the convenience of dividing the bases into open-chain andcyclic compounds has been the sole cause of my delay.Piperidine Hydrochloride.--No trace of hydrolysis could be detected7 c 2138 VELEY : THE AFFINITY CONSTANTS OF RASES ASeven in most concentratod solutions of this salt, a result t.0 beexpected, as Brodig (Zoc. cit.) found for piperidine a higher basicconstant, kb = 1-55 than that of any other nitrogen-containingbase ; its heat of neutralisation with hydrochloric acid is practicallyequal to that of sodium hydroxide. Piperidine has probably theconstitution of a hexamethylene, in which one CH2 group is replacedby the NH group.Coniine ( Propylpipevidine) Hydrochloride.-The result obtained wasprecisely similar to t,hat of piperidine.The stability of these hydropyridine hydrochlorides is otherwise ofgeneral importance, having regard to the number of natural alkaloidswhich are derived from a hydropyridine ring.a-Picoline liydrochloride.-Prepared in solution by dissolving a weighedquantity of the base in the required volume of N/20 hydrochloric acid.Only a few results could be obtained, as the limit of the methyl-orangemethod was almost reached.The hydrolysis value found a t 15' was1.9, giving for the dilution used a value, kb(la) = 5.4 10-8, which can onlybe regarded as a n approximation, although probably not widely re-moved from the true value as intermediate between those of pyridine,kb = 1.3 and trimethylpyridine, kb = 1.42 10-7,at the sttmetempera-ture.Quinoline Ba8ee.Quiiaoliue HycErocldoride.-The results obtaiued at 15' for two con-centrations are given below :v= 2 x 104.v=: x 104.1 -0 1.92.0 4.23-1 6.04 '1 7 '85.0 -v= 2 x 104. Y= 1 x 104. - 5.96.87.8 -8'9--Values of li; = 1.0 and 2.0 respectively; hydrolysis value = 15.6; hence1.63 10-9 ; this last value is in fair accordance with t h a t found,kb(60) = 7.4 by Walker and Astori (Trans., 1895, 67, 576) by theinversion of sucrose method, having regard to the difference oftemperature of the two sets of observations.Tetrahydroquinoiine HydrochZoridcr.-No hydrolysis could be detectedeven in concentrated solutions; the behaviour of this substance isthus perfectly analogous to the hydro-derivatives of pyridine.3 -~~ydroxyquinoline (Cuybostyil) Hydrochloyide.-A solution of thissalt was obtained by dissolving a weighed quantity of the base inN/2U hydrochIoric acid. The following results were obtained at lS0with two concentrations :v=z 104. v=i x 1041 '1 2'12 *o 4'0Y= 2 x 104. Y= 1 x 104. I 3.1 4'04 ' 2 4.DETERMINED BY THE AID OF MEI'HTIrORANQE. 2139Y= 2 x 104. Y=1 x 104.0.7 1'31 '3 2.51'9 3-8Values of k = 1.05 aud 2.08, corrected 1-03 and 2.07 ; hydrolysisvalue = 16.6 ; hence k,jgs) = 1-94 10 -Q.The general behnviour of hydroxyquinoline as compared withquinoline is similar to that of paminophenol as compared with aniline,in that the introduction of the hydroxyl group, although not causingany appreciahle difference in the affinity constant, yet produces theeffect that all reaction with the methyl-orange sooner comes toan end.2-n-leth~Zquinoline IZydrochloride.-A eolution of this salt was preparedas above, and two concentrations were examined a t 14" :Y= 2 x 104.v=1 x 104.2 ?i 5.02.5 6.22.5 7 '3Y= 4 x 104. Y= 2 x 104.0.9 1 *91.8 3.92-9 6.0Y= 4 x 10'.4.8 9.95.76.7v=z x 104.--Values of k = 0.95 and 2.0 ; corrected 0.97 and 1.95 ; hydrolysisvalue = 30.2 ; hence kb(15) = 3.62 10-10; this base is therefore weakerthan quinoline.Acridims.-I have to express my thanks t o Prof. Senier for kindlysupplying me with beautiful specimens of these bases ; my only regretis that they proved to be insufficiently soluble in hydrochloric acid ofthe concentration required for this investigation.Sect ion ZI.- Mutual Re Zat ionship.(1) Efect of Position on Isomerism.-The order of the affinityconstants of the isomeric derivatives of benzene is invariably p> m>o,or) in other words, the para-position presents a case of steric hindrance,but the ortho a case of steric furtherance; this generalisation ispr*ecisoly analogo!is to that arrived a t in the case of acids by Ostwald(Zeitsch. physikal. Chem., 1889, 3, 170 et seq.) and myself by themet hyl-orange method (ibid., 1906, 57, 147 et 8eq.). The results for kbare compared in the following table 2140 VELEP: THE AFFINITY CONSTANTS OF BASES ASp-Rase.Toluidincs ............... 4 - 5 lo-'"Chloroanilines ......... 1 *24 10-l'nromoanilines .........2.07Aminophenols ......... 6 'ti 1 O-gAnisidines .............. 5 *7Phenetidines ............ 2.15Dimetliyltolnidines ... 6-36 lo-!'nt-Rase. o-Pase.3.5 10-10 1-52- 3.086.58 9-16 10439-5 10-11 -- 2-18 lo-]!- 1-9 10-11- 4'64 10-10I n certain cases there is the same numerical ratio between corre-sponding isomerides :thus m-chloroaniline : p-chloroaniline = 6.58 1 0-l2 : 12.4 10-12 = 1 : 1 '9,and m-bromoaniline :p-bromoaniline = 9.5 lo-" : 20.7 10-l1= 1 : 2.2,also p-sminophenol: o-aminophenol = 6-6 10-9 : 0.22 10-9 = 30 : I,and p-anisidine: o-anisidine=5.69 : 0.19 loFg= 28.5 : 1.(2) E'ect of Substitution.-(a) The substitution of hydrogen bybromine produces a less effect on the affinity constant than that ofhydrogen by chlorine, a conclusion also analogous to that arrived a tby Ostwald in the case of the acids.(b) The substitution of hydrogen by the hydroxyl, methoxyl, orethoxyl groups in the para-position increases the affinity constant, butin the ortho-position produces but little effect.(c) As regards the substitution of hydrogen by hydrocarbon groups,whether in the amino- or hydrocarbon residue, it appears difficultto draw any very definite conclusion, although generally the effect ist o increase the basic constant, but there are certain exceptions.Bredig arrived at a similar uncertain conclusion .( d ) The effect of substitution of hydrogen by an amino-group whenattached to a carbon atom decreases the affinity constant, the diamineabeing hydrolysed uniformly to 50 per cent., but an amino-groupattached t o a nitrogen atom produces an opposite effect, for example,the case of phenylbydrazine as compared with aniline, which isanalogous to that of semicarbazide with carbamide and of amino-guanidine with guanidine alluded to in my previous communication.(e) The addition of hydrogen t o the pyridine and quinoline basesproduces a very great increase in the affinity constant, although, aspointed out above, such additive compounds may possess a differentconstitution, not roadilg expressible by structural formulce.Section 111.- I'emperuiwe-Coe$icients.Kohlrausch and Heydweil!er (Tied.Ann,, 1594, 53,209), from theirdeterminations of the electric conductivity of the purest water atdiff ersnt temperatures (and hence the temperature-coefficient referredto IS'), deduced by means of the van't IIoff gas law a generale q u a t i o n : .. . . . . . C = 0.03373 10-22500/T2 (DETERMINED BY THE AID OF METHPL-ORANGE. 2151for the ionic concentration C,a, or C(OH) per litre. By two independentmethods of calculation, they arrived at the values given in the firstline of the sncceeding table ; the values of k?, = (C,)2 (since CH= Cton,)calculated therefrom are given in the second column (compare Abegg,Sammlung Chem. und Chem.-techcn., Vortrage, 1903, 8, 242) ; inthird column, certain results obtained by Lundh (Meddel.Vetensk. Nobelinst., 1907, 2, 16) are added.0. 10. 15. 18. 26. 34. 42.Ionic concentrationJlitre lo-'. 0.35 0.56 - 0-8 1.09 1-67 1-93I C $ ~ ) .......................0.12 0-31 0'49 0'64 1-2 2.16 3.7............................. 0.31 0.46 - 1'05pri) - 2 9 4 (.LO) - ,,theK.50.2-486-155-17Abegg remarks upon the rapid increase of ionic dissociation of waterwith rise of temperature.I t appears, however, that the above values can be directly calculatedby the expression originally proposed by Harcourt and Esson (Phil.Trcm8., 1895, 186, :A, 861) for tha,relation of chemical change fortemperature, namely := m dk /dT . . . . . TI For on integration,which may be written in the simple formkTf/kT = (T/ T)m . . . . . . (4),logk-logk'=m(logT-logT) . . . . ( 5 ) .I n the above equations 3-5, k represents either CH or k,, TIf the value of C, at 0 is taken as 0.37 and ni= 11, andand m=28 (or preferably 22*5), then, the values a tabsolute temperature, and m R factor.k,=0*14different temperatures appear as under :0.10. 15. 18. 26. 34. 42. 50. 60.CH lo-' ...... 0'37 0.56 0.68 0.76 1.01 1.36 2.08 2-49 3.5k, l O - l 4 ... 0'14 0'31 0'47 0.58 1-02 1.85 4'3 6.25 12.25The agreement between the numbers in the two tables is verysatisfactory. Hence, therefore, the logarithmic increase of ionicdissociation due to increase of temperature varies as the logarithmicincrement of absolute temperature, or, to put the matter in anotherform, ionic dissociation of water as affected by temperature cannot bedifferentiated from other chemical changes, and consequently there isnothing remarkable in the increase of such dissociation with rise oftemperature.The graph of logk'llogk in terms of logT'/logT is astraight line, and this may serve as n convenient method of ascertain-ing the value of k , for any temperature.But from the Arrhenius' equation : kb/k, = (1 - x) V/x2, if k, is a2142 VELET: THE AFFINITY CONSTANTS OF BASES ASexperimental frinction of temperature, kb will likewise be of thesame order. I n the following table, the results obtained by variousobservers are compared with those calculated by formula (a), thevalue of the function nz being deduced ; most of the observations arereferred to a basis T= 283.The results are taken from the writings of Bredig, Walker, Lundkn,myself, and others; in cases in which different workers haveobtainedslightly different resrilts at the samo temperature by applying differentmethods, the letters ( A ) , (U), etc. are used.,Tempcraturc.10. 15. 25. 40. 50. 60.1.71 1-87 1'98 - - Fonntl1-69 1-81 1-99 - - Calc.1'42 2.05 3.05 3.75 - Found { ;:;; 1'42 1-94 3-01 4.00 - Calc.1.06 1*41(A) 2-38(A) 4'25(A) 6*19(A) 8*5(0) Found1*06(B) 2*00(C)1 -00 1.27 2.06 4'08 6.19 9.71 Calc.2.6 (12") 3*66(A) 4'57(A) 7*56(A) - 17.1(0) Found3.2 ( B ) 4'6 (C) 8.1 ( D )2*7l(lY) 3.07 4.64 8.34 - 17.7 Calc.10 *9( C) Found { l'P(12") - 2.6 - - 10.9 Calc.0*45(A) 1'4 (B) - - 3'61(C) Pound0.4 0'69 - - 3'42 Calc.{ E; Ammonia,nt=2Trimeth ylpyridine,lo-', m=9Pyridine, I O F 9nz=14Aniline, m=12o-Toluidine, 1*5(12")(A) - 3.2 (B) - -p-Tohidine, 1 O-y,m=13m=15The differences between the observed and calculated results are withone or two exceptions very small, especially having regard to the factthat the methods applied were in some cases very widely different.I n the case of very weak bases of the order of value kb 10-l' t oconcordance is less satisfactory, but as the determination of thehydrolysis of 90 per cent., or thereabouts, may amount t o 5 per cent.oreven more, discrepancies, especially at the higher temperature, cannotbut be expected.I t would follow, therefore, that if both kh and k, are exponentialfunctions of absolute temperature, then in the thermodynamice iuation+ = quantity of heat, k =constant of equilibrium, and, since R = 1.985of the unit of work in the gram-caloric (compare Nernst, Zeitsch.E'lektyochern., 1904, 10, 62 1)it follows that the heats of neutralisation (by the substitutionk = kw/ka) and the heats of dissociation (by the substitution k = ka) areexponential functions of absolute temperature.These can be directlycalculated for any temperature without having recourse to mean valuesor the application of empirical equations :+=RT2 2.3026 dlog 'QkldT . . . . (6),+=4*571Tedl~g'Ok/dT . . . (6 bis),k = 1 + a t + b t 2 , e t c . . . ' ' (7)DETERMINED BY THE AID OF METHYL-ORANGE. 2143or other arithmetical device3. I refrain from giving such calculationsof heats of neutralisation arid of dissociation, as I am awaro thatother writers have been engaged upon them ; my object is to pointout a simple and possibly more rational method.I am indebted toProfessor Wm. Esson, of the University of Oxford, for assistance in thissection.Summary.(i) It is shown by a number of determinations that the methyl-orange method gives results which are concordant within the limitsof experimental error with those obtained by the catalysis of methylacetate, inversion of sucrose, and electric conductivity mefhods. Ifthe last-named give accurate results, then the same equally applies tothe first. It is, of course, possible that the affinity constants of thebases may at some future date be revised, as they are deduced from thevalues of k, or Cfa), which at the present time are mainly based onthe determinations at different temperatures of the electric conductivityof the purest water obtained by Kohlrausch, and these in their turnare dependent on the evitluation of the ohm.(ii) Determinations are giveti of the hydrolysis and affinity constantvalues of some fifty bases derived from cyclic formula; the mutualrelationship and effects produced by the substitution of one or moreatomic proportions of hydrogen, whether in the nucleus or side-chain,by various elements or groups are discussed.(iii) The variation of the several constants with temperature isdealt with, and it is shown that in cases in which determinations ofthese constants have been made at different temperatures by the sameor different trustworthy methods, the experimental results are inaccordance with those calculated by Esson'a formula k,,/k, = (I',/T)m.Thus ionic dissociation, whether of water or electrolytes, cannot bediffererltiated in respect of temperature from any other change, and isgenerally regarded as of a wholly chemical nature.The importanceof this formula for the purpose of other calculations is also alluded to.Finally, I have again to express my obligations to various friends,who have rendered assistance by verbal or written suggestions, orsupplied necewary materials.Addendum.Since the above paper was written, a communication has beenreceived from Herr Lunddn, entitled '' Influence of temperature onthe internal energy and free energy OF electrolytic dissociations ofacids and weak bases" (Meddel. K. Vetensk. Nohelinst., 1907, 1,No. 12). I n this paper, certain formuls are discussed with th2144 MORGAN AND MICKLETHWAIT :purpose of referring affinity val ties, as influenced by temperature, tothermodynamic l a m . The equation given is :in which U=internal energy, also a function of T with two constants,namely, U= f(abT), and the simplest, as also that most in accordancewith observations, is U= a + bT.It will be noticed that the left-hand side of the above equation ( l a )differs from mine, log,,k~, -loglOkTZ, given in the text, only indegree, whilst the right-hand side refers the difference of affinityvalues to thermodynamic laws, and thus takes matters one stepfurther than that given in the text, namely, m(logl,Tl - log,oT,).As I was aware from private communications that Herr LundQnintended to take up the subject of the hoats of dissociation andof neutralisation with reference to affinity values, i t appearedequitable that this part of the subject should be left to him.V. H. V

ISSN:0368-1645    

DOI:10.1039/CT9089302122

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

2144 MORGAN AND MICKLETHWAIT :CCX1V.- Organic Dehatives of A ~ s e n i c . Pa9.t 1.Dicamp hory lursinic A cid.By GILBERT T. MORGAN and FRANCES M. G. MICKLETHWAIT.THE organic derivatives of arsenic have of late received increasedattention owing t o the discovery that certain of these substances areof therapeutic value, and, owing to the successful application ofsodium paminophenylarsonate ( L c atoxyl ”) in this connexion, manyexperiments have recently been made with the object of obtainingsimilarly constituted compounds. I n these researches the arsenichas been generally, although not invariably, employed in the form ofarsenic acid. Considered as a synthetical agent, arsenic acid has thedisadvantage of being hydrated and not very miscible with theordinary organic media, On the other hand, arsenious chloride is easilyobtained in the anhydrous state, and is readily miscible with non-hydroxylic solvents. Moreover, on account of its volatility, anyexcess of this reagent can often be removed by distillation.The experiments of Michaelis and his collaborators (Annalen, 1892,270, 140; 1901, 320, 271; 1902, 321, 141) have shown t h a tarsenious chloride may be employed as the vehicle for introducingarsenic into aromatic nuclei.The authors have examined the action of arsenious chloride oORGANIC DERIVATIVES OF ARSENIC.PART I. 2145compoiinds of a very dissimilar type, and in the present communicationthey wish to record the results obtained in the case of camphor.This ketone was employed in the form of its very reactive sodiumderivative, a substance which was first employed as a syntheticalagent by Haller (Compt.rend., 1891, 112, 1490; 1892, 113, 22),and more recently by Forster (Trans., 1901, 79, 987).The condensation of arsenious chloride and sodium camphor waseffected in dry toluene, and from the product of the reaction causticalkalis extracted an acidic substance, the composition of whichcorresponded with the empirical formula C,,H,,O,As.‘Sitration with standard caustic alkalis and the formation of asilver salt, C,,H,,04AsAg, and a cadmium salt, C,,H6008As,Cd,indicated that the substance was a monobasic acid, C20H3004AsH.Further evidence as to the constitution of the acid was gainedby a study of the products of its hydrolysis.The acid is not affectedby prolonged boiling with aqueous acids or alkalis, but, when fusedat a moderate temperature with potassium or sodium hydroxide,camphor (2 mols.) is eliminated and the corresponding alkali arsenate(1 mol.) is produced.C,,H,,02As0,Na + 2NaOR = 2CloHI6O + Na,AsO,,takes place quantitatively, and shows unmistakably that the compoundis dicumphorylarsinic ucid * having the constitution+This hydrolysis,A further confirmation of this formulation was afforded by theformation of a somewhat unstable chloiide, (C,,Hl,O),AsO*CI, producedby the action of phosphorus pentachloride on the alkali salts ofthe acid.The authors wish to reserve for the present the study of theaction of arsenious and other inorganic chlorides on organic compoundscontaining the group CH,*CO.* It should be noted that the expressiou “ camphoryl” has beeu used in tlicliteratiirc to indicate the thre, following groups :C,H,,/Co-CH- ,co-‘co- \CO-OH.CSHl4(d0 CSHW(1.) (11.) (111.)The authors feel justified in employing “ camphoryl ” for the first of those radicles,because, iu accordance with the terminology usually adopted, the acidic radicle (11)should be denoted by “ cainphoroyl ” or some similar name ending in L‘ oyl.” I nthis respect they follow the ruling already laid down in the case of tho groupsC,H,*CH:CH*CH,- and C,H,*CH:CH*CO-, which are indexed i n this Journal ascinnamyl and ciniiamoyl respectively21 46 MOROAN AKD MICKLEFHWALT :EXPERIMENTAL,Seventy-five grams of camphor were dissolved in 200 C.C.of warmtoluene, and converted into sodium camphor by the addition of 7.5gram., of sodium. The precipitated sodium derivative, suspended in200 C.C. of fresh toluene, mas slowly treated with 3s grams of arseniouschloride diluted with a b m t twice i t s bulk of the same solvent, themixture being thoroughly shaken and cooled. The condensation tookplace with considerable generation of heat, and a remarkable series ofchanges occurred during the addition of the chloride. At first themixture acquired a jelly-like consistence, and gradually assumed adeep crimson hue. This colour slowly faded while the mixtureregained its fluidity, until finally it consisted of a yellow, mobile solu-tion with a pulverulent, white precipitate of sodium chloride.Afterone hour, the mixture was warmed on the steam-bath, and throughoutthe experiment moistm-e was excluded.The mixture was now poured into water, and extracted with hotaqueous sodium hydroxide. The alkaline extract, when cooled andacidified with hydrochloric asid, furnished a brownish-white pre-cipitate, the yield of which was about 10 per cent, calculated onthe weight of camphor employed.This acidic product was crystrtllised from benzene, when almostcolourless crystals were obtained. Further crystallisation fromalcohol gave transparent, colourless, highly refractive, obliquelytruncated prisms melting with decomposition at 266'. This decom-position point was, however, considerably lowered when the acid washeated for some time at 150' :0.1300 gave 0.2752 CO, and 0.0930 H,O.0.1418 ,, 0.3038 CO, ,, 0.0982 H20.C = 58.41 ; H = 7.69.0.5132 ,, 0,1984 Mg,As,07. AS= 18.71.0.8870, titrated with standard sodium hydroxide solution, required0.08604 NaOH. The monobasic acid, C20H3002: AsO*OH, requires0.08653 NaOH.0.4890, in 25 C.C. chloroform in a 8-dcm. tube, gave a: +7.3';whence [u]: + 186.6O.DicumphoryZa?*~inic acid, (CloH,,O),AsO*OH, is almost insoluble inwater or petroleum ; it dissolves more readily in benzene, and is freelysoluble in chloroform or alcohol. From the last of these solvents i tseparates in lustrous, colourless crystals. I n titrating this sparinglysoluble acid, a weighed portion, dissolved in benzene, was shaken upwith water containing phenolphthalein, whon a sharp end-point wasobtained with either N/2-sodium or N/2-potassium hydroxide.C = 57-78 ; H = 7.95.C,oH,,O,As requires C = 58.53 ; H = 7.56 ; As = 18.29 per centORGANIC DERlVATIVES OF ARSENIC.PART 1. 2 \ 4 7The salts of the alkali metals and ammonium are extremely solublein water or alcohol. The calcium, strontium, barium, nickel, andcobalt salts are not precipitated in aqueous solutions; the ferric,mercuric, and cupric salts are almost insoluble in water.Silver dicamphoi*yZarsincte, (CloH150),A~0*OAg, was obtained as awhite, sparingly soluble precipitate from sodium dicamphorylarsinateand silver nitrate; it was amorphous a t first, but slowly becamecrystalline, this change being accelerated on warming the mixture :A g = 20.53.0.1398 gave 0.0287 Ag.C,,H,,O,AgAs requires Ag = 20.88 per cent.Cudmium dicamphorykursinate, [(C,,H,,O),AsO,],Cd, separated as asparingly soluble, white, crystalline compound on mixing strongaqueous solutions of cadmium chloride and potassium dicamphoryl-arsinate :0.4316 gave 0.0570 CdO. Cd= 11.40.C,,H,,O,As,Cd requires Cd = 12.17 per cent.From aqueous solutions of i t s salts, dicamphorylarsinic acid is setfree by acetic acid, but only a very slight precipitate is produced bycarbonic acid. Dicamphorylarsinic acid does not yield a n oxime ontreatment with hydroxylamine in hot aqueous or alcoholic solutions.Dicanzphwylarsinyl chloride, (Ol,H,50),AsO*C'l, obtained by theinteraction of potassium dicamphorylarsinate and phosphorus penta-chloride, separated from chloroform arid benzene i n colourlesscrystals melting a t 158" :0.2158 gave 0.0646 AgC1.C1= 7.41.C,oH300,C1As requires C1= 8.28 per cent.This substance is very sensitive to moisture, and is rapidly decom-posed on exposure to the atmosphere; its specific rotation, taken indry chloroform, gave [aID + 106".Hydrolysis of the A l h l i Dicumpl~orylul.sinat~.Although stable in hot aqueous solutions, the alkali dicamphoryl-arsinates, when evaporated with excess of caustic alkali until themixture assumed a syrupy consistence, underwent hydrolysis with theliberation of camphor and the formation of an alkali arsenate. Thecamphor was evolved quantitatively, and in one experiment 97 percent.. of the calculated amount was collected and identified by itsmelting point, specific rotation, and conversion irito camphoroxime (m. p.118'). The alkali arsenate was identified by conversion into copperarsenate, aud also by precipitating the arsenic acid as magnesiumammonium arsenate2148 DIXON AND TAYLOR: STUDY OF THE CONSTITUTION ANDWhen heated at 300°, dicamphorylarsinic acid and its alkali =Itsunderwent complete decomposition.The authors desire to express their thanks to the GovernmentGrant Committee of the Royal Society for a grant which has partlydefrayed the expenses of this investigation.SOUTH KENSINQTON, S. W.ROYAL COLLEUE OF SCIENCE, LONDON

ISSN:0368-1645    

DOI:10.1039/CT9089302144

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

2148 DIXON AND TAYLOR: STUDY OF THE CONSTITUTION ANDCCSV.-Study of the Constitution and P.r*operties of theBy AUGUSTUS EDWARD DIXON and JOHN TAYLOR.IT is well known that certain more or less electronegative atomiccomplexes, for example, CNS, CNO, CN, or NO,, may yield with agiven electropositive organic radicle in each case two isomeric com-pounds, the isomerism of which is conditioned by the mode of attach-ment of the particular atomic complex. Thus the chemical ,differencesbetween the two forms of ethyl rhodanide, C,H,(CNS), are satis-factorily explained by the constitutional formuls Et*S*CiN andEt.N:C:S respectively, .Our knowledge regarding the combinations of distinctly electro-negative organic radicles with such electronegative atomic complexesis confined in effect to the series of compounds derived from carboxylicacids. Here no case of isomerism has yet been observed, the samebeing true with respect to the combinations of hydrogen and of themetals with the atomic complexes just mentioned ;* for instance, noisomeride is known of hydrocyanic acid or of potassium thiocyanate.Ammonium thiocyanate, i t is true, has the same molecular compositionas thiourea, NH:C(SH)*NH,, but the production of the strictisomeride, namely, ammonium isothiocyanate, NH,*N:C:S, still remainsto be accomplished.Rhodanides of the carboxylic acids may be prepared by the actionof a suitable metallic thiocyanate on the corresponding acylogen, forinstance :(Rliquel, Arm.chi~n. phys., 1877, [v], 11, 295). Of such compounds,thirty or so have now been prepared.Since by direct union with an alcohol these rhodanides yield thecorresponding .acyl-substituted thiocarbamates, aud with primary orIthodanides of Inorynnic Radicles.Part I,ZCH,*COCl+ Pb(SCN), = PbCI, t SCH,*CO(CNSPROPERTIES OF THE RHODANIDES OF INORGANIC KADTCLES. 2149secondary nitrogen bases the corresponding thiocarbamides orthioureas, they must presumably be classed as thiocarbimides, R*NCS.Not infrequently, however, the two forms of change, namely,thiocnrbimidic union and thiocyanic decomposition :andoccur concurrently, the relative extents being determined by variousexternal conditions (Doran, Trans., 1905, 87, 331; Dixon andHawthorne, ibid., 1906, 89, 468), from which it might be imaginedthat the rhodanide constitutes an equilibrium mixture of thiocyanateand thiocarbimide in ratios determined by these conditions.This, however, is not the case,for the molecular refraction of acetylrhodanide is sensibly constant between 13" and 7 5 O , and the refractionvalue of its CNS-group is equal to that determined by experiment forvmious thiocarbimides, whilst differing widely from that found foraliphatic thiocyanates (Hawthorne, Trans., 1906, 89, 536).Furthermore, i t has been observed t h a t when a-acetyl-bb-diphenyl-thiocarbamide, CH,-CO*NH*CS-N(C,H,),, is caused to dissociateinto its constituents, namely, diphenylamine and acetylthiocarbimide,CI€,*CO*NCS, the latter is identical with ordinary acetyl " thio-cyanate," this chemical evidence going to confirm the conclusionalready reached by Havthorne on purely physical grounds.Carefulexamination of the properties, both physical and chemical, of severaldifferent acyl rhodanides has served to corroborate the view that,although the>e compounds may be caused to yield thiocyanic acid byhydrolysis, they are nevertheless thiocarbimidic in constitution (Dixonand Taylor, Trans., 1908, 93, 691).Whether an acyl thiocyanate is formed, even temporarily, from astrongly acid chloride and a metallic thiocyanate seems doubtful ;thus Miquel observed (Zoc. cit.) that when benzoyl chloride is added toalcoholic potassium thiocyanate, maintained a t O", the organic pro-duct of the interaction unites with the alcohol to form a substi-tuted thiourethane, and hence, presumably, consists of benzoylthio-carbimide :X*CO(CNS) + Y'NH, = X*CO*N H*CS*NHYX*CO(CNS) + Y-NH, = X*CO*NH, + H*SCN,COPh*NCS -t- Et*OH = COPh*NH*CS*OEt.Why acyl radicles should be so reluctant to enter into thiocyaniccombination it cannot at present be stated with certainty.Disposingcauses, however, may be suggested ; for instance, the similarity inelectrical character of the two constituent groups. Even amongstundoubted thiocarbimides of this class, the union between the acyl andthe rhodanic complex may very readily be sundered ; thus, so wellmarked a tliiocarbiuide as that of benzoyl gave with alkali murethan 88 per cent. of its containsd sulphur in the form of thiocyani2150 DIXON AND TAYLOR: STUDY OF THE CONSTITUTION ANDacid, and, what is still more rernmkable, when treated with alcoholicammonia yielded more than 50 per cent.of its sulphur as nmmoniurnthiocyanate (Dixon and Taylor, Zoc. cit.). Amongst purely hydro-mrhon thiocarbimides, this elimination of the rhodanic group is notknown to occur; in fact, it does not usu?lly happen even withhydrocarbon thiocyanates, which tend to yield mercaptans and thelike.Again, transformation of the *SCN group into *NCS is by no meansuncommon, even when the associated radicle is not definitely electro-negative, as in the case of ally1 thiocyanate. If conjoined with adistinctly acid radicle, and hence but loosely held, the rhodanic groupcould still more readily alter its mode of attachment, and would pre-sumably do so in whatever manner leads to the most stable kind ofunion between the t w o constituent groups.As to electrical character,it is not very easy to compare the two configurations of the rhodaniccomplex. But seeing that the thiocyanates of the alkali metals areneutral saline compounds, the residue *SCN must be strongly electro-negative, and in this respect comparable with the residues of themineral acids. On the other hand, the known combinations of thagroup *NCS do not appear to be saline, nor does it unite with themetals of the alkalis or alkaline earths; on these grounds, a t least,the group *NCS may be considered less electronegative than thegroup-SCN. Consequently, if a strongly acid radicle is conjoined, even forthe moment, with the group *SCN, the latter might pass rapidly intothe more electropositive configuration *NCS.On similar principles,the rhodanic group if transferred t o a distinctly electropositiveradicle, such as K, Na, etc., may be compelled to assume the form,*SCN. This would seem to be the case, for wheu acetylthiocarbimideis treated with sodium ethoxide in presence of benzene, the actiontakes place as follows :Ac*NCS + Na*OEt = Na*SCN + Ac*OEt(DjxoD, Trans., 1904, 85, 353). The rhodanic group of acetglthio-carbimide, which is desulphurisable by alkaline salts of lead or silver,is transferred, not to the ethyl, but to the sodium, and when thereattached, has lost the property of becoming desulphurised; had i tpassed (as *NCS) to the ethyl group, the new rhodauide would havebeen desulphurisable ; presumably, therefore, the cdnfiguration of thegrdup is changed.Sirice alkalis and alkaline nitrogenous bases tend to hydrolyse theacyl thiocarbimides with production of thiocyanic acid, whilst non-alkaline bases, such as the primary arylamines, have much less effectin this way, it might be anticipated that still more feeble basesPROPERTIES OF THE RHODANIDES OF INORGANIC KADICLES.2151such, for instance, as diphenylamine-would show even less power tocause hydrolysis, and, concurrently, more to enter into thiocarbamidicunion. Adequate material on which to judge is still wanting, but sofar as may be learned from the behaviour of acetylthiocarbimide, thisappears to be the case (compare Doran, Trans,, 1905, 87, 341 ; Dixonand Hawthorne, Zoc.cit. ; Dixon and Taylor, Zoc. cit.). It seems,therefore, riot improbable that what conditions the ‘‘ thiocyanic ”decomposition of acyl thiocarbimides is not any reluctance on the partof the *NCS groups to enter into ordinary thiocJrbimidic reactions,but rather the tendency of the electropositive material offered forcombination to seize instead directly on the electronegative group ofthe thiocarbimide, and so to liberate its rhodanic radicle.If it be true that strong electronegative character in an organicradicle may entail the attachment of the rhodanic group solely as *NCS,it is reasonable to anticipate the existence of a similar mode of unionamongst the rhodanides (at present known as ‘‘ thiocyanates ”) of well-marked non-metallic radicles.Hitherto but few non-metallic rhodanides have been prepared, theonly certainly known examples being the thiocyanates of phosphorus,silicon, and arsenic (Miquel, Zoc.cit.), together with phosphoryl‘‘ thiocyanate ” (Dixon, Trans., 1901, 79, 541). The silicon derivativehas been re-examined carefully by Emerson Reynolds, who concludes(Trans., 1906, 89, 204) that it is really a thiocyanate; on the otherhand, the phosphorus and phosphorpl compounds have been studiedto some extent from the chemical point OF view by one of thepresent writers (Dixon, Zoc. cit.), with somewhat different results.The latter study has now been resumed, in the hope of learning byphysical methods something further as to the constitution of thesetwo rhodanides.To this end, the molecular refractions have beenmeasured, but, since the inferences drawn rest on the interpretation ofthe numerical results, it seems desirable to indicate by reference toother cases how the experimental figures have been applied towardsthe solution of tho problem.Using the molecular refraction M, obtained from the formula :where p = molecular weight, pu = index of refraction for the spectralline, D, and d- = density at t” referred to water a t 4O, Hawthornefound (Zoc. cit.) for methyl and ethyl thiocyanates at the ordiuarytemperature the figures 32.1 and 40.3 respectively. These, less 9.0 andto4 OVOL. XCIII 7 2152 DlXON AND TAYLOR : STUDY OF THE CONSTlTUTlON AND16.7-the refraction values for CH, and C,H,*-gave as the effect ofSCN, 23.1 and 23-5, or a mean of 23*3 units.Ethylthiocarbimide and allylthiocarbimide gave at 15O, after deductionof the calculated values for the hydrocarbon radicles, 28.0 and 27.63for *NCS, and benzylthiocarbimide, after deduction of the mean valueobserved for C7H7 (obtained from chlorotolume and from benzylchloride), gave 27.84, or a mean refraction effeot for *NCS of 27.82.When this method was applied to acetyl rhodanide (AX, at Z O O = 46*1),the value 17.8 for acetyl being deducted, the differeuce, 28.3, lay SOnear to the above figure for *NCS that he decided in favour of theconstitution represented by the formula CH,*CO*NCS.The mean of all these values for 9NCS is 27.92, which differs byroughly one-third of a unit from the highest and lowest obtained.Cyclic thiocarbimides, for some reason not yet understood, giveresults far in excess of the calculated numbers.It is posible, never-theless, by determining the effect of t,he cyclic group in conjunctionwith CNS in a known compound, and by allowing for the former, toascertain the refraction value of the rhodanic group when conjoinedwith similar benzenoid radicles. Thus, if from the mean number forphenylthiocarbimide, namely, about 77.6 (Nasini and Scala, Gaxzetta,1886, 16, 70 ; Berliner, Dim, Breslau, I S86), there be deducted whatthe present writers consider the most probable value for *NCS, namely,28.1, the difference, 49.5, represents approximately the .refractionvalue of the phenyl group in such combinations.For example, it wasfound (Dixon and Taylor, Trans., 1908, 93, 692) that for o-tolylthio-carbimide, M, = 85.8 ; this, less 49.5 (Ph) and 7.7 (CH,), gives 28.6, anumber not far from 28.1, the above “most probable value” forNCS.Benzoyl rhodanide gave (Zoc c i t . ) MDx85.7, which, less 49.5 and8-5 (C,H, and CO), leaves 27.7; from this it was concluded that thesubstance is a thiocarbimide. I n like manner, carboxymethyl andcarboxyethyl rhodanides, CO,Me*(CNS) and CO,Et*(CNS), when com-pared with acetylthiocarbimide on the lines indicated, gave for the.NCS group the figures 38.7 and 27.9 respectively; of the sevenvalues given above for *NCS, the mean is 28.1, a number differingapproximately by one-half unit from the highest and the lowest.Considering the diaculty of obtaining and of preserving these substancesin a pure condition, that in calculating the molecular refractionthe specific refraction (pD - l / d ) , and hence the experimental error inits determination, may have to be multiplied by very large numbers(over 160 in the case of benzoylthiocarbimide), and lastly, that theend results are but differences depending ultimately on the precision* The atomic refractions used were :H=1.306: C’=5*092; C:C==l2*25; 0”=3’426; C1-9.864PROPERTIES OF THE RHODANIDES OF INORGANIC RADTCLES.21 53with which the other factors are measured and on a constant valuebeing obtained by these different combinations, the concordance of thevarious refraction values for the thiocarbimidic group seems reasonablyclose.Whilst, then, the results are obviously no more than mere approxi-mations to the exact figures (if, indeed, there be definitevalues a t all),they serve, nevertheless, to show that the group *NCS exerts on light :Itolerably constant effect, which is measurably different from that pro-duced by the isomeric configuration *SCN.To ascertain whether therefraction number, about 23.3, already obtained for the latter holds inthe case of other than purely aliphatic hydrocarbon ritdicles, we havenow examined benzyl thiocyanate, the molecular refraction in alcoholicsolution being calculated from the formula :(p- l ) - ( P ' = q r (p"- 1) - (loo-?.), 100 -- ___ + d cl' d"where p, p', and p"=indicee of mixture, substance, and solventrespectively for the D line, and d, d', and d" = densities corresponding,r being the weight of substance in 100 parts by wight of the mixture.The mean of two determinations in solutions containing respectivelyabout 11 and 13 per cent.of thiocyanate mas 75.7. This, less 52.3for the benzyl radicle (see above), leaves for the *SCN, 23.4, a figureagreeing closely with the mean value obtained in other cases, namely,23-3.On the basis, therefore, that a refraction number for the rhodanicgroup of about 23.3 units on the above scale implies the configurationOWN, and that of about 28.1 units the configuration *NCS, we haveexamined the supposed thiocyanates, P(SCN), and PO(SCN),.The preparation of this compound having already been described(Dixon, Zoc.cit.), details of the procedure are unnecessary. Instead,however, of ammonium thiocyanate, the hygroscopic charmter ofwhich entails some difficulties, the corresponding lead salt wasemployed. It may be noted, also, that the bumping and frothingduring distillation, which are always more or less troublesome, areconsiderably lessened if the phosphorus trichloride is freshly distilledbefore use.The boiling points previously recorded were confirmed, a specimentwice rectified distilling at 164-165' under a pressure of 16 mm. ;the density, given before as 1.487 at 15'/4O (different specimens whenwashed with water and redistilled gave also 1.483 and 1*488), was nowfound a t 1 6 O / 4 " to be 1.483.The refractive index of the oil approaching very nearly to the limit7 u 2154 DIXON AND TAYLOR : STUDY OF THE CONSTITUTION ANDof the highest prism in the Pulfrich relrftctometer employed, its valuewas determined by the method of mixture specified above.I n this way,pD mas found to be 1.71'739 at 15'; whence MD=99*17.The refractive index of phosphorus trichloride, as determined byOladstone and Dale (Phil. Trans., 1863, 153, 34l), when combinedwith the careful determinntims of its density by T h o r p (Trans., 1880,37, 334), gives for BID at 28.5' and a t 38", 44.96 and 44.97 respect-ively. This me checked, finding for p,, a t 150' the figure 1.5152;whence RID = 44.7. A determination by Nasini and Costa (Pub. dell.1st. chint. 12omcc, 111, 1891) gives by interpolation for the D-line thevalue 45.2 ; the mean of these three is 44.95.The refraction of thethree chlorine atoms being in round numbers 3 x 9.9, or 29.7, thedifference for the phosphorus is 15.25.Deducting now from the molecular refraction of phosphorus tri-rhodanide the above value for phosphorus, we have for the joint totaleffect of the three rhodanic groups 99.17 - 15.25 = 83.92, or, assumiugtliein all to be equal, about 28 units for each.So far, therefore, as, this purely physical method of examination maybe relied upon as :iffording evidence of chemicrl structure, the con-clusion seems justitied that phosphorus trirhodanide is not a thio-cyanate (MD for which would be about 85.1 units, instead of the 99.2found), but a thiocccrbimide.Chemical evidence to the same effect, as might be anticipated, ismore difficult to secure.For, as it has been mentioned already, therhodnnides of negative organic radicles invariably may be hydrolysedwith formation of thiocyclnic acid; and it is doubtless by reason ofthe ease with which in many cases this change takes place that suchparticular compounds as show the reaction have generally beenaccepted as thiocyanates. But, since the mere production of thio-cyanic acid by hydrolysis is plainly insufficient to characterise a givenorganic acid rhodanide as a thiocyanate, the formation of this sub-stance in the case of an electronegzttive inorganic rhodanide canequally afford no clue as to the constitution of tho material whichyields it.Indeed, considering the high affinity of phosphorus foroxygen, and its relatively slight tendency to form amino-compounds,one could scarcely anticipate the occiirrance of the thiocarbimidic "hydrolysis :P(NCS), + 3H20 = 3COS + P(NH,),.Only by cautious treatment, thereFore, avoiding the presence ofwater or strong bases, might one reasonably expect to make manifestthe thiocarbimidic power of a compound the molecule of which isobviously prone to total disruption (Miquel, Zoc. cit.). To present inthe absence of water a feeble base seemed most hopeful, since thehydrolytic effect (or the tendency of the basic residue to withdraPROPERTIES OF THE RHODANIDES OF INORGANIC RADICLES. 21.55the phosphorus) would be minimised, thereby giving to the sup-posed *NCS groups a chance to enter into their characteristicthiocarbnmidic combinations.To secure these conditions, aniline and the still more feeble diphenyl-amine were employed ; so far successfully, that definitive, additivethiocarbamidic combination has been accomplished, although not to thefrill extent betokened by the presence of three *NCS groups. Butthat additive change may to some extent be realised is shown bythe following experiments.Phoephol*us Trithiocavbimids and Aniline.-To 4-93 grams of freshly-distilled oil, dissolved in cold benzene, 2-22 grams of pure aniline, alsoin benzene, were added (instead of 2.24, the calculated weight foreqnal molecules).The precipitated granular solid was filtered off, andto the filtrate were added two or three drops more of aniline, thiscausing a slight further precipitate ; on concentrating somewhat andfiltering again, the filtrate when treated with aniline now remainedclear.The precipitates, after drying, weighed in all 7.15 grams ;the amount calculated for an equimolecular compound being 7,176grams, khat obtained represents 99.6 per cent. of the theoretical.I n the main product, a cream-white powder, ready-formed anilinethiocyanate was absent, for when the solid was shaken up with waterthe aqueous portion gave with ferric chloride a barely perceptiblecolour change, and no detectable reaction for aniline. On standingwith cold water, hydrolysis occurred slowly, the reaction with hydro-chloric acid and ferric chloride becoming gradually more mnrked, and,after some four or five days, intense. On boiling, the thiocyanicreaction was obtained a t once, a perceptible trace of hydrogensulphide being evolved ; aniline was now detectable, although invery small amount, and phenylthiourea crysttlllised out as the solutioncooled.That the phenylthiourea did not result through ordinary isomericchange of aniline thiocyanate, conceivably formed in the hydrolysis,was established by the following observations, Aniline thiocyanate,when heated to boiling in dilute aqueous solution together with nlittle alcohol, yielded in one minute no perceptible amount of phenyl-thiourea, as tested by the action of boiling alkaline lead or silversalts on the solution ; after three or four minutes’ boiling, a very slightdesulphurisation began to show, which increased steadily as the timeof boiling of the aqueous solution was prolonged; in the cold, noreaction was noticeable after many hours’ standing.On the otherhand, the solution of the phosphorus compound in alcohol gave withsilver nitrate a white precipitate, which was blackened gradually onstanding in the cold, or instantly on warming. The compound gavealso with cold dilute alkali an opalescent solution ; a portion of this2156 DIXON AND TAYLOR: STIJDY OF THE CONSTITUTION ANDwhen m3clified, gave with ferric chloride an intonso red coloration ;another portion, when treated with ail alkaline lead salt, gave aprimrose-yellow precipitate, which became black, gradually in the cold,or immediately on gentle warming.Phenylthiourea, dissolved inalkali hydroxide, behaved so far as the desillphurisation with leadsolution is concerned in precisely the same way, save that the darkeningwas somewhat slower in the cold,It has already been shown (Trans., 1904, 86, 359) that of the totalsulphur contained in this compound, about 4 per cent. escapes onrapid hydrolysis as hydrogen sulphide, and that of the remainder,about one-third crystallises out as phenylthioures (in practice, nine-tenths of this fraction was collected), whilst, about two-thirds appearas thiocyanic acid. Apart, therefore, from the slight change firstmentioned, the main decomposition may be represented thus :NHPh*CS*NH*P<NCS NCS + 3R,O =NHPh*CS*NH, + 3H*SCN + H,PO,.Very remarkable is this sharp union in the cold of a singlemolecule of aniline with but one of the three *NCS groups in the tri-thiocarbimide.Possibly, but not very probably, it may be duo tosteric hindrance that the remaining groups fail to combine; in thiscase, however, one would rather have anticipated the ready union oftwo *NCS groups with aniline, the difficulty arising in connexion withthe third. Cases, however, are not uncommon in which, if severallike atoms or atomic complexes are charged upon a single other atom,the atoms or complexes so conjoined show inequality of power tointeract. Thus, for example, of the two chlorine atoms in carbonyldichloride, but one rertcts very readily with alcohol, the resultantethyl chlorocarbon~ite uniting only slowly with excess of alcohol.Carbonyldithiocarhimide, CO( NCS),, too, when mixed with alcohol,takes up but one molecule to form SCN*CO*NH*CS*OEt (Dixon,Trans., 1903, 83, 87).With bases, it combines readily in equi-molecular proportions; two molecules of base are not taken UP inany rase so readily as one, and in certain instances (namely, withnaphthylamine and with benzylaniline), even although excess of baseis used, a single molecule alone enters into combination. Similarinstances might be multiplied, but it would serve no other purposethan to show that our knowledge of the chemical power of a radicle,singly held, cannot always be extended by mere arithmetic to caseswhere there are two or more, especially if these be attached to oneparticular atomPROPERI'IES OF THE RHODANTDES OF' INORGANIC RADICCES.2157Phosphor$ Tvirhodcmide, PO( CNS),.I n preparing this substance, potassium and lead thiocyanates weretried, and, as solvents in each case, benzene or cuniene, the best yieldbeing obtained from the lead salt with cumene. Previous distillationof the phosphoryl chloride was found very advnntngeous in reducingthe tendency of the solution to bump and froth during the fractiona-tion ; commercial cumene, which contains naphthalene, is ansuitable,for the latter, unless removed, is left ultimately mixed with therhodanide, and causes difficulty.The solvent was distilledoff under diminished pressure by the aid ofa water-bath; the residual oil was then collected separately and recti-fied.Its properties agreed with those already described (Zoc. cit.), theboiling points observed in various preparations being 159"/11 mm.,160°/12 mm., and 164'/14 mm., the previous figure being 171i0/31 mm.lts density, the mean of three closely concordant determinationsfrom different specimens, was 1.518 at 15"/4O. The reErnctive index atabout 1 5 ' ~ ~ s found to be, as the mean of three concordant determina-tions for material once rectified in each case, pD = 1.6882, and fromthree preparations, each doubly rectified, pD = 1.69 18. From thePefigures, MD = 100-02 and 100.48 respectively ; the latter valne is usedbelow.Since the phosphoryl group, as shown by Gladstone (Trans., 1870,23, 112), has an abnormally low refraction effect, at least in meta- andortho-phosphoric acids, i t was necessary to ascertain directly what thevalue is in phosphoryl chloride, POC1,.From Gladstone and Dales'determination (Zoc. cit.), namely, pD =1*4882 a t 17O, and Thorpe'scareful measurement of its density (Zoc. cit.), namely, 1.6805 at17'/4O, &fD for Pocl, = 44.6. This, less c1, (3 x 9.9, or 29'7), leavesfor the group i P 0 the value 14.9, something less than that of thephosphorus which it contains.Consequently, the total effect of the rhodanic groups in phosphorylrhodanide is about 100.5 - 14.9, or 85.6, one-third of which (assumingthem to be alike), or 28.5, gives the value of each; this figure isobviously much nearer to that representing *NCS (28.1) than the23.3 which measures the effect of *SCN.If phosphoryl rhodanidecontained three of the latter groups at the value named, MD would be84.8, instead of about 100.5.Judging from the above results, the conclusion appears to be justi-fied that phosphoryl rhodanide, like the corresponding phosphoruscompound, is not Q thiocyanate, but a thiocarbimide,/NCS0:P-NCS .\NC2158 DTXON AND TAYLOR : STUDY OF THE CONSTITUTION ANDNotwithstanding that phosphoryl trithiocarbimide is hydrolysedwith ease into phosphoric and thiocyanic acids, there is no difficultyin obtaining also from it the reactions characteristic of a thiocarb-imide. For example, the cold alcoholic solution, when treated withalkaline lead tartrate, gave a turbid mixture, which very quicklybecame black, owing to desulphurisation.Silver nitrate, followed byammonia in the cold, gave a like result, and mercuric or cadmiumsalts in presence of alkali yielded a t once, on gentle warming, thecorresponding black or yellow sulphide. To ascertain to what extentthe thiocyanic hydrolysis is accomplished in presence of alkali andwater, a weighed quantity of the oil (about l a grams) was dimolvedin hot water containing 5 equivalents of N-sodium hydroxide; thefaintly alkaline solution was neutralised exactly by very dilute nitricacid, made up to a known volume, and boiled t o expel a trace ofhydrogen sulphide ; the contained thiocyanic acid was then deter-mined by Barnes and Liddles' method, using N/lO-copper aulphate.Of the total sulphur present in the oil, 90.75 per cent.was found asHoSCN, a figure close to that obtained for benzoylthiocarbimide andfor carboxyethylthiocarbimide, namely, about 89 and 93 per cent.respectively (Dixon and Taylor, Zoc. cit. ).Phosphoryl Trithiocarbimide and Anihe.--To a benzene solution ofthe freshly-distilled oil, one molecular proportion of aniline wasslowly added, the latter also being dissolved in benzene ; the weight ofthe yellow, granular precipitate which formed at once, together withthat of another small quantity which separated from the mother liquoron standing, amounted to precisely the sum of the weightsof materialsemployed. The melting point, 121.5', with previous softening a t120-121', was practically identical with that observed before (Dixon,Zoc.cit,), and a sulphur determination, made as a check, fell a fractionof a per cent. below the figure calculated for an equimolecular com-pound. Cold water, shaken up with the solid, extracted from itscarcely a trace of thiocyanic acid, and no detectable amount ofaniline ; on standing, however, hydrolysis began to occur, the processrunning a course exactly similar to that with the correspondingphosphorus derivative. The action is very slow at the ordinarytemperature ; thus, in an experiment where a quantity of the additivecompound was mixed with about twenty times its weight of water,the mixture being shaken up frequently during a fortnight, thio-cyanic acid and phosphoric acid passed into the solution in slowlyincreasing amount; but on washing the residual solid until thefiltrate ceased to react for thioopanic acid when tested with ferricchloride, and again leaving the solid residue in contact with water,these two acids continued as before to accumulate in the solution.Witb dilute alkali, or with hot water, the hydrolysis takes placPKOPERI'IES OF THE RHODANlDES OF INORGANIC RADICLES.2159rapidly. Thus, when a weighed quantity of the solid was digested onthe water-bath €or twenty minutes with a slight excess over fourequivalents of N/lO-alkali, together with some water, and the solutionjust acidified and diluted to a known bulk, the latter mixture, by com-parison with a standard solution of thiocyanate and ferric chloride,Wits found to contain sixteen-seventeenths of the thiocyanic acid,which could result from the changeNHPh*CS*NH*PO(NCS), + 3H,O =NHPh*CS*NH, + 2H*SCN + H,PO,.The colorimetric method, according to our experience, working at ttconcentration of N/lOOO, gives results which are accurate to withinabout 5 per cent.of the total amount evaluated. Barnes andLiddles' process proved unavailable, the phenylthiourea formed in thehydrolysis combining with the copper solution to produce some doublecompound, the nature of which we did not investigate beyond verifyingthat it is also precipitated when copper sulphate is added to phenyl-thiourea in presence of alkali bisulphite ; it is not formed from thesetwo in the absence of the bisulphite.These results are so far confirmatory of those previously obtained(Zoc. cit) as to establish with reasonable certainty the propositions :(i) that phosphorgl trirhod%oide in the cold enters at once intodefinite chemical combination with a single moleciile of aniline, oneonly of its three rhodanic groups thereby becoming engaged with thebase added ; (ii) that, apart from a trifling side-reaction leading tothe production of hydrogen sulphide, the additive compound is hydro-lysed very readily into phosphoric acid, two molecules of thiocyanicacid, and one molecule of phenylthiourea; (iii) that the originaladditive compound does not contain aniline thiocyanate, neither doesthe phenylthiourea produced by the hydrolysis result from thetransformation of aniline thiocyanate, conceivably formed during theact of hydrolysis.What occurs, then, in the combination of aniline in the circum-stances named is this : of the three rhodanic groups attached to thephosphoryl residue, one alone absorbs the base, entering with it intodefinite thiocarbamidic combination ; the other two remain intact.On hydrolysis, the phonylthiocarbamido-complex is removed asphenylthiocarbamide (or phenylthiourea) ; the hydrolysis is completedby the elimination of the two remaining rhodanic groups, duringwhich, as with other acylthiocarbimides, a small fraotion of thesulphur escapes by thiocarbimidic hydrolysis as carbonyl sulphide,the main part of it decomposing aa (CNS) and yielding thiocyanicacid.The next point to be decided was whether more than one molecul2160 DIXON AND TAYLOR: STUDY OF THE CONSTITUTION ANDof aniline can be united with a molecule of the trirhodanide. Since asingle molecular proportion of aniline precipitates and removes com-pletely from benzene solution the whole of the dissolved rhodaaide,the experiment was now reversed, one molecular proportion of thephosphorus compound being added, drop by drop, in cold benzene totwo molecular proportions of aniline, similarly dissolved, and kept cool.AS before, a precipitate formod ; when washed with benzene and driedin the steam-bath, its weight amounted to 99.8 per cent.of tho totalweight of material employed for combination. The benzene motherliquor contained a mere trace of thiocyamic acid, but no detectableamount of aniline.The product, faint yellowish-white in colour, shrank :it 113' andmelted between 114.5 and 115.5'.0.407, fused with NaOH + KNO,, gave 0.600 BnSO,.The compound therefore is PO(NCS), + 2C,H,*NH2.As in the case of the preceding componnd, aniline thiocyannte wasnot present ready formed, for the solid when shaken up with waterwas practically insoluble, the aqueous portion giving mi t h hydrochloricacid and ferric chloride a barely perceptible red coloration, but, onboiling, the reaction was given abundantly.Strange to say, the second molecule of aniline is not held i n thesame thiocnrbstuiclic combination as the first, or iC it is, the decombina-tion occurs differently.For when the compound was hydrolysed as inthe preceding case, and the liberated thiocyanic acid measured colori-metrically (Earnes and Liddles' method proving inapplicable), th6nmoiint of tohis acid formed, as nearly its can be judged by this process,mas that corresponding with two-thirds of the totvl sulphur present.The hydrolysed mixture gave the reaction for aniline.How to explain this curious behaviour, save conjecturally, we donot yet know, but on the groiind that aniline thiocyanate is notpresent as such in the product (which, moreover, was at no stage ofits formation pasty, as is generally observed if this substance isformed), the hydrolysis may provisionally be represented as follows :(NHPh*CS*NHj,PO*NCS + 3H,O =On analysis :S = 23.2.C,,H,,ON,SP requires S = 23.58 per cent.NHPh*CS*NH, + NH,Ph + 2H*SCN + HsPO,.When one molecular p%oportion of the rhodanide was added tothree molecular proportions of aniline in the cold, a solid ~ 8 -p r a t e d , but part of the base did not enter into combination, for thebenzene liquor reacted freely for aniline.On warming the mixtureon the water-bath to about 65O, the solid melted to a clear oil, andthe benzene now no longer gave the reaction for aniline. Apparently,therefore, three molecules of the base had been absorbed, but oPROPERTIES OF THE RHODANIDES OF INORGANIC I:ADTCT,F,S. 2161poiwing off the mot8her liquor, nnd allowing the oily residue to stnnd, i tslowly changed into a yellow, pitchy resin, so unlike a definite chemicalcompound that no attempt was made to analyse it. With cold waterthe powdered resin behaved somewhat like the preceding compounds,save that the mixture when acidified and treated with ferric chloridegave a distinct, although not strong, red coloration.Phosphor$ Trithiocavbirnide and Diplmiylarnine. -From 10.574grams of thiocarbimide and 7.1 4 of diphenylamine (equal molecules),both in benzene, there separated 17.5 grams of a faintly yellow productcousistiug of microscopic needles.When heated in a narrow tube,these shrank slightly at 138", and melted between 140" and 141"(rincorr.). A srilphur determination showed the substance to be anequimolecular compound :0,377, fused with NnOH + KNO,, yielded 0.662 BaSO,. S = 24.2.C,7H,,0N,S,P requires S = 24.6 per cent.Cold water had little effect on this diphenyl compound, the mixtureat the end of four days, during mbich it was frequently shaken up,giving with ferric chloride no more than a faint red coloration; onboiling, a well-marked reaction was obtained.Under the action of dilute alkali hydroxide, hydrolysis occurredreadily; thus, when 5-85 grams of the solid were suspended in hotwater, and N-sodium hydroxide added, drop by drop, until the solutionbecame just alkaline to litmus, 48 C.C.were required. Since, for the aboveqriantity of substance, each 15 C.C. of normal solution represents oneequivalent, a little more than three equivalents had been absorbed.When cold, the mixture was separated by filtration from the white solid,which now no longer yielded thiocyanic acid when boiled with potassiumhydroxide, and was free from phosphorus ; it was recrystallised fromalcohol, and identified as nu-diphenylthiocarbamide.Its weight, apartfrom what remained in the aqueous portion (for the substance is notquite insoluble in water), amounted to 3-08 grams, that is, nine-tenthsof what could be formed according to the equation :NPh,*CS*NH*P(NCS), + 3H20 = NPh2*CS*NH2 + BH*SCN + H,PO,.All the phosphorus had passed into the aqueous filtrate, whichreacted intensely for thiocyanic acid, and gave the usual reactions forphosphoric acid ; it contained, in addition, a trace of dissolvedthiocarbamide.Phosphoryl trithiocarbimide, when added t o two molecular pro-portions of diphenylamine dissolved in cold benzene, yielded the aboveunimolecular additive compound in a somewhat impure condition ; themother liquor, when concentrated by evaporation, afforded a furthersmall crop of a mixture melting between 150° and 165O, and, whe2162 HHODANlDES OF INORGANIC RADICLES.allowed to evaporate to dryness, left n residue containing muchunchanged diphenylamine.Prom these results it would appear that diphenylamine, in the cir-cumstances given, is less disposed than aniline to form with phosphoryltrithiocarbimide a compound containing two molecules of the base.In this connexion, i t msy be recalled that, whilst the dithiocarbimideof carbonic acid, CO(NCS),, can unite with either one or two moleculesof aniline or of toluidine, i t combines with but a single molecule ofnaphthylamine or of benzylaniline, even although the latter bases bepresent in excess (see p.3156).Earlier. in this paper i t has been suggested that the mode of unionof a rhodanic group may depend on the character of the radicle towhich i t is attached. Since hydrogen, like the hydrocarbon residues,represents a kind of electrical mean between strongly electropositiveradicles, such as K, Na, etc., and strongly electronegative, such asCH,CO*, O:P<, and the like, i t also might be expected to yield thetwo rhodanides, H-SCN and H*NCS.It seems probable, however, that the great mobility of hydiogen,coupled with its generally electropositive character, may suffice topreclude its permanent association with the rhodanic complex, save inthe one form H*SCN, and similarly with other radicles, such as CNO,CN, NO,, etc., which with hydrocarbon residues can give isomericcombinations, whereas with hydrogen they yield in each case but a,single form.However this may be, the fact remains that when athiocarbimide is hydrolysed, the products may contain carbonylsulphide or thiocyanic acid, but not hydrogen thiocarbimide, €1-NCS.It being tolerably clear, in a general WRY, that the less electro-positive the base presented for interaction to an acidic thiocarbimidethe less is the resulting thiocyanic decomposition (and concurrently,the greater is the percentage of thiocarbamidic union), the ideaoccurred of trying whether chemical action could be brought aboutwith distinctly electronegative “ bases.” For, although the amidesdo not combine directly with thiocarbimides containing hydrocarbonradicles, yet diphenylamine, which is little disposed to unite withthese, does so vigorously with many acylthiocarbimides, and hence itseemed worth while to experiment on the lines indicated.The combinations attempted were : (i) benzoylthiocarbimide inbenzene or acetone with oxrzmide, benzamide, acetanilide, andurethane, all in the cold ; (ii) carboxymethylthiocarbimide withbenzamide and with urethane, also in the cold; (iii) acetylthio-carbimide with urethane in boiling toluene.I n no case could anysign of combination be detected.It is plain, therefore, that a certain amount of ‘‘basicity” isrequisite for the combination of ‘‘ base ” and thiocsrbimide ; moreFITZGERALD AND LAPWORTH : ESTER CATALYSIS. 2163over, acetylthiocarbimide can furnish with aniline the compoundab-acetylpheuylthiocarlnmide, whilst phenylthiocarbimide, i t appears,cannot unite with acetamide t o yield the same compound. Yet thehydrogen of the NH,-group in acetamide is not especially diilicult ofremoval, for it may be replaced directly either by bromine or bysodium. Ethylthiocarbimide, too, fails to combine with sodiumacetanilide (Dixon, Trans., 1899, 75, 384), and phenylthiocarbimidewith asparagine (ibid., 410) ; neither does acetyl chloride react withphenylthiocarbamide dissolved in aqueous sodium hydroxide (Dixonatid Hawthorne, Zoc. cit.), a liquid supposed to contain the sodium deriv-ative of phenylthiourea. In the present state of our knowledge, toexplaiu these facts is more than difficult.Although the only organic acyl rhodanides so far isolated are thosederived from carboxylic acids, there is some reason to hope thatcertain non-carboxylic acids may rtfford similar products. For whenthe chlorides of phenylsulphonic and ethylsulphuric acids respectivelywere heated in presence of hydrocarbon solvents with lead thiocyanate,the liquor in each case was desulphurised by lead and silver salts, andhence may have contained dissolved thiocarbimide (Dixon, Trans.,1897, 71, 640) Owing to the difficulty of securing complete inter-action without decomposing the organic product, these experimentswere abandoned until better methods should become available ; i t isnow intended to resume thc study, in the hope that more satisfactoryconditions may be realised. It is proposed, also, t o examine themolecuiar refraction of rhodanides containing inorganic radicles otherthan those of phosphorus and phosphoryl, with the view of learningwhether, in such cases, the above physical method will serve as ameans of distinguishing statically between the thiocyanic and thethiocarbimidic form of linking.CIIEMICAL DEPARTMENT,QUEEN’S COLLEGE,COBK

ISSN:0368-1645    

DOI:10.1039/CT9089302148

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

FITZGERALD AND LAPWORTH : ESTER CATALYSIS. 2163CCXVL-.Ester Catalysis and a Mod@cation of theTheory of Acids.By EDWARD FITZGERALD and ARTHUR LAPWORTH.THE main facts relating to the phenomena of catalysis by acids arewell known. They have been studied in the main with reference toesterification and ester aud sucrose hydrolyses. Thelinfluence of acidsas catalysts is known to be exerted in many other types of reaction, as2164 FITZGERALD AND LAPWORTH: ESTER CATALYSIS AND Afor example, in the bromination of carbonyl compounds, the decom-position of diazoizcetic ester (Bredig and Fraenkel, Ber., 1906, 39, 1756),and the transformation of hydrazobenzene into benzidine. Thenumerous theories which have been devised to explain the catalyticinfluence of acids on esterificution and ester hydrolysis have recentlybeen dealt with in a fairly complete manner by Acree (Amer.Chern.J., 1908, 39, 145), and therefore it is riot necessary fully toreview the question here from the historical standpoint. It is sufE-cient to say that Kastle appears to have beeu the first (Amer. Cherri. J.,1897, 19, 894) to have suggested the view now most generally held,namely, that the ions of the acid acting catalytically react with thesubstance undergoing change, forming an unstable addition productwhich subsequently yields the final products ; it is evident, however,that the same natural idea has occurred independently to otherchemists. The view now most generally held in reference to estercatalysis, is that the carbonyl compound forms a complex with thehydrogen ions.On the other hand, Goldschmidt and Udby (Zeitsch.physikal. Chem., 1907, 60, 728) claim to have establi>.hed that itis the alcohol which mainly forms the reacting initial additioiicompound or complex hydrion, but this claim cannot be accepted.The facts on which a receut discussion of the mechanism ofesterification and ester hydrolysis have been based (Acree andJohnson, Amer. Chem. J., 1907, 38, 301) are: that the velocityof catalysed esterification and, ester hydrolysis are usually nearlyproportional to the concentration of catalyst, where the latter isa powerful acid, and to the concentration of the carbonyl compound(ester or carboxylic acid); and further, that the activity of thecatalyst is roughly proportional to its so-called degree of disaociationas given by conductivity measurements.A slight lowering of the conductivity of acids was found by theseauthors to be produced by the addition of carboxylic ester.But theirsubsequent discussion of the question is based on the assumption thatthe velocity of esterification and ester hydrolysis is intrinsicallyproportional to the concentration of the alcohol and water respectively.This assumption is one which is made in most text-books on PhysicalChemistry, but was not sufficiently well justified to warrant therejection of any theory of esterification which did not ful6l thiscondition.It must be pointed out that the classical experiments of Berthelotand PQsn de Saint-Gilles do not throw any light on the question.Further the condition at equilibrium in a mixhre of alcohol, carb-oxylic acid, ester, and water is determined by thermodynamic lawsand must be the same whatever the path by which it is attained.The mechanism can only be decided after a study of the conditionMODIFICATlON OF THE THEORY OF ACIDS.2165affecting the initial rate of change in the absence of the products ofchange.A theory put forward by one of us having been assailed on theabove ground, experiments were made showing that, in pointof fact, the initial velocity of hydrolysis of an ester in acetoneis nearly independent of the water concentration over a widerange (Yroc., 1908, 24, 101, 152), but the erroneous conclusion wasdrawn that, on this account, theories demanding a proportionalitybetween the velocity nud water concentration were wrong.Theequivocal character of the results was clear from the fact that, withinthe same range of water concentration in acetone, the initial velocityof catalytic esterification is roughly inversely proportional to theconcentration of the water, but proportional to the concentrationof the alcohol, which is its analogue in the reverse reaction. Thenumbers obtained by Kistiakowsky (Zeitsoh. physikal. Chem., 1898,27,253 et 8ep.) also show that, within similar limits, similar relationsobtain, whilst Goldschmidt (Rer., 1896, 29, 2208 et seq.) was the firstto draw attention to the very great depression produced by smallquantities of water on the velocity of esterification in alcoholicsolution.I n addition to the points above referred to, it was found byPitzgerald and Lapworth (Zoc.cit.) that alcohol produced a veryslight lowering only on the velocity of catalytic hydrolysis in acetone,and that the initial velocity of esterification is roughly proportionalto the alcohol concentration.The solution of the question whether the initial velocity of hydrolysisof esters by acids and water is proportional to, or independent of,the concentration of the water was evidently necessary for the finaldetermination of the question of the mechanism of ester catalysis.During the interval since the publication of the preliminary notes, theauthors have been engaged in experiments on the velocity of eaterifica-tion of acetic acid under varying conditions, but have come to theconclusion that rapid progress towards the solution of the problem isto be made along different lines, and after a due consideration ofthe facts referred to above.Their reasoning has been based on the belief that the alcohol and thewater, so far as they take part in the esterification or ester hydrolysis,play similar parts.Now the velocity of esterification appears to beat the very first moment nearly proportional to the concentration of thealcohol, and therefore it seems impossible to avoid the conclu-sion that this is really also the case with the water, and thatthe general depressant effect of the increased concentration of waterexactly neutralises the acceleration which would otherwise be ob-served.The most obvious view of the respective effects of alcoho2166 FXTZGERALD AND LAPWORTH: ESTER CATALYSIS AND Aand water on ester catalysis is that, in solutions containing both, thetwo substances in question share between them some intermediateproduct, but on careful examination this fails to meet the case.No consistent hypothesis can be advanced until the possibility ofcombination of the catalyst itself with the water is considered.The theory advocated by the school of Arrhenius in thecase of thehydrolysis of, say, aniline hydrochloride by water, is that, as the resultof the dissociation of water in hydrogen and hydroxyl ions, the phenyl-ammonium ions unite ,with hydroxyl ions from the water to formfeebly dissociated phenylammonium hydroxide, and this, in turn,yields aniline and water.Further examination shows that this reallyexplains hydrolysis by assuming the base to be converted into arelatively inactive hydrate. This is easily seen on considering thef 011 owing expressions.Let a small quantity of a weak base in a solvent containing hydrogenchloride and water be considered. The following equations representthe relations usually supposed to obtain, where B=free base, BH,Othe undissociated hydrate (ionisable + non-ionisable), BH thecation, BHCl the undissociated hydrochloride of the base. Theequations are :(a) HCl = H + Cl ;(e) H,O = H + OH ; (f) B + HC1= BHCl ; ( 9 ) BH,O = B + H,O.( c ) BHCl= BH + 61 ; ( d ) BH,O = kH + OH ;To these may be added a seventh, which is not so frequently intro-duced, but which is mathematically consequent on the others, namely,( b ) BH=B+H.Expressing concentrations by bracketing the symbols, the law ofmass action leads to the following expressions, most of which are ingeneral use :Two of these being redundant, K, and K7 may be convenientlyexpressed in terms of tbe others ;hencMODIFICATION OF THE THEORY OF ACIDS.2167The following relations also result :1 K (BH,O) = -( B)( H,O) = - - - L~- (B)( H20),K7 K, K41 1(BHCl) = -(BH)(CI) = KT(B)(H)(CI),K, 2 3which express tho relationships between the concentrations of thecompounds of B with the active masses of the hydrogen ions, thechlorine ions, and the water.Whence it follows that if the hydrogen and chlorine ions remainnearly constant in amount or increase on addition of water," the onlyway in which the salt and its cation can disappear is by conversioninto uudissociated BH,O, as they are otherwise nearly independent ofthe amount of water present,The application of the Arrhenius view, then, to the case of catalysisinvolves the assumption that the water combines with the substanceaffected, thus rendering it inactive, If so, when esterification inalcohol is considered, it must be the carboxylic acid which forms aninactive hydrate, as the alcohol is in enormous excess.This, apartfrom its inherent improbability, is not capable of explaining thedepressions which are observed, and when the influence of water onthe bromination of acetone, referred to in another paper, is considered,the explanation is totally inadequate and must be rejected.The Hydmgen Iow of the Catalyst am Hydrated ?-Inspecting theexpressions above given for the equilibrium of a base in presence ofan acid and water, it is seen that the only other explanation of thereduction in concentration of the salt or its cation is that the hydrogenions disappear, that is, that water acts on them in virtue of its powerof forming oxonium salts.The assumption that such complexes maybe formed is in no way novel, and has been used by many chemists.What is novel in the present conception is that the introduction ofwater into alcohol containing hydrogen chloride mwt necessarily reducethe number of hydyogen ions, or, in other word8, of the amount ofavailable ?hydrochloric acid.Further, as acid catalysis, unless hydrolytic,occurs enormously faster in alcohol than in water, the number OFhydrogen ions in an aqueous solution of hydrogen chloride must beextremely small, even compared with one in alcohol, which itself mustbe regarded as a base.The mechanism of esterification in this view is intrinsically* The increase in conductivity of hydrogen chloride dissolved in alcohol consequenton the replacement of alcohol by water is usually attributed to a greater degree ufdissociaticn of the acids into H and C1 ions.VOL. XClII. 7 2168 FITZQERALD AND LAPWORTH: ESTER CATALYSTS AND Aproportional to (alcohol) x (carboxylic acid) x (hydrion) ; that ofhydrolysis to (water) x (ester) x (hydrion), and the apparent dis-crepancies between this, the usually accepted view, and experiment isdue to alterations i n the hydrion concentration which have not beenforeseen.It is not yet possible to ascertain whether the alcohol andt h e water, on the one hand, or the ester and carboxylic acid, on theother, form the reactive complex ions, as the same results will beobtained in either case. The important work of Stieglitz on thehydrolysis of imino-ester ions and the properties of carbonyl compoundsas a whole render the latter, and usual, view by far the more probableone.This question, however, assumes a secondary importance as comparedwith the broader reflections t o which its study has given rise. Theproposition that free hydrogen ions are responsible for the catalyticactivity of acids leads to the conclusion that they must be relativelyfew in number in aqueous solution.On the other hand, the originalconception of hydrogen ions was applied to explain the conductivity ofacids in aqueous solution, so that the terms are not synonymous.I n the latter case, they must be complex ions, probably of the formH,OH, if the analogy between water and ammonia is complete;the catalytically active hydrogen ions, if they have a real existence, aresimpler than these, probably H.The view that both types exist will perhaps prove useful in thetheoretical treatment of certain questions, but the alternative must beconsidered, for it has long been entertained in one form or another bya school OF chemists, including Armstrong and Lowry..The Velocity of Esteri$cation when no Water is Present.The velocity of esterification having been found to be over a widerange nearly inversely as the amount of water present, it was obviousthat the form of the curve expressing the variation of velocity withthe amount of water was roughly of the form of a rectangular hyper-bola, but that the hyperbola would cut the velocity axis was tolerablycertain, otherwise esterification with no water present would beinstantaneous.This being highly improbable, it, was clear thatthe curve near this point would have the form :when b and a were constants. The constant b was termed by theauthors the water value of the solvent long before its true significancewas understoodMODlFICATlON OF THE THEORY OF ACIDS.2169Z%e Theory of Goldschmidt and Udby.Goldschmidt and Udbg have discussed the question of the retardingeffect of water on the catalytic esterification of carboxylic acids inalcohol (Zeitsch. physikul. Chem., 1907, 60, 728). These authorsaccept, without discussing the view of Arrhenius, the idea thatthe procebs of catalytic esterification depends on the intermediateformation of complex hydrions by one of the substances taking part inthe change. They claim to prove that the alcohol must be the sub-stance which mainly forms the reactive complex ions, but their processof reasoning would indicate that when the initial concentration ofalcohol varied, the velocity would be unaltered, and this is contraryto experience.They adopt the view that the complex water ions, H,O, are thecarriers of catalytic activity of acids in aqueous solution, and theirviews are thus essentially opposed to that advanced in the presentpapers, which is that these are usually, if not always, ineffective ascatalysts.Had these authors but perceived that the hydrogen ions, or theavailable hydrochloric acid, diminish in amount when water isadded to alcoholic hydrogen chloride, they could not have formedthe main conclusion which is put forward in their communication.Nevertheless, they must be credited with the first attempt to explainthe anticatalytic effect of water on esterification in alcohol as theresult of complex ion hydrolysis,EXPERIMENTAL.The experiments described were all carried out at 25 +, 0*02*, usingflasks which had been steamed and then dried by a current of hot air.Except where adefinite statement is made to the contrary, the totalvolume of solution was made up with pure acetone to a total volumeof 25 C.C.The catalyst used throughout was hydrogen chloride, andduring the reactions had the concentration 0.0123 A? It was foundundesirable to prepare the preliminary solutions of the catalyst bypassing hydrogen chloride into acetone, as evidence was obtained thatinteraction occurred under these conditions ; for this reason the solu-tion of the catalyst was prepared by adding aqueous hydrogenchloride of known strength to dry acetone. This necessarily intro-duced a small quantity of water, but it was never found possible towork with less water than this, for the results were then discordant,owing, doubtless, to changes resulting in condensation of the acetone.Separate tests showed that the concentration of the hydrogen chloride7 ~ 2170 FITZGERALD AND LAPWORTH: ESTER CATALYSIS AND Ain the solution used did not change appreciably during the timeoccupied by an experiment.The quality of the acetone was found t o make an appreciabledifference, and it proved necessary to use highly purified material.Concordant results were obtained from acetone, from the bisulphitecompound obtained from Kahlbaum (A), or prepared and dried by us( B ) ; good results attended the use of acetone (C) which had beenprepared from commercial purified acetone by boiling i t with about3 per cent.of its weight of metallic calcium for some hours, andafterwards fractionating by means of an eight-section Young'sdephlegmating column.The following represent a comparative experiment with the threespecimens : water (0°253), alcohol (0.873), and acetic acid (1.143)grams, and the same amount of catalyst being added to three 25 C.C.flasks, which were then filled with acetone at 25O, quantities of 3 C.C.being removed from each and titrated from time to time; x is thetitre of the free acetic acid in C.C. of N/10 alkali.A . t = 12 65 lo' 135 li8:o k=0*02302 = 14.33 13.30 12'49 32.00B. t = 24 74 115 142 292x = 14-33 13.30 12.59 12.16 10.40 k=Q'0233C. t = 30 80 121 148 302z = 14.02 12'88 12.11 11.71 9.80 k=0'0243It is seen that the resuIts are not completely concordant ; for thisand similar reasons the authors have not attempted to express all thevelocity constants obtained in exactly the same measure.Theconstants for any one series, however, are strictly intercomparable,the individual experiments being made under identical conditions withonly one variant. The different series in acetone are to be regarded ascorresponding within a few per cents. only. It would be possible, ifit served any really useful purpose, to pass from one series to anotherby fixing the point at which the conditions of the series in pairscorrespond. The interest lies principally in the consideration of theinfluence of one variant at a time.The alcohol and acetic acid, which were as nearly as possibleanhydrous, were introduced in equimolecular quantities at 25" bycarefully standardised pipettes, except when either was a variable in aseries, when it was accurately weighed.I n all other cases, too, thequantities of the reacting substance were weighed in the flasks, partlyfilled with acetone, then placed in the thermostat for some time, afterwhich the catalyst in acetone was introduced, and the volume a t oncemade up with pure acetone to 25 c.c., all the liquids having previouslyattained the temperature of the thermostat. At measured intervalsof time, portions of 2 C.C. were withdrawn by means of a carefullMODlFlCATION OF THE THEORY OF ACIDS. 2171standardised pipette, and titrated with N/lO alkali, free fromcarbonate, I n tabulating the titres in each case, that part due to thecatalyst was first subtracted.It was qscertained that in the absenceof alcohol no measurable diminution i n the titre of acetic acid andhydrogen chloride occurred in wet acetone under the experimentalcondition.A word must be added with reference to the mode of estimatingthe initial velocities of change. The titres plotted against time givecurves which are not e&sily expressed by a simple mathematicalrelationship, so that other methods than the use of formuls had to beadopted. I n the case of the esterification numbers, the curvesat first are nearly of the bimolecular form, so that by plottingthe reciprocals of the titres against the time, a nearly straightline is obtained, from the slope of which the velocity a t the be-ginning was easily calculated.I n the experiments on hydrolysis nosuch simple relation could be found, and tangents mere thereforedrawn by hand to the smooth, plotted curves. This method was muchless satisfactory than the former, but yields results which are not farfrom the correct values, and in series VIII the numbers given areidentical, because the curves when graphed are indistinguishable in theinitial stages.The function k represents in all cases the diminution of the titreper minute, in c.c., at the commencernent (when t = O ) . For com-parison, the way in which L changes with the variable is addedin each instance.A . Estleri3cation.SERIES I.--Constctnts ; Water, 0.353 ; Acetic Acid, 1.1 43.Variant.Alcohol.(a) 0'873( b ) 1.098( c ) 1.713( d ) 2.043( e ) 2.728(f) 4566t = 1z = 13.85t = 2x = 13.84t = 2x = 13'74t = 3IC = 13'86t = 2x = 13'74t = 22 = 13.643412-973612.703312273012.323511.512911 '2088l l T 38211.437810'627510'47709-81648.90k x111 15210.77 9.96 3*51107 1479-76 8.78 5'40104 1419'45 8'35 6*51100 139 8.70 7.52 8-27987'45 6'29 133 12'8a.6. c. d. e. f-3-19 3'15 3.18 3.03 2'80 L x l O - ~ 3.20 -___alcoho2172 FLTZGERALD AND LAPWORTH: ESTER CATALYSIS AXD ASERIES II.--E$ect of Alcoimt on the Initkl Rate of Ester~&&m ofPhenylacetic Acid by Alcoliol in Ethereal Solution.Constants :Phenylacetic Acid, 2.00 ; Ether to 50 C . C .Alcohol. k x 10-2.%*= 13.84 13'16 12.22 11.70 11.10 10-48x*= 13.89 12% 11.84 11-10 10-38 9'62 lSs2(a) 2 C.C. t = 4 14 26 34 44 56( b ) 4 C.C. t = 3 1 4 19 27 37 49a. b.4.6 kx10-2 4.6alcohol* These titres include the hydrogall chloride present as catalyst.SERIES 111.-Efect of Methyl Akohol on the fnitial Rate of Esteri'j%a-Constants : Acetic Acid, tie? of Acetic Acid in Et?,?ereal aolzction.3.72 ; Ether to 100 C.C.Methyl slcohol. k x lo-?.(a) 10 C.C. t = 6 17 27 45 107x = 30.35 29.06 27'50 26'30 22.30 13*0z = 30'90 30.30 29'30 28'60 26-15 liS5( b ) 5 C.C. t = 9 20 34 47 109a. b.1 -3 1 *I k x - - _~methyl alcoholSERIES IV.-Constants : Water, 0.253 ; Alcohol, 0.8'73.Acetic acid.k x 10-2.(a) 2'738 t = 32 86 115 197 271b) 2.223 t = 29 58 111 191 267(c) 1'840 t = 26 55 110 192 266( d ) 1'473 t = 21 52 105 190 264( e ) 1'124 t = 17 51 104 188 263(f) 0.721 t = 15 49 100 184 2613: = 33.74 31'50 30'41 27'88 27'03 4'752 = 27'31 26.15 24.35 22.59 21'43 4'50x = 22'86 22'01 20-24 18-52 17'42 3'91x = 18'54 17.62 16'32 14'80 13-79 3'18z = 14-19 13.36 12-41 11'11 10-30 2*45x =: 9'29 8-80 8'06 7-18 6'54 1'72a. b. C. d. c. f.1.72 2.03 2.12 2'16 2.21 2-48 k x 10-2acetic aciMODIFICATION OF THE THEORY OF ACIDS. 2173SERIES V.-Comtants : AZcohoZ, 0.873 ; Acetic Acid, 1.143.Water.(a) 0.253 t = 16 49 94x = 14'38 13.67 12.70(b) 0.490 t = 20(c) 0.733 t = 24( d ) 0.985 t = 23(c) 1.426 t = 24(f) 2.172 t = 26x = 14'45x = 14.57z = 14.71x: = 14.85x: = 14.814913.895014.175114-505114-635414-779413.219513'679714-109814'4710014.59a. b.C.Water x k x 1 0 - 2 0-66 0.98 1-01SERIES VI.-B$ect of Water on the Initial14311'8214412.5114413'1214613.7324413.8424614.25d.0.85k xlz4:7 2.6024011-48 2*ooli4i8 1-381:4ig 0-870.570'34e. f.0.82 0.74Rate of EsterzJ$ccLtion ofAcatic Acid in Absolutc Alcohol.Alcohol to 50 C.C. ; HCl about X / l O O .Constants : Acetic Acid, 10 C.C. ;Water( a ) None t = 1'5 7 12 18 28z = 13'62 12'97 12-52 12.14 11.51z = 135'4 13'33 13.01 12'84 12.52x = 13.76 13'53 13-32 13.05(bj 0.5 C.C. t = 1 6 12 18 25(c) 1.0 C . C . t = 1 7 1 3 23For estimations, 5 C.C.of the solution were added to aqueous sodiumacetate, the whole being made up to 25 C.C. with water ; portions of2 C.C. were then titrated, and the mean results are those given.The depressions here noticed as water is added or formed are greaterthan could be accounted for on the assumption that water acts byhydrating the acetic acid, unless it be supposed t h a t one molecule ofwater would render several molecules of carboxylic acid inactive.SERIES V1I.-Constants : Vater, 0.253 ; Alcohol, 0.873 ; Acetic Acid1.1 43.Ethyl acetate. x: x 10-2.( a ) 0.182 t = 17 i 9 134 278x = 14'60 13-20 12-26 10'56 '."(b) 0'310 t = 28 SO 136 279 2-40x = 14'22 16.19 12.26 10'58(c) 0.715 t = 27 79 135 2773; = 14'23 13-24 12'40 10'81 2'29( d ) 1*0!!8 1 3 28 80 136 279x = 14.30 13.30 12.48 1092174 FITZGERALD AND LAPWORTH : ESTER CATALYSIS, ETC.SERIES VIT.-Constants : water, 0.253 ; Alcohol, 0.873 ; Acetic Acic1.143 (continued).Ethyl acetate.k x(e) 1.425 t = 29 81 137 2802 = 14-32 13.38 12-59 11.24df) 2'004 t = 29 84 140 283x: = 14.40 13.49 12.79 11.54 1'82(9) 2.158 t = 39 85 141 2842 = 13.96 13-27 12-59 11'44B. Hydrolysis.SEnIEs V I1 I.-Comtant : Ethyl Acetate, 1.666.Water.( a ) 0'253( b ) 0'536(c) 0.788(CZ) 1.010(c) 1.305cf) 1.7%(y) '2.536t = 42x = 0.27t = 443; = 0.35t = 45z = 0.33t = 47x = 0.35t = 482 = 0.34t = 50z == 0.292 = 52x: = 0.26840.56850'62850 -59860'59900 '55950 '54880-45134 3060'83 1'18136 2080.95 1.39136 2080'92 1.36137 2090.88 1.29140 2100.77 1.16140 2100'74 1.06143 2110'65 0.96k x 10-2.0.720.790.790.790.790.790.64SERIES IX.-Constants : Ethyl Acetate, 1.666 ; Water, 0.34 1.Alcohol. k x 10-2.None t = 54z = 0.420.431 1, = 56L - 0.38O*EOti t = 5 72; = 0'341.154 1 = 5s.r = 0-371.609 t = 62z 0'311 9 4 2 1 ZzZ 6 33: = o.:j!j2.918 t - 64.I; i 0.331320'961420.901460.831470 *831500.741520.731530'6COCKSEDGE : TELLURIUM DICYANIDE. 2175SERIES X.-Constunt : Wuter, 0.339.Ethyl acetatc.( a ) 1‘066 t = 53x = 0.26( b ) 1’381 t = 362 = 0‘21(c) 1’833 1 = 49z = 0.41( d ) 2‘282 t = 32z = 0.31( e ) 2,806 t = 443: = 0’54k x lo-”.89 131 1960‘41 0’49 ( 1 ) 0‘82 0’5869 133 1770’41 0.75 0’96 0’7383 124 1910’65 0 90 1.57 9965 136 169 1.180,63 1-22 (1) 1 5 7(f) 3‘225 t = 28 62 140 165z = 0.41 0.88 1-73 (?) 2.11( 9 ) 3’576 I = 4 1 76 133 182 1.82z = 0.67 1‘22 1’85 ( 1 ) 2‘62a. b. c. a. e. f. % ___- k x 1 0 - 2 0‘54 0’53 0.54 0’52 0’52 0’51 0.49ethyl acetateMuch of the expense incurred during this work was defrayed froma grant awarded by the Government Grant Committee of the RoyalSociety, for which the authors desire to express their indebtedness.COL1)SMITHS’ CULLEGE,NEW CILOSY, S.E

ISSN:0368-1645    

DOI:10.1039/CT9089302163

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

COCKSEDGE : TELLURIUM DICYANIDE. 2175CCYV 11.-Telluriurn Dicycunide.By HERBEHT EDWIN COCKSEDGE.ALTROUGR cyanides of both sulphur and selenium have been knownfor some time, the possible existence of a tellurium compound appearsnot to have been investigated.It was found that a cyanide of tellurium can be prepared by doubledecomposition between silver cyanide and tellurium tetrabromide, thereaction taking place in a suitable organic solvent.The tellurium tetrabromide was obtained by the cautious additionof bromide to powdered tellurium, the excess of bromine beingremoved by a current of dried nitrogen while the flask containing thesubstance was warmed.The details of a preparation are as follows : The tellurium tetra-bromide (35 grams), with twice the required quantity of well-drie2176 COCKSEDGE : TELLURIUM DICYAXIDE.silver cyanide (100 grams), was placed in a round-bottomed flask fusedto a reflux condenser, and about 200 C.C.of purified and dried benzeneadded. The flask was heated to about 90' in a water-bath continuously,with occasional shaking, for three days, when the benzene, in whichthe tellurium cyanide is not appreciably soluble, was decanted fromthe silver salts.It was found to contain much cyanogen bromide, and the reactionmay therefore be written :TeBr, + RAgCN = Te(CN), + 3AgBr + CNBr.The residue was then digested with dry ether, which dissolvedout the tellurium cyanide, forming a colourless solution.Inasmuch as the tetrabromide forms a deep yellow solution in ether,the absence of colour indicated that the reaction was complete.Afterevaporating the ethereal solution at the ordinary temperature, accessof moist air being avoided, colourless crystals were obtained, whichlost ether on warming; the substance proved to be a compoundof ether and tellurium dicyanide, 2Te(CN),,(C,H,),O. Analysis gave :Te = (i) 58.2, (ii) 58.8, and (iii) 59.8.Found, N = (i) 13-2 and (ii) 13.3.2Te(CN),,(C,H,),O requires N = 13.0 and Te = 58.9 per cent.It is known that the tetrachloride and tetrabromide of telluriumform similar compounds with ether.To prepare the dicyanide, Te(CN),, the ethereal solution obtainedabove was filtered into a distilling flask, and evaporated to drynessfrom a water-bath, the last traces of ether being removed by a currentof dried hydrogen.The cyanide so produced retained the shape ofthe original crystals, but was grey, owing to a slight coating oftellurium.The pure cyanide was obtained by distilling this product in avacuum, about half of the substance being lost in the process astellurium and cyanogen. The sublimed crystals were analysed :0.1571 gave 0.1114 Te.0'2218 ,, 0.0640 cyanogen. (CN) = 28.8.When exposed t o the air, the cyanide in a few minutes assumes theappearance of graphite, owing t o deposited tellurium.With water and alkalis, immediate hydrolysis occurs, and telluriumis precipitated in the form of black flocks. The course of thehydrolysis is similar to that of the dichloride and dibromide oftellurium :2Te(CN), + 3H,@ = Te + TeO(OH), + 4HCN.Te= 70.9.TeCCN), requires Te = 71.0 ; (CN) = 89.0 per cent.When heated in air, the cyanide burns with a pale blue flash.The decomposition of the compound into tellurium and cyanogeCOCKSEDGE : BOROS THIOCYANA'I'E. 2177takes place to a slight extent at looo, but more rapidly as thetemperature rises ; there is a sudden increase in the rate of evolutionof the gas at about 190°, a t which temperature partial sublimation ofthe cyanide occurs.The substance is slightly soluble in chloroform or carbon tetra-chloride ; methyl alcohol dissolves it in the cold without change, buthydrolysis occurs when the solution is warmed.At the ordinary temperature, one gram of the substance requiresabout 60 C.C. of ether for solution.CHRIST CHURCH LABOBATORY,OXFORD

ISSN:0368-1645    

DOI:10.1039/CT9089302175

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

COCKSEDGE : BOROS THIOCYANA‘I’E. 2177CCXVIIL-Boron Thiocyanate.By HERBERT EDWIN COCKSEDGE.THE thiocyanates of phosphorus and silicon were first described byNiquel (Ann. Chirn. Phy., 1877, [v], 11, 343) j they have since beeninvestigated by A. E. Dixon (Trans., 1901, 79, 541) and J. E.Reynolds (did., 1906, 89, 397).The corresponding boron compound was all uded to by Miquel, inthe paper mentioned above, as follows : ‘‘ Finally, after experimentsas yet incomplete, I can assert that boron bromide reacts similarlywith lead sulphocyanide to give a sulphocyanide with propertiesanalogous to those of the silicon compound.”Boron bromide reacts with silver thiocyanate with the formation ofboron thiocyanate, which is extracted from the product by means ofcold benzene.The boron bromide was prepared according to Gattermann’s method(Ber., 1889, 22, 195) by the action of bromine on crude boron,obtained by the action of magnesium powder on anhydrous borax.The final distillation was carried out with care, since the mercuricbromide formed after decolorisation of the crude product withmercury is carried over in appreciable quantities in the last portionof boron bromide vapour.TO prepare the boron thipcyanate, a small bulb of boron bromidewas placed together with twice the theoretical quantity of thoroughlydried silver thiocyanate in a well-stoppered bottle, pure benzene added,and the bulb broken by vigorous shaking.‘l‘he shaking was continuedfor a few minutes, after which the colourless solution of the thio-cyanate was filtered, and the benzene removed at the ordinar2178 COCKSEDGE : BORON THIOCYAKATE.temperature by means of a current of dry air.The substance wasdeposited in glistening, colourless crystals, and a further quantitycould be obtained by extracting the residual silver salts withbenzene.Traces of hydrolysis occur unless extreme care is taken, the crystalsbecoming clouded and discoloured as the solution becomes concentrated.Analysis gave :B = (i) 5.8, (ii) 6.3, and (iii) 5.8.N=(i) 21.6 and (ii) 22.3.S = (i) 51.6 and (ii) 51.8.The substance separates from benzene in short, rhombic crystals, orsometimes in the form of radiating needles. It crystallises from etherin thin, colourless plates.When heated on a platinum wire in the Bunsen flame, the thio-cyanate burns, leaving a charred residue, which, on ignition, givesboron nitride.In the absence of sir, it is largely deatroyed on heating,only a small portion distilling unchanged.A t looo the substance darkens considerably, and a benzene solutiondeposits brown flocks when it is boiled.When exposed to moisture or treated with alkalis, the thiocyanateis at once hydrolysed to boric and thiocyanic acids, a solution of ferricchloride giving an intense coloration.With the view of determining whether the substance possesses theconstitution of a thiocyanate, B(SCN),, or of a thiocarbimide, B(NCS),,its behaviour towards aniline was investigated.A. E. Dixon has shown (Eoc. cit.) that the corresponding phosphoruscompound acts as a thiocarbimide towards the base, yielding thecorresponding thiocarbamide, whereas from the work of J.EmersonReynolds the silicon compound exhibits the behaviour of athiocy anate.A solution of the boron compound in benzene was added to aconcentrated solution of aniline in the same solvent. Some heat wasevoIved, and a mass of white crystals mas precipitated. These werewashed by decantation with benzene, drained, and dried, access ofmoisture being avoided as much as possible.The crystals contained no boron, but gave reactions for aniline anda thiocyaoate; they melted at about 78O, softening before thattemperature was reached. The substance gave no thiocarbamidereactions when freshly prepared, but after boiling with water, orallowing it to stand for some time, a mirror of lead sulphide wasobtained on warming a portion with an alkaline solution of lead.The substance had in fact been converted into phenylthiocarbamide,B(SCN), requires B = 5.9 ; N = 22.7 ; S = 5 1 *9 per centTHE vIscosim OF FUMING SULPHURIC ACID.2179which melts at 154'; a specimen prepared from the original crystalsmelted at 153'. On analysis :0,0914 gave 14.2 C.C. N, (moist) a t 11' and 756 mm.0,4136 ,, 0,6679 BaSO,. S = 22.2.The above experiments thus indicate that the boron compoundin solution behaves as a thiocyanate rather than as a thiocarbimide.The boron remains in solution in the benzene probably as theanilide of boron, but it was not isolated as such ; the anilide, whichdoes not seem to have been described, is extremely soluble in benzene,and can only be obtained from a solution in that solvent byconcentrating and keeping the resulting gum for some time.N=18*6.C7H,N,S requires N = 18.4 ; S = 21.1 per cent.In conclusion, I wish t o express my best thanks to Dr. Baker forthe helpful interest he has taken in the above work.CERIST CEURCE LABORATORY,OXFORD

ISSN:0368-1645    

DOI:10.1039/CT9089302177

出版商:RSC    

年代:1908

数据来源: RSC