摘要:

UNSTABLE STATES OF SOLUTIONS OF SODITJM BEHENATE. 2751 CCCLXXVI1.-Unstable States of S01;zttiolns of Sodium Behenate. By MARY EVELYN Lma. PREVIOUS communications from this laboratory were devoted to describing the most stable forms of soap and its solutions. In the case of sodium behenate it was incidentally noted that the type of solution obtained could be radically affected by suitable treatment. For example on repeated rapid cooling the behenate solutions could be obtained at room temperature for a short period as limpid, mobile liquids whereas slow cooling produced the usual hard white curd. Reheating the mobile liquid of a 0*2N,-solution to about 90" produced a clear stiff isotropic jelly which quick cooling once more temporarily rendered fluid. Some of the most interesting solutions could only be kept less than half an hour.The appearance and behaviour of these solutions and their transitory states have been quantitatively examined. The task was undertaken by a team of experienced investigators, who worked simultaneously on portions of solutions prepared by Mr. G. M. Langdon. He also made the macroscopic observations. The microscopic study was undertaken by Mr. S. E. Wiltshire, Miss M. E. Kieser carried out the E.M.F. experiments Miss M. E. Ling the freezing-point determinations Misa K. M. Hay the indicator tests and Mr. W. C. Quick measured the conductivity. Sodium behenate solutions were made up in silver tubes by shaking the requisite quantities (Bunbury and Martin J. 1914, 105 417) of standardised alkali with weighed quantities of behenic acid m.p. 814-82.0" kindly made for us by Messrs. J. C. Crosfield and Sons Ltd. by the catalytic hydrogenation of Kahlbaum's erucic acid. The homogeneous soaps were transferred to thick-walled glass tubes which were sealed for optical investigation according to the method previously described (McBain and Langdon, this vol. p. 852). Parallel experiments were carried out with solutions made up in 1913 (McBain and Taylor 2. p h p i k d . Chem., 1911 76 179). The strengths used were 0.01 0.05 0.1 0.2 0.5Nw, i.e. mole per 1000 g. of water. The observations here recorded were repeated many times; e.g. a O*lN,-solution was alternately heated and cooled twenty times under diBerent conditions and the results were reproducible the only effect that varied being the number of " flocks " appearing in the mobile liquid.The stable forms of the behenate solutions at room temperature, with the exception of O-OlN, were solid white moist curds. Curd formation however could be suspended by special heat treatment 2752 LAING : as was well illustrated by the behaviour of a O*05N,-solution. On being heated to about 88" the curded O~05Nw-solution melted to a fairly mobile milky liquid containing a few white flakes. I f this solution were allowed to cool slowly more flakes separated and the whole gradually became a network of curd ; the transformation from Brownian particles in movement to short and then long fibres could be observed under the ultramicroscope. Photographs of such gradual transitions have been published elsewhere (McBain Darke, and Salmon PTW.Roy. SOC. 1921 A 98 395; Bogue .' Colloidal Behaviour," Vol. I pp. 41-29 ; Ivature 1921,107,45 ; Alexander, '' Colloid Chemistry Theoretical and Applied," Vol. I 1925). On cooling rapidly the white flakes which formed at about 75', rose to the surface leaving a clear lower layer. On heating to go", these flakes melted and the system consisted of two clear layers. As the tube cooled again curding took place in two stages the upper layer solidifying at 75" and the clear lower layer after some hours a t room temperature. The quantitative investigatian had to be carried out as quickly as possible before the homogeneous mobile liquid produced by rapid cooling set to a mass of curd fibres. The hydroxyl-ion concentration of the O-05Nw-solution at 18" was found by E.M.F.measurements with the hydrogen electrode to be 0-007N during the first hour but this value declined to O~OO08Nw when the clear liquid had solidified to form white curd. The con-centration of hydroxyl ions in the mobile liquid was shown by the indicator method using alizarin yellow G and Sorensen's buffers to be 0.007Nw a t W" and slightly higher at room temperature. The clear O~05Nw-sodium behenate a t 18" therefore is hydrolysed to the extent of 14% (= O-O07Nw-OH) and contains O-02lXW-acid soap expressed in terms of behenate or 0.014Nw in terms of sodium ; if this is formed as in the case of the palmitate according to the equation 3NaBe + H,O = NaOH + 2NaBe,HBe. Hence 42% of the total behenate radical is in the form of acid soap.This acid soap is colloidal and exerts no osmotic pressure (McBain Taylor, and Laing J. 1922,321 621). The osmotic data were obtained from depressions of the freezing point determined by the usual Beckmann method using inoculation : a t least four concordant readings were taken before a solution curded. The depression for the 0.06Nw-solution was 0.036". The hydroxyl ions present to the extent given above would correspond to a depression of 0.013" and together with the equivalent sodium ions would account for a depression of 0.026". The difference 0-OlO", which must be due to that part of the soap in solution as electrolyte, corresponds to 0.0027 g.-mol. of fully dissociated binary crystal UNSTABLE STATES OF SOLUTIONS OF SODIUM BEHENATE.2753 loidal electrolyte. What remains of the total concentration 0.05 -0.014 - 0.007 - 0.0027Nw = 0*0263N, must be the concentration of the undissociated neutral colloid. The constituents of this unstable but clear solution and their concentrations are very nearly those in Table I. TABLE I. Constituents of unstable O-05Nw-80dium Behenate a t 18". 1. Fr0mE.M.P. (OH') 0-007Nw l4o/ hydrolysis slka-3. Equivalent to Na,HBe O.O140N (Na-) 42% acid soap (colloid). 3. From lowering (Na.) = (Be') + (OH') 0.0097N, 4. Remainder (NaBe) O-O263N (Na) 53% neutral colloid. &ty. 5% dissociated so~p. The conductivity data are summarised in Table II. The con-ductivities of two samples of 0.05Nw-solution were measured a t intervals over a period of 20 hours and that of a O-lN,-solution at intervals during 18 hours after making up.The values recorded for the liquid are the means of those obtained within the first hour the curd values are those obtained after 18-20 hours. TABLE 11. Specific Conductivity ( K ) of Sodium Behenate Solutions at 18". Unstable liquid. Final curd. /. /- - / I Conc. (iVm). K. a%. K . a%-0.05 1-74 x low3 15.9 0-311 x 10-3 2.8 0.1 2.79 x lo- 12.8 0.42 x lC3 1-9 The degree of dissociation a calculated by dividing the actual conductivity found by the molar conductivity of sodium hydroxide at infinite dilution at 18" (V;x. 216.5) is 15.9% for the 0.05N,-solution a value slightly greater than that (14%) found by E.M.F. measurements ; the approximate agreement shows that the free hydroxide accounts for most of the conductivity.A more exact comparison may be made by calculating from the data of Table I the specific conductivity of the O-O5N,-solufion at 18". The products of the concentrations per C.C. of the various ions shown in Table I and their respective mobilities (43.6 for Na' 172.9 for OH' and 20.7 for Be') being added togebher the calculated value for the specific conductivity is found to be 1=69~lO-~. The agreement with the observed value 1.74 x is very close especially in view of the fact that different samples of unstable solutions were taken for these measurements ; one sample actually gave the value 1-69 x 10-3 reciprocal ohm. Full allowance having been made for the conductivity due to the hydroxyl ions in the final curd it is evident that the curd fibres, though not in solution (this was shown by analysis of the mother 2754 W G : liquor squeezed out from such curds) contribute to the residual conductivity.This is apparently due to the free ions of the electrical double layer of the very extensive surface of the h e fibres (compare Laing J. PhpimZ Chem. 1924,28 673; Laing and McBain J. 1920 117 1507). The data show that these super-cooled solutions are highly unstable the extent of hydrolysis being many times greater even than that for the solutions at 90". At the lower temperature after a short time the hydrolysis diminishes to a tenth of its value and the equilibrium shifts in favour of the formation of insoluble sodium behenate which separates in curd form from the solution.It seems possible that in the initial clear liquid the acid soap may peptise the neutral soap. Solutions of acid soap froth freely (McBain Taylor and Laing Zoc. cit.). The O-lN,-behenate solution in the unstable condition was similar to the O~05Nw-solution but was less hydrolysed. The concentration of hydroxyl ions due to hydrolysis was shown by the hydrogen electrode to be 0*0098N or 9.8% (afterwards falling to 04012N, when the clear liquid had set t o a white curd). The depression of the freezing point was 0.035". This would be fully accounted for by the free sodium hydroxide but as is seen from Table 11 there is still a small amount of conductivity to be accounted for as in the case of the 0*05N,-solution. The macroscopic and the microscopic behaviour of the 0*1N,-solution are just like those of the O~O5N~-solution described above, except that the instability increases with concentration.The 0.2AT,-solution was too unstable to permit of freezing-point determinations. This solution is very viscous and difKcult to prepare. It exhibited however a remarkable change in viscosity. The melted curd was a clear isotropic jelly at go" but on cooling, the gel " melted " to a mobile cloudy liquid. We have observed this curious phenomenon of gelation at a relatively high temperature and fluidity at a low temperature in only one other instance namely, in a solution of nitro-cotton in alcohol ; this is a clear elastic jelly at room temperature and a mobile fluid at the temperature of liquid air (observation by Mr. L. E.Smith in this laboratory).* This observa-tion can be readily explained on the basis of the theory of neutral colloids put forward by McBain (Trans. Faraday SOC. 1924,20,22). The hydroxyl-ion concentration of the O.Zfl,-solution is 0.005NW, indicating a hydrolysis alkalinity of only 2%. This value corre-sponds exactly with that found by the indicator method. Most of the soap of the O.ZN,-solution must be present as insoluble undis-sociated neutral colloid. * Compare Szegvari (Kohid-Ztg. 1924 34 34) who however used a more complicated mixture of solvent and non-solvent UNSTABLE STATES OF SOLUTIONS OF SODIUM BEHENATE. 2755 Whether cooled rapidly or slowly the O*SN,-solution of sodium behenate forms curd a t room temperature. It is a highly viscous gel at 90".It appears that ease of curding increases with rise of Viscosity, which takes place whenever separated matter (shown by streakiness) is present or upon lowering of temperature. Curd also forms more rapidly after the solution has been heated in glass. A sodium behenate solution separates into two layers on addition of 0*4iV,-sodium chlbride; whereas in the case of sodium palmitate of the same concentration twice this quantity of salt is required t o produce the same change. The salted-out system 0.05 N,-NaBe + 0*42N,-NaCl and also O.OSN,-NaBe + 0-59NW-Nac1 becomes homogeneous a t 100". This temperature is above that 72-75' at which the corresponding palmitate-sodium chloride system becomes homogeneous. Both facts are in accordance with the insolubility of sodium behenate at low temperatures.Neutral behenate solutions in the absence of sodium chloride, were never observed to separate spontaneously into two layers on standmg a t high temperatures as is the case with acid sodium palmitate (0-4N,-NaP O-lN,-HP). In appearance the acid salts of behenic and palmitic acids are very similar. On reviewing the behaviour of these colloidal behenate systems, one is struck by their analogy with certain crystdoidal system. When for example barium sulphate is produced rapidly from a mixture of barium chloride and a sulphate a highly supersaturated solution may be obtained which deposits matter in the colloidal state. On sudden cooling of the behenate solutions supersaturation with respect to neutral colloid sets in and similar amorphous, flocculent material is formed. Thus on cooling of either system, colloid or crystalloidal one gets separation of (crystalline) curd fibres on the one hand and of true crystals on the other. On standing in contact with their respective mother-liquors colloidal barium sulphate crystallises and colloidal sodium behenate curds. Summary. (1) Although the stable form of 0~05-0~5Nw-sodium behenate at room temperature is a hard white curd these solutions can be obtained temporarily as clear very mobile liquids which are hydro-lysed to an abnormally large extent. (2) The largest constituent of the unstable mobile solutions is neutral undissociated colloid the next largest being colloidal acid sodium soap with the equivalent quantity of free sodium hydroxide. There is only a very small proportion of dissociated soap. UNIVERSITY OF BEISTOL. [Received July 24th 1925.1 5 a

ISSN:0368-1645    

DOI:10.1039/CT9252702751

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

2756 TMERRY SULPHUR COMPOUNDS REMOVED FROM CCCLXXVII1.-Sulphur Compounds Removed from CL Persian Petroleum by Means of Sulphuric Acid. Part I . By EDWARD HENRY THIERRY. MABERY and SMITE (Amer. Ckm. J. 1891 13 232) isolated several organic sulphur compounds from a crude Ohio oil and established the presence of a series of dialkyl sulphides. Mabery and Quayle (ibid. 1906 35 404) obtained very different results during an investigation of a Canadian petroleum a series of saturated cyclic compounds named thiophanes of the empirical composition C,H,S being isolated; the actual compounds ranged from C,H,,S to C,,H,,S and a derivative of the substance C,H,,S also was prepared (see also von Braun and Triimpler Ber. 1910 43 543; Trochimovski J . RUM. Phys. Chem. SOC. 1916 48 880).More recently other workers have described the isolation and identi-fication of thiophen and its homologues in shale oil. The product now investigated was a sulphuric acid sludge from the rehing of Persian petroleum kindly supplied by Mr. Kewley of the Asiatic Petroleum Co. The oil that separated on dilution was carefully fractionated and of the twenty-nine fractions boiling below 120"/125 mm. four have been investigated. Three of these con-sisted essentially of methyl ethyl sulphide tetra- and penta-methylene sulphides. The fourth fraction was a mixture. It contained a compound C4Hl0S; this was not diethyl sulphide but sdlicient material was not available to determine whether it was methyl propyl sulphide or methyl isopropyl sulphide. All the fractions had an intense odour but the purest samples of the cyclic sulphides mere in no sense objectionable.The various compounds have been characterised by the preparation of a number of deriv-atives such as sulphonium iodides and double salts with mercuric salts. E X P E R I M E N T A L. The dark supernatant' oil obtained by greatly diluting the sulphuric acid sludge (12 litres) with water was shaken with sodium hydroxide and dried over sodium sulphate ; a filrther quantity was extract'ed from the diluted liquid with chloroform the total yield being 1800 C.C. The oil was distilled and the more volatile portions were fractionated five times at a pressure of 760 mm. ; the fractions obtained were (1) below SO" 0.5 c.c.; (2) 59-64' 90 c.c.; (3) 50-89" 8 C.C. ; (7) 89-92" 11 ex.; (8) above 92" 7 C.C. 6468' 11 c.c.; (4) 68-70' 33 c.c.; (5) 70-SO' 10 c.c.; (6 A PERSIAN PETROLEUM ETC. PART I. 2757 The oils boiling above 100"/760 mm. were fractionated eleven Table I shows the degree of separation achieved. times at 125 111111. TABLE I. Fraction. B.p./125 mm. C.C. Fraction. B.p.1125 111111. C.C. 9 up t o 60" 4 20 90-93" 30 10 60-63 12 21 93-96 12 11 63-66 20 22 96-99 9 12 66-69 3 23 99-102 19 13 69-72 5 34 102-105 28 14 72-75 6 25 105-108 16 16 75-78 10 26 108-1 11 14 16 78-81 70 27 111-114 35 17 81-84 75 28 114-117 20 18 S A 8 7 10 29 117-120 18 19 87-90 3 Residue (to be examined) Fractions 4 7 11 and 17 have been carefully examined. Fraction 4 contained 61y0 of chloroform. No satisfactory analysis was possible but the remaining liquid contained about 34.6y0 S.On shaking with mercuric iodide decanting and evaporating in a vacuum pale yellow crystals were obtained which dissociated very rapidly in the air and softened at 59" (Smiles J. 1900 77 164, gives m. p. 59' for CH3*S-C,H5,HgI,). The liquid (2 c.c.) reacted briskly with methyl iodide (1 c.c.) and mercuric iodide (excess). After 3 minutes the product was washed with ether and crystallised from aceton-ther; it then formed fine yellow needles m. p. 86" [(CH,)&IC,H,,Hg12 has m. p. 86" ; Smiles loc. cit.]. white crystals of methyl ethyl sulphide mercurichlmde were immediately precipitated on addition of alcoholic mercuric chloride to the liquid. Several crystallisations from acetone and water gave rather unstable crystals m.p. 101-102". Most of the mercurihalides here described are unstable and were purified with difEiculty immediately beginning to lose sulphide on exposure to air; the ultimate analyses therefore were unsatb-factory. Sintering frequently occurs during melting-point deter-minations and this together with the tendency to dissociate makes trustworthy observations difficult to obtain. Fraction 7 contained 0.5% of chloroform. The analytical Sgures found (C 56.4; €I 11.0) differ from those required for diethyl sulphide (C 53.3; H ll*lyo) but consideration of the resulta obtained with fraction 11 makes it very probable that the divergence in both cases is caused by admixture of about 6:h of a hydrocarbon, b. p. 100-105". The mercuri-iodide prepared as described under Fraction 4, formed unstable pale yellow crystals which did not soften below 100".The methylsulphonium iodide mercuri-iodide formed pale yellow crystals which melted at 54" after repeated crystallisation 5 A * 2758 THIERRY SULPHUR COMPOUNDS ETC. from acetone-ether and the mercurichloride unstable white needles which melted a t 68" after repeated crystallisation from acetone by cautious addition of water. Smiles (J. 1900 77 164) gives 52" as the m. p. of (C,H5),S,Hg12 and 67" as that of (C&€,),(CH,)SI,HgI, whilst for (C2H5),S,HgC12 Loir (Annden, 1853 87 369) records m. p. 90" and Abel (H. 1895 20 269) m. p. 119". These results indicah clearly that the compound is not diethyl sulphide. No addition compounds of the above types of the methyl propyl sulphides have been described.Fr&ion 11 was refractionated and the largest fraction b. p. 64-65"/125 mm. was examined. The liquid boiled at 120-121'1 760 mm. (Found C 56-6; H 9.8; S 34.0%). Diisopropyl sulphide (C 61.0; H 11.9; S 2701%) boils at 120-5"/763 mm. (Beckmm J . pr. Chem. 1878 17 459) and tetramethylene sulphide (C 54.5; H 9-1; S 3603%) at 119" (von Braun and Triimpler Ber. 1910 43 549). The divergence from the values for tetramethylene sulphide may be ascribed to the presence of a little hydrocarbon since derivatives were obtained in a pure state with comparative ease. The methiodide prepared in the usual way crystallised from alcohol in fine white needles decomp. 185-190" (Pound I 54.6. C,H,,IS requires I 5502%). The mercurichloride crystallised from acetone-water had m.p. 126" (Trochimovski loc. cit. gives m. p. 124-5-125.5"). Tetramethylene alphide mercuri-iodide, prepared in the usual way separated from acetonewater in white cry&ak~ m. p. 58". T'etr~m'eth~lenemeth~~lp~nium iodide rnercuh-iidide prepared as previously described formed yellow cryatals, m. p. 111". Fraction 17 was refractionated four times ; the largest fraction had b. p. 83-84"/125 mm. and 138*5"/742 mm. (Found C 58.5; H 9.8; S 31-3. Calc. for C,H,,S C 58.8; H 9.8; S 31*4%). Low results for sulphur were obtained unless oxidation was carried out for 15 hours at 180" and then after the pressure had been released for 10 hours at 250". In estimating the carbon and hydrogen the best results were obtained by weighing the liquid in a small bubbler which was then fixed to the end of the combustion tube the passage of the oxygen causing steady evaporation.It seems certain that the compound is pentamethylene sulphide (compare von Braun Zm. cit.). The mercurichloride was prepared, and crystallised from benzene. Pentamethylenemethylsulphonium iodide prepared in the muid way was converted into the sulphonium base by means of silver oxide; the solution was exactly neutralised with hydrochloric acid and gently evaporated to small bulk. The crystalline sulpbniur CONDEXSATIONS OF SODIUM D E R I V A ~ S m. 2759 c u d e obtained on cooling was precipitated from alcoholic solution with ether washed with acetone and dried in a vacuum over sulphuric acid. The white crystals thus obtained dissociated without melting on heating and decomposed slightly on long standing (Found C 46.7; H 8.7; Cl 22.85.C6H,c1s reQnires C 47.2; H 8.6; Cl 23.3:/,). Pentamethylene sulphone was obtained in very small yield by oxidising the sulphide (2 g.) with excess of permanganate solution; it crystallised from benzene-light petroleum in white plates m. p. 98". Pentamethylene sulphide mercuri-iodide prepared in the usual way, waa washed with ether and crystallised from acetone by cautious addition of water. The white crystals obtained m. p. 72-74", dissociated completely within a few hours when exposed to the air. The mercurichloride separated from benzene in white crystals m. p. 135-136" (Trochimovski gives m. p. 137.5"). The cUorophtinde was obtained by adding a few drops of the sulphide to a strong aqueous solution of platinic chloride; the yellow crystals that separated after a few hours were crystallised from acetonewater. [Found Pt 35-4. (C,H,&),PtCl requires Pt 36.4%]. Perdu-methylenemethylsuZphonium iodide mercuri-iodide prepared aa previously described separated from acetone-ether in yellow cryatals m. p. 78". Trochimovski (Zoc. cit.) gives m. p. 98-5-99". The author expresses his thanks to Professor Donnan for suggesting this work and to Professor Collie and Dr. Brads for valuable advice given during its progress. THE RALPH FOSTER LABORATORY OF ORGANIC CHEXXSTRY, UKIVERSITY C0IJ;EOE. [Received February 26th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702756

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

CONDEXSATIONS OF SODIUM D E R I V A ~ S m. 2759 CCCLXX1X.-Condensations of the Sodium Derivatives of Trimethylene Glycol and Glycerol. By ARTHUR FAIRBOURNE and GRAHAM EDWARD FOSTER. IN extension of the work on the condensation of l-chlor0-2:4-dinitrobenzene with glycerol (J. 1921 119 1035) and ethylene glycol (ibid. p. 2077) the similar condensation in the cam of trimethylene glycol has now been investigated. A solution of the sodium derivative is readily obtained by dissolving sodium in excess of trimethylene glycol and may be used for effecting the condensation. In spite of the large excesa of glycol present and although monosodium glyceroxide gives rise to onl 2760 FAIRBOURNE AND FOSTER CONDENSATIONS OF THE one product in the correspondmg reaction (Zoc. cit. p.1037) both mono- and bis-dinitrophenyl ethers of trimethylene glycol are produced even when the chlorodinitrobenzene is added slowly. 5!H,mOH 9H2*OH ~H2'0*C6H,(N02)2 CH -+ (1.) YH + $ 3 3 2 (11.1 bH,*OH CH2- O*C,H,( NO,) CH,*O*C,H,(NO,), The relative yields of these ethers vary with the concentration of the sodium derivative and therefore may be regarded as dependent on the tendency to set up the equilibrium ~H,-O*C,H,(NO,) FH,*OH ~H,*O*C,H,(NO,) F;H,*OH CH,*OH CH2-ONa C€€,*ONa CH,*OH it being assumed as in the two previous papers that the primary condensation involves merely the replacement of the sodium by the substituent group : On this assumption depend the arguments previously put forward in support of the structure of glycerides (Zoc. cit. p. 1035).Doubt was cast on its validity however by the accidental preparation of the bisdinitrophenyl ether above mentioned and by the further discovery that tri-substituted derivatives of glycerol can be obtained by treating monosodium glyceroxide suspended in an inert solvent, with one equivalent of certain acid chlorides a reaction not con-templated in the previous papers. QH,*OE vH,*S03Ph F]H,*OH CH,*ONa CH,*SO,Ph CH,*OH Moreover such trisubstituted products were obtained from disodium glyceroside under identical conditions : p 2 -1- YH2 <t vH2 + y"2 R*O-Na + C1*C6H3(No2) -+ R*O*C,H3(N02),. 3VH-OH + 3Ph*S02C1 + yH*SO,Ph + 2YH*OH FH,*CO,Ph 7H2*OH bH,-CO,Ph CH,*OH 3C,H,O&a + 6PhCOC1 * 2 'H*CO,Ph + VH*OH It w a ~ rmlised that the formation of these substances might be due to direct interaction of labile chlorine atoms and hydroxyl groups, yH,*ONa 5!H200 *C6H3(N02) CH + 2C1*C,H3(N0,) -+ CH, &**OH 6H2*O*C,H3(NO,) ' the excess of the sodium derivative merely serving to destroy the hydrogen chloride thus formed.Glycerol ethylene glycol an SODIUM DERIVATIVES OF TRIMETHYLENE GLYCOL ETC. 2761 trimethylene glycol were therefore heated separately with l-chloro-2 4-dinitrobenzene in presence of calcium carbonate and tri-methylene glycol mono-2 4-dinitrophenyl ether was treated similarly in presence of sdEcient inert solvent to dissolve all organic matter but in no case was there a trace of ionisable halogen in the product. It appears clear therefore that no condensation between halogen atoms and hydroxyl groups occurs during the reactions with chlorodinitrobenzene and that the chlorine removes the sodium in the may previously assumed.The production from sodium glyceroxide of the tri-ester mentioned above might be explicable in the light of Fischer’s observation (Ber. 1920 53 1621 1634) that mono-esters of polyhydric alcohols in ethereal solution in presence of a catdyst such as potassium carbonate or sodium ethoxide are moderately rapidly transformed into di-esters and free alcohols. A similar explanation is untenable, however in the cam of trimethylene glycol bisdinitrophenyl ether, for when the mono-ether was treated with a solution of sodium in trimethylene glycol under the conditiom existing during the condemtion with chlorodinitrobenzene no bis-ether was found in the product the very different solubilities of the mono- and bie-ethers in acetic acid rendering the absence of the latter easily provable.The a-structure of monosodium glyceroxide (loc. cit. p. 1036) has been codrmed by the following series of reactions using isopropyl-idene glycerol (Irvine Soutar and Macdonald J. 1915 107 337; %her Ber. 1920 53 1589) X denoting p-C6H4*N0 or 3 5-C,H,(NO,), YE[,=OH YH-OH (111.) CH,*CO,X SCOCl YH,-OR YH-OH -GG+ YH,*OH ( CH,*ONa VH-OH h-/?-HCl-f E X P E R I M E N T A L. Trimethylene Glycd Mono-2 4-dinitrqhenyl Ether (I).-Sodium (1.14 g . ) WBB dissolved in small portiom to prevent charring in 40 C.C. of trimethylene glycol and the solution waa stirred and heated a t 100” while a suspension of 10-2 g.of 1-chloro-2 4-dinitrobenzene in 30 C.C. of the glycol waa gradually added. Heating and atirring were continued until t,he chlorodinitrobenzene dissolved (4 hour). The product wm poured into ZOO0 C.C. of 20% acetic acid an oi 2762 FAEELBOURNE AND FOSTER CONDENSATIONS OF THE being precipitated. The whole was boiled for 30 minutes; most of the oil had then redissolved and the remainder had crystallised (A). The solution waa filtered and cooled to 0" after 24 hours. The colourle~ needles deposited were dried in a vacuum over sulphuric acid and recrystallised from benzeneligroin (b. p. 4-0-60"). The ether thus obtained (yield 6 g.) m. p. 52" was soluble in ether, benzene alcohol acetone or acetic acid and sparingly soluble in water or ligroin (Found N 116.C&€,,,O,N requires N 11.55%). The ace@ derivative prepared by heating the ether for a few minutes with 2 vols. of acetyl chloride and acetic anhydride (equal parts) and boiling the product with much water separated from the filtered solution in long colourless needles m. p. 85" the yield being nearly quantitative (Found C 46.1 ; H 4.45 ; N 9.9. Cl1H1,O,N, requires C 46-4 ; H 4.25 ; N 9.9%). The benzoyl derivative was prepared by shaking a warm mixture of the ether and benzoyl chloride with successive small quantities of 20% sodium hydroxide solution added in sufficient amount fo prevent the orange colour from being discharged; water was then added. The benzoyl derivative obtained as a semi-solid mass on cooling the mixture separated from alcohol in colourless crystals, m.p. 95" soluble in most of the common organic solvenfs (Found : N 8.2. Cl6HI40,N2 requires N 8011%). Trimethylene Glycol Bis-2 4-dinitrophenyl Ether (=).-The substance (A) mentioned above was sparingly soluble in alcohol, ether or acetone but by recrystallisation from boiling glacial acetic acid the bis-etk was obtained in colourless needles (yield 0.5 g.) m. p. 180" (Found C 44.0; H 3.2 ; N 13.4. C15H12010N4 requires C 44.1 ; H 3.0; N 13.6%). Glyceryl Tri-p-toluenesulphonate C,H5(0*S02*C7H7),.-Disodium glyceroxide was prepared by the method of Lobish and Loos (Mon&h. 1881 2 842) (Found Na 33.0. A mixture of equimolecular proportions of either mono- or di-sodium glyceroxide and p-toluenesulphonyl chloride in dry ether or benzene was kept for 24 hours then boiled under reflux for hour, and filtered.The glyceride obtained on distilling off the solvent slowly solidified and crystallised from alcohol in colourless needles, m. p. 103" (Found C 51.6 51-8; H 4.8 4.8; S 174; M cryo-ecopic in benzene 564. CeaH,609S requires C 52.0; H 4-7; S 17.3%; M 554). Glyceryl tribenzenesulphonate obtained in a similar way from benzenesulphonyl chloride crystallised from alcohol in needles, m. p. 80" (Found C 49.0; H 3.9. C2,H,0gS requires C 49.2; H 3.9%). Action of Benzoyl CAloride upon Sodium G1yceroxides.-The Calc. Na 3343%) SODIUM D E R X V A ~ S OF TRIMETHYLENE GLYCOL ETC. 2763 producta obtained by the action of an ethereal solution of benzoyl chloride on mono- and di-sodium glyceroxides were not identical.Monosodium glyceroxide yielded a-monobenzoyl glycerol (compare loc. cit. p. 1340). Disodium glyceroxide yielded tribenzoyl glycerol which even after repeated crystallisation from ligroin melted at 7 1 7 2 ' (Found C 71.25 ; H 4-95. Chlc. C 71.3 ; H 4.95%). The m. p. is given by Skraup (Nonatdi. 1889 10 393) as 75-76*5" by Balbiano (Ber. 1903 36 1574) as 71-72" and by &a& (itid., p. 4341) as 76". A comparison of these references and others showed that the substance melted at 76" or 72" according as it had been crysfallised from alcohol or ligroin. The above product was there-fore c r y s t a b d from alcohol. It then melted at 76". Subsequent recrys-tion from ligroin (b. p. W o o ) or slow solidification of the fused material reduced it to 72" again.Action qf p- A'itrobenzuyl CMOnde upon Monosodium G1yceroxide.-Monosodium glyceroxide was treated with an equivalent quantity of p-nitrobenzoyl chloride in ethereal solution and the reaction carried out in the usual manner. The product obtained by filtration and evaporation of the solvent was an oil which solidified on cooling and c r y a w from chloroform in needles m. p. 107". A mixture of this with a specimen of a-mono-p-nitrobenzoyl glycerol (m. p. 107") prepared by Fischer's method (Be. 1920 53 1596) also melted at 107'. In the preparation of isopropylidene glycerol as an inter-mediate product in the second method the resulting liquid boiled at 78-79"/10 mm. isoPropylidene Glycerol 3 5-Dinitrobenzocate (IV).-A mixture of 11.6 g.of 3 5-dinitrobenzoyl chloride and 8-2 g. of dry quholine WM dissolved in 15.6 C.C. of chloroform 6.7 g. of isopropylidene glycerol were slowly added with cooling and the whole was kept for 2 days. The product was shaken successively with water, dilute sdphuric acid sodium bicarbonate solution and water then dried over ignited sodium sulphate and the solvent removed. The residual oil solidified on cooling and crystallised from hgroin (b. p. M O O ) -benzene in colourless needles (yield SO%) m. p. 85", eoluble in benzene ether or chloroform and nearly insoluble in ligroin (Found N 8.6. Glycerol a-Mono-3 5-dinitrobenzacte (ID).-(a) A mixture of equivalent quantities of monosodium glyceroxide and 3 5-di.nitro-benzoyl chloride in ether was kept for 2 days and then heated under reflux.The suspended matter which had little or no a)kdine reaction was filtered off and the solvent evaporated. The reaidurtl oil which solid.ified crystallised from chloroform in colourleas needles m. p. 118" soluble in alcohol ether or benzene; it also C1&€140$2 requires N 8.6%) 27M MACDONALD AND HINSHELWOOD TBE FORMATION AND crystallised easily from water (Found N 9-75. C,oH,oO,N, requires N 9.79%). (b) A mixture of 5 g. of isopropylidene glycerol 3 5-dinifro-benzoate and 100 C.C. of N/2-hydrochloric acid was stirred and heated at 70-80" for 1 hour. The clear liquid was decanted and deposited glycerol a-dinitrobenzoate on cooling. This after being dried in a vacuum over sulphuric acid and crystallised from chloro-form (yield 700/,) melted at 118" alone or mixed with a specimen prepared by method (a). The authors wish to express their indebtedness to the Chemical Society for a grant to one of them (A. F.) which has partly defrayed expenses incurred in this work. Kx~a's COLLEQE LONDON W . C . 2. [Received A?tg?ist 7th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702759

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

27M MACDONALD AND HINSHELWOOD TBE FORMATION AND CCCLXXX.-The Pormation and Growth of Silver Nuclei in the Decomposition of Silver Oxalute. By JAMES YOUNGER MACDONAD and CYRIL ~ToRM-~N HINSHELWOOD. TRIS paper contains first a description of a sensitive method for making direct measurements of the instantaneous rate of reaction in a chemical change where gas is evolved and secondly an account of its application in the investigation of certain interesting phenomena relating to the thermal decomposition of silver oxalate. The decomposition of solid substances frequently off ers the appearance of being autocatalytic the rate of change increasing as the reaction progresses. This is in many instances due simply to an increase in the surface of the solid during the course of the trans-formation (Phil.Nag. 1920 40 569) but it can also be due to the circumstance that the reaction is facilitated by the presence of nuclei of one of the products. To whichever cause the acceleration is due the relation between the velocity of change and the amount of reaction which has already taken place is a very complicated one. The determination of this relation from measurements of the total change 2 which has taken place a t any time t depends upon the drawing of tangents to curves of x and t a procedure involving a large proportional error. The following method was therefore adopted for obtaining direct readings of the actual velocity a t different times during the reaction. The solid is allowed to decompose in a small bulb kept a t constant temperature in a vapour bath The bulb is connected with GROWTH OF SILVER NUCLEI IN THE DECOMPOSITION ETC.2765 M c M gauge and the gaseous products of the reaction are removed by a continuously running Gaede pump. The experiments must be made at temperatures where the rate of evolution of gas is not too great so that the pump is able to mainbin a fairly high vacuum in the apparatus. At intervals measurements of the rate of reaction are made by turning off the tap leading to the pump and raising the mercury in the M c M gauge for a pressure reading. At the moment when the mercury cuts off the bulb of the gauge from communication with the decomposition vessel a stop-watch is started. The pressure reading is completed and the mercury lowered com-munication with the decomposition vessel being once more estab-lished.At the end of a suitable time a second reading of the McLeod gauge is made the watch being stopped at the moment when the mercury once more cuts off the gauge from the rest of the apparatus. In the actual experiments pressure increases of the order of 0.1 or 0.01 ram. were measured in periods of time varying from 45 seconds to 15 minutes in reactions lasting several hours or days. The readings therefore can be regarded as instantaneous. By the use of gauges of various degrees of sensitiveness in different experiments it is possible either to follow the reaction over its whole course or to make a more detailed study of the initial stages. No investigation has previously been made of the mechanism of the decomposition of silver oxalafe.It is usually assumed that the change takes place in accordance with the simple equation C204Ag,= 2Ag + 2C0,. This was confirmed by an analysis of the residue which was more than 99.8% silver and of the gas, which was pure carbon dioxide containing no trace of carbon monoxide. If the reaction involved the intermediate formation of carbonate or oxide carbon monoxide would necessarily appear in the gaseous products. Various specimens of silver oxalate behaved very differently, falling roughly into two classes. One class decomposed with the most marked acceleration the maximum velocity being about 200 times greater than the initial velocity. The other class showed very much less acceleration and the velocity instead of passing through a sharp maximum remained steady over a large part of the whole course.Specimens of this second class were on the whole about ten times as stable as those of the first class. The difference w a ~ traced to one factor in the method of preparation. All the speci-mens were prepared by precipitation of silver nitrate with sodium oxdate. Those precipitated under such conditions that the sodium oxalate was in excess throughout belonged to the unstable accelerat-ing type whilat those precipitated with silver nitrate always in excess belonged to the stable feebly accelerating type 2766 MACDONALD AND HMSHELWOOD THE FOR.MA!LTON AND The method of preparation was carefully standardised. The precipitant which was not to be in excess was run slowly as a k e continuous stream in the course of about 4 hour into a solution of the other salt which was vigorously agitated by a mechanical stirrer.All the solutions were very dilute-an obvious precaution in view of Richards' well-known investigation of the occlusion difEiculties of Stas-and the precipitation was carried out in black-ened vessels at the ordinary temperature. The silver oxalate was repeatedly washed by decantation and dried in a vacuum desiccator kept in a dark cupboard. As far as we are able to judge all factors were exactly the same in the preparation of the two types of silver oxalate except that one or other precipitant was in excess. The autocatalytic acceleration is not due to carbon dioxide since it takes place in a vacuum. It is not due simply to increase in surface as with potassium pemanganate and some other solids (Eoc.cit.) since it cannot be eliminated by preliminary grinding. It must be due therefore t o nuclei of solid silver formed in the decomposition. Since the initial velocity is very small compared with that finally attained the whole course of the reaction is evidently governed by the formation and growth of these nuclei. The decomposition of solids is essentially a surface phenomenon. More-over the devitrification of glass which depends upon the formation of crystal nuclei is known to start from the surface since the wash-ing of the surface with dilute hydrofluoric acid removes the tendency to further devitrification on heating. It is very probable that in a similar way the silver nuclei are formed at the surface of the oxalate crystals.The formation of nuclei and their subsequent growth are independent phenomena both of which are extremely sensitive to the presence of foreign substances (compare Zsigmondy " Kolloid-chemie," 1922 p. 144). When silver oxalate is precipitated with excess of silver nitrate and sodium oxalate respectively there will probably be Werent ions adsorbed. The different behaviour of the oxalate prepared by these two methods is to be attributed to the effect of the adsorbed ions on the chance of formation of silver nuclei in the solid and on their subsequent growth. As the silver oxalate was always very thoroughly washed during preparation only the definitely adsorbed ions need be taken into account. The decomposition bulb was protected from light by a covering of tinfoil.About fifty experiments were carried out with twelve specimens of oxalate. Some of the results are in the following tables and curves; t is the time in minutes and v the velocity of reaction in arbitrary units GROWTH OF SILVER NUCLEI IN THE DECOMPOSITION ETC. 2767 Temperature 131.8'. (a) Silver oxdata precipitated with excess of d u m oxalate. ( b ) Silver oxalate precipitated with excess of silver nitrate. t . U* t. t'. 5 5.3 39.5 756 12 60 43 628 18 147.5 49 434 21 216 53 340 25 384 60 192 28.5 725 75 154 30.5 958 96 46 32.5 850 140 28.5 35-5 888 263 13-3 This specimen waa precipit,ated with a very large excess of oxalate, and is one of the most unstable. t . U. t. U. 3.5 7 240 48 10 13 270 50 33 32 305 48 43 28 335 31 47 33 360 24 60 31 420 18 105 50 540 13 150 43 600 6.3 180 43 The rise and fall in velocity ie quite real and presumably connected with the fact that the oxdate grains are not quite uniform.Using a more sensitive gauge it is possible to see in more detail the initial variations in rate. The fDllowing results were obtained with a rather more stable specimen of oxalate. Up to 100 minutm, the decomposition amounts to about 1% only. Temperature 131.6". t. V. t. 2'. t . U. t. U. 5 3.4 32.5 45.8 77.5 224 135 477 12-5 3.9 37.5 62.8 86-5 255 149 616 17.5 5.8 47.5 107-2 97-5 310 165 649 22.5 15.6 58.5 152 110.5 374 198.5 680 27.5 26.8 67-5 183 121 407 204-5 618 In this experiment the maximum rate of neitrly 3000 wit8 reached in about 6 hours.It is worth while to give in full the results of one more experiment, made at 110" with a specimen of the accelerating type. Attention may be directed to the long period of steady velocity following the sharp fall from the maximum. t. 5 15 25 40 60 85 135 170 245 313 438 533 0. 1.09 1.22 1.28 1.79 2.70 4-72 12.0 18-6 35.7 50-0 69-4 90-8 1. 759 832 881 936 1,126 1,197 1,331 1,400 1,607 1,737 2,293 2,310 V. 182 214-5 224.5 251 298 276 228 189.5 115 98.0 78.0 82-9 t. 2,405 2,575 2,813 3,127 3,858 4,303 5,180 6,012 6,708 8,873 9,617 13,920 19,700 U. 83.2 83.5 78.7 72.9 51.4 45.9 33.7 25-7 19-3 16-7 14.1 8-7 5.6 The relation between the velocity and the amount decomposed G.N. Lewis investigating the some- is not by any means simple 2768 MACDONALD AND HINSHELWOOD THE FORMATION AND what similar decomposition of silver oxide (2. physikd. Chem., 1905 52 310) thought that the results could be expressed by the simple equation for homogeneous autocatalysis dz/& = kx(u - z). It is difficult to see how the complex process of nucleus formation and jgowth can be so represented. The applicability of the equation to the silver oxalate decomposition can be tested in two ways. (a) &/dt is plotted against t and by square counting a curve of x and t is constructed. It is then readily seen by plotting log [d~/dt/(a - x)j against log x whether the rate per unit amount FIG.I. Influence of the inetlwd of precipitation on thc decomposition of silver ox&&. 20 40 Time in minuterr. Curvea I and II silver oxalate precipitated in preeence of wee88 of aodiurn oxaktd. of oxalate is a linear function of x. It is not. The rate depends upon a power of x which not only varies but is always less than unity. (71) For the very early stages of the reaction as measured with a more sensitive gauge the equation reduces to dxJdt = kx, but to account for the fact that the reaction starts at all this has in any case to be written dxldt = E (z + xo) where xo is a small constant quantity which determines the actual initial rate. From this it follows that log dz/& = h! + constant. This gives a con-venient means of plotting the results without resorting to the laborious process of square counting.The following table contains a set of typical results the figures referring to the initial stages of ~ u r v e s III and I V excerr8 of silver nitrate GROWTH OF SILVER NUCLEI IN THE DECOMPOSITION ETC. 2769 one of the experiments already quoted (second table). dx/& = v. When t = 5 log TJ = 0.53. loge - 0.53 log w - 0.53 t - 5. log w - 0.53. t - 6 t - 5. logv - 0.53. t - 5 12.5 0-23 0.0184 53.5 1-652 0.0309 17.5 0-663 0.0379 62.5 1-713 0-0274 22.5 0.898 0-0399 72.5 1.820 0.025 1 27.5 1.131 0.0412 81-5 1.877 0.0230 32-5 1.268 0.0390 92.5 1.961 0-0212 42-5 1.500 0.0353 105-5 2-043 0.0194 Iqluence of Adsorbed Gases on the Silver NucEei.4ome experi-ments were also made in which the silver oxalate was allowed to decompose in a small bulb connected with a gas burette the rate of reaction being measured simply by the total evolution of carbon dioxide.The results were most unexpected. Sometimes there was no trace of acceleration even with specimens prepared by precipit-ation with excess of sodium oxalate. At other times the acceleration made its appearance after varying intervals of time in an uncon-trollable manner. This was all traced to the infiuence of the air initially present in tjhe bulb. Further investigation showed that oxygen has a pronounced poisoning influence on the reaction. This is evidently due to its being adsorbed on the nuclei of silver aa soon as they are formed on the surface. Their growth is thus hindered *or stopped.Experiments carried out in an atmosphere of carbon dioxide followed almost exactly the same come as those carried out in a vacuum and the influence of nitrogen appears to be but slight. Fig. 2 shows clearly the pronounced poisoning influence of air. The explanation is now obvious of the puzzling results obtained when silver oxalate is allowed to decompose in a bulb initially fUed with air which is gradually replaced by carbon dioxide; there is a sudden acceleration of the reaction when the air is all displaced from the surface of the crystals. In order t o study the reaction under conditions where the poisoning effect of air waa constant, experiments were made in a stream of air the rate of reaction being measured periodically by cutting off the stream and allowing the pressure to rise.The stream was sufKciently slow for there to be no appreciable coohg effect as the air passed through a consider-able length of heated tubing before actually coming into contact with the silver oxalate. In a continuous stream of air or even in the presence of still air the reaction is spread out over a time about ten times as long as in a vacuum or in presence of carbon dioxide. The poisoning effect is relatively more marked with the unstable accelerating specimens precipitated with excess of sodium oxdate than with those precipitated in presence of an excess of silve 2770 THE FOBNATION AND GBOWTH OF SILVER NUCLEI ETC. nitrate since in the latter the acceleration is already to some extent inhibited. The changes in colour which accompany the decomposition a m interesting the white oxalate passing through pale to deep brown and then becoming black.When the reaction is nearly complete some sort of recrystallisation of the silver seems to occur and the whole mass becomes almost white. Addition of the h a 1 product does not cause an increase in the rate of reaction. Evidently coamr particles of silver are not effective in catalping the change in the same way as the minute nuclei formed in the space lattice of n u . 2. Influence of air on the decomposition of silver oxukste. 100 80 20 0 60 120 180 240 Time in minutea. the oxalate crystals themselves. Experiments were made on the influence of previous grinding. This produced some increase in the rate of reaction but did not eliminate the autocatalysis aa with potassium permanganate and some other solids.The influence of temperature was investigated with a few of the specimens. It is normal and more or less uniform throughout all stages of the decomposition. Over the range 100" to 150" the rate increases approximately 2.7 times for 10". Summary. The thermal decomposition of silver oxalate takes place in accord-ance with the simple equation (CO*OAg)2 = 2Ag + 2C0, PURVIS THE INFLTJENCE OF DIFFERENT NUCLEI mc 2771 Its rate is governed entirely by the formation and growth of nuclei of silver in the space lattice of the oxdate crystah. These processes are sensitive to the presence of adsorbed ions, since silver oxalate precipitated in presence of excess of sodium oxalate behaves quite Merently from that precipitated in presence of excess of silver nitrate. This is in some respects analogous to the influence of adsorbed ions on the photo-sensitivity of silver bromide described by Fajans and Frankenburger (2. EEektrockm. 1922 28, 499). In a vacuum and in an atmosphere of carbon dioxide the rate of reaction is the same but the presence of oxygen has a very pro-nounced poisoning effect on the silver nuclei. This is an example of catalytic poisoning of a new kind. The influence of adsorbed ions and of oxygen seems to show that the nuclei must be first formed at the surface of the oxalate crystals rather than at any point in the interior. PHYSICAL CHEmsmy LABORATORY, BALLIOL COLLEGE ~LND TRWITP COLLEGE, OXFORD. [Received July 4th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702764

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

PURVIS THE INFLTJENCE OF DIFFERENT NUCLEI ETC 2771 CCCLXXX1.-The Inpuence of Different Nuclei on the Absorption Spectra of Substances. IN previous papers (J. 1914 105 590 1372) the author described the absorption spectra of substances containing several benzene nuclei and it was shown that the phenomena were very different in substances containing two three and four benzene residues even when the nuclei with which they were combined had no specific absorption. The aim of this communication is to describe the absorption spectra in the ultra-violet region (1) of substances in which each nucleus shows specific absorption when uncombined and (2) of substances in which only one of the nuclei shows specific absorption. Alcoholic solutions of the following substances were examined : Salicylic wid,.phenyl salicylate o-acetoxybenzoic acid benzyl salicylate thymol dicylafe camphor camphor dcylate theo-bromine theobromine salic ylate t heo bromine o- acetoxybenzoate , caffeine caffeine SalicyIate caffeine benzoate caffeine citrate, caffeine hydrochloride phenazone phenazone salicylate quinine, quinine salicylate and quinine o-acetoxybenzoate. Most of the substances were examined in the first instance in M/200-solution, By JOHN EDWARD PURVIS 2772 PURVIS THE INFLUENCE OF DIFFERENT NUCLEI but theobromine and caffeine and their salicylates were soluble only in about &2/2,OOO-&rength. A condensed cadmium spark was the source of radiant energy. Hartley’s observation (J. 1888 53 641) that this substance has two bands in the ultra-violet region has been confirmed.Salicylic acid. FIG. 1. Oscillation jrquencies. 30 32 34 36 38 40 43 44 Upper curve8. Lower czcmrs. I PhenyE salicylatc. I Theobmnine. I1 o-Acetoxybenzoic acid. II Theobmmine ealicyEafte. I11 Camphor ealicylate. III Theobrmine o-acetoxybenzoate, Pirenyl sdicylate. This has two bands like those of the acid. On comparing photographs of the two substances it was clear that there was a shift towards the red end and the less refrangible band of the salt was not so strong as that of the acid; and also the more refrangible band was better marked. Fig. 1 I (upper series) gives the curve for the salt. The replacement of the hydrogen in the hydroxyl group by acetyl has produced a strikurg change in the absorption (Fig.1 11 upper series). The less refrangible ba,nd a t o-Acetoxybenxoic mid ON THE ABSORPTION SPECTRA OF SUBSTANCES. 2773 1/G650 (1,2740) is much weaker and is shifted f0Wr;trds the more refrangible regions. When the spectrum is compared with that of salicylic mid or phenyl salicylafe the more refrangible band is represented by an extension of the rays from 1/A4150 ( M 8 ) to 1/14350 (X2298). The general appearance of the absorption is not unlike that of benzoic acid and this is usually assigned to the benzene nucleus. Thymol salicylate. Benzyl sdicylate. The bands of these two substances were similar to those of salicylic acid and phenyl aalicyl-ate and mered chiefly in position correspondmg to difEerences in their respective molecular weights. The three benzene bands of the benzyl nucleus do not appear as they do in such substances as dibenzyl carbamate and benzyl chloride (Purvis J.1914 105, 1372; 1915 107 496). The curves have not been reproduced. The curve (Fig. 1 III upper series) shows that the two bands of the acid have not been very much affected. The dif€erences are that the less refrangible band is not so strong as that of mlicylic acid or of phenyl salicylate and the more refrangible band is weaker. Camphor has a weak band at 1,h3480 (X2870) aa described by Baly Marsden and Stewart (J. 1906 89, 979) and c o h e d by Hartley (J. 1908,93,961) and by the author (J. 1915 107 643). The&onsine ; theobromi?ie salicybcste ; theobromine o-aceioxybenz-ode. Cafjeine ; cufjeine salicylste. Hartley (J. 1905 87 1796) describes the absorption spectra of theobromine *and caffeine.His photographs show a defhite band in theobromine but not in caffeine. In the text he states that " there is a sudden lengthening of the spectrum and its enfeeblement between 1/X3675 (A2720) and 1/X3794 (A2635) as if an absorption band was indicated hereabouts of a very feeble or ill-defined character." The author has repeated the observations and finds that caffeine has a definite band like that of theobromine but shifted a little more towards the red end. The curves of theobromine and its salts (Fig. 1 I lqwer series) show that the rays passing through theobromine salicylate rapidly step out between 1/h3030 (13298) and 1/~3350 (U980) and there is a band at 1/13650 (X2740). It is obvious from this that the acid nucleus exerts some iduence on the absorption.The curve of theobromine o-acetoxybenzoate shows considerable Merences. It is not unlike that of theobromine itself but narrower and the ultimate effect is comparable with that of salicylic acid and o-acetoxybenzoic acid described above. Solutions of caffeine and caffeine salicylate show similar pheno-mena to theobromine and theobromine salicylate. Cageine benzoate cageirze citrate cageine hydrochE0n'd.e. Soh-Camphor sazicyhte 2774 PURVIS THX ~ I J E X C L OF DIFE"EBIENT NUCLEI tions of these salts give results like those of the base itself except in regard to the positiom of the bands which vary according to the molecular weighta. The author (J. 1915 107 966) showed that benzoic wid has a weak band at lfh3600 (k2770) and also that there was a rapid step-out of the rays from about 72320 into the FIG.2. OscilEdion frequencies. 30 32 32 36 38 40 42 44 U m e r curues. I Phmzone. 1 I .-Lower curves. I (continuous) Quinine. 1 -28mm. M/2000 -Fi ~ 2 8 m r n . E M/20000 .x, 3 2 % - 5 28mm. 2 1M/2000 x - s G --28 rnm. -* 211/20000 I1 PhAazone salicylste. I1 (dash) Quinine saZicylate. I11 (d.aah and dot) Quiaine o-acetoxybeneoate, Schumann region. Hartley and Hedley earlier (J. 1909 91 314) had indicated the presence of the weak band only. It is clear, therefore that the acid nucleus has not affected the general form of the caffeine absorption. Neither citric acid nor hydrochloric acid gives specific absorption in these ultra-violet regions.The curves have not been reproduced. The curve shows (Fig. 2 upper curves) that phenazone has two wide bands at 1/13600 (X2776) Phnazone ; phenazone salicykrte ON THE ABSORPTION SPECTRA OF SWSTBHOE~. 2775 and l/A4150 (~2409). The salt shows a rapid extension of the m p between 1/X3050 (A3270) and 1/X3260 (X3066) and two weak bands a t l/A3400 (BW) and 1/h4100 (l2438). Aa in theobromine and caffeine the rapid extension of the rays may mean the remnant of the less refrangible band of salicylic acid. Hartley (Phil. Tram. 1885 176 471) first described two bands in solutions of quinine at about 1/A3100 (13225) and 1/X3600 (2770). Dobbie, Lauder and Fox (J.? 1911 99 1254; 1912 101 77) described a third weak band at 1/X3740 (h2670).The author has repeated these experiments and fin& only a very weak indication of this third band. The curves (Fig. 2 lower curves) show that the original quinine bands have sdered some changes in strength and position in the salicylate. Both the bands of the salicylate are w d e r than those of the base. In the case of the o-acetoxybenzoate there is a return to phenomena not unlike those of the base itself and there is a shift back nearer to the latter. These changes are comparable (although the differences are not so great) with those of salicylic acid and o-acetoqbemoic acid and of theobromine and its salts described above. The rapid extension of the rays from l/A4100 is noticeable in all three substances. ResuZts.-The chief results of these observations are (1) the bands of phenyl benzyl thymol and camphor salicylates are com-parable with those of salicylic acid the differences from the latter, and from one another being chiefly in position and strength; (2) the basic nucleus is the chief agent in the specific absorption of the benzoate citrate and hydrochloride of caffeine ; (3) in the salicyl-ates of theobromine caffeine phenazone and quinine the acid nucleus modifies that of the basic nucleus to a larger extent but least in the quinine compound (4) in o-acetoxybenzoic acid and in the o-acetoxybenzoates or' theobromine and quinine the replacement of the hydrogen of the hydroql group by the acetyl group exerts a very great influence on the final absorption.It is clear therefore that the specific and the general absorption of these substances depend upon three factors; (a) the nature of the base ( b ) the nature of the acid and ( c ) the presence of hydrogen in the hydroxyl group.Now benzoic acid has a very weak band at 1/A3600 (x2777) and phenol a very strong one at 1p670 (2720). The carboxyl group in the one and the hydroxyl group in the other destroy the well-known bands of benzene and the hydroxyl group replaces these by a much stronger one than is produced by the carboxyl group. It appears from these experiments that the replacement of the hydrogen atom of the hydroxyl group by another radical not itself possessing any specific absorption decreams the Quinine quinine salicylate quinine o-metoxybenzoate 2776 GOSS AND INGOLD THE POSSIBLE ENHANCED absorption capacity of the other parts of the molecule or to put it another way the vibration of this hydrogen atom is a very powerful factor in the absorption. PUBLIC HEKLTH CHEMICAL LABORATORY, CAMBRIDGE. [Received September 14th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702771

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

2776 GOSS AND INGOLD THE POSSIBLE ENHANCED CCCLXXXI1.-The Possible Enhanced Activity of Newly-formed Molecules. By FRANK ROBERT Goss and CHRISTOPHER KELK INGOLD. IN the course of investigations carried out during the past few years the authors have frequently been unable to confirm an apparently obvious reaction mechanism by preparing the supposed intermediate products and subjecting them to the conditions of the original experiment ; the substances either remained unaltered or behaved differently from expectation. Similar experiences have been recorded by others and the phenomenon appears sdciently widespread to give some support for the suggestion that intermedi-ates may be produced in a reactive condition in which they are capable of changes which cannot occur after the energy associated with the formation of the compound has been dissipated.This hypothesis of " nascent molecules " is of course not new; but it is one which should be accepted only after conclusive evidence has been furnished and whilst it is not claimed that the observations recorded in this paper constitute sufficient grounds for embracing ao far-reaching a hypothesis they appear to possess some sig-nificance from this point of view. Two mechanisms suggest themselves for the formation of the cyclobutane ester (IV) (Markovnikov and Krestovnikov Annalen, 1880 208 334) from a-chloropropionic ester (I) and sodium eth-oxide the elimination of hydrogen chloride is either inter-molecular, in which case 7-chloro-a-methylglutaric ester (11) is the inter-mediate product or intramolecular ethyl acrylate (In) being first formed : $!H2*CHCI*X CH,-CHCI-X X'CHmCH3 (11.) '4 (-i~(-p.x XCHXH (III.) ,H XCH-CH (IV.) X*mmCH (''1 1' \% CH,:CH.X (X=CO,Et) The chloro-ester (11) haa been prepared and subjected fo the It gave no action of sodium ethoxide under the same conditions ACTIVITY OF NEWLY-FORMED MOLECULES.2777 detectable quantity of the cyclobufane eater but on the other hand yielded the cyclopropane ester (V) together with the lactonic ester (VI) the unsaturated eater (VII) and the ethoxy-ester (VIII). H,C<CH(Co@t)'? (vI.) CH(CH,)- CO C02E t*CHMe-CH:CH*CO& t CO,Et*CEKMe*CBj.CE( OEt )*CO,Et (VII.) (VIII.) Acrylic ester (111) was treated in a similar manner. Again no cydobutane ester could be detected but only its unsaturated isomeride a-methyleneglutaric ester (IX) which waa the chief product apart from P-ethoxypropionic ester (X).(IS-) C02EtCH2*CH2*C( :CH2)*CO& t E t OC%42H2*C0&t (X.1 Although these experimenta provide no direct evidence of the intervention either of (11) or of (III) in the series of changes leading to the cyclobutane ester (IV) it may not be inappropriate to suggest fhat if the later change depends on the energy of formation of the intermediate probably it is acrylic ester that acts in this way; for not only are four-membered rings produced on the whole more easily by additive synthesis than by the closure of a chain but also the double linking in acrylic ester is more likely to derive temporary activity from it8 own formation than are the chlorine or methyl-hydrogen atoms of (11) from a reaction in which they are not directly concerned.In this connexion the suggestion may tentatively be advanced that the double bond in acrylic ester is possibly semi-polar when first produced (which it would be if hydrogen and chlorine were removed from chloropropionic ester, not as atoms but as ions) although it is undoubtedly non-polar in the ordinary substance (Sugden Reed and Wilkins this vol., p. 1525). It has been observed (J. 1922,121,1552) that a-campholenic acid (XI) when warmed with an alkaline suspension of silver oxide becomes partly converted into camphor (XIII) and the suggestion. was advanced that reduction to dihydrocampholenic acid (XII) first occurred. This reaction has again been investigated and both cis- and trans-dihydrocampholenic acids have been subjected to similar experimental conditions ; both however remained unaltered.C,HI,-CH2*C02H + C8Hl,DC]&oC02H + C H 1 4 q i 2 (XI.) (XII.) (XIII.) Other case8 have been observed in connexion with the opening of the cyckpropand ring. It has been shown that methoxy 2778 GOSS AND INQOLD TEEE POSSIBLE E " C E D cyclopropanes on treatment with demethylating agents yield first cyclopropanols which may undergo further conversion info open-chain ketones the extent of the latter reaction being limited by its reversibility and the consequent equilibrium which varies from case to case : In the case of the methoxy-ring acid (XIV) the corresponding keto-acid is of course acetosuccinic acid (XV) which if acid is used as demethylating agent passea info laewlic acid with loss of carbon dioxide.It is more remarkable however that when concentrated alkali is employed laevulic acid is still the sole product, although acetosuccinic esters yield mainly succinic and acetic acids, and only a small proportion of laevulic acid under these conditions. On the other hand if alkali of the same strength is used to open the ring in the cycbpropene acid (XV1)-a reaction which in view of the known tendency of glutaconic acids to add on water in the presence of alkalis giving p-hydroxy-acids (e.g. XVII) can scarcely be supposed to proceed ot,herwise than through acetosuccinic acid-only succinic and acetic acids are produced. (XIV.) (XVI.) WhiISt the most the mechanism formulated below has been establiahed probable one for the formation of Balbiano's acid (XXI) from camphoric acid (XVIII) by oxidation Pandya and Thorpe (J.1923 123 2858) synthesised the intermediate hydroxy-ring acid (XX) but could not convert it into Balbiano's acid. Although working with other ends in view they were struck by this and suggested that the real intermediary was the opposite stereo-isomeride to that which they had synthesised; it can however, readily be seen from models that the intervening hydroxy-acid should possess precisely the codguration of the acid which Pandya and Thorpe synthesised and found unreactive. Other similar instances involving the failure of a ring to open have been recorded from time (XVIII.) ax.) fo time-and some of these are now under investigation.HO-$JMe*CO,H HO*CH*C02H + ?Me2 (XIX.) ACTIVITY OF NEWLY-FORMED MOLECULES. 2779 E X P E R I M E N T A L . Action of Sodium E t M on Eayl a-ChlurFo@nate.-Ethyl a-chloropropionate prepared from pure dry lactic acid (Briihl, Ber. 1876 9 35) was treated with sodium ethoxide as deacribed by Markovnikov and Krestovnikov (loc. cit.) and by Haworth and Perkin (J. 1898 73 336). To 20 g. of the ester at SO" dry sodium ethoxide (10 g.) was added in small portions ; the temperature waa kally kept at 100" for 3 minutes and after cooling the product was poured into dilute acid and isolated by extraction with ether. As stated by Markovnikov and Krestovnikov it consisted mainly of ethyl a-ethoxypropionate b.p. 50°/4 mm. This was converted into ifs amide which melted a t 63" after crystallisation from petrol (b. p. 40-40") and was identified wit.h that described by Wurtz (Ann. chim. 1860 59 174) (Found C 50.9 ; H 10.0. Calc., C 51.2; H 9.5%). The remainder (about 10%) of the product, b. g. 120"/4 mm. consisted of the cycbbutane-1 3-dicarboxylic ester which was converted by hydrolysis into the corresponding acid m. p. 170° as described by Markovnikov and Krestovnikov. Action of Sodium Ethoxide on Ethyl u - C ~ r o - y - ~ t h ~ ~ l u ~ r ~ Ethyl a-chloro-y-methylglutarate (this vol. p. 393) waa prepared by treating the lactone of ethyl a-hydroxy-y-methylglutarate with phosphorus pentachloride and pouring into alcohol. The decom-poaition with sodium ethoxide (12 g.and 40 g. of the ester) was carried out as described above and the product was completely hydrolysed. The acids were digested for some days with an aqueous suspension of precipitated calcium carbonate and the filtered solution waa concentrated and allowed to crystallise; the calcium salt of the trans-cycbpropane acid (m. p. 168") then separated. The filtrate from the calcium salts was worked up for organic acids, which were converted through their silver salts into benzyl esters. The portion of these boiling below 240°/15 mm. yielded the original lactone on hydrolysis. By distillation at 1 mm. the leas volatile esters were separated into a small preliminary fraction from which on hydrolysis a-methylglutaconic acid together with a liquid acid (probably the ethoxy-acid described below) was obtained and a fraction (32 g.) b.p. 230-260" which on hydrolysis gave a liquid consisting as analysis indicated mainly of the ethoxy-acid. This waa purified by careful distillation of the ethyl ester b. p. 126-129"/12-14 mm. (Found C 58.1 ; H 9-0. C12HB05 requires C 58.5; H 8.9%); the liquid acid was recovered by hydrolysis (Found C 50.2; H 7-5. C,H,,O requires C 50.5; H 7.3%). Adion of Sodium E t h d e on Ethyl Acqlute.-Ethyl acrylate wit8 prepared from ethyl ap-dibromopropionate by R80hm's method VOL. CXXVII. 5 2780 GOSS AND INGOLD THE POSSIBLE ENHANCED (Ber. 1901 34 573). The reaction was carried out exactly as described in the case of ethyl a-chloropropionate except that for 20 Q. of ester 15 g. of sodium ethoxide were employed.The products were isolated in an identical manner and again consisted to the extent of nine-tenths of a liquid distilling at 50"/4 mm. and one-tenth of a liquid distilling at 120'14 mm. The former waa shown to be ethyl @-ethoxypropionate (compare Purdie and Marshall, J. 1891 59 475) by conversion into the corresponding amide deacribed by Kilpi (2. physikd. Chm. 1912 80 184) which was crystallised from water; m. p. 50" (Found C 50.6; H 10.1. Calc. for C,H,,O,N C 51.2; H 9.5%). The high-boiling fraction consisted of ethyl a-methyleneglutarate and yielded on hydrolpis the corresponding acid m. p. 130" (Rohm Ber. 1901 34 427). a- Campholenic Acid and a-Cumphlenumide.-dl-Campholeno-nitrile b. p. 100"/5 mm. was prepared by the method of Tiemann (Ber.1895 28 2167) from d-camphoroxime and obtained in 75% yield. It was converted into a mixture of the acid and amide by boiling 3 g. with a solution of 5 g. of potassium hydroxide in 25 C.C. of ethyl alcohol. Addition of water precipitated the amide, m. p. 122" and more was obtained by extracting the filtrate. The acid extracted after acidification of the mother-liquor distilled at 137"/1 mm. a-Campblanic Acid.-The cis-acid was prepared by the reduc-tion of a-campholenic acid with hydrogen and platinum black (Lipp Ber. 1922 55 1883). The truns-acid was obtained by reducing a-campholenamide in the same way (Eoc. cit.) and hydrolysing the a-campholanamide h t formed by boiling for 50 hours with 3 g. of potassium hydroxide in 15 C.C. of alcohol. Action of Silver Oxide on a-Camphlenic Acid and a-Campholanic Acid.-a-Campholenic acid and cis- and tram-a-campholanic acids were added in separate experimenfs to a suspension of 2-5 g.of silver oxide in a solution of 0.5 g. of calcium oxide in 25 C.C. of water. In the experiment with a-campholenic acid the silver oxide was rapidly reduced and the amount of camphor deposited in the condenser reached a maximum after 4 hours' heating. The saturated acids however gave no trace of camphor under similar conditions even after several days and the silver oxide remained apparently unaltered. Action of Hydrochloric Acid on 3-Met7wxy-3-methykyclopropane-1 2-dicarboxylic Acid.-The acid prepared as described by Goss, Ingold and Thorpe (J. 1923 123 3358; this vol. p. 468) was boiled for 2 hours with ten times its weight of 20% hydrochloric acid.From the product a quantitative yield of lawulic mid was It was distilled at 140"/1 mm. The acid was distilled a t 141"/1 mm ACTIVITY OF NEWLY-FOBXED MOLECULES. 2781 obtained which was identified by direct comparison and through its semimbazone and phenylhydmzone the m. p’s of which were not depressed by admixture with genuine specimens of the respec-tive substances. The lac tone of 3- hydroxy -3-methylc~propane-1 2-dimboxylic acid was unaffected by this treatment. Action of Potassium Hydmri.de on 3-Mei%xy-3-dykyclo-~zrcrpane-1 2 - d i . c u ~ l i c Acid-The acid ww boiled f p 30 minuta with 64% aqueous potassium hydroxide. From the cooled solution ether extracted lsevulic acid which was identified as described above.The lactone of 3-hydroxy-3-methylcyclopropane- 1 2-dicarboxylic acid wa8 unafiected by the same treatment. Action of Hydrobromic Scid on the Metbxy-acid Fomndon of 3- Methyl- A2-cyclopropene- 1 2-diCarboxyZic Acid.-The methoxy-acid was boiled for 1 hour with 20 paris by weight of concentrated hydrobromic acid and the resulting solution was diluted and extracted with ether methylcyclopropenedicarboxy~c acid being obtained. Action of Potassium Hydroxide on 3-M&yl-A2-cycloprope~-1 2-dicarboxylic Acid.-(1) The ring-acid was boiled for 2 minub with 55% aqueous potassium hydroxide and the solution was cooled strongly acidified and extracted with ether. Unchanged material was recovered. (2) The experiment was repeated the time being increased to 30 minutes. The product consisted of a mixture of the cy&-propene acid and succinic acid which were separated by fractional cryst&Uisation and identified by direct comparison. (3) The ring-acid wit8 boiled for 2 minutes with 64% potassium hydroxide. On working up for acids a mixture of the cycbpropene acid and succinic acid WM obtained. (4) The above experiment wit8 repeated the time being increased to 30 minutes. The solid product consisted solely of succinic acid. Acetic acid also was produced but this wit8 detected by qualitative tests only and was not purified. We desire to thank the Chemical Society for a grant which has defrayed part of the expense of this investigation. THE UNIVERSITY LEEDS. [Received May 2let 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702776

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年代:1925

数据来源: RSC

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2 782 READ AND COOK: CCCLXXXII1.-Researches in the Menthane Series. Part I . By JOHN READ and SON MARY RITCHIE COOS. THE information hitherto available respecting dl-menthone is derived mainly from the work of Pickard and L i t t l e b q on the catalytic reduction of thymol (J. 1912 101 109) and a note by Wallach on the catalytic reduction of synthetic dl- Al-p-menthen-%one (Annden 1913 397 217). It is questionable whether a pure specimen of dl-isomenthone had been prepared and recog-nised it8 such prior to the work of Hughesdon Read and Smith on the reduction of piperitone (J. 1923 123 2916). The " inactive menthone" prepared by Wallach gave the semicarbazone (m. p. 212") characteristic of dl-isomenthone whilst the derived oxime (m. p. 79-80") corresponded with dl-menthone.These and other apparent inconsistencies in the literature of the subject have now been satisfactorily explained and it has been found possible to convert dl-piperitone at will into derivatives of either series. Alkaline reduction of dl-piperitone (1 below) yields a mixture of liquid and solid menthols in which it has not proved possible to detect &-menthol or dl-ncomenthol ; a preliminary examination of the menthols concerned indicates that they are derived from dl-isomenthone rather than from dl-menthone. By means of the operations summarised below this material was transformed suc-cessively to dl-isomenthone (3) d-menthol (4) and dl-menthone (5). In a further series of operations (6 7 and 8) a more direct passage from d-piperitone to dl-isomenthone and dl-menthone was secured : ( 1 ) d-Piperitone I (Hydrogen and palladium) I + 1 .1.J. 1 I (Sodium and alcohol) dl-&oMenthols I I (Chromic acid) Q-isoMenFhone (6) d-isoMenthone (Sodium 'and alcohol) (Sodium &d alcohol) + J. dl-Menthol [ + d-iaoMenthols] (7) Q-Menthol [ + d-hoMenthols] I I (Chromid acid) J. dl-Menthone (Chromic 'wid) 4 (8) dl-Menthone relationships may be explained on the basis of the establish-ment of definite dynamic equilibria between isomenthone an RESEARCHES IN THE MENTHONE SERIES. PART I. 2783 menthone in the presence of alkali and under other influences. The main product of the alkaline reduction of dl-imenthone is dl-menthol which may be separated to a large extent in the c-l-line form from the rtssociated liquid material.The latter is probably composed largely of dl-menthol accompanied by a liquid mixture of dC-isomenthols. From the above considerations it is clear that by repeated oxidation and reduction this liquid by-product may be used as a source of further quantities of crystdine d-menthol. When dl-menthol is oxidised by chromic acid in the final operation it yields practically pure dl-menthone which shows little tendency to isomerise into dl-isomenthone in the presence of this reagent. By treating the resulting d-menthone with alcoholic alkali how-ever it may be transformed info the equilibrium mixture of dl-menthone and W-iaomenthone. Through the careful avoidance of disturbances due to the use of alkaline reagents it has been p i b l e to prepare a number of pure derivatives of d-menthone and dl-isomenthone the melting points of which are indicated in the following summary : Derivative.dl-GoMenthone. dl-Menthone. Wallch's value. Oxime ........................... 99-100" 81-42' 79-80" Beneoyloxime .................. 55.5 72-73 69-70 tkooxime ........................... 94-95 114-1 15 Semicarbezone (a) ............ 225 185-186 219 87-88 - 9 ) (8) ............ 177- 178 161 The melting points of the semicarbazones of dl-isomenthone were observed by Eughesdon Smith and Read (loc. cit.). The values quoted in the laat column suggest that the " inactive menthone " described by Wallach (loc. cit.) consisted of dl-isomenthone from which the oxime was prepared in an alkaline medium. dLd80-Menthoneoxime is remarkable by reason of its capacity for forming well-developed crystals so that for the first time it becomes F i b l e to submit a menthoneoxime to a complete goniometric examination.dl-Menthone and W-isomenthone may most readily be discriminated by preparing the oximes or semicarbazones in weakly acid solutions. Up to the present attempts to reduce piperitone to menthol or menthone in an acid medium have been unsuccessful the ketone being practically unaltered by such reagents as tin and concen-trated hydrochloric acid or zinc dust and glacial acetic acid. Dis-tinct evidence was obtained of the formation of an appreciable amount of dl-a-phellandrene during the alkaline reduction of dl-piperitone the relationship being of particular interest in view of the occurrence together of the laevo-modifications of these two subbnces in various eucalyptus oils 2784 READ AND COOK: EXPERIMENTAL.Produd obtained through an Initial Alkaline Reduction of dl-Pipen'tone.-l. The piperitone used throughout this work wm extracted from the essential oil of Eucalyptus dives using sodium bisulphite ( J . sot. c h m . Id. 1923 42 339~). 2. In order to avoid all possibility of the formation of optically active products the piperitone (a0 g.) was racemised by means of alcoholic sodium ethoxide prior to reduction with sodium and alcohol (J. 1923 123 2270 2918). Altogether 880 g. of dl-piperi-fone yielded 820 g. of crude menthol which was submitted fo two systematic distillations under diminished pressure. The first fraction (b.p. to 87"/10 mm.) had an odour similar to that of a-phellandrene its physical characteristics (J. 1923 123 1660), together with the ready formation of a nitrosite melting at 106-107" and resembling that of dl-a-phellandrene indicated that the fraction consisted essentially of this terpene. A further series of reductions carried out with piperitone which had been carefully freed from phellandrene by two successive fractional distillations under diminished pressure gave a crude product (223 g.) containing 9.1% of a similar fraction with the following physical characteristics : b. p. to 87"/10 mm. ahe -1958" (1-dcm. tube) n r 1.4798. It therefore appears conclusive that dl- a-phellandrene is formed to an appreciable extent in the alkaline reduction of dl-piperitone.The total yield of menthols was 4204%. 3. Upon oxidation with chromic acid (AnnaZen 1889 250 325), a total quantity of 410 g. of the liquid product (b. p. 95-97"/10 mm.) yielded 332 g. of a liquid possessing the characteristic odour of menthone. When distilled twice under diminished pressure 37% of the product distilled up to 82"/8 mm. (ab' -0.18" nhF 1.4553), and 40% at 82-85"/8 mm. (ar -0-34" n;' 1.4571). The latter fraction was used in preparing the derivatives described below and appeared to consist essentially of dl-igomenthone. 4. Upon reduction with sodium and alcohol in the usual manner, a specimen of the dl-isomenthone just described (24.7 g.) yielded a product (24.0 g . ) which distilled almost completely a t 10Q-105"/15 mm. Three distinct fractions each boiling over a range of one degree between 102" and 105"/15 mm.and having n',"'= 1-4640, deposited crystalline material on cooling the liquid becoming permeated in each instance with h e radiating needles reachmg a length of 2 em. When separated and dried on porous plate the three specimens melted a t 32-34" and yielded the characteristic dl-menthyl hydrogen phthalate. 5. The menthone obtained by oxidising the crystalline dZ-mentho RESEARCHES IN THE MENTHONE SERIES. PART I. 2785 from the preceding operation resembled the product described under (8) below and thus consisted essentially of dl-menthone. Prodwh obtained through an Initial Caddytic Reduction of dl-Pipfi'tone.4. Carefully purified dl-piperitone (50 g.) wm hydrogenated at the ordinary temperature under a pressure of 0.25 atmosphere in presence of colloidal palladium (J.1923 1x3, 2921). The mixed yields from four operations when systematically distilled under diminished pressure gave a main fraction b. p. 90-93"/18 mm. n:' 1.4580; this was optically inactive and appeared to be practically identical with product (3) thus con-sisting of d-isomenthone. 7. Upon reducing 18 g . of the preceding product with sodium and alcohol a yield of 15.5 g. of crude menthol was obtained. This failed to crystallise but when fractionally distilled the portion passing over a t 107-112"/23 mm. (9.3 g.) furnished 2.3 g. of crystals, which possessed the pronounced odour of ordinary menthol and melted a t 32-34". Not only these crystals but also a liquid fraction of somewhat lower boiling point (105-107"/23 mm.; ng. 1.4686) yielded the characteristic dl-menthyl hydrogen phthalate (Pickard and Littlebury Zoc. cit.). 8. dl-Menthol (m. p. 32-34"; 54 g.) was oxidised with chromic acid in the usual manner except that the temperature wit8 raised to 70" in order to decompose the black crystalline chromium compound. The crude product (45.1 g.) when distilled passed over almost completely a t 85-89"/12 mm. and had ng 1.4641. The preparation of the derivatives described below showed it to consist essentially of dl-menthone so that it was identical with product ( 5 ) and differed from products (3) and (6). dl-Menthone possesses a characteristic peppermint odour which is if anything even more pronounced than that of I-menthone.dl-isoMenthone, on the other hand has a decidedly fainter odour of the same general character. De?imtices of dl-isoMEnthne.-dl-isoMenthneoxime was pre-pared from d-isomenthone (b. p. 82-85'/8 mm.) obtained in preparation (3) above by treatment in the usual way with hydroxyl-amine acetate (J. 1922 121 586) 92-4 g. of the ketone yielded 100-4 g. of crude oxime which crystallised partly when kept for a short time in a vacuum desiccator. The crystalline material (35 g.) dried on porous plate melted indefinitely between 85" and W" but attained a constant m. p. 99-100" after three recrystallisations from warm light petroleum. The substance is readily soluble in organic solvents but when pure it crydallises from light petroleum with great ease in magnificent transparent prisms distinguished by their high lustre.The crystals wer 2786 READ AND COOK: kindly measured by Mr. T. V. Bsrker M.A. of the Department of Mineralogy University of Oxford who reports that they are anorthic with forms a m b M c & and rarely 0 developed in the proportions indicated by Fig. 1. The elements a b c = 2.049 1 1.281; a = 112" 12' p = 116" 17' y = 86" 57' were computed from the following results of measurement of four crystals : a(100). m ( i ~ o ) . b(010). ~ ( 1 1 0 ) . ~(001). &(oil). o(ii1). ... 0" 0' 0' 0' 0" 0' 0" 0'*67" 48' *134' 18' 134" 18' p ... 0 0 56 51(14) *82 6 *110 17 *62 48 75 23(3) 52 18(20) Optically t,he extinction is nearly straight with the vertical edge, and an optic axis lies just within the field (Found C 71.1 ; H, 11.1.CIoH,,ON requires C 71.0; H 11.2%). The mother-liquors from the recrystallisation of the oxime dl-isoMenthoneoxime. deposited an oily product when con-centrated by evaporation ; when kept for some time this material furnished a further quantity of the crystalline oxime described above but no other crystalline oxime could be isolated. The lower fraction of dl-isomenthone (b. p. to 82"jS +mm.) from preparation (3) behaved similarly when oximated. dl-isoMenthone prepared by the catalytic reduction of &I-piperitone (6) gave a similar product which however, furnished a considerably higher pro-portion of the crystalline oxime. Fractions melting indefinitely between 60" and 75" were obtained from the mother-liquors but no indication was forthcoming of the presence in these of dl-menthoneoxime.Benxo~l-dl-isomentitoneoxime was prepared by benzoylation in pyridine solution its a viscid oil which was induced to crystallise with great difficulty. The crude product after drying on porous plate melted at 52-54". After three successive recrystallisations from light petroleum in which the derivative is very soluble the melting point became constant at 55.5" the pure substance separat-ing in massive transparent prisms suitable for goniometric ex-amination. The product obtained by benzoylating the oily mother-iquor from the crystalline oxime could not be induced to crystallise (Found C 74.7 ; H 8.9. C,,H,O,N requires C 74.7 ; H 8.8%). dl-isoMenthoneisooziiize prepared by dissolving crystalline dl-iso-menthoneoxime in cold concentrated sulphuric acid (Wallach, Annulen 1894 278 304) crystallised from hot water containin RESEARCHES IN THE MENTHOSE SERIES.PART I. 2787 a little alcohol in fine glistening needles m. p. 94-95'. The product of the reaction appeared to be homogeneous (Found: C 70.2; H 11-1. CloH,,ON requires C 71.0; H 11.2%). Derimtizm of dl-Ment7mne.4-Menthone from preparations ( 5 ) and (8) above when oximated in the manner described for piperitme (J. 1922 121 586) yielded d-menthoneoxime (m. p. 81-82") associated with a considerable amount of oily material. Unlike the stereoisomeric dl-isomenthoneoxime this derivative could not be obtained in crystals sufliciently well developed for goniometric examination. Attempts to benzoylate the crystalline oxime by the Schotten-Baumann method gave unsatisfactory results but by the use of pyridine an oily product was obtained which after extraction with ether and keeping in a vacuum desiccator crystallised spontaneously.The substance crystallised from light petroleum in small trans-parent plates or glistening prisms m. p. 72-73". BenzoyE-dl-. menthoneoxime is very soluble in all the usual organic solvents ; it does not form such well-developed crystals as benzoyl-dl-iso-menthoneoxime (Found C 74-7 ; H 8.6. Cl,H,Oa requires C 74-7; H 8.8%). The oily material from the mother-liquor of the crystalline dZ-menthoneoxime yielded a viscid liquid when benzoylated in pyridine solution. dl-Me~~thoneisooxime prepared from crystallised d-menthone-oxime in the manner indicated above crystallised from hot water containing a little alcohol in fine soft needles m.p. 114-115', and was readily obtained pure (Found C 69-9; H 10.9. C,&€,,ON requires C 71.0; H 11.2%). Upon allowing d-menthone (10.5 g.) to react with semicarbazide in the manner described in a previous paper (J. 1923 123 2920), a crystalline product (10.2 9.) was readily isolated. By continued fractional crystallisation from hot methyl alcohol a small fraction of dl-mentbne- a-semicarbazone was eventually obtained this forms characteristic and well-defined glistening prisms m. p. 185-186" (Found C 62-1 ; H 10.2. CllH210N3 requires C 62.5; H, 10.O~o). The bulk of the product however consisted of small, glistening needles of dl-menthone- p-semicarbcczone m. p. 161-162" ; this derivative is more soluble than the isomeric compound (Found : C 62.7; H 10.3y0). No semicarbazone characteristic of dl-iso-menthone could be isolated from this product; an intermediate product melting at about 177" when mixed with dl-isomenthone-p-semicarbazone (m. p. 177-178"; J. 1923 123 2922) softened a t 158" and melted indefinitely between 169" and 176'. It may be remarked that dl-isomenthone- a-semicarbszone (m. p. 225") is by far tlhe least soluble of the semicarbazones of the optically inactive 5 B 2788 COLVIN THE IONIC ACTIVITY PRODUCT menthones ; its absence from the above reaction-product thus affords a criterion of the freedom of the specimen of dl-menthone from dl-komenthone. We express our thanks to the Department of Scientific and Indmtrial Research for a maintenance grant to one of the authors (A.M.R.C.). The investigation is being continued. UNITED COLLEGE, UNIVERSITY OF ST. ANDREWS. [Received July 6th 1926.

ISSN:0368-1645    

DOI:10.1039/CT9252702782

出版商:RSC    

年代:1925

数据来源: RSC

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2788 COLVIN THE IONIC ACTIVITY PRODUCT CCCLXXX1V.-The Ionic Activity Product of Water in Glycerol- Water Mixtures. By JAMES COLVIN. MEASUREMENTS have shown that a very marked increase occurs in the activity of hydrogen ion derived from hydrogen chloride in aqueous solution in the presence of a solvent-displacing agent, generally a non-electrolyte such as sucrose or glycerol (Moran and Lewis J. 1922,121 1613). It is of interest therefore to determine the activities of hydrogen and hydroxyl ions in a solution containing a eubstance such as glycerol with a view to obtain the value of the ionic activity product of water i.e. the product of the hydrogen-and the hydroxyl-ion activities. Should the product remain constant independent of the concentration of glycerol it would permit of the determination of hydroxyl-ion activities by the hydrogen electrode which is in many cases more convenient to use than a direct hydroxyl-ion electrode such as the Donnan-Allmand electrode.Measurements of the activities of hydrogen and hydroxyl ions were therefore carried out in solutions of N/lOO-sodium hydroxide, containing various amounts of glycerol. EX P E R I M E N T A I,. The sodium hydroxide solution was prepared from metallic sodium and water free from carbon dioxide. The glycerol had been previously employed for conductivity measurements. For the measurements of the E.M.P. of the cells a Cambridge-Paul potentiometer reading to 0.1 millivolt was used in conjunction with a mirror galvanometer. To avoid stray currents the potentio-meter and galvanometer were mounted on glass insulated from earthed iron sheets by paraffin wax.The cells were maintained in a thermostat a t a temperature of 25" & 0.05" OB WATER. ULYCERObWATEB &IXTfTRES. 2789 The Activity of Hydrogen Ion in Aqueous Sdutions of Sodaum Hydroxide and GZycerd.-The cell employed wa,s of the following type: pt N/lm-Na*H I S a t . ~ a N-Calomel + H I Glycerol I I -The electrode consisted of platinum foil coated with platinum black and was placed for 10 minutes in boiling water before use, following the procedure of &and (J. 1909 95 2151). The hydrogen gas was prepared by the electrolysis of a solution of cawtic soda and was washed by paming through a wash-bottle containing the solution under investigation. The gaa thus being saturafed with water vapour at the same pressure as the vapour pressure of the solution in the cell no concentration changes could occur in the solution due to evaporation.As some doubts have been expressed as to the trustworthiness and reproducibility of the hydrogen electrode in alkaline solution, it was thought advisable to carry out some preliminary measure-ments on the cell, N/lO-NaOH Sat. KC1 N-Calomel + I I I The following results were obtained : cell ............... 1 2 3 4 5 6 E.M.P. (volts) 1.0412 1.0415 1.0411 1-0412 1.0415 1-0411 The mean value of the E.M.P. 1.0413 volts is in satiafactory agreement with the value 1-0416 volts obtained by Harned ( J . Amer. Chem. SOC. 1916 37 2460). As the reproducibility of the hydrogen electrode was thus satis-factorily demonstrated measuremenfs were made using N/100-sodium hydroxide in presence of various amounfs of glycerol.As the quantity of glycerol in the solution increased a longer time w m required for the electrode to attain equilibrium ; in all cams, however the values could be reproduced. The activities of the hydrogen ion were calculated by means of the formula xH. = 0.282 + 0.059 log,,pX.. The absolute potential of the calomel elec-trode ww taken to be 0.56 volt at 18". The temperature coefficient of the electrode is 040068 volt per degree hence the value at 25" is 066443 volt (compare Chroustchov and Sitnikov Compt. rend., 1889 108 941). The results obtained are in Table I. The glycerol produces a very marked increase in the activity of hydrogen ion in the solution of alkali.6BS 2790 COLVIN ! THE 3ONIC ACTIVITY PRODUCT TABLE I. G. of glycerol E.M.P. in per 100 C.C. volt. - TH'. QH' x 1012. 0-0 0.9870 0-4222 1.16 12.6 0.9661 0.4013 2.62 20-0 0-9580 0.3932 3-60 25.2 0.9530 0.3882 4.40 40.0 0.9406 0.3758 7-06 The Activity of Hydroxyl Ion in Aqueous Solutiom of Sodium Hydroxide and Glycerol.-The electrode employed was that described by Doman and Allmand (J. 1911 99 845) and consists essentially of a layer of mercuric oxide superimposed on a layer of mercury, the electrode vessel then being Med with the solution under investigation. The electrode reaction is given by the equation HgO + H,O + 2E = Hg + 20H', so that the equation for the electrode potential becomes where E' is t.he elect,rode potential in solutions where all the activities are equal to unity.Since the activities of the mercury and solid mercuric oxide are constant they may be included in the k t term on the right-hand side. For dilute solutions the activity of the water remains sensibly constant. Hence the equation for the electrode potential in dilute solutions may be written The value of the term E was determined experimentally by the following method. - Hg HgO I N/lO-KOH I Sat. KC1 i N-Calomel + was found to be 0.1178 volt at 25". This gives the value 0.4470 volt as the electrode potential in X/lO-potassium hydroxide. The activity of hydroxyl ion in the solution can be obtained from the data of Knobel ( J . Amer. Chem. Soc. 1923 45 70) for the mean activity of potassium hydroxide in aqueous solution.On the assumption that the potassium ion has the same activity in solutions of p o w -ium hydroxide and of potassium chloride of the same concentration, by employing the data of Noyes and MacInnes ( J . Amer. Ckm. SOC., 1920,42,239) for the activity of potassium ion in potassium chloride solutions the value 0.0825 is obtained for the activity of hydr-oxyl ion in N/lO-potassium hydroxide. By putting this value in the expression for the electrode potential the value 0.3823 volt is obtained for E,. x O H ~ = E - 0.059 log, aoH. The E.M.F. of the cell OF WATER IN GLYCEROGWATER MIXTURES. 2791 When glycerol is present however it is no longer justisable to The expression for the equate the activity of the water to unity.electrode potential becomes in which Eo has the value found above. Measurements &th the Donnan-Allmand Electrode.-The mercury used in the cells was distilled in a vacuum. The mercuric oxide was prepared by heating the nitrate until no more brown fumes were evolved. The nitrate itself was prepared by acting on re-distilled mercury with nitric acid (d 1-2) and recrystallising from nitric acid. The product thus obtained gave very reproducible results. At firs% a large electrode vessel wfts used but was soon discarded in favour of a smaller type as equilibrium was then more readily attained. xOH 2 Eo + (0*059/2) log,o aHaO - 0.059 log^^ uOH,, The cells set up were of the type In all cases readings of the E.N.F. were taken at intervals of 24 hours from the time of setting up the cell.In general with N/lOO-sodium hydroxide alone present equilibrium was attained within 48 hours. With glycerol present the E.M.F. declined with time hence a series of readings taken at intervals of 24 hours for the first' 3 days were averaged to gke the E.M.F. of the cell. As five cells for each concentration of glycerol were set up and the readings averaged considerable confidence is placed in the results, which are in Table 11. The activity of the water in glycerol-water mixtures may be obtained from the vapour pressure data of Perman and Price (T'runs. Furaduy SOC. 1912 8 $4) at 70". The activity of the water which may be taken as the ratio of the vapour pressure of the solution to the vapour pressure of the solvent is regarded as independent of the temperature (Lewis and Randall, " Thermodynamics," p.349). TBBLE 11. G. of glycerol per 100 C.C. E.M.F. TOH'. UH&. aOH' x 10'. 0 0-0604 0-5044 1-00 0.883 12.6 0-0394 0-5254 0-98 0.373 20-0 0-03 14 0.5334 0.96 0-270 25.2 0.0266 0.5382 0.94 0.221 40.0 0.0147 0.5501 0.89 0.135 The glycerol produces a marked decrease in the activity of the hydroxyl ion 2792 C O L ~ THE IOHIC ACTIVITY PRODUCT OF WATER ETC. The I m i ~ Activity Product of Wuter.4ufficient data have now been obtained to calculate the ionic activity product and also the dissociation constant of water in presence of glycerol. The results are in Table III. TABLE III. G. of glycerol uE* x UOEP x 1014 per 100 C.C. a H - x 10l2. U O H ~ x 10'. am,-,. ap* XUOHJ x 1014.aE10 0 1.16 0.883 1.00 1.02 1.02 12-6 2.62 0.373 0.98 0.98 1-00 20.0 3.60 0.270 0.96 0-97 1.01 25-2 4.40 0.221 0.94 0-97 1-03 40.0 7-06 0-135 0-89 0-95 1.07 The value of the dissociation constant of water i.e. aH.x a,=,/ aHtO remains practically constant over the whole range up to 40% of glycerol the deviations from constancy being very small in com-parison with the changes in the activities of the individual ions. At the same time since the changes in the activity of the water effected by the presence of the glycerol are relatively small the ionic activity product of the water maintains a reasonably constant value. Summary. 1. Electrometric measurements of the activities of hydrogen ion in aqueous solutions of sodium hydroxide in presence of glycerol have been made at 25". 2. The Donnan-Allmand electrode has been used to determine the activity of hydroxyl ion in solutions of sodium hydroxide containing glycerol. 3. The dissociation constant of water remains constant for the solutions containing up to Myo of glycerol; the ionic activity product does not exhibit appreciable change over the same range. The author wishes to acknowledge his indebtedness to the Department of Scientific and Industrial Research for a grant which enabIed him to carry out this investigation. Muspaam LABORATORY OF PHYSICAL AND ELECTRO-CHEMISTRY, U m ~ s r r y OF LIVERPOOL. [Received September 28th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702788

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

METHODS OF MEASUIUNG THE P O ~ Y OF SURFACES. 2793 CCCLXXXV.-A Comparison of Methods of Measuring the Polarity* of Surfaces. By NEIL K. ADAM ROBERT S. MORBEILL and RONALD G. W. NORRISH. “ POLBRITY ” has been recently measured by Norrish (J. 1923, 123 3006) the measure being the catalytic activity of the surface for the combination of ethylene and bromine. Another mewure of polarity is the attraction of a surface for water or the work W , required to separate the surface from water in contact with it; W is related to the angle of contact 8 of water with the solid surface by the relation T being the surface energy of water (Adam and Jessop this vol., p. 1863). Yet another indication of polarity is the objectionable property which some oil varnishes possess of condensing water on the varnished surface in a moist atmosphere and ‘blooming.’ Varnished surfaces which bloom easily may be considered more polar than non-blooming surfaces.This paper is an attempt to elucidate the nature of the “ polarity ” by comparing the results of the different methods of measurement. Glass stearic acid para& wax two non-blooming varnishes, A and B and one blooming varnish C were compared. The non-blooming varnish film was composed of a hard copal resin incorporated in linoxyn containing lead and manganese catalysfs. The blooming varnish film contained a rosin ester in tung oil “ oxyn,” with a manganese catalyst. Both for angle of contact and for catalysis measurements the varnish was coated on glass and allowed to dry in a current of air (5 litres per hour) at 40-55” until constant in weight.The volatile thinners of the varnishes were expelled and the drying oils oxidised as completely as possible. In the tables k is the initial velocity coefficient k’ gives the catalytic effect in terms of k expressed as percentage of the value for glass 8 and W (ergs per sq. em.) are defined above and W’ is the attraction for water as percentage of the attraction of water that “polar” is applied to substances (and to groups therein) which tend to dissolve in water and “ non-polar ” to those which dissolve in hydrocarbon solvents. This broad distinction of groups into two classes is a moat useful working hypothesis for many investigations and a more definite under-standing of its nature and causes is much needed.The term “ polarity ” is here used in this sense leaving entirely open the question whether there exists any resemblance to physical objects of unsymmetrical field of force such as W = T(l + cos 6), * The terms “ polar ” and “ non-polar ” have become general in the bar-qets.-N. K. A 2794 ADAM MORRELL AND NORRISH A COMPARISON OF for itself. The angle of contact method will not detect attractions for water greater than that of water for itself attractions equal to and greater than this giving zero angle. Glass has an attraction for water at least as great as that of one water surface for another. Catalytic action measured on dry ethylene and bromine. Surface. k. k' . e. W. W'. Glass .................. 0.05 1 100 0" not less than 100 Varnish .A ............0-048 94 95 66.6 45.5 Varnish C ............ 0-112 220 60 109.5 75 PtwaEin wax ......... 0.003 6 105 54 37 Stearic acid ......... 0-086 168 100 60-5 41 146 Caiulytic action measured on moist ethylene and chlorine. Glass .................. 9 . 7 ~ lo-' 100 0 146 100 Varnish B ............ 4.0 ) 41 95 66-6 45.5 Varnish C ............ 11 ,) 113 65 104 71 P a r a n wax ......... 0.01 )) 0.1 105 54 37 The angle of contact measurements were made as described by Adam and Jessop and are accurate to about 5". The velocity coefficients for the ethylene-bromine reaction were determined as described by Norrish fairly good constancy being obtained for the first five minutes of reaction. Ethylene and chlorine in the moist condition were employed for the second series as it has been found - possible thus to obtain more reproducible results than with dry ethylene and bromine; but owing to the higher pressure used there was appreciable attack of the varnish surfaces by the chlorine, which impaired the constancy of the velocity ' constants.' Details of the ethylene-chlorine method w-iil be published shortly.The values calculated as bimolecular coefficients are given for the first two minutes of reaction and afford a comparison of catalytic activity adequate €or the present purpose. The figures for reaction rates are of course not comparable between the two series. The angle of contact measurements were taken on the varnishes within a minute or two of immersion in the water. If allowed to soak these surfaces gave an angle lower by 10" or in some cases 20° the effect of soaking being more marked the greater the angle of contact.Evidently the attractions for water parallel the veiling properties of the varnishes. It appears that if the attraction is more than about 70% of that of water for itself the varnish veils; if less than 46 to 50% it does not veil. We attempted also to grade varnishes in respect of their veiling properties by angle of contact measure-ments but owing to the effect of soaking in water these could not be made sufficiently accurately to distinguish varnishes with METHODS OF MEASURINQ THE POLARITY OF SURFACES. 2795 slight tendency to veil from non-veiling varnishes. The varnishes which were found to be more polar by the angle of contact method were also more polar by the catalytic meamre.There is however considerable disagreement between the polarities of the surfaces of different kinds as measured by the catalytic method and by angle of contact. Glass has less catalytic power than either stearic acid or the veihg varnishes but very much greater attraction for water; and stearic acid which haa only a very slightly greater attraction for water than paraffin wax, has enormously greater catalytic activity. It would of c o r n , be possible to ascribe the difference to the “ polarity ” which c a m attraction for water being of a different kind from that which confers catalytic activity; but such an ad hoc assumption would be particularly unreasonable as it is not improbable that water itself is concerned in the catalysis.Adam and Jessop concluded that the evidence of angle of contact measurements on long-chain compounds pointed to the polar groups in stearic acid being buried in the interior. Hence it appears that in the catalytic measure-ments the reacting gases penetrated the surfaces to a short distance. The nature of the oxidised varnish surfaces is unknown we con-sider it possible that ethylenic linkings are present. In this way it would be possible for the stearic acid and varnish surfaces to present more catalytically active groups than a glass surface, which must be presumed practically impermeable to the gases. By penetrating the solid to a depth of only the length of a few molecules it would be possible for the gases to reach more polar groups than &re to be found on an equal area of glass.If this is the correct explanation it involves the assumption that the depth of the ‘ surface ’ is much greater for the catalysis than for the angle of contact measurements. Varnishes differ in their absorption of, and permeability to water and no doubt to gases also ; but we have not data enough to attempt a prediction of catalytic activity for Merent varnished surfaces taking this factor into account. This factor of permeability requires further investigation; in Adam and Jessop’s paper some evidence was given that there is more depth involved in the case of crystal flakes of the long-chain amine hydrochlorides than with the other long-chain aliphatic substances used. Nevertheless we feel that qualitatively it supplies an adequate reason for the difference in behaviour of Merent ‘ surfaces ’ to reagents. Para& wax is not a catalyst because no matter how far the g- may diffuse into the interior no polar groups are encountered. [Received October 9th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702793

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

2796 BRITTON AN ELECTROMETaIC AND A CCCLXXXVL-An Electrometric and a Phase Rule Study of some Basic Salts of Copper. By HUBERT THOMAS STANLEY BRITTON. THIS paper deals with experiments made to ascertain which of the many basic sulphates and chlorides of copper are definite compounds. Basic sulphates have been reported ranging in com-position from 2CuO,SO to 15cuo,so3 with varying water contents. Pickering (J. 1910 97 1851) regarded the latter &s a complex salt of orthosulphuric acid and bivalent and what he supposed to be quadrivalent copper atoms and Noyes (J. Amer. Chem. Soc., 1916 38 1947) suggested that 3CuO,SO3,2&0 might be the dihydrated cupric salt of the same acid. The basic chlorides which have been described contain from 1 to 4.5 atoms of copper for each atom of chlorine.Naturally occurring basic sulphates and chlorides are langite 4Cu0,S03,4H,0 ; brochantite containing from 3 to 4 mols. of CuO for 1 mol. of SO, together with vary-ing amounts of water and atacamite 4Cu0,2HC1,3H20-the number of molecules of water varying from 2 to 5. Bell and Taber (J. Physical Chem. 1908 12 171) and Young and Stearn ( J . Amer. Chem. SOC. 1916 38 1947) who studied the bmic sulphates of copper from the point of view of the phase rule, obtained very conflicting results and were unable to prove the existence of a definite basic sulphate ; doubtless because they used substances which approached equilibrium very slowly. It has long been known that an amorphous blue precipitate, agreeing very closely in composition with 4&0,S0,,4H20 is produced by treating copper sulphate solution with an insufficiency of alkali (Kane Ann.Chim. Phys. 1839 72 270; Smith Phil. Mag. 1845 23 501 ; Field ibid. 1862 24 124). Williamson ( J . Physical Chem. 1923 27,790) analysed the precipitates obtained by treating molar solutions of copper sulphate with different quantities of alkali. Pickering showed (Chem. News 1883 47, 181) that between 1.4 and 1-5 equivalents of potassium hydroxide completely precipitated the copper and that the amount pre-cipitated at any stage of the reaction was directly proportional to the amount of alkali added. He also found a temporary alkalinity to phenolphthalein when 1.5 equivalents of alkali had been added. Similar observations were made by the author using the oxygen electrode (this vol.p. 2152). Apart from the little recorded by Kenrick and Lash Miller (Trans. Roy. Soc. Canada 1901 7 iii 35) no systematic work has been done on basic cupric chloride. The precipitate forme PHASE RULE STUDY OF SOME BASIC SALTS OF COPPER. 2797 when NIS-copper chloride solution was treated a t 85" with NjEi-potaasium hydroxide until all the copper had been precipitated had the formula C u ~ 3 C u 0 2 ~ 0 . E X P E R I M E N T AL. In order to study the mode of precipitation of copper sdphate by sodium hydroxide electrometric titrations with a copper electrode were carried out. A copper wire electrode fused into a glass tube was completely immersed in 100 C.C. of H/lOO-copper sulphate solution which was connected through a saturated soh-tion of potassium chloride to a normal calomel electrode.The FIG. 1. i E.&f.P.'s between the copper and the calomel electrodes were measured by means of a potentiometer and a capillary elect-meter. The electrode was about 2 111111. in diameter and was covered with finely divided copper deposited electrolytially from N/lO-copper sulphate solution. That electrodes so prepared worked satisfactorily in copper sulphate solution will be seen from the following measurements. At Z O O the E.M.F. of the cell Cu I 0-OlH-CuSO I saturakd KCl I N-calomel ww - 0.006 volt. Therefore E h Cu I o ~ o ~ ~ - ~ s o = + 0-283 - 0.006 = 0-277 volt. 0-01M-Copper sulphate being taken as 54.7% dissociated (A = 114, and bol~ = 62-a) 0.277 = EPhh + 0.029 log 0.00547. Whence EPmh = 0-343 which is in agreement with the recent value of Jellinek and Gordon (2.physikd. Chem. 1924 112 214). Three typical titration curves are given in Fig. 1. The cupric 2798 BRITTON A N ELECTROMETRIC AND A ion concentration scale was calculated from the formula Eoh. = - 0.060 - 0.029 log [cu"]. The dotted line gives the theoreticaI change in copper-ion concentration calculated on the assumption that 4CuO,SO alone is precipitated. Curves 1 and 2 plotted from results obtained with an electrode having a thin coating of copper (deposited during 5 minutes' electrolysis) and curve 3 (electrode heavily coated during 1 hour's electrolysis) show that the electrodes became untrustworthy as soon as a precipitate appeared. Deduced from the curves the values for the concen-trations during precipitation are much too small and those for the concentrations when precipitation was complete and the solu-tions had become alkaline are obviously too large.High E.M.F.'s were obtained immediately precipitation was complete but these fell in the course of 5 minutes to more or less steady values. The effect of the heavy deposit (curve 3) was to render the electrode even more irregular as may be seen from the second portion of the curve. The curves show that sudden changes in copper-ion concentration occurred when 1-73 (curve l) 1.5 (curve a) and 1.63 equivalents (curve 3) of sodium hydroxide had been added. In titration 2, the alkali was added very slowly and the mixture was stirred until any green gelatinous precipitate which might have formed had become pale blue and apparently amorphous.In the other two titrations the alkali was added more rapidly and although the reactants were thoroughly mixed stirring was not maintained until the precipitate appeared to have become homogeneous. These experiments show once again that the nature of the pre-cipitate obtained depends on the manner in which the alkali is added. Rapid addition necessitated the use of a larger quantity for complete precipitation and consequently the gelatinous pre-cipitate obtained was more basic than the blue amorphous * precipitate produced on careful addition of the alkali. This is the reason why Harned ( J . rlmer. Chem. Soc. 1917 39 352) required in his similar titration of copper sulphate solution six-sevenths of the theoretical quantity of the alkali.The Anomalous Behaviour of Copper Electrodes in Presence of Copper Hgdroxide.-The foregoing observations become of im-portance in view of the recent measurements of Jellinek and Gordon (h. cit.) of the solubility product of cupric hydroxide. * Here and elsewhere in this paper the term " amorphous precipitate " is used to denote the non-gelatinous apparently amorphous precipitates obtained when alkali hydroxide is added slowly to dilute solutions of cupric salts. They are sharply distinguished from the gelatinous precipitates produced by rapid mixing PHASE RULE STUDY OF SOME BASIC SALTS OF COPPER. 2799 They precipitated their copper hydroxide from copper sulphate solution with an insufficiency of sodium hydroxide-exactly the condition for obtaining basic copper sulphate! The washed pre-cipitate wa8 suspended in alkali solution and the copper-ion con-centration was measured by means of a copper electrode.Their values for [cu"][OH']2 at 20" varied from 0.7 x the mean being 1.7 x 10-13 but they could not conhn this by measuremenfs with copper oxide. It is interesting to c o m e e thew values with those obtained from the curves (Fig. l) assuming for the moment that the observed E.M.F.'s gave a true measure of the copper-ion concentration and that the basic precipitates had been completely decomposed by the excess of alkali. The hydroxyl-ion concentration when 40 C.C. of 04932N-sodium hydr-oxide had been added the ionisation of the alkali being assumed to be complete was 10-l'gl and the cupric-ion concentration was lO*'S5 (curve 1 ; E.M.F.= 0.217 volt) 10-8'62 (curve 2 ; E.M.F. = 0.190 volt) and 10-7'59 (curve 3 ; E.M.F. = 0.160 volt). Therefore [Cu"][OH']2 is 4 x 10-14 (curve l) 3-6 x (curve 2) and 3.9 x 10-l2 (curve 3). Although these values are meaningless, they are of the same order as those of Jellinek and Gordon. The precipitation of basic copper sulphate does not begin until p H 5.6 has been attained and from the method described by the author (loc. cat.) the presence of the sulphate in the precipitate being assumed not to affect greatly the precipitation p ~ it follows that the solubility product of cupric hydroxide is probably of the order lo*.* Jellinek and Gordon do not refer to the work of Tmerwahr (2.u w g . Chem. 1900 24 269) on the potentials of copper elec-trodes in baryta solutions containing colloidal copper hydroxide or ignited copper oxide. The E.M.F.'s were so irregular that she did not calculate the solubility product of cupric hydroxide. Calcu-lation shows that the solubility product varies from 3 x 10-l2 to 8 x for the colloidal hydroxide and to 8 x 10-23 for the ignited oxide. Allmand (J. 1909 95 2151) traced the erratic behaviour of the copper electrode to the reaction cu" + Cu 2Cu' takmg place at the electrode cuprous hydroxide being formed and arrived by an indirect method at the value lO-l9 for the solubility product of cupric hydroxide which is of the same order as that calculated from the precipitation pH viz. 1030. Jellinek and Gor-don who stated that fo their knowledge no value for the solubility to 3.0 x * For the titration given in this vol.p. 2131 the limiting [Cu"] was equiv-alent to 0.6 C.C. of N/lO-sodium hydroxide in 120 C.C. Therefore [Cu'.] = 0*3/120M/10 = I O - ~ ~ . [OH'] = 10-14+5'b = Whence [m*][OH']a = lo-" 2800 BRITTON AN ELECTROMETRIC AND A product of cupric hydroxide is recorded in the literature had evidently not aeen Allmand's paper. This reducing action of the copper electrode accounts for its irreversible behaviour in the titrations and the exceptionally low voltages obtained in No. 3 show that the reduction process was being considerably influenced by the nature of the layer deposited on the electrode. 'The System CuO-SO,H,O at 25".The substances used in the investigation were selected for their capacity to enter rapidly into equilibrium namely the amorphous basic sulphate free sulphuric acid and copper sulphate solution.The stock basic sulphate was kept a8 reactive as possible by suspending it in water. For certain equilibria wet hydrated copper oxide had to be used. The amorphous basic sulphate was prepared by adding X/lO-sodium hydroxide (about 1-2 mols. for each mol.'of copper sulphate) drop by drop and with continuous shaking to 10 litres of b l / Z O -copper sulphate every care being taken to prevent the formation of any gelatinous precipitate. The precipitate was washed by decantation yith 20 to 30 litres of water pressed on a Buchner funnel and immediately immersed in water (Found in air-dried mmples CuO 67.2 67.6; SO, 17.1 17.2.4Cu0,SO3,4%0 requires CuO 67-7; SO, 17.0y0). On keeping the precipitate, which wa8 quite insoluble in wafer in different quantities of sulphuric acid over-night in every case 1.33 mols. of copper sulphate passed into solution for each molecule of sulphuric acid employed, thereby showing that the ratio of copper to sulphate in the residual solid remained unaltered vix. 4 1. Quantiti- of the basic sulphate were placed in liquid phases (100 to 200 c.c.) composed of sulphuric acid and copper sulphate in various proportions the quantities of acid being such that the rests should be small (about 2 g.). The mixtures were placed in a thermostat at 25" and shaken daily. Equilibrium was attained in less than a week but 2 or 3 months were allowed to elapse before the final check analyses were made.The results shown in tthe most basic part of the isotherm necessitated the use of hydrated copper oxide. This was prepared by precipitation from a dilute copper sulphate solution a t about 50" with a small excess of sodium hydr-oxide. It was somewhat dehydrated and brownish-black but it had to be deposited a t a moderately high temperature so that it should not be so gelatinous that it could not be washed free from alkali and sodium sulphate. This hydrated oxide was also used with sulphuric acid to confirm some determinations of the equilibria of mixtures prepared from the basic sulphate. The analyses of the various liquid phases and rests are in Table I PHASE RULE STUDY OF SOME BAS10 SALTS OF COPPER. 2801 Liquid phases.- yo CUO. 0 0 0 0 0 0 0.02 0.09 0.12 0-58 3.17 5-54 7.17 9.28 % so,. 0 0 0 0 0 0 0.02 0.09 0-12 0-58 3.19 5.56 7-18 9-33 TABLE I. R0sts. CUO. 84-45 80.85 77-56 73.75 69.50 67-78 67.90 26.36 9-24 7-89 31-23 15-96 24.10 Eutectic % so,. 6.17 8.79 11.77 13-82 16-90 17-30 17.60 6-77 2.43 2.46 9-85 7-75 10-37 Mol. SO,\ mol. CuO. Solid phases. 0.073 CuO (hydrated) and 0.108 9 9 9 9 0.151 9 9 9 9 0.186 9 9 9 7 0.242 0-255 4cuo,ib3,4H26 4CuO,SO3,4H,O. 9 9 99 9 9 79 9 9 97 0.3 14 4Cu0,S03,4H,0 and CuS0,,5H,O. The h t six sets of data show that the addition of sulphuric acid to the hydrated copper oxide failed to cause any solution until the solid phase had assimilahd sufficient sulphuric acid fo convert it into the basic sulphate containing 4CuO to ISO,.Neither copper nor sulphate could be found in the colourleas liquid phases. The analyses given are those of the air-dried solid p h w . These changed in colour as their sulphate content increased passing from the brownish-black of the hydrated oxide through increasingly brighter shades of brown to greenish-brown and finally to the greenish-blue colour of the 4 1 salt. The basic sulphate did not change in colour on boiling but decomposed on addition of varying quantities of alkali yielding more basic products having similar colours. The results given in Table I are plotted in Fig. 2 ; the section BC has been constructed from the data of Bell and Taber (h.cit.). The solid-phase which was in equilibrium with the liquid phases represented by AB was 4Cu0,S03,4€&0 for the tie-lines joining the points corresponding to each liquid phase and the point corre-sponding to its respective rest all pass through the point D which indicates that the solid phase contained 67.7% CuO 17-070 SO,, and 15-3y0 q 0 (Schreinemakers). Had the solid phases in equili-brium with water as liquid phase been mixtures of two definite solid phases it would have been expected that the points repre-senting their compositions would lie on the straight line joining the two points corresponding to the compositions of the two solid phases. If in the present system the rests comprised mixtures of the basic salt 4~O,SO3,4H& and a definitely hydrated copper oxide this line would have been one joining the point D to the The other liquid phases were copper sulphate 2802 BRJT!FON AN ELECFROMETRIC AND A point corresponding to the particular hydrated oxide on the H,O-CuO axis.Actually the points lie on one of two straight lines, DE and DF where E represents Cu0,0.28Hz0 and F CuO,O-05%0. It appears from the phase rule that as the liquid phases which were in equilibrium with these highly basic rests were of fixed composition as far as could be ascertained the rests were composed of two solid phases. Bearing in mind the gradual change in the colour of the rests it seems probable that the two solid phases were the 4 1 sulphate and copper oxide hydrated to varying extents.The degree of hydration of the copper oxide although by no means fixed was of the same order as that found in the ordinary precipitated black copper oxide i.e. corresponding approximately to Cu0,0-25Hz0. There appeared however a tendency for the hydration to become considerably less as the proportion of the 4 1 salt became predominant shown by those points which fall on DF. It follows from this work that a t 25" there is only one basic sulphate of copper viz. 4cuo,so3,4H,o. Sabatier (Cmpt. rend., 1897 125 101) prepared it from copper oxide and copper sulphate solutions (not exceeding 1M). He stated that the salt was con-verted by saturated copper sulphate solution into a green salt, 5Cu0,2S0,,5H,O treatment of which with water regenerated the 4 1 salt.This green salt was probably the ordinary 4 1 salt with copper sulphate adhering. In support of this view is the fact that the rest belonging to the liquid phase which contained 7.17% CuO (Table I) had after filtration on a Buchner funnel a composition corresponding approximately to the formula 3&o,so3, although as its tie-line shows the actual solid phase was the 4 1 salt. Precipitation of Basic Cupric Chloride.-When N/lO-sodium hydroxide or ammonia was added slowly with shaking to M/lOO-cupric chloride solutions pale blue amorphous precipitates were obtained and the mother-liquors became alkaline to phenolphthalein, precipitation being complete after the addition of 1-5 equivalents of alkali. If the additions were made quickly precipitates did not separate until about 1 equivalent of alkali had been added but the solutions became more and more colloidal and alkalinity occurred after the addition of 1-53 equivalents.When however more concentrated solut'ions were rapidly mixed dark blue gelatinous precipitates were obtained which if the amount of alkali added did not exceed 1.5 equivalent's could be transformed by vigorous shaking wit'h the mother-liquor into paler blue amorphous forms. Provided that not more than 1.5 equivalents of alkali had been added during their formation the amorphous precipitates did no PHASE RULE STUDY OF SOME BASIC SALTS OF COPPER. 2803 blacken on boiling; if a precipitate happened to be gelatinous it darkened temporarily but became pale blue and amorphous on continued boiling.The System CuO-HCl-€&O at 25".-This system was investigated in exactly the same manner as the previous one. The substances used were moist hydrated copper oxide moist basic cupric chloride, hydrochloric acid and cupric chloride solution. On being washed by decantation much of the basic chloride passed into pale blue, colloidal solution and did not settle out after standing for a week. The colloidal solution was siphoned off and replaced by water, and the process was repeated during a month until the remaining precipitate was free from impurities. Samples which had been either air-dried or dried over fused calcium chloride agreed closely in composition with the formula 4Cu0,2HC1,3H20 (Found CuO, 72.0; HCl? 16.5. Calc. CuO 71.5; HCl 16.4%). The salt was amorphous and insoluble in water; but after it had been boiled with water the latter gave a faint opalescence with silver nitrate.Equilibrium was attained in about a week but the final analyses were not made until 3 months had elapsed. The first four sets of data in Table I1 refer to solid phases which had been air-dried. The liquid phases were water. No copper chloride dissolved until each molecule of hydrated copper oxide had reacted with 0-5 equivalent of hydrochloric acid. Thereafter the solid phase was 4Cu0,2HC1,3H20 as shown by the point of intersection of the tie-lines in Fig. 3 and the liquid phases con-tained cupric chloride only. TABLE 11. Liquid phases. yo CUO. 0 0 0 0 0-16 3.90 8.35 15-22 18-52 21.24 25-59 -+ yo HCI.0 0 0 0 0-15 3.57 7-66 13-96 17-03 19.49 23-51 7 yo Cuo. 90.28 79.30 74-07 72.47 52-80 55-37 56.45 56-04 55-72 51-67 Rests. rr yo HCI. 0.03 11.49 i4-90 16.57 12.56 1349 14.60 16-35 16-90 18.14 Mol. H>l/ mol. CuO. Solid phases. 0.001 CuO (hydrated) and 4Cu0,2HC1,3H20. 0.315 Y 9 Y Y 0438 0-499 ~ C U O ~ H C ~ ~ ~ H ~ O . 0-517 9 9 9Y 9 9 9 9 4Cu0,2~C1,3HzO and CuC12,2H,0. The rests which had attained equilibrium with water after being allowed to settle for a month presented a striated appearance, pale green layers underlying layers of varying shades of dar 2804 BRITTON AN ELECTROMETRIC AND A brown. The layers were roughly separated from one another by spraying with a very fine jet of water.The uppermost contained the least chloride about 0.1 equivalent for each molecule of copper oxide and the bottom pale green layers contained the most about 0-3 equivalent. It was not possible to isolate the bottom layers quite free from the more basic brown particles; probably the amount of chloride actually present in them was greater than 0.3 equivalenf. These observations seem to indicate that each of the highly basic rests was composed of a mixture of two solid phases as required FIG. 2. 3\03 FIG. 3. by the phase rule and from Fig. 3 there appears to be no doubt that these were the definite basic chloride (greenish-blue) and dark br_own copper oxide of varying hydration. The basic chloride 4Cu0,2HC1,3H20 and the rests which con-tained more than 0.315 equivalent of chloride tended to pass into colloidal solution.Attempts were made to get some idea of the composition of the colloidal suspensions and it was found that the basic chloride aggregates contained from 0.27 to 0.33 equivalent of chloride for each molecule of copper oxide. The curve in Fig. 3 corresponding to those liquid phases whic PHASE RULE STUDY OF SOME BASIC SALTS OF COPPER. 2805 exist in equilibrium with dihydrated cupric chloride was drawn from Foote’s data (J. A ~ T . Chm. Soc. 1923 4.5 663). Basic C U M Nitrate.4kveral basic nitrrttes have been described containing from 1.7 to 3 atoms of copper for each molecule of nitrate. The pale bluish-green precipitate formed when alkali, insufEcient for complete reaction is added to a dilute cupric nitrate solution has been shown by many workers h correspond to the formula 4CuO,2HNO3,2qO.The mineral gerhardtite hM the same composition; in some specimens however the water content appears to be 1H,O. When N/lO-sodium hydroxide was carefully added to cupric nitrate solution precipitation was complete and the solution became alkaline to phenolphthalein after the addition of 1.5 equivalents. The composition of the precipitate agreed with the above formula (Found CuO 66.8; HNO, 26.4. Calc. CuO, 66.3 ; HNO, 26.2%). The basic nitrate was insoluble in water, but on boiling with water it soon blackened and some passed info colloidal suspension. The salt wcts also much more readily decom-posed by alkali than was either the sulphate or the chloride 80 much so that when alkali was added rapidly to a cupric nitrate solution alkalinity was not produced until 1.9 equivalents had been added.Basic Cupric Bromide.-The basic bromide produced by the oxidation of cuprous bromide and by the prolonged digestion of a solution of cupric bromide with copper oxide (Richards Chem. New4 1891 63 75; Sabatier Cmpt. rend. 1897 125 103) has the formula 4Cu0,2HBr,2H20. The substance produced on gradual addition of alkali to cupric bromide solution has apparently not been examined. N/lO-Sodium hydroxide gave a pale blue amor-phous precipitate and the mother-liquor became alkaline to phenol-phthalein after approximately 1-5 equivalents had been added. This result suggests that the precipitate contained CuO and HBr in the molar ratio of 2 1.The (air-dried) precipitates formed by vary-ing amounfs 6f alkali however were slightly more basic [Found : (a) CuO 60.55 ; HBr 29.4. (b) CuO 61-0 ; HBr 30.3 corresponding respectively to 4Cu0,1*91HBr,2.93&0 and &0,1.95HBr,2G?€&O]. It is fairly certain that they were essentially the 4 2 bromide, although the data are insufficient to state what was the exact water content. The basic bromide was insoluble in water and did not blacken when boiled with it. In common with the basic nitrate and the basic chloride it had a marked tendency to pass into colloidal suspension when treated with water 2806 BRITTON AN ELECTROMETRIC AND A Discussion. It has been shown that of the many basic sulphates and chlorides of copper which have been reported only one definite sulphate and one dehite chloride exist a t 25" uix.4Cu0,H,S0,,3H20 and 4Cu0,2HC1,3H20. Similar nitrate and bromide compounds have been shown to be produced by precipitation with alkali under similar conditions viz. 4Cu0,2HN0,,2H20 and 4Cu0,2HBr,2(?)H20. They are similar not only in composition but also in form colour, and insolubility. All these salts are precipitated from solution at hydrion concentrations of about 10-5'6. The similarity in their composition seems to be due to an intrinsic property of either the copper atom or the copper oxide molecule. Previous workers have attempted to account for the sulphate and the nitrate as complex salts of ortho-acids but such an explan-ation cannot be applied to the basic chloride or the basic bromide.The usual way of representing these basic salts as if they were double salts e.g. CuS0,,3Cu(OH),,H20 is unsatisfactory for they have none of the properties of double salts inasmuch as they are insoluble. Werner (Ber. 1907 40 4444) on the basis of his co-ordination theory regards them as the normal salts of a hypothetical hexolcupric base e.g. [Cu(Ho>C~)~S04,H20. HO This represent-ation seems to be equally open to objection. Such a constitution would suggest that contrary to the facts the salt has to some extent the capacity of dissolving which by comparison with diEcultly soluble salts of metals e.g. lead and silver is in some way con-nected with the nature of the acid radical and would ionise in solution into " hexolcupric " and sulphate ions.The comparative inertness of these basic compounds to reaction and their similarity in properties to copper hydroxide seem to show that they are essentially compounds of this base of some unknown kind. Until something is known about their constitution it is perhaps better to represent them thus (k4(0H),SO4,H2O. Were it known that the co-ordination number of bivalent copper is 6 the Werner theory might be considered to supply a tentative explanation why these basic salts contain copper and the acid in the equivalent ratio of 4 1. The ammine compounds of cupric salts have such widely varying compositions that no definite co-ordination number can be assigned. If the constitution of the cupric complexes in ammoniacal solutions be considered the co-ordination number is probably 4.Chatterji and Dhar state (Discussion on Colloids Faraclay and ph3!8. Soc. 1920 124) that the blackening on boiling of copper hydr PHASE RULE STUDY OF SOME BASIC SALTS OF COPPER. 2807 oxide can be prevented by the addition of a little normal salt, which is adsorbed and thus renders the copper hydroxide stable. They do not appear to hare considered what may be the effect of the formation of basic salts. The retention of the colour on boiling is a property of such salts-less marked it is true in the case of the nitrate (see pp. 2801 2803 2805). Since the foregoing pages were written Kriiger has published some work on the basic sulphates of copper ( J . pr. Chem. 1924,108, 278). He obtained a product having the formula 4Cu0,s03,4H20, and also basic sulphates whose analyses although irregular, indicated the formuh 4Cu0,S0,,3.5H20 4Cu0,S03,5H,0 and 3Cu0,SO3,2-5H,O. The water contents of the fht two of these three substances are probably due to imperfect purification and the last is undoubtedly a mixture of the definite basic salt and copper sulphate. Summary. (1) According to the manner of mixing and the quantity of alkali used either apparently amorphous or gelatinous precipitates may be obtained by adding alkalis to solutions of the sulphate, chloride bromide or nitrate of copper. (2) The individualities of the basic salts Cu,(OH),S0,,H20 and Cu,(OH),C~,H,O have been established. (3) The behaviour of the Cu[Cu(OH),,NaOH electrode has been shown to be erratic and the value of Jellinek and Gordon for [Cu"][OH']2 untrustworthy. (4) Observations have been made on the darkening of suspen-sions of basic copper salts on boiling. (5) The constitutions of the basic salts have been discussed with special reference to Werner's co-ordination theory. The author takes this opportunity to express his thanks to Professor Philip F.R.S. for kindly granting facilities and to the Department of Scientific and Industrial Research for a personal grant. IMPEFUAL COLLEGE OF SCIENCE AND TECHNOLOGY, LONDON. [Received July 9th 1925.

ISSN:0368-1645    

DOI:10.1039/CT9252702796

出版商:RSC    

年代:1925

数据来源: RSC