摘要:

98 XI.--On certain ~~ze72yZthiocnrbamates. By H. LLOYD SNAPE, D.Sc., Ph.D. IN a paper (Trans., 1885,47, 778) published in this Journal some years ago, I described the action of phenylic cyanate on phenylic mercaptan, a phenylic salt of pheny lthiocarbamic acid, having the formula CGHS*S*C0*NHC6H5 being formed ; and I pointed out that an isomeride in which the oxygen and sulphur atoms had exchanged positions might be expected to be obtained by the action of phetiyl- thiocarbimide on phenol. That experiment, and also the action of the same thiocarbimide on phenols, I had proposed to investigate, but., unfortunately, it has been impossible for me to do this until recently. Meanwhile, the reaction with phenol itself has been inves- tigated by Professor A. E. Dixon (Trans., 1890, 57, 268) ; but, as this had escaped my attention until my experiments had been com- pleted, and I had obtained a purer product and a better yield, a few notes on my own examination of this reaction may be advantageously added. .Pheiaylthiocarbinaide and Phenol.These two substances were heated, in molecular proportion, in a sealed tube at temperatures varying from 100' to 280°, and for periods varying from 2 to 67 hours ; contrary to Dixon's experience, I found that the higher the temperature, provided it was not allowed to rise much above 270°, and the longer the time during which these substances were heated together, the better was the yield of the thio- carbamate ; the temperature should not be allowed to rise above 280°, as decomposition then sets in, and the product is a nearly black mass, from which it is difficult to separate the required crystals.I obtained the best yield after heating the mixture for nearly three days, the temperature for the greater part of the time varying from 250' to 280'. The product, a viscous, brown liquid, when allowed to stand in the cold, gradually deposited crystals, until, in from three to four days, the whole appeared to have become solid. The yield, under the above circumstances, after washing, pressing, and drying (as described by Dixon), amounted to nearly 25 per cent. of the theo- retical; Dixon, working at a lower temperature and heating for a shorter time, obtained only 7 per cent. These crystals were nearly pure, and were readily obtained in perfectly pure condit.ion by crys- tallisation from absolute alcohol, as well formed, highly lustrous, pale yellow leaves or needles, which melted sharply at 148' (Dixon found the melting point to be between 249' and 151').The substanceSNAPE ON CERTAIN PHENYLTHIOCARBAMATES. 99 could alao be crjstallised from glacial or dilated acetic acid, but was insoluble in ether and light petroleum. A determination of sulphur, by Carius' method, gave the following result. 0.126 yielded 0.129 BaS04. S = 14.03 (Dixon found 13.48). C,,HI1NSO requires S = 13.97 per cent. The other properties described by Dixon for the phenyl salt of 9-phenylthiocarbamic acid were confirmed. So much difficulty having been experienced i n effecting combina- tion between phenylthiocarbimide and phenol, it was to be anticipated that an action between the former substance and more complex phenols would not readily occur, and, actually, I found it impossible to effect a combination between the above-named thiocarbimide and either resorcinol or quinol.I also tried the effect of heating phenyl- thiocarbimide with glycol, but again without effecting direct corn- bination. The experiments are briefly summarised below. Yhenyt thiocarbimide and Resorciizot. These two substances were heated together in a sealed tube, in the proportion of twice the molecular weight of the former to once that of the latter; after two hours at 100" to 150°, no change was observable, and, even after heating for another hour a t 180°, the resorcinol crystallised out on cooling, and the thiocarbimide had acquired a slightly darker colour. On heating for a further period of 2+ hours at 175-18@", a beautiful, blood-red liquid was obtained, from which crystals of resorcinol separated on cooling; the red oil smelt strongly of the thiocarbimide, did not solidify on further cooling, was insoluble in water, readily dissolved in alcohol, glacial acetic acid, and benzene, but at once separated again as an oil on evaporating these solutions.The oil appeared to be the product of a partial decomposition of the thiocarbimide, and I could not find any trace of the formation of a thiocarbamate. Phenylthiocarbirnide and Quinot. Tho results obtained on examining the behaviour of this pair of substances, when heated together, were similar; up t o 180°, very little change was obseived.After heating for 15 hours at 200°, crystals of quinol separated unaltered, but the thiocarbimide bad again sustained some decomposition, the colour having diatinctly deepened, and at 220" a black mass was obtained, but no thiocarb- amate. I next endeavoured to effect a reaction between these two substances by hating them together first in benzene solution and then in glacial acetic acid solution. The decomposition of the thio-100 SNAPE ON CERTAIN PHENYLTHIOCARBAMATES. carbimide, as was to be anticipated, did not take place at as low a temperature as before, but again there was no indication of combina- tion occurring between the two substances. Phenylthiocarbimide and Glycol. On heating these two substances together for four hours at 265O, a few minute crystals separated, but I could not succeed in obtaining a sufficient quantity for examination, and longer heating only resulted in effecting decomposition, the entire liquid acquiring a deep, brownish-black colour.From this oil I failed to isolate any crystal- lisable substance ; it dissolved in alcohol, ether, glacial acetic acid, and benzene, but, on evaporating these solutions, only oily drops, consisting of the original materials employed, together with decom- position products, were obtained. Having thus failed to effect combination between phenylthiocarb- imide and dihydroxy-compounds, I next endeavoured to prepare the isomerides of the thiocarbamates I had hoped in this way to obtain, by the action of phenylic cyanate on the corresponding thiophenols, and I completely succeeded, both in the case of dithioresorcinol and of dithioquinol.These thiophenols J prepared by the method described by Koerner and Monselise (Cazzettn, 1876, 6, 133--1421, and found no difficulty in obtaining them in a state of purity, possessing the exact melting points given in the paper by the above-named chemists. I n the necessary previous preparation of the respective calcium salts of meta- and para-benzenedisulphonic acids, I noted, however, an error in IVatts’s Dictionayy (1, 458), which may possibly mislead others. It is there stated that, in separating these calcium salts by crystal- lisation, the meta-salt separates $&, whereas the reverse is the case. I was unable to refer to the original papers, and, though i t seemed unlikely that only the calcium salt of the meta-acid should be less soluble than that of the para-acid, I was only able to determine this with certainty by the later preparation of the sulphonic chlorides.Metaphenylene PTLeiz2/lthiocarbama.te. Phenylic cyanate and dithioresorcinol, in the theoretical propor- tions, were heated in a sealed tube by meam of a water bath contain- i n g a solution of common salt; after about half an hour, crystals commenced to separate, and, a few minutes later, the whole solidified to a crystalline mass. This was washed with cold absolute alcohol, to remove any excess of phenylic cyanate, the crystals themselves being almost insoluble in this solvent; they were also insoluble in water, but were dissolved by ether and also by gkicial acetic acid, and could readily be recrystallised from these liquids. From glacialSNAPE ON CERTAIN PHENTLTHIOCARBAMATES.101 acetic acid, the thiocarbamate separated in the largest crystals, these consisting of white needles, as much as 1 cm. in length, wbich gradually grew in the solution in beautiful tufts. They melted at 178-159", and beiow that temperature were stable; at a higher temperature, however, the substance decomposed with energetic evolution of hydrogen sulphide and other gases possessing an un- pleasant odour ; but the sulphur was not removed by merely heating some of the crystals in a test-tube with an alkaline solution of lead hydroxide. On heating the crystals with fuming nitric acid, a very fine, wine-red solution was obtained. An estimation of sulphur, by Carius' method, gave the Eollowing result.0.112 gave 0.138 BaS04. The reaction which had occurred is therefore represented by the S = 16.92. C2,H,6Nz0,S2 requires s = 16.84 per cent. eqnat ion C,HeC,(SH), + 2CsH,*NCO = C6H4(SoCO*NH*C6HS)2. Paraphen ylene Phsn ylthiocarbanzat e. Phenylic cyanate and dithioquinol likewise readily enter into com- bination, even at the temperature of a water bath. It is not even necessary that they should be heated in a sealed tube, but it is better to do so, if only to protect the phenylic cyanate from the air, and thus to prevent the formation of carbanilide. The crystals formed were at first pale yellow, but, after repeated recrystallisation from boiling acetic acid, they were obtained as small, pure white needles ; the individual form of these was scarcely observable by the naked eye, but they tended to group themselves in tree-like aggregates. They were soluble also in ether, but in neither Rolvent was this substance so soluble as the meta-isomeride, nor did it yield large crystals so readily ; i t mas insoluble in water, and scarcely soluble in cold alcohol, but dissolved in boiling aniline. The crystals melted at 200--202°. The behavionr of the substance when heated to a higher temperature, and also on heating with nitric acid and with an alkaline solution OE lead hydroxide, respectively, was similar to that of the meta-compound. A determination of d p h n r , by Carius' method, gave the following r e d t . 0.1 gave 0.123 BaS04. which closely corresponds to the percentage (see preceding) theo- retically required. S == 16-89 per cent., University Cottege qf Wales, Aberystwyth.

ISSN:0368-1645    

DOI:10.1039/CT8966900098

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

102 XI.-Periodides of Tlxobromine. By GEOJAGE ELLIOTT SHAW. APPARENTLY the only periodide of theobromine hitherto known is that described by Jorgensen (Bey., 1869, 2, 463), who prepared it by mixing a solution of theobromine in strong hydrochloric acid with potassium iodide and allowing it to stand. It crystallises in nearly black prisms, h a v i q the formula (C,H,N~O,,HI),,I,. When ztttempt- i n g to prepare the compound by this method, however, i t was found that the nature of the product depended on the relative qnantities of hydrochloric and hydriodic acids present ; moreover, it is preferable to add hydriodic acid rather than to use potassium iodide, so as to avoid the crystallisation of potassium chloride. With hydrochloric acid in large excess, thin plates were obtained, nearly black by re- flected light, but pale brown by transmitted light, and giving a red powder.They contained chlorine as well as iodine. Analyses were made of two different crystallisations. I. 0.3288 gave 0.3600 AgI + AgCI. 0.3505 of this gave 0.2369 AgC1. 11. 0.1808 gave 0.1994 AgI + AgC1. 0.1860 of this gave 0.1259 AgC1. These numbers agree with the formula (3C,H8N,o,,2HC1,HI),,I,. Corresponding to I = 45.00 and Cl = 6.51. Corresponding to I = 44.87 and C1 = 6.73. Found. r-A--7 calculated. I. 11. I ....... 45.18 45.00 44.87 per cent. C1. ...... 6-32 6-51 6.73 ,, With a smaller proportion of hydrochloric acid, another compound is obtained in rhomboidal prisms, nearly opaque and black, but trans- mitting a little ruby light. 0-3342 required 8-55 C.C.N/10N4S203 solution, equivalent to 32.30 per cent. “ exterior iodine,” using this term, as applied by Tilden, f o r the loosely combined iodine. It also gives a red Fowder, The analytical results correspond with the formula BC,H,N,O,H C 1,HI,I2. Found. 7 Calculated. J. 11. Exterior iodine ..... 32.57 32.36 52-30 Iodine as HI ....... 16.28 16.25 Chlorine .......... 4-55 4.50 - - By using enough bydriodic acid, long, greenish-black needlesSHAW : PERIODIDES OF THEOBROMINE. 103 separate, containing no chlorine and giving a green powder; the same substance was deposited from the mother liquors from which the previous compound had crystallised out. Analysis proved it to be the compound described by Jorgensen, ( C~H$J"O~,HI)~,LI. Ca,lculated. Formd. Total iodine .. . . * . 73-65 73.68 Exterior iodine,. . . 55.24 55-07 This periodide is easily obtained as a dark green powder by simply adding excess of iodine dissolved in potassium iodide solution 01' hydriodic acid to a solution of theobromine hydrochloride ; the pre- cipitate cannot bo washed, however, as it is immediately decomposed by water, alcohol, or ether, but the strengt.h of the solutions used does not affect the composition of the precipitate. After draining well on the filter pump, the greater part of the remaining iodine and hydriodic acid can be removed by allowing it to remain over potash or by exposure to air ; the compound begins to decompose, however, before the free iodine has completely disappeared. 5'7.94 and 57.47 per cent. exterior iodine and 75-97' per cent.total iodine were obtained from specimens just beginning to show signs of decomposition instead of 55.24 and 73.65 per cent. Tn some experiments, a mixture of these compounds was obtained, and was recrystallised from weak alcohol containing hydriodic acid and iodine, the last two being used to prevent formation of free theobromine. The acidity of the solution was about 3*5/N and the iodine about N/5. Hydrated crystals were deposited containing no chlorine. Two crops were analysed, and the numbers obtained corre- rjponded with the formula (C,HaN,02,HI),,I,,2Hz0. Found. 7 r--h-- Calculated. I. 11. Exterior iodine. , . . . 43.74 43.28 43.24 Iodine as HI .. . . . . . 21-87 21.47 21.82 Water ....... .. .. 3.11 - 3.38 This compound is homologous with a caffeine periodide,' C~HION~~Z,HI,I~,HZO obtained by Tilden (Chem.Xoc. J., 1865,18,99). The two compounds containing chlorine form the intermediate terms of a series, of which (3C7H8N4O2,3RCl),,T6 and (3C,HaN40,,~HI)& would be the extremes. In the hope of obtaining the latter compound, theobromine was dissolved in a saturated solution of hydriodic acid; green needles gradually separated on exposure to the air, but they ccntained more iodine than the desired compound.104 FRXNKLASD AND MACOREUOR : ETHEREAL SALTS (c,H8~40z,HI)~,16 requires a lit,tle more exterior iodine, which, perhaps, was lost on drying. Calculated for Calculated for (3C;H8N4On,3HI)J2. (C;H8N,O,,HI)4,T,. Found. Exterior iodine.. . 29.14 38-16 3 7.30 Iodine as HI ..... 29.14 25.44 25.30 This is j u s t half the amount of exterior iodine present in Jorgen- sen’s compound. Perhaps t,he relationship of these compounds is best shown by the amount of iodine and water attached to 2 mols. of the normal halogen salt, ( C7H8N402,HX)2. 1. Those containing hydrochloride have . 2. That from strong hydriodic acid bas .... 3. The hydrated crystals have ............ 4. Jorgenseu’s compound has. ............. 1,. 13. I, + 2H20. I,. I n conclusion, I must thank Messrs. Howards and Sons, of Strat- ford, in whose laboratories this work was carried out, for the full facilities so kindly given.

ISSN:0368-1645    

DOI:10.1039/CT8966900102

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

104 FRXNKLASD AND MACOREUOR : ETHEREAL SALTS XII1.-Elhereal Salts of Active aizd Inclctive Monoben- xoyl-, Bibenzoyl-, Dipkenacetyl- and Dipropionyl- glyceric acids. By PERCY FRANKLAND, Ph.D., B.Sc., F.R.S., and JOHN MACGREGOR, M.A. IN pursuing our investigations on the relationship between chemical constitution and optical activity, we have prepared a number of derivatives of active glyceric acid (dextrorotatory) in which the carboxylic hydrogen is replaced by positive radicles, whilst the hydroxylic hydrogen atoms (either one or both) are replaced by the acid radicles benzoyl and phenacetyl. It will be remembered that we hare already (Trans., 1893, 63, 511, 1410, 1419, and 1894, 65, 750) prepared a number, not only of the ethereal salts of active glyceric acid itself, but also of active diacetylglyceiic acid, the com- pounds under consideration in tho present communication being intended to throw further light on the influence exerted on the rota- tion by making these substitutions in the molecule. Methylic Dibeiuoy lglljcerate (Active).This was prepared by running active methylic glycemte from a dropping funnel into twice the calculated quantity of benzoylOF ACTIVE AND INAC'I'IVE GLYCERIC ACIDS. 105 chloride, contained in a flask heated at 120" and finally to 1gO" by means of an oil bath; a vigorous action takes place, hydrogen chloride being given off. The excess of benzoyl chloride was distilled of€ under reduced pressure, and the residue then frac- tionated under diminished pressure ; this was attended with some difficulty in consequence of the solidification of the distillate in the lateral tube of the distilling flask.A large part of the liquid passes over at 245-247". After some hours, the distillate crystallised in tufts of long, flat needles radiating from centres ; these crystals are easily soluble in chloroform, acetone, and benzene, soluble also, especially on warming, in methylated spirit, from which recrystal- lisat'ion can most advantageously be effected, the long, radiating needles having the appearance of thistle-down. The crystals melt at The crystalline substance was submitted to hydrolysis with 58-59'. alcoholic caustic potash with the following results. I. 1.2500 gram required 0.6449 gram KOH for hydrolysis. 11. 1.1032 ), ,, 0,5706 7 , 7 7 7 9 I. 11. 100 parts by weight of substance required KOH for hydrolysis .., . . . . . . . . . . . . . 51.59 51.73 100 parts by weight of methylic monobenzoylglycerate, CIIH,,O,, 100 parts by weight of methy!ic dibenzoylglycerate, C&1606, On combustion the following results were obtained. 0.2093 gave 0.5044 CO, and 0.0927 H,O. require 50.00 parts KOH. require 51.86 parts KOH. Calculated for methylic Calculated for methylic Found. dibenzoylglycerate. monobenzoylglycerate. Carbon.. , . 65-72 65.85 58.93 per cent. Thus, both hydrolysis and combustion clearly show that the sub- stance is pure methylic dibenzoyl and iiot monobenzoylglycerate. Owing to the high melting point of this substance, the rotation had to be determined at higher temperatures in a state of fusion, and the rotation for ordinary temperatures deduced by extrapolation.The density, compared with water at 4", was determined at 65' and '39" respectively. Hydrogen., 4.92 4*%3 5.35 ,, a 6 5 0 ~ 1.1836. d 99O/4" 1.1581. from which it appears that the diminution in density proceeds by 0*00075 for 1" rise i n temperature. VOL. LXlX. I106 FRANKLAND AND MACGREGOR : ETHEREAL SALTS The substance was submitted to polarimetric examination at the following temperatures i n a tube 44 mm. long, placed in an air chamber surrounded by a water jacket. Observed rotation. aD in 44 mm. tube. Temp. 80.5'. ..... +10*26' 77.0 ...... 10.51 74.0 ...... 10.67 71.5 ...... 10.79 67.0 ...... 11.10 63.5 ...... 11.30 59-5 ...... 11.57 Density compared. with water a t 4'. 1.1720 1.1 746 1.1769 1.1787 1.1821 1.1 847 1.1877 [a1 D.+ 19.89O 20.33 20.60 20.80 21-33 21.67 22-13 On plotting out the above figures on a diagram (see p. 122) in which the specific rotations are represented by ordinat,es and the temperatures of observa,tion as abscissse, it is found that the observed specific rotations lie almost exactly on a straight line, from which by extrapolation the value for the specific rotation at 15' can be obtained as [aID = + 26.89'. This value may therefore serve for purposes of comparison with active compounds which have had their rotation determined at that temperature. Methy lic Dibenzoylglycerate (Inactive). This was prepared in substantially the same way as the active compound above, The solutions in methylated spirit exhibited less tendency to crystallise than similar solutions of the active compound, hut ultimately very similar crystals, long needles 1 inch in length and radiating from centres, were obtained ; these melted at 44-46", or about 14Obelow those of the active compound.0.2483 gave 0.5978 COz and 0.1093 H,O. Methylic dibenzoylglycerate, Cl8HI6O6, requires C = 65.85 ; H = 4.88 per cent. The crystals are soluble in the same solvents as those of the active compound. The molecular weight of this compound, as determined by the cryoscopic method, has been ascertained in benzene, nitrobenzene, ethylene dibromide, and acetic acid solutions (see next paper, p. 123). In these solutions, there is no evidence of the existence of the double molecules corresponding to a racemate, the cryoscopic values for the molecular weight being essentially similar to those obtained for the active methylic dibenzoylglycerate.The following results were obtained on combustion. C = 65-66 ; H = 4.89.OF ACTIVE AND INACTIVE QLYCERIC ACIDS. 107 Ethylic Dibe?azoylglycemte (Active). This was prepared in the same way as the corresponding methylic compound, by running the active ethylic: glycerate into an excess of Inenzoyl chloride heated t o 149-175'. On subsequent fractionation, the greater part distilled over under diminished pressure at 240-260°, and eventually the true boiling poiiit was found to lie between 254' and 258' under about, 10 mm. pressure, 0.2498 gave 0.6096 C02 and 0.1185 H,O. C = 66.56 ; H = 5.27. C,9H1806 requires C = 66.67 ; H = 5.26 per cent. During the severe weather of the last winter this liquid began t o crystallise, and by means of these crystals it was found possible to start its crys tallisation in strong alcoholic solution.A further quantity of this active ethylic dibenzoylglycerate was subsequently prepared with the object of obtaining it., if possible, without distillation. The excess of benzoyl chloride was removed by distillation under diminished pressura, and the residue in the flask was dissolved out with alcohol, but the alcoholic solution could not be brought t o crystallise even on sowing with some crystals of the previous preparation. The alcohol was, therefore, distilled off, and the residue, after being washed with a solution of sodium carbonate t o remove any benzoic acid that might have been formed from the benzoyl chloride, was dissolved in ether and washed with water.The ethereal solution was evaporated, and the residue placed in it vacuum desiccator, a crystal of the previous pi-eparation being added ; crystallisation could, however, not be induced. This undis- tilled product was also submitted to combust'ion and to polarimetric examination in benzene solution ; these determinations, however, showed that it was of inferior purity and inferior rotatory power to the preparation obtained by distillation. The product was therefore distilled under diminished pressure, and in the distillate crystallisa- tion was induced by sowing with a crystal from the prerious pre- paration. The crystals, which are needles radiating from centres, melt at 25'; they are much more soluble in alcohol than the cor- responding methyl compound. 0.2522 gave 0.6144 GO, and 0.1192 H,O.C = 66.44 ; H = 5.25. C19H,,0s requires C = 66.67 ; H = 5.26 per cent. The optical activity of this crystalline specimen was determined i n benzene solution, and found to be the same as that exhibited by the benzene solution of the first preparation, which had a t the time only been obtained in the liquid state. Thus, the liquid ethylic dibenzoyiglycerate obtained in the firsti preparation by distillation alone, and that obtained in the secoiid I 2108 FRANKLAND AND MACGREGOK. : ETHEREAL SALTS preparatioii by distillation and subsequent crystallisation were of equal purity, as determined both by combustion and by polarimetric observation. The density, compared with water a t 4", was determined a t 60" and 98.5" respectively. a i50/40 1.2010.a 60°/40 1.1596. d 9 8 . ~ / 4 0 1.1282. The substance was submitted to polarimetric examination at the following temperatures. Observed rotation. Density compared Temp. CZD i n 44 mm. tube. with water a t 4'. 1.1 D- 83.0'. ..... +10-02O 1.1407 + 19.95' 60-0 . . . . . . 11-49 1-1596 22.52 49.5 ...... 12.11 1.1693 23.53 22.0 ...... 13.65 1.1946 25.96 16.5 ...... 13.87 1.1996 26.28 On plotting the above figures on a diagram (see p. l22), it is found that the specific rotations for the temperatures from 83' to 49.5' lie almost exactly on a straight line, whilst the line joining the values for the lower temperatures exhibits a very slight but distinct droop. Thus, i f the value of the specific rotation for 16.5" be calculated from the change i n rotation between the higher temperatures of observation, the following values are obtained.Value of [a]D a t 16.5", calculated from specific rotations observed at + 27-39'. . . . . . . . . . 83-60.0" +27.06 . . . . . . . . . . 83-49.5 M hich values depart, therefore, but slight'ly from the actually observed r d u e for 16.3", which was found to be [a]D = +26*23". On further extrapolating the value of [alD for 15" fyom the values actually obtained for 22" and 16*5O, the result is Temperatures. +26.50 .......... 83-22.0 [ a ] D = +26*37" for 13". which is only 0.5" inferior to the specific rotation calculated for the inethylic compound at the same temperature. I n thus extrapola- ting, it is difficult to know which part of the line t o calculate from; thus, in the above we have taken as the basis of calcula- tion the variation in rotation between 22" and 16*,5O, a range of tem- perature which is wholly below the melting poiiit of the compound, namely, 25".A more rational mode of extrapolation would appear 10 be to calculate from ranges of temperature which bear the same relationship to the melting points of the two compounds. Thus, the inethylic compound melts a t 5g0, and the ethylic a t 25" ; we should,O F ACTIVE AND INACTIVE GLYCERIC ACIDS. 109 therefore, calculate in the case of the former from the variation in observed specific rotation hetween 80.5' and 59.5', whilst in the case of the ethylic salt from the variation between 49.5' and 22".Calcu- lating in this way, the values become [ U ] D for 15". Methylic diberizoylglycerate . . . . . . . + 26.89 E thy lic 9 , . .. .. .. +26-58 In consequence of the very slight difference between the specific rotations of methylic and ethylic dibenzoylglycerates at the tem- peratures referred t o above, we thought it desirable to ascertain their rotations at a much higher temperature, and for this purpose we passed a current of aniline vapour through the jacket chamber surronnding the internal metal tube in which the glass polarimeter tube is placed. In this way, a constant temperature of 183' was obtained in the in- ternal tube, but as at this temperature it would have been impossible to use the india-rubber rings, with which we ordinarily bring a gentle pressure to bear on the glass discs closing the ends of the polarimeter tube, we employed instead small spiral springs of copper wire, which answered the purpose admirably.The following resulhs were obtained- Methy lic? diben zoy lgly cerate. Ethylic dibenzojlglycerate. aD = +4*12'. Z 44 mm. a, = +4*02'. Z 44 mm. d 183'/4" 1,0951. d 183'14' 1.0599. c- -v----d at 183'. The specific rotations of these compounds at this high temperature may also be arrived at, by extrapolation from the observations made at lower temperatures, arid these calculated values are in both cases most remarkably concordant with the above experimental results ; thus, the extrapolated values are for 18.3' Methylic dibenzoylglycerate . . . . [a]D = +9*01' Ethylic 9 ) . . . . ,, = + 8 * i 8 In order to ascertain whether exposure to this high temperature had permanently altered the rotatory power of these compounds, the rotations were again taken in the same specimens at one of the lower temperatures at which they had been previously determined, with the result that precisely the original figures were obtained.We have thus shown that the rotation of these two compounds is exceedingly sensitive to temperature, [a]= at 15' being i n each case three times as great as it is at 183". (See also diagram, p. 122).110 FRANKLAND AND MACGREQOR : ETHEREAL SALTS P~opylic Dibenzoylglycerute ( A c t i v e ) . This was prepared on the same lines as the corresponding methylic and ethylic compounds. The active propylic glycerate was run into twice the calculated quantity of benzoyl chloride a t 140°, and the mixture then raised to 180'.After removing the excess of benzoyl chloride by distillation, mach difficulty was experienced in distilling the residue a t a low pressure, in consequence of violent bumping, nor was this tendency to bump removed by dissolving the et4hereal salt i n ether and then washing with a solution of sodium carbonate. Ultimately, after repeatNed fractionation, the main distiliate passed over between 267' and 269". This product, on combustion, yielded the following results. I. 0.2436 gave 0.5992 CO, and 0.1221 H,O. C = 67.09; H = 5.57. 11. 0.2341 ,, 0.5769 ,, ,, 0.1191 ,, C = 67.21; H = 5.65. C2,H2,06 requires C = 67-42; H = 5.62 per cent. The density, compared with water at 4", was determined a t 15", 25O, 60', and 98*5', d 15'14" 1 1807 ; d 60*0°/4" 1.1399 ; d 25"ld' 1.1727 ; d 98*5"/4" 1.1079.from which it appears that the diminution in density proceeds by 0*00080 for 1" rise in temperature between 15' and 25', by 0.00094 for 1' between 25" and 60', and by 0.00083 €or 1' between 60" and 98.5'. The substance was submitted to polarimetric examination at the following temperatures in a tube 44 mm. long, placed in an air chamber surrounded by a water jacket. Observed rotation UD in 44 nim. tube. Temp. 19.5' . . . . . +10.73' 340 .. . . . 10.10 38.0 . .. . . 9.96 48.0 . .. . . 9-53 56-0 .. . . . 9.10 68.2 . .. .. 8-47 78.0 , .. .. 8.02 87.0 ..... 7.54 Density compared with water a t 4'. 1.1771 1,1642 1.1605 1.1511 1.1436 1.1331 1.1250 1.1175 cab + 20.71O 19.71 19-50 18.81 18-08 16.99 16.20 15.34 These figures have been plotted on a diagram (see p.122), from which it appears a,gain that the line joining the specific rotations taken a t the higher temperatures is almost straight, but that it drops slightly with the lower temperatures. In extrapo1at)ing the value of [aID for 15', we have no melting point to take into consideration, as we have only had to deal withOF ACTIVE AND INACTIVE GLPCERIC ACIDS. 111 this substance in the liquid state ; we may therefore reasonably cal- culate from the variation in specific rotation observed between 38O and 19*5", Erom which results the value [ a ] , = +21*00 for 15". The rotation of the propylic is thus markedly inferior to that of either the methylic or ethylic compounds. Methylic Diphenylacetylg lycerate (Active).The method of preparation was similar to that employed in the case of the other ethereal salts described above. The active methylic glycerste was run into a large excess of the phenylacetyl chloride ; the action appeared to commence at BOO, becoming more vigorous at 105' ; the temperature was finally raised to 160'. After the excess of phenylacetyl chloride had been removed by distillation under diminished pressure, the residue was washed with a warm solution of sodium carbonate, extracted with ether, separated, and the ethereal solution washed with water. The ether was then removed by distil- lation, and the residual liquid fractionated at low pressure, the main distillate being obbined at 265-273'. This distillate was agairz washed with sodium carbonate solution, extracted with ether, shaken up with animal charcoal, as it was slightly coloured, and then dried in a vacuum desiccator.A combustion made with this product showed it to be impure methylic diphenylacetylglycerate. It was further purified by repeated distillation in 8 vacuum, hhe boiling point being 266-270" under 1 7 mni. pressure. On combustion, t8he following results were obtained. 0.2385 gave 0,5877 CO, and 0.1231 H,O. The density was determined at the following temperatures C = 67.20; H = 5.73. C,oHzoOs requires C = 67-41 ; H = 5.62 per cent. d 142"/4O 1.1975 ; cl 41"/4' 1.1737 ; d 8Oo/4O 1.1404. from which it appears that the diminution in density proceeds by 0.00089 f o r 1' rise in temperature between 14.2' and 41°, and by 0.00085 for 1' between 41' and SO3.Polarimetric determinations were made at the following tempera- tures. Observed rotation, Density compared Temp. U D in 92.35 mm. tube. with water a t 4O. La] D. 14.5'- . . . . -17.76' 1.1972 - lCi-06O 34.0 -35.0". . . . -16.62 1.1794 - 15-25 45.5 4 6 . 5 . . . . -16.03 1-1694 - 14-84 49.5 -50.5 . . . . -15.88 1-1660 - 14.74 61.0 -62.0 . . . . -15.58 1.1563 - 14.40 69.0 -70.0 . . . , -15.08 1.1495 - 14.20 77.5 - . . . . -14.88 1.1427 - 14.10112 FRANKLAND AND MACGREGOR : ETHEREAL SALTS Thus the introduction of the two phenylacetyl groups has an entirely different effect from the introduction of the two benzoyl groups, for whilst ruet>hylic dibenzoylglycerate is strongly dextro- rotatory, the diphenylacetylglycerate is levorotatory, in fact even more so than methylic diacetylglycernte. This profound difference in the rotatory effect produced by tlie beiizoyl and phenylacetyl- groups respectively will be again referred to later (see p. 119).Although the diphenylacetylglycerat e resembles the diace tyl- glycerate so closely in its rotation, there is one point in which it strikingly differs, and that is in the sensitiveness of t h e rotation to temperature; thus, from the above table it will be sem that tho lsvorotation becomes diminished with rise of temperature, whilst in the case of the diacctylglycerates, as we Iiave already shown (Trans., I 894, 65, 765), the laevorotation increases with increase of tempera- ture, the same being true of the glycerates themselves. The clibenzoyl- glycerates, again, have their dextzorotation diniinished with increase of temperature.These remarkable differences in beliaviour with regard to tempera- ture obviously indicaf e that the dissymmetry of the molecule which leads to the laevorotation of the glycerates and diacet~ylglycerates becomes exaggerated with rise of temperature, whilst the dissym- metry of the molecule which occasions the laevorotation of the diph en y lacetyl gl y cerat e diminishes with increase of temperature, arid similarly the dissymmetry which brings about the dcxtrorotatiou of the dibenzoylglycerates becomes moderated by rise of temperature. Methylic ~Ionotenzoylglycerate (Active). The active rnethylic gljcerate was mixed with the calculated quan- tity of benzoyl chloride in the cold.There was no visible action until the mixture was heated to 83", and it became vigorous a t 100' ; the oil-bath was finally raised to 180°, and maintained there for 20 minutes. The product, after being washed with sodium carbonate solution, and with water, was put into a vacuum desiccator, but crystallisation did riot ensue. Numerous unsuccessful attempts mere made to obtain crystals by using the most varied solvents, in conjunc- tion with a freezing mixture ; benzene, aldehyde, chloroform, toluene, aniline, ether, acetone, methglated spirit, propylic alcohol, carbon tetrachloride, and light petroleum were all emplo_red, to 110 purpose. In i i g h t yetrolenrn, the liquid was only very slightly soluble. The liquid was stibmitted to conrbust>ion, with the following results.0.2368 gave 0.5120 CO, and 0.1072 H20. Methylic monobenzoylglycerate, CllH1206, requires C = 58.93 ; H = 5-36 per cent. C = 58.97; H = 5.03.OF ACTIVE AND IXACTIT7E GLYCEBIC ACIDS. 1.13 The liqnid, which analysis had thus shown to be pure metbylic monobenzoylglycerate, was examined with the polayimeter. a, = + 5.95"; t = 13' ; d 1 3 ' / 4 O = 1.2655 ; 1 = 50 mm. It was then distilled under a reduced pressure of 10 mm., when This distillate, on polarimetric examination, gave the following about one-half of it passed over between 180' and 240'. results. U D = +7*13'; I = 50 mm.; t = 13'. Thus this distillate possessed a considerably higher dextrorotation than the original liquid from which it was obtained, clearly pointing, therefore, to the fact that the original liquid was a mixture of the two possible isomeric methylic monobenzoylglycerates, and from our subsequent experiences with the ethylic compouud, there can be little doubt tlhat the more volatile part is the a-modification with the higher dextrorotation, whilst the /3-compound with the higher boiling point, and which remained for the most part in the distilling flask, must have a lower dextrorotation, or even a 1Evorotatioa.Tbe quantity of material a t our disposal was not sufficient to enable u s to obtain either of these isomers iii a pure state, so that for the present we have had to be content with having indicated this probable relationship between their rotations, namely, that the nzethy2ic a-monobenzoylglycerate is dextrorotntory, but much less s9 t h a n metltylic dibenzoylglyctrate, whilst methy lic f3-monobenz~ylglycerate i s certainly less dextromtatory thaw the a- compound, and possibly even hvorotatory. (For another possible explanation of these phenomena see p.115.) dlet h y 1 ic $Ion obenzoy lglyce rate (51 active). This was prepared in the same way as the active compound, only using inactive methylic gljcerate. On drying the product, the ethereal solntion of which had been washed with sodium carbonate solution and water in the desiccator, it became pasty and turbid, i n consequence of the appemacce of small crystals, the quantity of which iucreased after prolonged standing ; a large proportion of t h e material, however, still remained as a viscid liquid. The ci-ystals were found to be very so!uble in alcohol, chloroform, and acetone, but recrystallieation from hot benzene prored most serviceable for their purification ; in this way the cr,ystals are obtained in small, nodular groups, exhibiting a radiated structure.The melting point of the purified crystals was 92.5-93-5'. 0.2431 gave 0.5213 CO, and.0.1170 H,O. C = 58.48 ; H = 5.35. Methylic monobenzoylglycerate, C,1H,20,, requires C = 58.93 ; H = 5-36 per cent.114 FRANKLAND AND MACGREGOR : ETHEREAL SALTS The product was again recrystallised from benzene, after which the melting point was found to be 92-5-93', and 0x1 combustion the fol- lowing results were obtained. Methylic monobenzoylglycerate, CllHI2O5, requires C = 58.93 ; H = 5.36 per cent. The substance was again recrystallised, and another combustion 0.1197 gave 0*3570 CO, and 0.0594 H,O.CllHlZO5 requires C = 58.93 ; €3 = 5.36 per cent. As already pointed out in the case of the active compound, there should be two mcthylic monobenzo~lglycerates, but whether the crystals thus obtained are the z- or the p-compound we have not yet directly determined ; from the fact, however, that the crystals appeared in the originally liquid product, and that a large portion of the laotter permanently remained in the liquid state, i t wonld appear probable that both the a- and the ,%compounds had been formed in the reaction, and that the one was crystallisable, and the other not. It may fur- ther be suggested that, by analogy, the crystallisable substance is probably the p-, and the unorptallisable the a-, compound; thus a-chloropropionic acid is ti liquid boiling a t 186', whilst /3-chloro propionic acid is a solid, the melting point of which is variously given as 35.5-41' by Krestovnikoff (J.Russ. Chenz. SOC., 11, 248): and 58" by Richter (Zeit. f. Chew,., 1868, 451) ; again a-chlorobutyric acid is a viscid liquid (Markovnikoff, Annulen, 1870, 153, 241), whilst P-chlorobutyric acid is a crystalline body, melting at 98 -- 99" (Mark- ovnikofi, Zeit. f. Chem., 1868, 621). Similarly a-bromopropionic acid is a liquid boiling a t 205.5", and solidifying a t -17" (Keknl6, Anmden, 1864, 130, IS), whilst p-bromopropionic acid is a solid, melting a t 61.5' (Richter, 2 e i t . f . Chem., 1868, 449). 0.2112 gave 0.4530 COz and 0.1039 H,O. C = 53-50 ; H = 5.47.made. C = 58.55 ; H = 5.51. Ethylic Il.loizob~tzoylgllJce,.ate (Actice). This was prepared in the same way as the two methylic mono- benzoylg1ycerates described above. After washing the crude product with sodium carbonate solution and water, it wa3 placed in the vacuum desiccator, in which, after six Reeks, it began t o crystallise, but the greater part remained liquid. The crystals were pressed between filter paper, and dissolved in hot, light petroleum, from which, on cooling, radiating needles were obtained, melting at 62". Still finer crystals were obtained from petroleum spirit (b. p. 80-117'). Thus in this case again it would appear that both the a- and the /3-compounds are formed in the reaction, and that one of these isON ACTIVE AND INACTIVE GLPCERIC ACIDS.113 crystallisable, and the other not, and for the reasons given above, the crystallisable one is in all probability the P-compound. The above crystals were submitted to combustion, with the follow- ing results. 0.2503 gave 0,5527 CO, and 0.1332 H20. C = 60.22 ; H = 5.91. 0.2293 ,, 0.5057 ,, ,, 0.1220 ,, C = 630.15; H = 5.91. ClzHlaOs requires C = 60.50 ; H = 5.88 per cent. The crystalline ethylic monobenzoylglycerate was examined polari- metrically in a stmate of fusion, at the following temperatures. Observed rotation, aD. Temp. 2 = Mmm. Density, t0/4'. [.ID- 67.0". ..... -4.98 1.1547 - 9.80" 78.5 ...... -4.88 1.1438 - 9-70 88.3 ...... -4.88 2.1344 -9.77 Thus the solid ethylic monobenzoylglycerat,e, which is presumably the P-compound, has a strong lzevorotation, which, moreover, remains practically unaltered by change of temperature, and thus difters markedly from all the disubstituted ethereal salts of glyceric acid which we have examined.The liquid portion of the crude ethereal salt, from which the above solid ethylic P-monobenzoylglycerate had crystallised, was examined in the polarimeter, and was found to possess a dextrorotation. This is, therefore, as in the case of the methylic monohenzoylglycerate, con- sistent witb the supposition that there were two et hylic monobenzoyl- glycerates formed, of which the solid one (doubtless the /+-compound) was obtained in a pure state, and was found to be levorotatory, whilst the liquid one (doubtless the a-compound) is dextrorotatory. We would, however, point out thaii the facts also admit of another explanation, namely, that whilst the solid ethylic monobenzoyl- glycerate possesses the IEvorotation given above, the dextrorotation of the liquid frnm which it separated may be due to ethylic dibenzoyl- glycerate.A similar explanation would also fit the facts in the case of the methylic compound. We cannot positirely decide between these two alternative hypotheses until we have prepared these com- pounds on a larger scale. Particularly interesting with regard t o the solid ethylic moLo- benzoylglycerate are the circumstances (1) that its specific rotation is almost identical with t h a t of ethylic: glycerate itself (for a fuller discussion of this point see p. lZO), and (2) that the specific rotation is extremely insensitive to temperature.This insensitiveness is evident from the figures given above, but we have submitted it to a still more severe test by determining the specific rotation" at 136-13'7" * The ethylic monobenzoylglycerate used in this experiment was not quite pure.11 6 FRANKLAND AND NACGIREGOR : ETHEREAL SALTS (using the vapour of xylene in the jacket-tube of the polarimeter), with the following result. ED = - 4-22' ; t = 136.5' ; Z = 44 mm ; d 136*5'/4' = 1.0886 ; As pointed out in the footnote below, the substance used for this experiment was not quite pure, its rotation at 71" being slightly below what it should be ; on increasing the specific rotation at 136.53 in the proportion 9.07 : 9.75 :: 8-81 = 947, we obtain the corrected [ a ] D = - 9-47' at 136.5', or almost exactly the same figure as for the lower temperatures at which the observa- tions were previously made.The specific rotation of this ethylic rnonobenzoylglycerate is thus almost wholly independent of tempera- ture, our experiments showing that it suffers only the most trivial diminution in value between 67' and 136.5'. The relationship between ethylic glycerate and ethylic monobenzoyl- glycerate is thus a very remarkable one, for whilst the molecular dissymmetry of the latter remains pracbically constant at all tem- peratures, the molecular dissymmetry of the former (leading to lavo- rotation) increases with the temperature, and at 15' its molecular dissymmetry (as measured by specific rotation) happens to be equal to the uniform molecular dissymmetry of the ethylic monobenzoyl- glycerate molecule.Thus we have formerly (Trans., 1894, 65, 769) shown that the specific rotation (lavo) of ethylic glycerat'e increases by 0.035' for 1' rise in temperature, so that assuming this increase to proceed uniformly, at 136.5', the specific rotation of ethylic glycerate would be 13-19', and therefore greatly in excess of that of ethylic monobenzoylglycerate, The exact temperature, in fact, at which coincidence between their specific rotations should take place is 33.8'. These relations strikingly indicate t h e importance of taking into account temperature in conrection with the comparison of the specific rotations of different active substances. Methylic dip yopion ylgzycerate (Active). The method of preparation was the usual one of running the plycerate into excess of the acid chloride, but a difficulty arose in consequence of the propionyl chloride containiug phospliorus com- having suffered slight decomposition through a distillation to which it had been submitted, as was shown by its rotation a t 71" being aD = -4.59", 1 = 44 mm., the 5gure previous13 found with the pure substance.OF ACTIVE AND INACTIVE GLYCERTC ACIDS.117 pounds, which it nppears to be practically impossible to remove, owing to the proximity of their boiling points (propionyl chloride b.p. 80', PCI, b.p. 76", POCI, b.p. 107"). On examining the crude product, i t was found to be slightly dextrorotatory and to fume in con- tact with air ; on refractionating, the lower distillate, which fumed, showed a high dextrorotation, whilst the higher fraction had a laevo- iotation.As it was found impossible to entirely remove the fuming liquid by fractionation, the laevorotatory compound was washed successively with a solution of sodium carbonate and with water, then dried in a vacuum desiccator, and subsequently distilled ; the distillate thus obtained did not fume, and gave the following polarimetric result. CCD = -11.5"; I = 99.2 mm. at 148". This liquid was again distilled, but the amouut of distillate obtained was so small that the rotation could not be ascertained with t.he requisite accuracy, but it was approximately aD = -11.6-11*9" ( I = 99.2 mm.). The dextrorotation of the fuming liquid referred t o above was doubtless due to the presence of chlorine derivatives of glyceric acid formed by the action of the phosphorous compounds in the propionyl chloride used.A second preparation again yielded a crude product which fumed in the air, and this instead of being distilled was washed with a solution of sodium carbonate as described above. By repeated fractionation of t h i s washed product, a liquid was obtained having a rotation aD = -12.2" (I = 99.2 mm.) a t 14.2'. this was again fractionated, and the distillate then gave substantially the same rotation as before, thus a, = -6.23" (I = 50 mm.) a t 1.5*2=. The rotation was found to be considerably influenced by tempera,- ture, and, as in the case of the diacetylglycerates, the rotation increases with rise of temperature. The specific rotation m'ty be calculated from the above figures, and the density, which was found to be d 15'/4" 1.1349, thus This rotation is slightly inferior to that of methylic diacetyl- glycerate, which we have previously shown (Trans., 1893,63, 1430) to be [a], = -12.04".It is to be anticipated, therefore, that the di- butyr~lglycerates will exhibit a further diminution in levorotatioii and so on for the series of fatty acid radicles. Although the fact that the rotation obtained was essentially the same for the two118 FRANKLAND AND MACQREGOR : ETHEREAL SALTS separately prepared specimens of methylic dipropionylglycerate points to the rotation being correct, still we give the figure with some reserve in consequence of the phosphorus compounds present in tho propionyl chloride employed having conceivably interfered with the optical purity of the product. On combustion the following resnlts were obtained.0,2912 gave 0.5478 GOz, and 0.1818 H,O ; C = 51.30 ; Hz6.94. Again for hydrolysis with alcoholic potash. 11. 0.9426 ,, ,, 0.6798 ,, ,, = 72.22 ,, Calculated for methylic dipropionylglycerate = 72.41 ,, CIoH,,O6 reqnires C = 51.72; H = 6-90 per cent. I. 1.0506 gram required 0.7566 gram KOH = 72.01 per cent. Xunzrnary and Conclusions. (1.) Whilst the ethereal glycerates are laworotatory, and the diacetylglycerates more l~vorotatory still, the dibenzoylglycerates are powerfully dextro-rotatory, thus (1) H\ /CH2*OH (31, C Met.hylic glycerate [a]= = -4 'SO". (59) COOCH,/ \OH (17) (1) H\ /CHC*OH (31) C Propylic glycerate. i87) COOC,H/ '\OH (17) [alD =: - 12-94".(1) H\ /CH2*0C2H30 ($3) C (73) COOC2H,/ \OC,H,O (59) Ethylic diacetylglgcerate. [aJD = -16 -31'. (1) H, ,CHyOC;H,O (135) C (59) COOCH,/ \OC;H,O (121) Methvlic dibenzoylglycerate. [a]; = + 26 '89" (at 15"). [MID = + 88 5?0". ( 1 ) H\C/CH2*OH (31) ($3) COOC&.' 'OH (17) E thylic glycerat e [alD = -9*1S0. (1) H\ /CH2*0C2H30 (73) C (59) COOCH~/ \OC,H,O (59) Meth ylic diacetylglycerate, [.ID = -12'04*. C ( 8 ; ) COOC3H7/ \OC2H30 (59) (1) H\ /CH2*OC2H@ (73) Prop-ylic diacetyIglycerate. [a]= = -19 %7". (1) H, ,CH,.OC7H,O (135) C (73) COOC,H,/ \OC:H,O (121) Ethylic dibenzoylglycerate. [aID = + 26 '58" (at 15'). [MID = + 90 *go'. (1) CH2*OC7H,O (135) (87) COOC,H/ \OC;H,O (121) Propylic dibenzoylglycerate. [a]D = + 21 *ooo (at 15'). [MID = -k '74 *76". (2.) We have already shown (Trans., '1893, 63, 1415, and 1894,OF ACTlVE AND INACTIVE CILYCERIC ACIDS.119 65,754) that' in the series of the glycerates and the diacetylglycerates respectively, the rotations rise with the positive radicle, attaining in each series a maximum at the isobutyl compound. In the series of the dibenzoylglycerates, on the other hand, the rotations diminish from the methylic salts onwards, the rotations of the methylic and ethylic salts being almost identical, but considerably greater than the normal propylic. As the dextrorotation is conditioned by the benzoyl groups, whilst the positive radicles alone condition a negative rotation of the molecule, we should anticipate that by increasing the magnitude of the positive radicle the tendency towards a negative rotation would be increased, or in other words that ihe positive rotation would be diminished, and this is actually found to be the case.It would, however, have been anticipated thatl this diminution in posi- tive rotation should have proceeded more regularly, and that the positive rotation of ethylic dibenzoylglycerate should have been coil- siderably inferior to that of the methylic compound. If this line of argument be correct it is further to be anticipated that this diminution in the positive rotation of the dibenzoylglyce- rates will continue until the isobutylic compound is reached, beyond which the positive rotation should again increase. This point we have not yet had time t o determine. (3.) Whilst the presence of the two benzoyl groups thus condi- tions a positive rotation, the result is entirely otherwise if two phenacetyl groups be introduced iastead.Thus we have found methylic diphenacetylglycernte to be laevorotatory (1) H\ /CH,*OCJ3;O (149) C (59) COOCH,/ \OC,H,O (135) Methylic diphenacetylglycerate. [uJD = -16*06" (at 14'5'). In fact this compound has almost exactly the same rotation as ethylic diacetylglycerate, aiid a little higher rotation than that of methylic diacetylglycerate. This is a most striking illustration of what we have before called attention to (Trans., 1893, 63, 535), that the rotation is more power- fully influenced by the qualitative character than by the mere mass of the groups attached to the asymmetric carbon atom. (4.) We have also prepared some of the monobenzoylglycerate~.Of each of these, there should, obviously, always be two isomeric: modifications, according as the benzoyl gronp enters the glyceric acid molecule in the a- or in the P-positim. These compounds were obtained by mixing the calculated quantities of benzoyl chloride and [MI* = -57 ' 1 ' 7 O .120 FRANRLAND AND MBCGREGOR : ETHEREAL SALTS ethereal salt of glyceric acid and t,hen heating themixture as long as hydrogen chloride was evolved ; both isotners appear in every case to be formed. I n the case of methylic monobenzoylglycera~~e (active), both isomers being liquid, we have not yet been able to separate them perfectly from each other. We have, however, shown that the lower boiling isomer, which is in all probability the a-compound, has a greater dextrorotation than the higher boiling and, presumably, ,&compound ; i n fact the latter may even be l&vorotatory.A solid methylic monobenzoylglycerate (inactive) was obtained which melted at 92-5-93'. In the case of ethjlic monobenzoyl- glycerate (active) the higher boiling, and, therefore, presumably p-compound is solid (m. p. 6 2 O ) , and has been purified by repeated crystallisation. It is lsvorotatorg, and has almost exactly the same rotation as ethylic glycerate itself. Methylic a-monobenzoylglycerate. Dextrorotatory liquid. Met hylic /3- monoben zoy lgly cerat e. Less dextrorotatory liquid than the a-compound. (1) H\C/CH2*oH (31) (1) H\ /CH2*OCjH,O (135) C ( J 3 ) COOC,H,/ \OC;H@ (121) (73) COOC~H,,' \OH (I7) Ethylic a-monobenzoylglycerate. Ethylic 8-monobenzoylglycerate.Dextrorotatory liquid. [a]D = -9.80" at 67", but insensitive to temperature, hence probably the same a t 15'. (Melting point SZ".) [MID = - 23.32". The almost exact equality between the specific rotations of ethylic glycerate (;a], = - 9 . 1 8 O ) and of ethylic P-monobenzoylglycerate ([aIn = -9.80') is extremely remarkable, for it would surely be anticipated that the displacement of a single atom of hydrogen by such au enormous group as the benzoyl radicle should produce a pro- found change in the dissymmetry of the molecule as measured by' specific rotation. This replacement of hydrogen by benzoyl, wit'hout much effect on the rotation, is only realised in the case of the CH,*OH-group of ethylic glycerate, for, by replacing tlie H in ths OH-group by C,H,O, the product is dextrorotatory (see ethylic a-monobenzoylglycemte) , and, therefore, entirely different, even in, the sign of its rotation, from the original ethylic glycerate. (5.) The remarkable phenomenon of replacement without marked change in rotation is also exhibited in the case of the methylic diphenyl- acetylglycerate referred to in (3), for, as there pointed out, the rota- tion of this compound ([RID = -16.06' a t 14.5O) differs but slightly from that of methylie diacetylglycerate ( [ a ] , = -12.04'), althougliOF ACTIVE AKD INACTIVE GLYCERIC ACIDS.121 the constitutJona1 change is of such a profound character as the dis- placement of two hydrogen atoms by two C6H15-groups. (6.) Methylic dipropionylglycerate ([a]D = -10*97"), again, ex- hibited only a very slight difference in rotation from methylic diacetyl- glycerate ([a]= = -12*04"), although the constitutional change is considerable, consisting as it does in the replacement of two atoms of hydrogen by two CH3-groups.(7.) It is worthy of remark, that in all these cases in which snbsti- tution is attended with comparatively little change in rotatory power, the substihtion takes place at a point which is comparatively remote from the asymmetric carbon atom ; whilst in those cases in which the substitution is so near the asymmetric carbon atom that it is only separated froin it by a single atom of oxygen, the change in rotatory power is very considerable. Thus, turning for illustrations of this principle t o the experimental material which we have ourselves furnished in this and previous communications, we find i3) (9) Paasiige from glycerates to dibenzoylglycerates causes great change in specific Passage from glycerates to diacetylglycerates causes pest change in specific Passage from glycerates to diphenylacetylglycerates cauees great change in Passage from lactates to benzoyllactates causes great change in specific rotation.,, glycerate to a-monobenzoylglycerate causes great change in Passage from methylic glycerate to ethylic glycerate causes great change in Passage from ethylic glycerate to propylic glycerate causes smaller change in Passage from propylic glycerate to isobutylic glycerate causes still smaller Passage from propylic glycerate to normal butylic glycerate causes practically Passage from normal butylic glycerete to heptylic glycerate causes very little Passage from heptylic glycerate to octylic glpcerate causes very little change Passage from metliylic dibenzoylglycerste to ethylic dibenzoylglycerate causes Passage from ethylic glycerate to ethylic B-nionabenzoylglycerate causes prac- Passage from methylic diacetj-lglycerate to methylic dip%enylacetjlglyceratc rotation.rotation. specific rotation. >> ,, acetyllactates >, 1 ) ,, specific rotation. specific rotation. specific rotation. change in specific rotation. no change in specific rotation. change in specific rotation. in specific mtation. practically no change in specfic rotation. tically no change in specific rotation. causes very little change in specific I &tion. An exception to the above rule is afforded by the specific rotations of the three dibenzoylglycerates which we have prepared, and in which we found that passage from the methylic to the ethylic com- VOL.LXIX. K122 ETEEREAL SALTS OF ACTIVE, ETC., GLPCERIC ACIDS. pound was attended with less effect on the rotaiion than passage from ethylic to propylic, although the latter substitution is more remote from the asymmetric carbon atom. Again, the same phenomenon is exhibited by the extensive mate- rial which has been furnished by Witlden (2eit.physikaZ. Chem., 1895, 17, 264) in connection with the derivatives of malic acid. Thus, bearing in mind the arrangement of the groups around the assym- metric carbon atom, SOOH p z , H C-OH -9 COOK the following results will be seen to show that replacement of the carboxylic hydrogen atoms produces ti considerable effect on the rotation ; but a much greater effect is obtained by replacing the hydroxylic hydrogen ; whilst after this latter hydrogen has been re- placed, all further substitutions carried out in the substituting group itself are almost entirely without influence on the rotation.Dimethylic malate.. . . . . . . . . Diethylic ,, . . .. .. . . .. Dipropylic ,) . . . . . . .. . . Diisopropglic ,, .... . .. .. niisobutylic , , . . . . . . . . . . Diamylic , , . . , . . . . . . . Dicaprylic , , . . . . . . . . . . C 4 D . - 6.85" - 10 -18 - 11 *62 - 10 '41 (about) - 11 *14 - 9-92 - 6-92 (about) Dimethylic acetylmalate. . . . . ,, propionylmalate . ), butyrylmalate . . . ,, isobutyrylmalate .,, isovalerylmalate . ,) chloracetylmalate ,, bromacetylmalate Dietliylic acetylmalate . . . . . , ,, propionylmslate . . . :, butyrylmalate.. . . . ,, isobutyi*ylmalate. . . ,, isovalerylmalate . . ., ,, bromecetylmalste. . , , brompropionylma- late.. . . . . . . . . . . , , brom butyry lmalate ,, bromisobutyrylmu- late.. . . . . . , . . . . -22.92 - 22 9 4 - 22 -22.36 - 22 -39 - 23 '30 - 22 '40 - 22 5 2 - 22 -20 -22.28 - 21 a99 - 22 *07 - 22 '48 -22.48 - 28 9 6 -22-57 Dipropplic acetylmalate . . . . ,) chloracetylmalate ,, butyrylmalate. . . . ,, isovalerylmalate.. ,, bromacetylmalate. Diisobutylic acetylmalate . . ,, butyrylmalate.. ,, isovalerylmalate ,, bromacetylma- late - - . . . . , , ialD. - 22 '85O - 23 -52 -22 .a - 21 '68 - 22 '24 -21 '88 - 21 '68 - 19 -91 - 20 '38 Maldiamide . . . . . . . . . . . . . . Malic acid . . . . . . . . . . . . . . . . Maldianilide . . . . . . . . . . . . . . Maldi-o-toluide . . . . . . . . . . . . Maldi-ptoluide.. . . . . . . . . . . Mal-B-nttghtbyl . . . . . . . . . . - 38 '0" - 5 * 75" - 60.0" - 66 -5" - 70 '0" - 51 '5" Chlorosuccinic acid . . . . . . . . 9 9 anhydride.. . Y, chloride . . . . Dime thylic chlorosuccinate. . Diethy lie .. Dipropy lic >, .. Diisobutylic ,, .. 9 , 'Diamy lic Y J .. -I. 52 '0' + 31 '0" (HboUt) + 29 -53 -I- 41 '42 + 27.50 t-25.63 + 21 '57 (about) + 21 -56 The rotation of these compounds was taken in solution.+ 27 -I 18 + 9 0 II 6 e J 1 -9 - 18 INFLUENCE OF TEMPERATURE ON THE SPECIFIC ROTATION OF COMPOUNDS DESCRIBED. --T-ROTATION OF ACTIVE COMPOUNDS I N ORGANIC SOLVENTS. 123 Dimethylic bromosuccinate.. + 51 -18 Dipropglic bromosuccinate.. + 38 '05 Dietbylic 11 . . -I- 40.96 1 Diisobutylic ,, .. +23*56 Thus in the above series such a change as that from dimethy'lic acetylmalate to dimethylic chloracetylmalstte is essentially similar to the change from methylic diacetylglycerate to methylie diphenyl- acetylglycerate; and in both cases the effect on rotation is remark- ably small. In malic acid, the hydroxyl group being directly attached to the asymmetric carbon atom, corresponds to the a-hydroxyl group in glyceric acid, and replacement OP this hydrogen in both case:: pro- duces a profound change in the rotation. Still rnore pyofound is the change in the rotation if the whole of the OH-group is substituted ; as, for example, in the passage from dimethylic malate to dimethylic chlorosuccinate. Again, i t appears that the replacement of the hydroxylic hydrogen by a hydrocarbon radicle produces far more effect on tfhe rotation than the substitution of the same atom of hydrogen by an acid radicle containing the same number of carbon atoms ; thus a com- parison map be made between 7 H2.C 0 OCH, Hg;:ECH3 H q O * C2H3G SH2* CO 0 CH, H - c OH bOOCH, COOCH, Q COOCH, [.ID = - 6 ' 8 5 O [uID = f60.9B0* [ u ] D = -22'92" ( Walden). (Purdie and W~lliamson) (Walden). Trans., 1895, 979.

ISSN:0368-1645    

DOI:10.1039/CT8966900104

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

ROTATION OF ACTIVE COMPOUNDS IN ORGANIC SOLVENTS. 123 XIV.-Rotation of Opticully Active Compounds in Oyganic Solvents. By PERCY FRANKLAND, Ph.D., F.R.S., and ROBERT HOWSON PICKARD, B.Sc. IN pursuing the study of the connection between optical activity and chemical composition, the investigation is frequently hampered by the circumstances that the active compounds under examination are solid at those temperatures at which polarimetric observations can be conveniently made, and that the optical activity displayed b j the substance in solution is liable to enormous variations according to the pn~ticular solvent employed. Great importance, therefore, attaches to the discovery of any relationship between the real optical * The sign f is employed, as it has not yet been determined whether dextro- ethoxysuccinic acid is derived from dextro- or from levo-maic acid ; in either casr, lrowerer, our statement above is strongly supported by the facts.K 2124 FRANKLAND AND PlCKhKD : ROTATION OF activity of a particular substance and the variable activity which it exhibits in different solvents. This problem has been attacked in a very suggestive way by Breundler (ThBses pre’sente’s Ci la Faculte’ des Sciences de Paris, 1894) in connection with his interesting researches on the derivatives of tartaric acid, and his conclusions are summarised in the two follow- ing statements. “ When a solvent gives normal figures for the molecular weight of the dissolved active compound, it does not alter its rotatory power for any concentration. “On the contrary, if the solvent gives abnormal figures for the rotatory power, it causes the compouud to undergo some change, and yields also abnormal cryoscopic and ebullioscopic figures.In this case, the concentration influences [a],, which departs from the normal value in proportion as the solution is more dilute.” The latter mode of behaviour is ascribed by Preundler to the operation of a dissoci:ition process in neutral organic solvents analo- gous to that which takes place in saline solutions. The double importance of this subject, from the point of view of optical activity on the one hand, and from that of the dissociation theory on the other, appeared to render i t highly desirable that the validity of these conclusions should be tested by further experiments, and for which some of the optically active compounds prepared by one of us were particularly well adapted.The experiments which we have carried out with this object con- sist, firstly, in the determination of the optical’ activity of a pure sub- stance in the liquid state, secondly in the determination of its activity a t different dilutions in solidifiable solvents, and, thirdly, in the cryoscopic determination of the molecular weight of the active sub- stlance in the same solvents a t similar dilutions. The optically active substance which served for the greater number of our experiments was met hylic dibenzoylglycerate, which cryatallises in beauxiful, slender needles melting a t 58--59O, and often upwards of an inch in length. The optical activity and molecular weight of methylic dibenzoyl- glycer ate were determined in the following solvents :-Benzene, acetic acid, ethylene dibromide, and nitrobenzene.Experirnerh with Benzene as Xolvmt. I n order to test the cryoscopic apparatus employed, which was of the ordinary Beckniann type with a thermometer graduated i n bnndreths of a degree Cent.., the following determinations were made with naphthalene.OPTICALLY ACTIVE COMPOUNDS IN ORGANIC SOLVENTS. 125 0 -3; 0 0 -865 0 -945 1 -360 1 '710 2 '100 2 '595 3 -010 3.380 , 4.320 C~yoscopic Determinntioir s with Naphthalene in Benzene. Xolecular weight of Naphthalene = 128. Molecular depression for Benzene = 49 (Raoult, Aimales d. Chim. et Phys., [6] 2, 1884). Weight of benzene in grams. 37 '4965 9 , 9 , 37 .;020 37 -4965 37 -2020 37 * 4965 Weight of naphthalene in grams.0.6345 0'7555 1 -1842 1 -6545 1 'ti800 2 5320 3 '2540 8 *3070 Grams of naph- thalenein 100 grams of solu- tion." 1 -6 1 -9 3 -0 4 -2 4.3 6 -3 8 -0 8 -1 Depression of freezing-point in "C. 0.685 0 -810 1 -285 1 9.45 1 -770 2 -660 3 -395 3-440 Molecular weight deduced. 121 '1 121 '8 120 '4 128 -9 125 -0 124 *4 126 '3 125 -6 The above figures, which approximate to the theoretical molecular weight of naphthalene, show that the arrangement employed was capable of yielding accurate results. In the next instance, a similar series of cryoscopic determinations was made with active methjlic dibenzoylglycerate (derived from dextrorotatory glyceric acid). Cryoscopic Determinations with Active Methylic Bihenzoylglycerate i i ~ Benzene.Molec ttlar weight of Methglic Dibenzoylglycerate = 328. Weight of benzene in grams. Weight of methylic diben- zoylglycerate in grams. 0 -1567 0 -3489 0 .3787 0 -5559 0 -7144 0 %8€3 1-1010 1.2920 1 -4439 1 *8644 Grams of subst,ance in 100 grams of solution. 2 -3 5 -0 5 -4 7 *8 9 *8 11 -0 14 '3 16 -4 18 *O 22 -0 Depression of freezing-point in "C. Indicated molecular weight. 315 -5 300 *5 298 -6 304 -2 311 '2 314 '4 316 -0 319 *8 318 *2 321 ' 5 * The percentage of substance employed is, throughout the paper, given in The terms of 100 parts of the solution and not of the solvent, as is usually done.126 FRANKLAND AND PICKARD : ROTATION OF Granis of solvent (benzene). In this series i t will be seen that the indicated molecular weights of the ethereal salt are in all cases decidedly below the theoretical, the values being, on the whole, smallest for the most dilute solu- tions, and rising with increased concentration.The molecular weight of an optically active compound at once raises the question as to what is the molecular weight of the corre- sponding inactive '' racemate." This question was discussed many years ago by Perkin (Trans., 186'7, 20, 149), who was, however, unable to obtain the molecular weights of the ethereal salts of tartaric and racemic acids by vapour density determination, but came to the conclusion that their molecular weights must be identical in consequence of the identity of t h e boiling points of the correspond- ing ethereal salts of the tartaric and racemjc acids. As far as we are aware, however, this point has not yet been investigated by means of cryoscopic and ebullioscopic methods for racemates dissolved in organic liquids.* We proceeded, therefore, to make a similar series object of this is to render the percentage composition of the solutions submitted to cryoRcopic examination directly comparable with that of the solutions examined in the polarimeter.* Since making these experiments, we End that K. Auwers (Zeit. physikal. Chem., 1894, 15, 51) has cryoscopically examined methylic and ethglic lactates (in- active Gf course) in benzene solution, with the following results. Meth,ylic lactate (inactive), C4H8O3 = 104. Grams of Grams of substance Observed Molecular weight substance. to 100 grams solvent.! depression. deduced. 15 -00 J Y J Y J J YJ Y ? ?, Y > Y Y 97 J Y J J Y 9 0 '1050 0 2220 0 *5555 1 -0205 1 '3920 0 -70 1 '48 3 -70 6 -80 9.28 0 '347 0 -662 1 '430 2 -271 2 '801 EthyZic lactate (inactive).C6H1,,03 = 118. 0 -0600 0 -1090 0 -3258 0 *6225 0 -9862 1 -3265 1 -5350 1-7725 0 -40 0 -73 2 -17 4 -15 6 -57 8 -84 10 -23 11 -82 0 -183 0 -302 0.831 1 *463 2.101 2 -535 2 -945 3 -294 98 9 110 -0 127 -0 14'7 -0 162 '0 107 -0 118.0 128 -0 139 '0 153.0 171.0 170.0 176.0 There is no reference made to the possibility of the lactates being present as racemised molecules, and the very high values obtained for the molecular weights are attributed exclusively to the abnormal behaviour which is exhibited by hydroxy- compounds in general. This conclusion can, however, obviously be only provision- ally drawn in the absence of any information as t,o the cryoscopic behavionr of the corresponding active compounds.OPTICALLY ACTIVE COMPOUNDS IN ORGANIC SOLVENTS.127 of cryoscopic determinations with inactive methylic dibenzoylglyce- rate, a substance which also crystallises in long, slender needles melting at 44-46', whilst the active body melts at 58-59'. The solubility of the active and inactive compounds in alcohol was also found to be very different ; thus at 1 2 * 8 O , 100 parts by weight of methylated spirit dissolves 1.96 part of active, and 5.33 parts of inactive methy lie diben zoy lgl ycerate. Cryoscopic Determinations with Inactive Methylic Dibenzoylglycerate in Benzene Solution. Molecular weight of inactive methjlic dibenzoylglycerate (calculated as a racemate) = 328 x 2 = 656.Weight benzene grame of in 5 -8980 8 *2791 8 -2791 5 .:980 Weight of methylic diben. zcylglycemte in grams. ~~ 0.2281 0 -2350 0 *4602 0 -4559 0.6542 0 -8111 1 -0280 1 -3430 1 -5917 1.8346 Grams of substance in 100 grams of solution. 3 . 7 3 ' 8 5 -2 7.1 7 -3 8 -9 11.0 13.9 16.1 18 -2 Depression of freezing point in O C. ---- I 0.600 1 0-640 ~ 0'915 i 1.240 1 '285 1 570 1 -980 2 '560 3 -015 ! 3.445 Indicated molecular weight. 308 *7 309 ' 8 297 -7 305 -4 301 -3 305 -7 307 -3 310 -5 312 *4 315 -2 The above figures f o r the molecular weight are obviously substan- tially the same as those obtained with active methylic dibenzoylgly- ccrate, and clearly indicat.e that in the benzene solution the molecules of the oppositely active ethereal salts, which give rise to the inactive com- POUnd, are not i n coinbination. The figures afford, moreover, in their divergence from the ca.lculated weight of the single molecule, a con- firmation of the results recorded above for active methylic dibenzoyl- gl ycerate.It will be interesting now to compare with these cryoscopic measurements the polarimetric determinations made with similar solutions of active methylic dibenzoylglycerate in benzene. The results are recorded in the following table (p. 128). These figures show that the rotation [aID of the ethereal salt in benzene solution is greatly in excess of its rotation in the pure state, and, further, that the rotation increases slowly, but unmistakably, with the dilution of the solution. From the diagram given on p.140, it will be seen that the rate of increase in rotation proceeds very steadily wit.h the dilution until the highest dilution is reached, when128 FRANKLAND AND PICKARD : ROTATION OF an abrupt rise in the rotation was observed. But, on extrapolation, it is found that., even with infinite concentration, the rotation is con- siderably in excess of that experimentally obtained with the pure substance in a state of fusion. Thus, on producing the straight line beyond the diagram t.0 100 per cent. concentration, the value [aD] = + 3 3 * 3 O is obtained, whilst the rotation of the pure substance at 15" is [a]D = +26.89'. Rotatiova of Benzene SINutims of Actice Methy& Dibenzoylglycerate. [a],, for methylic dibenzoylglycerata in the pure state a t 15' C.= -I- 26.89". Weight of benzene solution in grams. 4 "1633 3 -4963 3 -3259 6 *2430 4 09486 Weight of substnnce in grams. 0 -1435 0.1691 0 *2914 1 - 2191 1 *6916 Grams of aubstsnce in 100 grams of solution. 3 -0 4 - 7 7.2 19'5 39.1 empera- Density of Observed ture a t solution rotation, at tempem- which a,,, in rotation of 100.47 mm. o~~~~~~~ and densitj tube. withLwahr were deter, at mined. + 1-23O 0.8929 14.5" 1.86 0.8962 16.5 2.87 0.9017 16.5 7 -80 0.9411 15.0 13.76 0.9847 145 Specific rotation, ca3D. + 45*70° 44 '01' 43 *66 42 -26 40 '72 EXPERIMENTS WITH ETHYT~EX E DIBROMIDE AS SOLVENT. A similar series of experiments was made both with the active and inactive methylic dibenzoylglycerates i n ethylene dibromide solution (see next page). The ethylene dibromide employed, both in the cryo- scopic and polaritnetric determinations, was dried with calcium chloride and redistilled (b.p. 129'). Thus, in the case of the ethylene dibromide solution there is little or no evidence of dissociation, even with the highest dilutions employed, whilst in the more concentrated solutions the indicated values for the molecular weight are distinctly excessive. The values obtained in the case of the inactive compound are substantially the same as those for the active. The melting point was 10". Jt In order to ascertain wliethcr the rotation is affected by the solution being kept, this particular solution was preserved 18 hours before examination, whilst the other solutions vere examined a t once. The result shows that no change appears to take place, as the figure obtained falle into line with the others.OPTICALLY ACTIVE COMPOUNDS IN ORGANIC SOLVENTS.129 Depression of the frcezing-point in "C. Cryoscopic Detewninatioias wiih Active and Inactive Jfeethylic Dibenzoyl- glycemtes in Ethylene Dibromide Sokition. Molecular weight of methylic dibenzoylglycerate = 328. Molecular depression for ethylene dibromide = 118. Indicated molecular weight. Weight of ethylene dibromide in grams. 9 '7573 25 -2479 19 9 9 *Y573 25 $479 9 %73 ?t t ? 3 9 3 ) 1 ) 15 -7778 5 5932 15 "7778 5.5932 7 9 7? 1 ) t f >> Weight of methjlic diben- zoy lglycerate in grams. (0 0 2078 0 -6784 0.9805 1 -2457 1 -4982 0 -6807 0 -7809 0 '9238 1 -0589 2 * 7747 2 -9323 3 -1297 3,3903 1 *3553 1 -7050 0 *2125 0 '0963 0 -4595 0 -3107 0 -4031 0 -4643 0 -5596 0 -7146 0 -9003 (bj Grams of substance in 100 grams of solution.2 *o 2 -6 3 -7 4 '7 5 -6 6 -5 7 - 4 8 '6 9 -8 9.9 10 -4 11 *o 11 -9 12 *2 14 *9 lnactive Corn2 1 '3 1 -7 2 ' 8 5 '3 6 -7 7 *6 9 '0 11 '3 13 -8 0.780 0 -985 1 -415 1 -755 2 -090 2 *470 2 -740 3 *240 3 -695 3 *725 3 *885 4 *155 4 -525 4 '630 5 -745 0 -475 0 -580 1 *040 1 -900 2 '450 2.870 3 -460 4 -290 5 -290 ound. 322 -2 321 -9 323 -8 331 9 336 -0 333 -3 344.7 344.8 346 -6 348 -1 352 -7 352 * 1 350' 1 354 -0 358 -8 334 *6 350 -3 330 -5 345 *o 347 -1 341 '3 341.2 351 *4 359 -0 The results given in the table on p. 130 were obtained on examining similar solutions in the polarimeter. Thus, the rotation for all concentrations is greatly inferior to that exhibited by the pure substance in a state of fusion ; there is, more- over, very little variation with the concentration, but such as there is leads to the stronger solutions having-a distinctly higher rotation than the weaker ones.This slightly greater rotation is thus obtained in the case of those solutions which yield the markedly high values for the molecular weight as determined by the cryoscopic method. The relationship between the rotation and concentmtion is best seen by reference to the diagirtm 011 p. 140. By producing the straight line beyond the diagram until a coccentration of 100per cent. is reached, the value [a]D = + 3 2 O is obtained, and which is con- siderably in excess of that actually pielded by the pure substance.130 Weight of substance, in grams. FRANKLAND AND PICKARD : ROTATIOX OF Grams of substance in 100 grams solution.Rotation of Ethylene Dibrornide Solutions qf Actice Methylic Dib enzo y l g lcerate . [ a ] D for methylic dibenzoylglycerate in the pure state at 15" = + 26.89'. 0 -3695 0 -8982 1.1146 2.5857 3.0936 Weight of ethylene dibromide solution, in grams. 3 '3 6 -6 10.9 15.4 22-3 10 -9492 13 -5373 10 -1979 16 *8104 13.8365 Observed rotation, a=, in 100.47 mm. tube. Density of solution at tempera- ture of observation compared with water s t 4O. Tempera- ture at which rotation was ob- served. + 1 -38" 2 -78 4 a36 6 '33 9 '03 2 * 1286 2 -0749 2 '0103 1 '9494 1 *a538 CQID i 19 .IS0+ 20 -09" 19 -77 21 -02 21 -69 EXPERTMFNTS WITH NITROBENZENE AS Sor,vmiT. A similar series of cryoscopic determinations was made both with active and inactive methylic diben~oylglycerat~e in nitrobenzene solu- tion.The nitrobenzene employed bothin these and in the mbsequent polarimetric measurements had a constant boiling point of 20i0 and melted at 5.4". The cryoscopic determinations gal-e very irregular results ; wc have, however, recorded them in the following table. The figures from the cryoscopic determinations (next page), although disappointingly irregular, show that the indicated mole- cular weight is distinctly greater in nitrobenzene than in benzene, many of the values found approximating closely to the theoretical, irrespectively of the concentration. In spite of their irregularity, tfhe general tendency of the figures is to show that with the greatest dilution the molecular weight is lower than the theoret,ical, and with the highest concentration that it rises above the theoretical.As regards the indicated molecular weight of the inactive com- pound, all the values obtained very closely approximate to the theo- retical weight of a siagle molecule, and thus confirm. the conclusion arrived at in the case of tbe benzene and ethylene dibromide solu- tions, that the oppositely active molecnles of which the inactive compound consists are not in combination in the solution. On now turning to the polarimetric determinations made with the nitrobenzene solution of the active compound, the following results were obtained (see second table on next page). meter. * These solutions were made up 18 hours before examination with the polari-OPTICALLY ACTIVE COYPOUNDS 1N ORGANIC SOLVENTS.131 Cryoscopic Determinations with Active a d In,actire Me fhylic Dibenzoyl- glycerate i n Nitrobe.lzzene SiCOlutioiB. (a). Active Compound. Molecular weight of methylic dibenzoylglycerate = 328. Molecular depression for nitrobenzene = 72. 4 '4 6 '5 '7.4 8 '8 9-7 11 '5 14 '9 17 '2 Weight of nitrobenzene in grams. 1 -000 1 *545 1 -760 2 -160 2 -390 2 -860 3 -785 4.500 5 -2072 5 '4957 5 * 2072 5 '2072 5 -4957 5 -0482 5 '2072 5 -4957 5 *id72 5 '0482 6 '2072 5 '4957 5 '0764 5 4 5 7 97 9 ) 7 9 9 9 9 9 9 ) 97 Weight of sitbstance in grams. Weight. OE substance in grams. Density of G~~~~ of Observed solution at in 100 QD in Of mm. observatior compared grams solution. tube. wit,, ~ a t e r a t 4". substance rOtat,iOn 0 *0925 0 '2247 0 -2919 0 '3780 0 -4702 0 '4681 0 -6501 0 -6333 0 -6580 0 -7367 0 .8?8S 0 -9519 0 -9642 1 -0019 1-1507 0 -23'36 0 -3536 0 - 4064 0 -4936 0 *5452 0 -6623 0.8919 1 -0563 (b) * 0 *1668 0 -2632 0.6795 0.9950 1.8694 Grams of substance in 100 grams of solution.2.4 +0'58 1.2079 5 -5 1-40 1.2082 11.3 2.94 1.2082 17.4 4-60 1'2096 28-1 7-54 1.2164 1 -7 3 '9 5 '3 6.7 7.8 8 '3 10 -5 11 '1 11 '2 11-8 13 '7 15 -4 36.0 16 '1 17 -3 Depression of freezing point in O C. 0 -420 0.900 1 -270 1 -655 1 -910 2 -050 2 '500 2.665 2 -810 2 -885 3.495 4 -015 4 -030 4 -290 4 -475 Indicated molecular weight. 304'5 327 -1 317% 315 -8 322 -5 315 -7 340 -7 338 -9 323 -8 334 *4 329 -2 327 '8 341 -2 329 '8 336 *9 331 -3 324 -6 327 -5 324 -1 323 -6 328 *4 334 '2 338 -9 Rotation of Nitrobenzene Solutions of Active Methylic nibenzoylglycerate.iaJD from ethylic dibenzoylglycerate in the pure state a t 15" C. = + 26.89". ~~ ~ Weight of nitro- benzene solution in grams. ~ ~~ 6 -9157 4.7130 5 * 9898 5 "7157 6 -6643 Temperu- ture a t which rotation was observed. bl, . 15'-0 15 *9 16 *3 16 '6 15 -5 + 16.83 20 -62 21 '33" 21 '75 21 -99 * This solution was made up 18 hour# before polarimetric examination.132 FRAXKLAND AND PICKARD : ROTATION OF From these figures it will be seen that, although the observations were made over a very wide range of concentration, the specific i~otat~ion only suffered comparatively slight change. The specific rotation was only aboilt one-half of that exhibited in benzene solu- tion, and was markedlyinferior to that possessed by the pure sub- stance in a state OP fusion.Moreovei-, whilst in benzene the rotation increases with the dilution, in nitrobenzene it diminishes. The relationship is best seen from the diagram on p. 140, from which it may also be shown tbat, by extrapolating, the value for infinite con- centration closely approaches, although it is sIightly below, the experimental value for [a]D obtained with the pure siibstance in n state of fusion. Thus, by producing the straight line beyond the diagram until it reaches n, concentration of 100 per cent., the value obtained for [a]D is + 25', whilst the pure substance actually gives 1231, = +26.89'. EXPERIMENTS WITH Acenc ACID AS SOLVENT. The acetic acid employed boiled at 118", and had a melting point of 10.4', a specimen with higher melting point not being available at thc time.C'ryoscopie Detemzinations with A d i r e a d Inrxctivc Meth ylic Dibenzoyl- glycerate in Acetic acid Solution. Molecular M eight of methylic dihenzoylgljcerate = 328. Moleciilar depression for acetic acid = 39. Weight of acetic acid in grams. Weight of substance in grams. Grams of substance in 100 grams of soliit ion. Depression of freezing point in "C. 1 ndicated niolecular weight. 3 '7355 5 -0224 3 '7500 3 -8540 5 *0565 3 "7500 4 -3326 5 * 0 2 4 3 -9021 3 -7500 5 -0224 3 -8540 3 *go21 4 -3326 5 -0224 0 -0785 0 *l806 0' 1636 0 '2089 0 -3016 0 *3197 0 -3609 0 '4212 0 '3645 0 -4362 0.6145 0 '5733 0 - 6324 0 -6998 0 -9775 (a). Actire Compound. 2 -0 3.4 4 - 1 5 -1 5 -6 7 -8 7 -7 7 -7 8 ' 5 10 -4 10 -9 12 -9 13 -3 13 -9 16 -2 0 -250 0 '460 0 '495 0 -690 0 -710 0 -970 1 *ooo 1 -045 1 * o w 1 '330 1 *515 1 '840 lmb30 1 *850 2 -345 327 -9 304 '9 343 *7' 306 '4 327 -6 342 *9* 324 -9 313 -0 337 '3 341 el+ 315 -0 315 '3 329 -0 340-5 823 .% * I t will be obser.red that these figures, wliic.1~ are the niost errtitic, were allOPTICALLY ACTIVE COXPOUNDS IN ORGAMC SOLVENTS.133 4 *4101 0 '1145 77 0 -2725 >? 0'3947 9, 0 -5317 Y9 0 -6869 2-5 0 '300 337 * 5 5 '8 0 -770 312 -9 8 . 2 1 *095 318 -8 10 -7 1 -335 339 *5 13 *4 1 "150 346 '8 From the above figures, it will be seen that the results were of a more erratic character than wit.h the other solvents, the values f o r the molecular weight being sometimes above and sometimes below the theoretical. This is doubtless to be accounted for partly by the molecular depression possessed by acetic acid beiug smaller than that of the other solvents, and partly to the very hygroscopic character of the glacial acid, both circumstances which would tend to diminish the accuracy of the determinations.Another circumstance which must have interfered with the accuracy of the results was that the quan- tities of both solvent and substame employed were exceptionally small. In the case of the inactive compound, again, the cryoscopic deter- minations negative the existence of a double molecule racemate i n the solution, the values obtained for the molecular weight being essentially similar to those obtained f o r the active compound. Solutions of active methylic dibenzoylgl.ycerate were also examined polarimetrically, with the following resu 1 ts.Rotntioa of Acetic acid Solutions of Actice Methylic Dibenzoylglyceyate. [.ID f w methylic dibenzoylglycerate in state of fusion a t 15" C. = + 2689". Weight of acetic acid solution in grams. 7.6560 5 -0756 5 -8478 7.6152 6 -030'7 Weight of substance in grams. 0 -1313 0 '2430 0 *5548 1 *0356 1 -1219 Grams of substance in 100 grams of Bolution. 1 . 7 4 - 7 9 ' 5 13 -6 18 -6 Obs en-ed rotation, a=, iu 100.47 mm tube. + 0 -@do 1-71 3 '31 4 *79 6 -55 Density of solution a t tempera- ture of observutior compared with water a t 4 O . ' 1 -0561 1-0694 1 -0699 1 '075G 1 -0820 Tempera- ture a t which rotation was observed. 1 6 ' 2 O 16 -7 15 -6 16 *8 16 -3 34 -34" 32 '27 32 *45* 32 '61 32'38* obtained in a single series of experiments in which successive additions of thcb substance were made to one and the same p a n f i f y (viz., 3.75 grams) of the solvent.* These solutions were prepared 18 hours before pdarinietric examination.134 PRANKLAND AND PICKARD : ROTATION OF .-- The figures obtained for [ a ] ~ are all in excess of that obtained for the piire substance in a st'at'e of fusion at 15O, but they change com- paratively little on varying the degree of concentration ; the highest dilutions, however, exhibit the greatest rotcation, and by reference to the diagram on p. 140 it willbe seen that the acetic acid solutio~i gives values for [ a ] ~ , which approximate more closely than in the case of the other solvents t o the value obtained for the pure substance, On extrapolation for infinite concentration, moreover, it is found that the value for [ a ] D almost exactly coincides with the value obtained for the pure substance.Thus on producing the acetic acid straight line beyond the diagram, the value [a]= = +27*2O is obtained for 100 per cent. concentration, the pure substance giving [a]= = +26.89' at 15". I-- EX PERIRIENTS MADE WITH SOLUTIONS OF ACTIVE ETHYLIC DIACETYT,- GLY C E RATE. The striking contrasts between the results, both cryoscopic and polarimetric, obtained with benzene and acetic acid solutions of active methylic dibenzoylglycerate, rendered it desirable to ascertain whether similar results would be yielded in the case of other active substances. To this end, cryoscopic and polarime tric determinations were made with benzene and acetic acid solutions of active ethylic diacetylglycerate.The preparation and properties of this compound have already been described by one of us (Percy Frankland and Macgregor, Trans., 1893, 63, 142.2), and the following results were now obtained with its solutions in benzene and acetic acid re- spectively. ethglic diacetyl- glycerate in grams. Cryoscopic. Determinations with Benzene Solutions of Active Ethy lic Diacety lg lycernte. Molecular weight of ethylic diacetylglycerate = 218. Molecular depression for benzene = 49. substance in 100 grams of solution. Weight of benzene in grams. 0.1261 0 -3700 0 *5208 0'6451 0 -7223 0 *7988 3 -4 9'4 12.7 16 *8 18 -3 i 35.2 Depression of freezing- point in "C. Indicated molecular weight . 0 ,830' 2 -380 ' 3-320 1 4-050 4 '410 4 *855 208 -7 214 -1 215 -5 ' 218-8 225 '0 226 '1OPTICALLY ACTIVE COMPOCNDS 1N ORGANIC SOLVENTS.135 The above figures show that the solutions of ethylic diacetyl- glycerate in benzene give nearly true crjoscopic values for the molecular weight. The values for the higher dilutions are somewhat below the theoretical, whilst with increasing concentration they rise somewhat above it. The rotation of these benzene solutions was now investigated. Rotation of Benzene Solutions of Active Ethylic: Diacetylglycerate. [a],, for pure ethjlic diacetylglycerate at 15" = -16.31. Density a t ture of observation compared with water at 40. tempem- Weight of benzene solution, in grams. Tempera- ture at which rotation was observed. 4 '0621 7 '4943 0.8948 0.9580 Weight of ethylic diacet,yl- glyccrat,e, in grams.15.3" 15.0 0 '2153 2 -2290 Grams of substnnce in 100 grams oE solution. 5 *3 29.8 Observed rotation, an. in 00-47 mm tube. - 0 '82" -4*24 - 17 -20" - 14 -83" Thus with a low concentration the value for [a]= is somewhat greater than that exhibited by the pure substance, whilst with a, high concentration it is somewhat below the latter. Similar experiments were then made with solutioris of ethylic diacetylglycerate in acetic acid. Cryoscopic Determinations with Acetic acid Solutions of Active Ethylic Diacetylglycerate. l\folecular weight of ethylic diacetylglycerate = 218. Molecular depression of acetic acid = 39. Weight of acetic acid, in grams. Weight of ethylic diacetyl. glgcerate, in grdm s. 0 *0531 0 '1208 0 '2337 0 -4678 0 -7709 0 '925'7 Grams of substance in 100 grams of solution.1 '0 2 -4 4-5 8 -8 13 9 16 -1 I Depression of freezing point, in "C. Indicated molecular weight. 0.310 0 -705 1 -270 2 -040 3 -250 3 -860 135 *? 138 -3 148 -6 185 '2 191 *6 193 *6 The results present a striking contrast to those obtained in the case of benzene, for with all the concentrations investigated the values * This solution stood €or 18 hours before it was examined.136 FRANKLAND AND PIGKARD : ROTATION OF Observed rotation, ~ D Y in 100.47 mm. tube. for the molecular weight were greatly below the theoretical, the values rising with the concentration. Thus whilst with benzene for a concentration of 15.2 per cent. the cryoscopic value for the mole- cular weight was normal, with acetic acid for a concentration of 16.1 per cent.the value for Ihe molecular weight was much lower than with a concentration of only 3.4 per cent. in the case of the benzene, Rotation o j Acetic acid Solutions (,f Actire Ethyl ic liiacetylglycerate. [alD for pure ethylic diacetylglycerate at 15' = - 16 -31. Density a t tempera- ture of obserratior compared with water Weight of acetic acid solution, in grams. 4 -8922 5 -4825 Weight of e thylic diacetyl- glycerate, in grame. 0 -1651 2 -3775 Grams of substance in 100 grams solution. 3 *4 25 -0 Tcmpera- ture of observatioi of rota- tion. -5.28 1.0783 15.4 - - L - O 3 O I 1-0599 I Calp -288*'74O - 19 '44* Thus, with a concentration of 3.4 per cent., the value for [ a ] D is much greater, and, even wit,h a Lmcentration of 25 per cent.? con- siderably greater than that exhibited by the pure substance. These results are of particular interest, as showing that even in the case of two compounds so closely allied as methylic dibenzoylglycerate and ethylic diacetylglycerate, there may be this great divergence in the optical and cryoscopic properties, according to the solvent, employed, The experimental results recorded in the previous pages may bo thus summarised :- 1.Cryoscopic determinations show that inactive methylic di- benzoylglycerate does not exist as a racemised molecule when dis- solved i n benzene, ethylene dibromide, nitrobenzene, or acetic acid respectively. The values for the molecular weight are in all cases similar to those obtained under the same conditions for that of active methylic dibenzoylglycerate.2. The cryoscopic values for the molecular weight of methylic di- benzoylglycerate vary according to the solvent and the concentration employed. With benzene, all the values are below the theoretical. With ethylene dibromide and with nitrobenzene, the values are with low concentration below, and with high concentration above the theoretical. I n the case of acetic acid, the values are, with all con- centrations, sometimes above and sometimes below the theoretical. 3. In all cases, the specific rotation [a]= of active methylic di. f This solution stood for 18 hours before examination.OPTICALLY ACTIVE COJIPOUNDS I N ORGAKIC SOLVENTS. 137 bcnzoylglycernte is more or less affected by the solvent. In the case of benzene, the values of [a]= are much in excess, and in that of ethylene dibromide and nitrobenzene they are much below the value of I n the case of acetic acid, the values for [a]= most closely approximate to that of the pure substance.4. Low cryoscopic values for the molecular weight of methylic dibeiizoylglycerate are accompanied by high values for the specific rotation, and vice versc2. 5. This relationship between specific rotation and indicated mole- cular weight is borne out by the behaTiour of ethylic diacetylglyceratc in benzene and acetic acid respectively, but i n this case the low molecular weights and high rotations are obtained in acatic acid, the high molecular weight and low rotations in benzene. 6. The real rotation of the active compoucd cannot be directly calculated from the rotation of its solution, even hen the cryoscopic examination of that solution shows the molecular weight to be normal.Thus for methylic dibenzoylglycerate in acetic acid solutions giving normal molecular weights, [a]D was too high, whilst. conversely in nitrobenzene and ethylene dibromide solutions, giving normal inolecular weights, the values of [ u J D were too low. By graphic cxtrapolation for infinite concentration, as in the diagram on p. 140, lrowever, all three solvents give 1-alues at any rate approximating to the actual specific rotation obtained with the pure substance. In the case of benzene, on the other liand, all the solutions examined gave molecular weights below the theoretical, and the produced rotation curve gives R value for [a]D a t infinite conceiitration which departs rnore widelyfrom the real value than do the produced curves for nitrobenzene, ethylene dibromide, and acetic acid.It would appear, therefore, that even a moderately accurate estimate of the real rotation can only be arrived at by the study of solutions giving normal molecrilar meights, and extrapolating for infinite conceiitrstioii on their rotation curves. Thus the real specific rotation of methylic dibenzoylglycerate is for the pure substance. [a]= = +26.89" a t 15" C., whiIst [a]D calculated by extrapolation from benzene solu- tion values.. ........................... = +33-3" calculated by extrapolation from acetic acid solution values.. ........................ = 3-27-2 calculated by extrapolation from nitrobenzene solution values ......................... = 3-25.0 calculated by extrapolation from ethylene di- bromide solution values.................. = + 32.0 calculated from mean of the above extrapola- tion values.. .......................... = +29*4 TOL. LXIX. L ,, ,, ,, ,,138 FRANKLAND AND PlCKhRD : ROTATION OF Moleculrtr Moleculer [ u ] froni weight weight benzene (theoretical). , (cryoscopic) . solution. Propylic diacetyl- + 1 - 2 O . - tar irate 7. Our experiments show that the rotation of an active substance may be either raised or depressed by solvents ; similarly, the mole- cular weight, ci~yoscopically measured, may be either raised or de- pressed by solvents, the variations in the rotation being doubtless dependent on the variations in molecular weight.Now, the varia- tions in molecular weight can be most consistently explained on the assumption of dissociation and association processes taking place, both of which may go on concurrently. The phenomenon of dissociation is most conspicuously exhibited i n the case of the benzene solution of methylic dibenzoylglgcerate and in that of the acetic acid solution of ethylic diacetylglycerate. I n both cases, the cryoscopic values for the molecular weight are markedly below the theoretical figures. The effect of this assumed dissociation is in both cases to greatly increase the rotation. The act.ive ion must, however, be different in the two cases, as the dibenzoyl- glycerate is dextrorotatory, whilst t'he diacetylglycerate is laevo- rotatory, although both are derived from one and the same active glyceric acid (dextro-) .By dissociation of the dibenzoylglpcerate, the rotation becomes more dextrorotatory, whilst by dissociation of the diacetglglycernte the rotation becomes more laevorotatory. It must not be supposed, however, that the effect of dissociation is invariably to increase the rotation ; thus, in Freundler's experiments on the tetra-substitut ed tartrates, the dissociation was accompanied by diminution in the value of [ o I ] ~ , thus [U]D real. ---- + 13 *4" (Loc. cit., 1). 114). If, in the case of methylic dibenzoylglycerate, high values for specific rotation are shown by cryoscopic measurement to be acconi- panied by dissociation, we should naturally infer that low values for [a],, must be due to the opposing influence of association.* Such low values for [a]D we find in the case of the ethylene dibromide and nitrobenzene solutions of methylic dibenzoylglycerate.The variation in [%ID f o r differences of concentration is compara- tively small in the case of these two solvents, but such as it is, t.his * Just as there is a t present no 6 priori means of ascertaining whcthei* dissocia- tion will be attended by increase or by decrease in the value of [U]D, 80 there is none for predicting the effect on [ a ] ~ of association.OPTICALLY ACTIVE COJIPOUNDS I N ORGAEU'IC SOLVEKTS. 139 variation takes place in the opposite sense to that which goes on in the dissociating benzene solution, for with high dilution in the case of ethylene dibromide and nitrobenzene there is a diminution in the values for [%ID (see the diagram on p.140). These low values for the specific rotation would thus find the readiest explanation on the bypothesis of association becoming more pronounced the greater the dilution of the solution. Of such association at high dilutions there is, howerer, no direct evideiice from the cryoscopic determinations, the indicated molecular weights in the case of ethylene dibromide, and still more so in the case of nitrobenzene being somewhat below the theoretical value. On the other hand, with these two solvents at high concentrations, the indicated values for molecular weight are considerably in excess of the theoretical. But if these high indicated molecular weights were tho result of association we ought to find the values f o r [a]D simultaneously falling, whilst, as a matter of fact, they rise with the coticen tration.The only polarimetric confirmation of this cryoscopic evidence of association which we can find in our experiments is in the case of the benzene solutions of ethylic dincetylglycerate. Here the most con- centrated solutions give indicated molecular weights in excess of the theoretical, the value of [a]D calculated from such solutions being less than the value of [a]D for the pure substance, and since the dilute solutions give cryoscopic evidence of dissociation accompanied by excessive vaiuea for [a]=, we can conclude that association and deficient values for [a]D are connected, and that the deficient value for [a]D with high concentration is confirniation of the association cryoscopically indicated.Amongst the experimental material furnished by Freundler (Zoc. cit., p. 117) there are the following cases exhibiting cryoscopic evidence of association. Benzene i3olzctions. Active compound. ---- Metliglic tartrate. . . Propglic ,, . .. Molecular weight (t,heoretical). 178 234 --- Molecular weight (found). [ u ] ~ measured [.]I, obtained on t,he with the pure substance. I solution. - 8 . F + 2 -14' + 20 -1 I Eth y Eerie Dibyornide So Itition. -0.6" I + 12'44p I 326 I I 234 Propylic tartrate. . . ~~ Thr;s, in all the above cases, the cryoscopic determinations afford140 F’RANKLAND AND PIOKARD : ROTATIOX OP strong evidence of association, and yet the effect on the rotation is quite irregular, for in the benzene solution the effect on the rotation of methylic tartrate is negative, whilst in that of propylic tartrate it is positive.There is of coume nothing surprising in t,hese results, a,s association with the molecules of the same solvent may produce opposite rotatory effects in the case of two different active com- pounds, a,nd association with the molecules of two different solvents mayproduce opposite rotatory effects in the case of one aad the same active compound. In his experiments on the tetra-substituted tartrates. Freundler finds evidence, in several cases, of dissociation in organic solvents, and is of opinion thatl the dissociation consist.s in the splitting off of the two acid mdicles* substitnting the two alcoholic hydrogen atoms of the t,artaric acid.Our experiments, however, clearly show that the molecules of the fully substituted glycerates dissociate otherwise. Thm, as already poiri ted out, methylic dibeneoyl- glycerate dissociates in bezzone, and the active ion is moye dextro- rotatory than the undissociat,ed molecule. Ethylic diacetylglycerate, on the other hand, dissociates i n acetic acid, and the activc ion is more powerfully lavorotatorg than the nndissociated compound. Thus, the two active ions difler not only in sign but enormously in degree, whilst, if the acid radicles were split off, the only differ- ence in their constitution would be the presence of methyl in the one and of ethyl in the other, thus 7 H,- o i C, H,O CH,*O/ I C2H,0 CH*O/C;H,O , . . . . . . .. . . . . . . .. . .. . QH* O/C,H,O , ................. . . bOOCH, COOC2H5 Methylic dibenzoylglycerate Ethylic diucetylglycerate (dextrorotatory). (levorotatory). But we know that the dextrorotation of the dibenzoylglycerates is conditioned by the benzoyl gi‘oups, and the methylglyceryl and ethylglyceryl ions could not possibly differ in rotation to the extent which the ions in question actually do, hence .me regard the dissocia- tion as almost certainly taking place as indicated below QH,*OC,H,O $IH,*OC2830 YH*OCqHjO , QH*OC.&B30 COO: CsHJ COOiCH, I Q This supposition is quite out of harmony with Yerkin’s experiments on diethylic benzoyltartrate, in which it was found that by hjdrolising with an insufficient quantity of alcoholic potash benzoyltartaric acid was formed, the ethyl groups being eliminat,ed, whilst, the benzoyl groups remained atAached (Trans., 1867, 20,141).SPECIFIC ROTATlON OF METHYL DIBENZOYLGLYCERATE IN VARIOUS SOLVENTS (BENZENE, ACETIC ACID, NITROBENZENE AND ETHYLENE OIBROMIDE. )OPTICALLY ACTIVE COMPOUNDS IK ORGAKIC SOLVENTS. I4 I substance in grams. This process would leave the active ions cliffering profoundly in eon- stitutiou as they do i u rotation. We have recently obtained further evidence bearing on this point., in connection with the rotation of ethylic monobenzoylglycerate. This substance which has been prepared by one of us in conjunction with Mr. MacGregor is in all probability the /3-compound, OF the formula $lHz*O C7H5O YH*OH CO 0 C2H5 I n a state of fusion, the specific rotation of this substance is [ a ] , -9*80", whilst, with a benzene solution, the following resuIt was - - grams solution. ---- obtained. Weight O f benzene solution, grams. PI_ 9 -5558 I 1*3701 1 14.3 0 bserved rotation aD in 1984 mm. tube. -__ - 0 '925O Density of ture. I ---- I 0.9194 1 15.5" Thus the activity of the substance in beiizene solntion was far less laevorotatory than in the purs state, a circumstance which is quite in harmony with the supposition t,hat in benzene solution the molecule is more or less dissociat'ed into a C2H5-ion and the complex active ion CloH,O,. Tor, as already pointed out, in these ethereal salts of glyceric acid, dextrorotation is conditioned by the piweence of benzopl groups in place of the hydroxylic hydrogen atonis ; whilst lsvorotation is conditioned by the positive radicles replaciiig the carboxylic hydrogeo; now if, in the above substance the benzoyl group were split off in the dissociation supposed to take place in the benzene solution, then the molecule should become more laevo- rotatory; on the other hand, if it is the ethyl group that is split off we should anticipate t h a t the molecule would become more dextro- rotatory by virtue of the more prepondernt'ing influence obtained by the benzoyl group; and this is precisely what takes place, for in benzene solution t,he substance actually becomes more dextro- rotatory, or rather its lm-orotation i8 greatly diminished. Mason College, Birmi?zgh an1 .

ISSN:0368-1645    

DOI:10.1039/CT8966900123

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

142 XV.-TJi P ~~Iolcc~~lar Volumes of Organic Substcrnces in Solution. Ry W. W. J. NICOL, M.A., D.Sc., F.I.C. THE sixth report of the Committee on Solution presented to the meeting of the Chemical Section of the British Association in Edinbui*gh in 1892, contained a short, notice of some preliminayy experiments on this subject. My attention waH first directed to this question in 1883, when I was the first to show that in the case of salts in dilute aqueous solution, the difference between the molecular volumes of. the salts of any two inetals is a constaiit, irrespective of the salt radicles with which tlle inetals are combined, and that the same holds good with regard to any two salt radicles. In the course of the experiments necessary to establish this law, I had occasion to determine the molecular volumes of the sodium and potassium salts of formic, acetic, and butyric acids, and found that an increase of CH, in the molecular weight was attended by an increase in the molecular volume of approximately 14.3 (PhiZ.Mq., 1883, 16, 131). A t the conclusion of the paper, I pointed out that " this method of investigating the moleculai- volumes of salts is, in all probability, capable of extension to organic substances, and that, by comparing solutions of various organic bodies which differ by one or more CH, groups, or in other respects, it may be possible to determine the volume of these differences. Such s d u tions need not necessarily be aqueous." In the Repoi-t above referred to (Brit. Assoc. Reports, 1892, 261), the following passage occurs : " This point appeared worthy of further examination, inasmuch as, if dissolved substances are under com- parable conditions when the solution is sufficiently dilute, as seeins most probable from a consideration of the physical properties of such solutions, then the apparent molecular volumes in dilute solution could be compared in the same way as the molecular volumes a t the boiling point, and thus the atomic volumes of the varicus elemenfs could be determined with greater ease and certainty than at the boiling point.The present communication relates to the increase in molecular volume in dilutc solution, produced by the successive additions of the group CH,, in the ethereal salts, and partakes largely of the nature of a preliminary iiote : the appearance of some recent communications on the same and closely allied subjects rendering it necessary that 1 should place 011 record the work that I have already done. The metliod of investigation is as follows:-Fifty C.C.of theVOLUMES OF ORGANIC SUBSTANCES I?; SOLUTIOX. 143 solvent is weighed to the nearest milligram, slid 2 C.C. of the ethereal salt in question is added and again weighed to the nearest milligram. The specific gravit'y of the solutiou, the composition of which is thus known, is determined in duplicate, br means of capped Sprengel tubes immersed in a constant temperature bath a t Z O O , the variatiou of the temperature of which does not exceed *O*Ol". The accuracv of the specific gravity determinations is shown by the fact that the mean difference between any two duplicate deteyminations does not exceed 0.000017.From the composition of the solutions and their specific gravities, their molecular volumes are calculated in the usual way, and the molecular volume of the solvent being known, the differences are the apparent molecular volumes of the dissolved salts. The ethereal salts were obtained from Schuchardt, and, as far as the quantity at my disposal permitted, were fractionated, that fractioii being used which most closely agreed with the generally accepted boiling point: there is, however, every reason to believe t,hat thc small differences observed below are due, in man7 cases, to impurities present in these salts. Table I contains the experimental results; it has iiot been con- sidered necessary to tabulate the composition and specific grayity of TABLE I.-Xolecidu~ Volumes of Ethered Salts i i ~ d{fererLt XoltieiLts.Ethereal salt. Methylis acetate . . . . . Ethylic iormate.. . . . . Aniylic formate.. . . . . Butylic acetate*. . . . . . Ethylic bntgratet.. . . ,, oxslate.. .. .. ,, benzoate. . . . . ,, salicylate . . .. :, malowate*. . . . ,, valerate.. .. .. Amylic acetate. . . . . . . Etliyiic succinate.. . . . Aruylic benzoate . . . . . ,, valerate.. .. .. Molecular weight. 74 74 111; 116 116 146 150 166 160 130 130 174 192 172 Xy lene. 80 - 2 81 -1 131 -4 131 -9 131 -5 136 do$ 142 -4 147 *8 149 -4 149 '5 167 *O 191 - 5 200 '3 - Benzene. 80 '4 82 -0 133 ' 3 134 *O 132.3 135 -6 142 -7 148 -3 151 *6 150 -1 150.8 166.8 192.1 201'5 88 pc? cent.alcohol. 80 *1 81 -1 133 -3 134 '3 132 -8 136 -0 143 '0 147 '2 153 '6 150.6 150 5' lti8 -0 192 -9 203 *I Water a t 20' C = 1, the above = C.C. per gram-molecule. each solution, but only the molecular volumes of t h e ethereal salts in the three solvents, xylene, benzene, and 88 per cent. alcohol, on the supposition that the volume of the solvent remains constant'. * Of doubtful purity. t 1 C.C. to 50 C.C. xylene. $ 1 C.C. to 50 C.C. xylene.144 NICOL : THE MOLECULAR VOLUMES 80 -7 131 '4 131.9 131 -5 131 *6 149 '4 149.5 149 -5 50 -9 47 *9 --- In Table 11, the results for isomers are collected together ; as the result of this comparison, it is seen that methylic acetate has a con- siderably smaller volume than ethylic formate, a point already observed in the case of their molecular volumes a t the boiling point, and in accordance with the general law observed by Elsasser (Annulen, 1883, 218, 302) a t the ordinary temperature, and by Schiff (ibid., 1883, 220, 325) at the boiling point, that in the case of isomeric salts, the one with the smaller acid radicle has the greater volume.That the other isomeric ethereal salts in Table I1 do not show this clearly is probably due to their not being the normal compounds. I f a comparison be made of the mean values for each set of isomers, we find that the first addition of 3CH, is attended by a greater increase of voluine than tbe second, which is not obseived in the boiling point cleter minations. 'I"imE II.--Xolecidar l5dumes of Isoniesic Ethereal Stilts in different Solvents.81 -2 133 -3 134 -0 132 *3 133 -2 150 -1 150.8 150 *5 52 -0 47 '3 .-__- ---__I_- Ethereal salt. Meth.vlic acetate .................. E thy lic f orinate ................. Mean.. .................. -_------ Amglic formate.. ................. EtEyvlie butyrate .................. Butylic formnte. .................. -- Mean ................... Ethyvlic valerate. .................. Amylic acetate.. .................. Mean. ................... Increase for first 3CH2. ............ .. for second 3CH2.. ........ Mean value of CH,. ........... -------- Xjlene. Benzene. ! I----- --- 80 *2 80 -4 16-5 I 16-6 88 per cent. alcohol. --- so -1 81 '1 80 -6 133 -3 134 -3 132 *8 133 *4 150 -6 150 -7 150 *? 52 *8 47 -3 16 *7 --- --- --- -- In Table I11 are given the mean values of CH, as obtained from a comparison of the homologous compounds, and the 6nal mean may be taken as the approximate volumes of CHz in the three solvents.B'urther, Table I cont'ains data relating to four ethereal salts not taken into account in the above comparison. Ethylic oxalate, malonate, and snccinate differ respectively by CH,, comparing the first and last, 2CHz = 31.0, 30.6, 32.0, in the three solvents, a volume much smallerOF ORGANIC SUBSTANCES IN SOLUTION. 145 TABLE IIL-Mecw~ value of CH2 from a Comparison of Ethereal salts. Formates ........................ Acetates. ........................ Valerates ........................ Benzoate8 ........................ Isomere ......................... Mean.. .................. -----___- 1 I -- ]--I--- 17 -4 1’7 -6 17-5 17 -5 16 -7 than that found above; the cause of this may lie in contraction, brought about by the separation of the carboxyl groups, for it is evident that the introduction of CH2 here, is not comparable with the passage from the methyl to the ethyl group. This point requires further investigation. A comparison of the volumes of ethylic benzoate and salicylate gives the value of the group OH = 5.4, 5.6, 4.2. The important question as to the reason of the differences observed between t’he volumes of the same substance in the three solvents must be left over until the effect of dilution on the molecular volume has been fully examined in the case of solvents of widely different moleculnr weight : it is, I believe, closely connected with the question of the aggregation of molecules in solution ; the solvent with the heavier molecules, xylene, breaking down these aggregations more completely, brings about a diminution of the molecular volume.

ISSN:0368-1645    

DOI:10.1039/CT8966900142

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

OF ORGANIC SUBSTANCES IN SOLUTION. 145 XVL--Action OJ Sugars on Arnmouaiaca I Silver Nityute. By JAMES HEN DERSOX, B. Sc., 1851 Exhibition Scholar, University College, Dundee. WHILE recently pursuing a research in which it was essential that very small quantities of sugars produced in the course of experiment should be estimated quickly and accurately, and as the requirements were such as to preclude the adoption of any of the various copper- reducing methods, the author was led to undertake this research, with the view of discovering a method whereby such an estimation could be satisfactorily accomplished. The principle of the method adopted in this case, like Fehling's, is based on the fact that alkaline solutions of certain metals undergo reduction when heated with certain oxidisible compounds, such, for example, as sugars.Tollens VOL. LXIX. M146 HENDERSON :- ACTION OF SUQARS (Be),., 1883, 16, 921) has shown that when dextrose is heated with smmoniacal silver nibrate, the number of atoms of silver reduced for each molecule of dextrose varies according as a great>er or smaller excess of the silver solution is employed, a3 shown in the following results which he obtained. Ratio of 1 mol. of dextrose to atome Silver taken, Silver reduced. of silver. 104.3 102.44 12.29 115.6 108.00 12.96 176.8" 147.39 1'7.69 The quantity of silver nitrate originally taken was thus only slightly in excess of that used up by the dextrose. Experiments conducted under the above conditions cannot be expected to yield very constant. results, as the amount of silver nitrate employed in each case is evidently insufficient to ensure the complete oxidation of the sugar to some definite final stage ; it appeared to me, however.that this could be readily effected by heating the dextrose for a suffi- cient length of time with a fairly large excess of silver nitrate. Preliminary experiments were accordingly made with a view to determine what influence, if any, time, and the presence of tt larger or smaller quantity of ammonia exerted on the reduction of the silver nitrate by the sugar. .A Holutioii of aninionia of sp. gr. = 0.88, diluted with three times its own volume of water, was added to a given volume of decinormal solution of silver nitrate until the preci- pitated oxide was just redissolved ; a knoivn volume of a standard solution of dextrose was then added, and the mixed solutions intro- cluced into a boiling tube, and heated by means of steam issuing freely from a small copper boiler, into the neck of which the boiling tube was slipped, the greater part of the tube being thus subjected to the action of the vapoui-. After heating the solution at 100' for a definite time, a ltnowii volume was taken out by means of a pipette, cooled, diluted with water, and the reduced silver collected on a filter, and thoroughly washed with distilled water; the mixed filtrate and washings were then acidified with strong nitric acid, and titrated with K/50 ammonium thiocyanate, iron alum being used as an indicator.This strength of ammonium thiocyanate solution was used throughout, except in estimating the reducing powers of cane sugar, dextrin, and starch, where a decinormal solution was employed.This mode of estimating the unreduced silver nitrate was invariably nsed throughout the whole of the research. The influence of time m i the reducing action of the sugar was first of all ascertained in the following manner. A known volume of a standard solution of Jt In presence of caustic soda.ON AMIIOSIBCAL SILVER KITRATE. 147 dextrose was added to 40 C.C. of decinoi-ma1 silver nitrate, containing ammonia just sufficient t o keep the precipitated oxide in solution. and the mixed solutions heated a t 100' in the manner alreadj- described. Five C.C. of the solution were taken oat a t various inter- vals, and the amount of unreduced silver nitrate estimated.Time of heating Dextrose. at looQ c. reduced. 20 milligrams. 0.33 min. 1.64 C.C. I 5.0 mins. 1-66 ,, Amount of AgNO, N,'10 This, then, would seem to indicate that with the above ratio of con- centration o€ dextrose to silver, the reducing action of the sugar ceases in about half a minute from the start. The next experiments were made with the view of ascertaining the influence of ammonia on the reducing power of dextrose. A known volume of a standard solution of dextrose was mixed with 20 C.C. of clecinormal silver nitrate containing 5 C.C. of ammonia solution, and the mixture heated a t 100'. The same volume of ammonia solution was added in every case, although the strength of the solution varied throughout the series from 1 : 3 to 1 : 7.Five C.C. were taken out at various intervals, and the excess of silver nitrate estimated as before. The final ratio of silver nitrate reduced to that remaining in the solution was the same in each case. namely, 1 : 2. Dextrose. Strength of tmmonia solution 1 : ' i 1 : 6 1 : 5 1 : 4 1 : 3 1 : 3 Time of heating. 0.33 mine. 7'25 ,) 12'41 ,, 0'41 ,. 4-00 ,, 13-05 *, 0.33 ., 0.70 ,, 5 ' 5 8 :. 5-41 ,. 14-58 ,, i 27 -08 ,, BgXO, Nil5 reduced. 1-92 C.C. 1.64 ), 1-46 ,, 1-68 ,, 1.46 ,, 1-64 ,, 1.53 ,) 1-53 ), 1.55 ,, 1-50 ,. 1-49 ,. l . G i ), 1'52 ,, 1.45 ), 1-44 ,. The resnlts obtained above are sufficient to denionsirate the ratliev interesting fact that, provided the concentration of silver nitrate to tlextrose remains t h e same throughout the series, the strength of the ammonia solution employed does not appreciably influence the amount M 2148 HENDERSON : ACTION OF SUQARS i Time of heating.of reduction of the silver nitrate ; and further, when the above con- centration is adopted, it would appear, from the numbers obtained, that prolonged heating of the solution affects the reducing power of the sugar to a very limited degree. The next series of experiments was undertaken with the object of ascertaining the effect produced by varying the amounts of dextrose, the quantity of silver nitrate taken being the same in each experiment. A known volume of dextrose solution was added to 20 C.C. of decinormal silver nitrate containing 5 C.C. of ammonia solution, made by diluting ammonia, sp. gr. 0.88, with thrice its volume of water.The solution was then heated at looo, 10 C.C. taken out at intervals, and an estimation made of the unreduced silver nitrate in that volume o l solution. Ratio of dextrose taken to A:!zcz!10 silver nitrate reduced, expressed in milligrams. Dextrose. 10 -0 milligrams 10.0 ,, 7.0 , Y 10’0 ,, 4 - 0 :, 17% ,, ----__.----- 30 C.C. 6 *65 C.C. 1 : 3’51 30 Y Y 6-64 ,, 1 : 3.51 30 9 , 4.60 ,, 1: 5.52 30 Y, 6 *65 ,) 1 : 3-51 30 ,? 2-60 ,, 1 : 10 ‘53 40 9 , 11’73 ., 1 : 2’42 Prom these results we dednce the fact that, provided the amount of silvernitrate takenis the same in every case, the arnoiint of reduc- tion of the silver nitrate present in the solution is proportional to the amount of dextrose present. From the quantity of silver nitrate reduced by a given volume of a standard solution of dextrose, we am able to calculate the “ factor ” for ammoniacal silver nitrate, that is, the number of molecules of silver nitrate which are equivalent to 1 mol.of dextrose. The following series of experiments was undertaken, with the object of ascertaining the true value of this factor. I I I Ratio of silver AgNo, N/lO. AgNO, (N/10) Dextrose‘ 1 nitmte reduced to I reduced. 1 that remaining in solution. Factor. -- 11 -97 11 -95 11-97 11 -80 11 5% 12.06ON AMMONIACAL SILVER NITRATE. 149 AgN03 (NilO). Five C.C. of ammonia solutionof the same strengthas before (1 : 3) were mixed with 30 C.C. of decinormal silver nitrate, and to this was added a definite volume of a standard dextrose solution. After heating a t 100" for eight minutes, the whole solution was cooled, diluted, and the reduced silver filtered off, the excess of silver nitrate being esti- nisted in the usual manner.The dextrose used in the above experiments was a pure specimen obtained by recry stallisation from water. With ordinary commercial glucose, the following results were obtained. The following results were obtained. Ratio of silver AgKO, (Silo) nitrate reduced to reduced. that remaining in Factor* solution. Glucose. --- 17 *5 milligrams 10'0 )) Taking the mean of the results of the first series, we obtain the factor value 11-9. Soxhlet (J. pr. Chem., [2], 1880, 21,227) has clearly established the fact that in the case of the reduction of Fehling's solution by dextrose the dexlrose equivalent has by no means a constant value, but, on the contrary, is entirely dependent on the particular circumstances under which the reduction is effected.The causes chiefly affecting the reduction of the copper solution in the case of dextrose are dilu- tion? concentration of solutions, and the time of heating. As a consequence of this, therefore, when estimating dextrose in different, solutions, the results are comparable only when the experiments are conducted under precisely the same conditions of dilution, &c. As has already been shown in the case of the reduction of silver nitrate by dextrose, the influence of time ceases after 5-10 minutes ; more- over, it would appear that, provided the solution be heated for a sufficient, length of time, namely, 8-10 minutes, and prorided also that the ratio of concentration of the reduced silver to the silver left in the solution does not fall below 1 : 2, the amount of reduction of the silver nitrate is dependent solely on the quantity of reducing sugar present in solution. This at once suggests a method for the quantitative estimation of dextrose in dilute solutions.A series of estimations was next pereormed for the purpose of t,esting the accuracy of the value obtained for the dextrose factor. 2.5 C.C. ammonia solution of the usual strength (1 : 3) were added to 10 C.C. of decinormal silver nitrate, a known volume of standard dextrose solution was then added, and the solution heated at 100' for150 HENDERSON : ACTION OF SUGARS Milligram taken. 5.0 5 . 0 10 n o eight minutes. The reduced silvei- was next filtered off, and the excess of silver nitrate determined by titration. The fsctor used was that obtained in the previous experiments, namely 11.9.Milligram found. 5 *o 4.9 9 . 4 Dextrose. Cane sugar. AgNO (N/10) reduced. dgNOs @/lo). Time of heating. Ratio of silver nitrate used to that remaining in solution. 1 : 3.07 1 : 3.2 1 : 1.59 AgN03 (N,/10) reduced. 3.32 C.C. 3-25 ,, 6-23 ), Evidently, therefore, with a ratio rarying from 1 : 2 to 1 : 3 fairly accurate results can be obtained. CYnrLe Sugar. A pure specimen of cane sugar was prepared by recrystallisation from ethylic alcohol. A known volume of a standard solution of the pure sugar was heated at 100' for a certain length of time 1vit.h 20 C.C. of decinorma1 silver nitrate and 5 C.C. of ammonia solution (1 : 3) ; at the conclusion, the solution remained perfectly clear, exhibiting no signs of reduction of t,he silver nitrate, subsequent titration of the whole solutlion proving that no action had taken place.I I 160 milligrams 20 9 , 10 mins. 1 25 9 ) A dilute solution of cane sugar is therefore incapable of effecting the reduction of ammoniacal silver nitrate when the above concentratioii is used, but if stronger solutions of the sugar aye used, and more especially if the mixed solutions are heated for a longer period, the cane sugar begins to be slowly oxidised at the expense of the silvey nitrate ; this in all probability is due to the slow hydi-olysis of the disaccharide molecules by the alkali, sugars being formed which of course are capable of being oxidised by silver nitrate.This secondnr.y action is even more marked in the case of Fehling's solution ; at first no signs of reduction are observable, but, on continued boiling, they very soon begin to manifest themselves. This inability on the part of the silver solution to effect the oxidation of thc cane sugar may be ntilised as the basis of a niehhod for the estimatioii of dextrose in presence of cane sugar.ON AMMOSIACAL SILVER NITRATE. 151 Milligrams klien. 6.04 grams of dextrose and 4.063 grams of cane sugar were dis- solved in water, and the solution made up to a litre. A given volume of this solution was then heated a t loo3 with a known volume of decinoimal silver nitrate and 2.5 C.C. of ammonia solution (1 : 3) for a, certain time, the reduced silver filtered off, and the excess of silver nitrate determined in the usual wa,j-.Milligmms fourd. Dextrose. A gNO, (NilO) AgN03( N/10) reduced. 4- *85 C.C. 3-26 ,) 3-30 ,, 3.15 ), 3.w ,, Time. 8 inins. l2 J? 18 ) > 23 J ) J J Ratio of silver nitrate reduced to that left in solution. 1 : 1-06 1 : 2.1 1 : 2'1 1 : 2 '03 1 : 4'5 The presence of cane sugar in the solution appears to retard the oxidising action of the silver nitrate to a slight extent. A quantity of silver nitrate sufficient to oxidise a known amount of dextrose to a certain stage in a given time is incapable of doing so in presence of cane sugar in the same time ; this retarding action may be remedied either by increasing the time of heating, or perhaps better by increw- ing the amount of silver nitrate.Dextrin urzd Stas.ch. A specimen of ordinary dextrin was purified by dissolving it i n water, filtering, and precipitating with 90 per cent, alcohol ; the pre- cipitate was then washed with strong alcohol and dried in a vacuum desiccator. The reducing power of each substance was then estimatect by heating a definite volume of the standard carbohydrate solution for eight minutes at loo3 with 10 C.C. of decinormal silver nitrate and 2.5 C.C. of ammonia solution (1 : 3). AgNO, (N/10) reduced. AgNO, (NjlO). Dcxtrin : 16 -2 milligrams , . . . . . . . Starch: 4.05 ,) ~ ~~ Hence dilute solutioiis of dextrin and starch, like cane sugar, do Reducing sugars can be esti- not reduce ammoniacal silver nitrate. mated, therefore, in presence of either or both of these compounds.152 Lsvulose.,-- 10 milligrams 10 ,. 10 7, 10 11 HENDERSON : ACTION Ol!' SUGARS AgN03(N/10). *gNo3 (N/lO) Time Of reduced. heating. ---- ---- -_- 30 C.C. 6 -38 C.C. 8mins. 30 ,) 5-38 l l 15 ), 40 9 1 5 '57 1, 8 ,, 60 11 5-80 J l 8 9 1 Scheriiig's Lev 14 lose. The method used in determining the reducing power of this sugar was identically the same as that adopted in the case of dextrose. ~ I &]actow. AgNo~(Njlo) Time Of reduced' heating- I I Ratio of silver 1 nitrate reduced to 1 Factor. I that left in solution. Ratio of silver nitrate reduced to that left in solution. --- 1 : 4-57 1 : 4 '57 1 : 6.17 1 : 9.34 10 d milligrams 10'0 ,, 7.0 11 - Factor. -.- ----'-- 6 -73 C.C. 1 8 mins. 1 :3*4 12.11 I 1 : 3.4 12.07 4-70 l . 1 : 5-37 12 '08 9 -7 9.7 10 '0 10 -4 As with dextrose, the reducing power of levulose is but slightly influenced by the time of heatinK after eight minutes, Galactose.A pure specimen was obtained by recrystdlisation from ethylic alcohol. A standard solution of the pure sugas was then prepared, and a given volume heated at 100' with 30 C.C. of decinormal silver nitrate and 5 C.C. of ammonia solution (1 :3). After a certain interval, the reduced silver was filtered off and the excess of silver in the solution estimated as usual. The resalts of these experiments were as follows. - ~~ Factor = 12.08 (mean). As in the case of dextrose and levuloee, time exerts little or no influence on the reducing power of galactose after eight minutes' beating at 100'. It, will be obseived that the mean of the values obtained for the factor is almost equal to that of dextrose (11.9).Lactose. Tbe sugar used in these experiments was obt.ained by recrystallisa- tion from aqueous alcohol. A standard solution of this pure sugar was prepared and its reducing power estimated as in the previous cases.ON AMRIONIACAL SILVER NITRATE. 153 40 C.C. 40 Y , 4Q 7 9 40 9 9 40 9 , ~~ ~ Lactose. 2 T O C.C. 4.19 ,, 4.60 ,, 5 - 3 0 ,, 6-75 ,, AgNO, (N110). -- 8mins. 1 : 13.80 16 ,, 1 : 8-54 20 ,, 1 : 7.69 25 ,, 1 : 6.54 30 ,, 1 : 4.92 AgNO, (N 110) reduced. Time. Ratio of silver nitrate reduced to that left in solution. Factor calcula. ted for Qm 9 -72 14 -76 16 5 6 19-08 24 '30 ~~ ~~ ~ ~ Maltose. The specimen of maltose used in these experiments was prepared in the following way.A saturated solution of the sugar in alcohol was allowed to remain for more than a fortnight in a corked flask ; the solution was then filtered from the maltose which had separated, and the alcohol allowed to evaporate slowly in the air. A standard solution of the sugar thus obtained was then prepared, and the reducing power estimated in the usnal manner. AgNO, (N, 10) required. 0 -95 C.C. 1.27 ,, 7-25 y y 1-07 ,) Rat,io of silver nitrate reduced to that left in solution. 1 : 20 '05 1 : 17.6 1 : 14.69 1 : 4 . 5 Factor calc ula- tea for c12. 3 *40 3 -85 4'57 26 *lo Hence when either lactose or maltose is heated with ammoniacal silver nitrate under conditions sufficient to oxidise the same amount of any of the monosaccharides, dextrose? galactose, or levulose, to a definite final stage, only a very small proportion of the disaccharide becomes oxidised. The results of the time experiments in the case of lactose and maltose would lead 11s to suspect a gradual hydrolysis of the sugar by the ammonia as the beating is continued. The results obtained may be thus sumniarised. (1) When dextrose, levulose, and galactose are heated with am. moniacal silver nitrate under the given conditions, a definite fzctor can be obtained in each case. (2) Cane sugar, starch, and dextrin, when heated under the same conditions, exert no reducing action on ammoniacnl silver nitrate.154 TILDEN AND BARNETT: THE NOLECULAR WEIGHT (3) In tbhe case of lactose and inaltose a definite factor cannot be got, owing to the gradual hydrolysis of the disaccharide molecnles by the ammonia. Uizhersity C d e g e , Dzwdee, Deceinbes, 1895.

ISSN:0368-1645    

DOI:10.1039/CT8966900145

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

154 TILDEN AND BARNETT: THE NOLECULAR WEIGHT XVI1.-The iWolecuZw Weight and F o r m d a of Phos- p hokc Ada ychide a l a d of M P t ap hosp hor ic A cid. By W. A. TILDEN, D.Sc., F.R.S., and R. E. BARNETT? B.Sc., Assoc. R.C.S. Plzoyhoric Adayd?-ide. Considerable advances have been made within recent years in the study of compounds of the elements belonging to the phosphorus group, and among the results established may be remarked especially the fact that the oxides generally., and wveral of the sulphides, con- form to the molecular type of the elements themselves, that is, they cont,ain four atoms oE phosphorus, arsenic, or antimony. The formulm, As40G, and Sb40s, have been est.ablished for arsenious and antimonious oxides respectively by the vaponr density deterniinations published by V.and C. Neyer (Ber., 1879, 12, 1117, 1282). The formulae, P406, aiid P406S4, have in like manner been settled by Thorpe and Tutton (Trans., 1890, 57, 551, and 1891, 59, 1022), and the lower sulphide has the corresponding formula, PASs, calculated from the density of its vapour (Isumbei.t, C.R., 1886, 102, 1386). The case of the higher sulphide will be discussed later on. The compound described by Thorpe and Tutton under the name of phosphorus tctroxide (Trans., 1886, 49, 833), is regarded by them as having the molecular formula, P204, and hence as the analogue of nitrogen tetroxide, but no determination of the vapour-density has yet been attempted. Phosphoric anhydride alone remains unexamiued among the com- pounds of phosphorus which are volatile without dissociation, but it is usually still expressed as pentoxide, P,O,, from analogy with the sulphide, the vapour density of which has been determined by V.and C. Meyer (Bey., 1879, 12, 610). According to Shenstone and Beck (Trans., 2893, 63, 475), phos- phoric anhydride usually contains lower oxides of phosphorus ; for the preparation of the pure oxide we have, therefore, adopted their process with slight modifications. The sublimed product, after pass- ing together with dry oxygen through the heated platinum sponge,AND FORJfULX OF PHOSPHORIC ANHYDIIIDE, ETC. 155 was collected in a narrow tube of hard glass united by means of tho blowpipe tlo the end of the combustion tube. When full, this tube was drawn off at its junction with the combustion tube, exhausted by the Sprengel pump and sealed.Separate small portions could then be sealed off for successive experiments. The oxide thus obtained was chiefly in the form of a crystalline crust adherent to the glass, but also partly in a loosely flocculent con- dition. When free from phosphoric acid, i t does zot melt on the application of heat, but sublimes rapidly below a red heat. An attempt was made to melt the oxide in a tube attached to an apparatus in which i t could be exposed to a pressure of nearly 7 atmospheres. On applying the flame of a spirit lamp, however, the substance sublimed without melting. I n order to determine the vapour-density of this substance, it is necessary, on account of its extremely hygroscopic nature, to avoid contact with ordinary undried air.Platinum is the only available substance capable of resisting to a sufficient extent its action at a red heat, though even platinum is liable to be corroded, especially in the presence of oxygen (Barnett, Trans., 1895,67,513). Hence peculiar difficulties stand in the way of exact determination of the density of the vapour of phosphoric anhydride, and the results of our earlier experiments were unsatisfactory owing to various causes which it is unnecessary to discuss here, being attributable in most cases to in- sufficiently high temperature, or to some imperfection in the ap- paratus. It may, however, be stated that the value deduced for the molecular weight was in erery case more than double the nnm- ber, 142, which corresponds f o the himula, P,O,.The method used was Victor Xeyer’s air expulsion process. The apparatus consisted of a c3;- lindrical platinum bottle, 70 cm. high and 6 cm. in diameter, hold- i n g about 300 C.C. and haviug a tubular neck 40 cm. long by 1Q cm. internal diameter. Into the end of t,his platinum tube w as fitted a glass tube with two branches ; one, a narrow bore gas-leading tube, a , the other a short straight tube b, which could be closed by a stopper. The top of the glass tube was closed by a1.56 TILDEN AND BARNETT: THE MOLECULAR WEIGI-IT rubber stopper traversed by a perforation through which passed, gas-tight, a glass rod having a mark upon it so that i t could always be pushed in to the same extent. The small tube containing the substance could be inserted into the rubber stopper from below, and would be held in the perforation until pushed out by the glass rod.The source of heat was in the earlier experiments a gas muffle, but this was afterwards replaced by a gas furnace in which the platinum bottle could stand upright. It was found necessary to protect the platinum from contact with the furnace gases, and ac- cordingly we procured some glazed fireclay cylinders closed at one end, into which the bottle would just slide, and with this covering i t was placed in the furnace. The top of the cylinder projecting into the air was packed with asbestos card 80 as to prevent cooling by convection. The expelled air was at first collected over oil of vitriol, but as this was inconvenient it was replaced by kerosene of known density and vapour-pressure.I n order to fill the bottle with dry air, a long tube passed through the rubber stopper to near the bottom of the bottle. As the end of this tube when wholly of glass was found to collapse when hot, about 30 cm. of the lower end was replaced by a tube of platinum foil, Bulbs filled with oil of vitriol and phosphoric anhydride were connected with the side-branch, and thus a current of dried air entered here, passed down into the bottle, and escaped up the long tube. This operation was performed after the platinum bottle had been heated to the requisite tlemperature and all was ready for the experiment. By making use of the same side-branch and long tube at the end of an experiment, the vapour could be expelled and the apparatus left ready for a second operation.An approximate estimation of the temperature obtained was made by means of the melting-points of salts. A few crystals of the dry salt were wrapped in a little cylinder of platinum gauze and lowered into the bottle when heated. Suspended at a distance of 2 c.m. from the bottom, sodium chloride was always melted, while potassium sulphate only showed signs of incipient fusion. The latest values for the melting-points of these salts are 815' and 1078" respectively (V. Meyer, Riddle, and Lanib, Bcr., 1894, 27, 3128). It may, there- fore, be concluded that the temperature in the later experiments was in the neighbourhood of 1000°. The little tube containing the phosphoric anhydride having first been nicked by a, file near one end, and wrapped in a piece of platinum foil, was weighed, A crack was then started in the tube by the application of a hot rod, the extremity broken off, and the tube in- stantly fixed in its place.The glass was weighed after the experi- ment was over and it was always found that the two pieces fitted together perfectly.AND FORMUL,Q OF PHOSPHORIC ANHYDRIDE, ETC. 157 The following results were obtained in the manner described. Weight of Vol. of air phosphoric reduced to Vapour Moleculay No. anhydride. 0" and 760 mm. density. weight. 1 . . . . .. 0.2533 gram 15.96 C.C. 177.0 354 2 ...... 0-0841 ., 5.06 ,, 185-0 370 3 ...... 0.2055 ,, 14.02 ,, 163.0 326 4 .. .>.. 0.1904 ,, 13.83 ,, 153.6 307 5 .... .. 0.2600 ., 18.22 ,, 163.0 326 6 .. .. .. 0.1859 ,, 12-33 ,, 167.5 335 Calculated molecular weight, for P,Os = 142, for P,O,* = 284.Experiments numbered 3, 4, 5 and 6 were made at a temperatuiae much higher than I and 2. The trustworthiness of 2 is much less than that of the others on account of the small quantity of substance operated on. For the sake of comparison, a determination of the rapour density of mercury was made immediately before the last ex- periment, and as it gave the value 99.3, it is obvious that the opera- tion mas rightly conductcd. The numbers for phosphoric anhydride therefore undoubtedly point to the formula P401, for this substance, though even at the temperature of bright redness it seems to be only imperfectly gasified. It seems remarkable that while the 4 atoms of phosphorus remain associated in this compound and in the oxjsnlphide, P406S4, dis- covered by Thorpe and Tutton, the molecule should divide when the whole of the oxygen is raplaced by sulphur giving the pentasulphide, P,S,.It is noticeable also that the lower sulphide is represented as P,Ss on the evidence of the vapour density (Isambert, Compt. rend., 1886, 102, 1386). Now, supposing the molecular constitution of the higher sulphide to be P4S10, and that on vaporisation it dissociates into P,S, and S4, the vapour density would have the value (7.67) found by V. and C. Meyer. The boiling point of the so-called penta- sulphide is 530°, and Meyer determined the density at a temperature described as a d w k red (" Die Teinperatnr war so gewahlt, dass das Blei dunkle Rothgluth zeigte," Rer., 1879, 12, 611). A very low red heat, as shown by fireclay bricks, corresponds to about 700".The density of sulphur vapour at 606' was found by Biltz, using Dumas' process, to be 4.734 ; and from estimations through a range of lower temperatures it was found steadily t o diminish from 7.937 at 467.9". It may fairly be supposed, therefore, that the density of sulphur vapour at, say, 650°, assuming this as approximately the temperature of the lead bath in Meyer's experiments on phosphorus pentasulphide, would be somewhat less than 4.7, though not very much less, as i t is evident, on plotting Biltz's figures on squared paper, that the curve is very irregular, and that there has been a sudden fall in value from138 TILDEN AND BARNETT: THE MOLECULAR WEIGHT the figure given immediately before.* Assume the density at a '' dark red " heat to have been 4.3, then equal volumes of such rapour and the vapour of P,S, mould give a mixture having the mean density of 45+10-9/2 = 7.7, which is almost exactls the value found by V.and C. Meyer. The vapour of phosphorus sulphide is brownish- yellow, and, though paler, is similar in colour to sulphur vapour. Altogether the proof that the highest sulphide of phosphorus is a. pentasulphide is far from complete, and certainly the densit.$ of its vaponr cannot be accepted as evidence bearing on the case of the corresponding oxide. Metctphospphoric acid. I n the course of preparing successive batches of phosphoric anhy- dride, our attention was repeatedly drawn to the presence of drops of liquid in the front part of the tube when the distillation was COII- ducted a t too high a temperature.On these occasions the fused, glassy residue usually left in the platinum boat WAS not to be seen, and we came to the conclusion that the drops consisted of metaphos- phoric acid, and that this compound is far more readily volatile than is commonly supposed. H. ROSC, i t is true, states (ArtnuZen, 1830, 76, 2, 13, and 1851, 77, 319) that inetaphosphoric acid volatilises at a bright, red heat, bnt i t has never been regarded as a compound that could be easily distilled. With the knowledge of this fact, however, we thought that it might be possible to take the vapour density, and that the results would be interesting. The acid was prepared by dissolving commercial phosphoric anhy- dride in nitric acid, evaporating the solution in a platinum dish anti1 the liquid ceased to evolve bubbles of mpour, and then boiling away about half of it in a platinum crucible heated to redness.Samples of the residue were then quickly taken out by means of a little platinum dipper, dropped into ft small tube of platinum foil, and immediately enclosed in a glass tube, which was sealed up and weighed. Two determinations of density made a t a bright red heat gave the following results. Calculatd for. r-------\ I. [I. HPOp H,P,O,. HAPJOIp 76.8 78.2 40 SO 160 * The three last values gircii in Biltz's table (Be,,., 188S, 21, 2017) :we as fol- lows :- Temperature. ..... 680.9" Drnuitp. ..... 5.607 ? I ...... 5809 ........ 5'412 ,, ...... 606.0 ........ 4.734 from which it is clear that great accuracy cannot be claimed for these result,s.AND FORMULA OF PHOSPHORIC ANHYDRIDE, ETC.159 Experiments showed, however, that the acid prepared in this man- ner was liable to vary in composition as to the percentage of anhy- dride it contained. It was therefore necessary to analyse every specimen of the phosphoric acid of which the vapour density was taken; in all cases it was found that it contained a quantity of anhydride in excess of the amount, 88.75 per cent., which corresponds to the formula (HPO,),,. The two following series of experiments were made on two different preparations. Nuaaple 1. 0.0978 gram gave v. d.. . . . 0.1070 ,, ,, . . . . 69.1 1 71.6 1 Mea,n v. d. = 70.3. 1.4798 ,, 90.18 per cent. of phosphoric anhydride. Sample II.Fg*9}Meiln v. d. = 69.8, 0.0861 gram gave T. d.. . . . 0.0719 ,, ,, . . .. 69.7 = 90.86 per. 0.7880 ,, 90.79 ,, 9 , 1 Mean cent. anhydride. 1-2997 ,, 90.94 per cent. anhydride Sample I contains therefore 8'7.25 per cent. (HPO,),,, and 12.75 per cent. anhydride, corresponding to 12H2P,06,P4010 ; and Sample II has 81.2 per cent. (HPO,),, and 18.8 per cent. of anhydride, corresponding to 8HaPzOs,P4010 approximately. It is obvious from the three series of experiments, that although the composition of metaphosphoric acid varies a little, the vapour of this substance consists chiefly of a dimetaphosphoric acid, HZP206, which is apparently liable to undergo partial dissociation at a high temperature, and even during ebullition to part with 8 small quantity of water.Comtitzi tion. It is, perhaps, idle to speculate as to the possible constitution of compounds such as the oxides and acids of phosphorus, but a, few words may not be out of place. The group o f 4 atoms of phosphorus is a very stable form of struc- ture, inasmuch as it bears very high furnace temperatures without breaking up. It is only at a white beat that there is eridence of even incipient dissociation (Biltz and V. Meyer, Ber., 1889, 22, 725). The molecule of phosphorus being represented as - - =P - P=160 PHOSPHORIC A KHYDRIDE AND METAPHOSPHORIC ACID. i t is evident that there are but 12 units of disposable valency. This can only provide for the accession of 6 atoms of oxygen, unle,, 0s we assume either the linkage of oxygen to oxygen in a chain, or the disruption of the bond between the phosphorus. The former is so improbable a hypothesis in the present instance that we are reduced to the latter, and the formula of the two oxides assume the following shape, in which the dot represents phosphorus. Formulce somewhat in this sense have already been suggested for P406 by Thorpe and Tutton (Trans., 1890, 57, 563). On the intro- duction of water the molecule of phosphoric anhydride is divided into two parts, and metaphosphoric acid results, which, from the formula given above for the anhydride, would have the constitution I. ,OH 0 = P-OR I 11. 0 From this the usual formula for pyrophosphoric acid, 11, is immeiii- ately derived, Royal College of Science, Loledon.

ISSN:0368-1645    

DOI:10.1039/CT8966900154

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

161 XVII1.-On y-P~~eizoxy-de?.ivcit~ves of Malonic acid and Acetic acid, and various Compounds used in the Synthesis of these Acids. By WILLJAM HEXRY BEETLEI-, EDWARD HAWORTH, and WILLTAM HEKRY PERKIN, jun. THIS paper contains a description of a number of compounds which were prepared in the course of a research, not yet completed, on the synthesis of methylisopropyltetramethylenedicarboxylic acid, This acid possesses especial interest from the ~H2*~(CH3)*COOH CHz*C( CsH,).COOH' fact that itssformula was f o r a long time considered as the most probable expression of the constitution of camphoric acid. Our idea in attempting to synthesise this acid was to prepare in the first instance a3~~-methylisopropyladipic acid, C 0 OH* C H ( CH,) * C H2.C H2*C H (C,H,) C 0 OH ; to brominate this acid and then to treat the dibromo-acid thus formed with finely divided silver.4: H2G B r ( C H3) C 0 OH CH2* CBr (C3Hi)*COOH In attempting to synthesise az,-rnethylisopropyladipic acid we have met with unexpected difficulties. It was known from the work of Bevan Lean (Trans., 1894,65,997 ; compare also Perkin and Prentice, Trans., 1891, 59, 819, and Guth- zeit and Dressel, Annalen, 1890, 256, 180-188), that, starting with ethylic butanetetracarboxylate, 7 H2*v ( C H3) .C 0 0 H + 2AgBr. CH2.C (C3H7) C 0 0 H + 2Ag= (C 0 OCZH,),CH*CH2* CH2eCH (COO C2Hb) 2, and treating this ethereal salt with sodium ethoxide and methylic iodide, and then agein with sodium ethoxide and isopropylic iodide, it was not possible to obtain ethylic methylisopropylbntane tetra- carboxylate from which the desired acid could easily have been pre- pared, because when this ethereal salt (1 mol.) is treated with sodium (1 atom) and methylic iodide (1 mol.) the dimethyl derivative, is at once produced with regeneration of half of the ethylic butane- tetracarboxylate, so that i t was found necessary, in order to prepare methylisopropyladipic acid, to resort to indirect methods.The following experiments were therefore instituted, and although many of them gave interesting results, we have not been able, so far, in any ( CO 0 CzH,) ZC (C H3) C H2* CH2* C (C H3) (C 0 0 C2H5) 2, TOL. TJX1X-S N162 BENTLEY, HAWORTH, AKD PERKIN : case to obtain sufficient of the methylisopropyladipic acid for analysis and an examination of its properties.(1) The action of sodium etboxide and ethylene dibromide (or chlorobromide) on various mixtures of ethylic methylrnalonate and ethylic isopropylmalonate was studied i n the hope that, in this way, e t.hylic methyl isopropyl bn tanete tracarbox y lat t: might be formed. (COOC2H5)2CNa*CH, + BrCH2*CH2Br + CNa(C,H,)(COOC,H,), = (COOC2~tr,)2C(CR~)*CH,*CH,*C(C,H~) (COOC2HJ2 + 2NaBr. but, at the most, only very small quantities of this ethereal salt could be obtained, and from it no well defined acid could be isolated. ~H2*CH2*~*CH3, w:ts prepared and co 0- (2) Methylbutyrolactone, converted into ethylic y-bs.omethylmet?iyZacetate by treatment with hydrogen bromide and subsequent etherification ; this ethereal salt was then digested with the sodium derivative of ethylic isopropyl- malonate, when it was anticipated that the following decomposition would take place. ( COOC2H6),CNa*C3H7 + BrCH,.CH,*CH ( CHJ)*GOOC2H5 = (C 0 0 CzH,),C (CSH, )*CH,*CH2*CH (CHs) COO C2H6.From this etbylic rnethyliaopropylbutanetricarboxylate, the desired acid could then be obtained by hydrolysis and elimination of 1 mol. of carbon dioxide. Unfortunately, during this reaction, the brom-ethereal salt is evi-. dently for the most part decomposed into methplbutyrolactone and ethylic bromide, so that in this instance again very small quantities only of an ethereal salt of high boiling point were obtained. Some considerable difficulty was experienced in preparing methyl- butyrolactone, and a number of experiments on the action of glycol chlorhydrin on the sodium compounds of ethylic methylmalonate, and ethplic methylacetoacetate, under widely different conditions, failed to give condensation products from which this lactone might readily have been prepared by hydrolysis.Ultimately considerable quantities of methyl butyrolactone were obtained in the following way :- 8-Bromethyl phenyl ether was first prepared by the action of ethylene dibromide on sodium phenoxide in alcoholic solution, CsH5*ONa + BrCHz*CH2Br = CsH,*0.CH2.CH2Br + NaBr, and from this, by digesting it with-the sodium compound of etliylic methylmalonat e, ethyZic yphenoxyethyl-a-methylmalonate was ob- tained. C6H5*O-CE12*CH2Br + NaC(CHJ (COOCzH5)2 = C6H5-0.CH2*CHz*C (CH,) ( cooc2H6)2 + NaBr.7-PHENOXT-DERIVATIVES OF RIALONIC ACID, ETC. 163 This ethereal salt on hydrolysis yields the corresponding acid, which, when heated at NO", loses 1 mol.of carbon dioxide with formation of ~,-p~eenoxyethy7methyZacetic acid, C,H5*O*CH,*CH,*C13(CH,)*COOH; the latter, by the action of fuming hydrobromic acid, is decomposed into phenol and 7-bromethglmethylacetic acid. C,H5*O-CH,*CK,*CH(CH,).COOH + HBr = C6H5*OH + BrCH,*CH,*CH( CH,)*COOH. Roiling with sodium carbonate solution readily decomposes this bromo-acid with formation of methyl Eutyrolactone, BrCH,*CH,.Cj'H*CH, YH,*CH,*qH*CH, + HBr. - - COOH 0-- GO After these experiments had been completed, a paper by R. Marburg appeared in the Berichte (1895, 28, 8 ) describing a different method for preparing m ethylbutyrolactone, which is briefly as follows :- Nthylene dibromide is digested with the sodium derivative of ethylic methylmalonate, when the product of the action is found to contain ethylic y-brometlzylmethylmalonate, CH,Br*CH,Br + NaC(CH~)(COOC,H,), = NaBr + CH2Br*CH2*C (CH,)(COOC,H,),.This etbylic salt, on hydrolysis with barjta water, yields the barium salt of "1- h ydrcxy ethy lmeth ylmalonic acid, CH,(OH)*CH,*C(CHJ (C00)2Ba. The free hydroxy acid is not capable of existence, as, on acidifying its barium salt, it a t once decomposes with elimination of water and formation of a-methylbut,yrolactonecarboxglic acid, H,*CH,*Q (CH,) 43 0 OH, and this on dry distillation yields methylbutyrolactone with evolution of carbon dioxide. The properties of the substance prepared in this way are identical with those of the methglbutyrolactone obtained by us by the method described above.0- co During the course of this investigation many difficulties were encountered which necessitated the preparation and examination of a number of substances which at first sight may appear to have little connection with the synthesis mentioned above. Such of these sub- stances as are mentioned in this cornmnnication may be tabulated for the sake of reference, they are the following:- Glycol phenyl ether, C6H5~O~CH~*CH,~OH. /3-cldorethyl phenyl ether, C6H5*0* CHZ* CH,CI. N BIG4 BENTLEY, HAWORTH, AND PERKIS : p-bromethyl phenyz ether, C6H5*0*CH2*CHzBr. Ethylene diphenyl ether, C6H5*0.CH2*C~2*0.C6H5. Met hy Zene diphen y 1 ether, C6H5*0 c Hz* 0. C6H5, y- Phenox yethy Zmalonic acid, c6H5*O*C H2*CH,*CH(C OOH) :.y-PhenoxyEutyric acid, C6H5*O*CHz.CH2*CH2*COOH. gH2*CH,.pH2 co 0- But yrolactone, Di~henoxyeth~lmalonic acid, (C6HbO*CH2*CHz)zC (COOH),. Diphenoxyeth y lacetic acid, ( C6H50*CH2*CH2),CH* C 0 0 H. P-Pl2enoxyethyl-y-hydi.oxybzLtyric acid, P-Bthozyethyl phenyl ether, c6H5*o*cH2~cH2*o*C2H5. y-Phenoxyethyl-a-methylrnalonic acid, C6H5*O*CH2*CH2*C (CH3) (COOH),. 7- Phenox yet hy 1- a-meth y lacetic acid, f: H2*CH2*yH*CH3 co O-- Met h y 1 but yro Zuc tone, a-~ethyl-y-bromobuty?uic acid, CHT,Br*CHz*CH(CH3)*COOH. A few of the above compounds have been prepared previously, and in these cases we have only given details where we have been able to effect improvements in the preparation. We are still engaged in experiments on the preparation of methyl- isopropyltetramethylenedicarboxylic acid, and hope soon to be able to lay before the Society an account of the results obtained.At the same time we are continuing the examination of some of the substances tabulated above, and especially interesting results are anticipated from the study of the hydrolysis of diphenoxyethylacetic acid. Glycol Monophenyl Ether, C6H5*O*CHz*CH2*OH. To obtain this substance, sodium (1 atom) was dissolved in ethylic alcohol, phenol (1 mol.) and glycol chlorhydrin (1 mol.) added, and the mixture heated in a reflux apparatus until neutral. The alcohol was then distilled off, water added, and the product extracted with ethei-. After washing well, first several times with dilute caustic soda to remove phenol, and afterwards with water, the ethereal solution was evaporated, and the residue distilled under diminished pressure ; the whole distilled between 163" and 166' (80 mm.pressure), the 3-ield being very good. A portion boiling at 165' was collected for analjsip, and gave the following numbers.y-PHESOSY-DERIVATIVES OF Bt ALONIC ACID, ETC. 1 6 5 0.1316 gave 0.0864 H,O an3 0.3358 CO,. This ether is a colourless, thick, oily liquid, insoluble in water, but C = 69.59 ; H = 7.28. C9HlOO2 requires C = 69.56; H = 7.24 per cent. readily soluble in ether or alcohol. / j . ChZorethyZ PhenyZ Ether, C6H5*O*CH2*CHSCl. This has already been obtained by Henry (Bull. Xoc. Chim., 1883, 40, 323) by treating potassium phenoxide with ethylezie chloro- bromide ; in preparing large quantities of this compound we operated as follows.To an alcoholic solution of sodium phenoxide (1 mol.) ethylene chlorobromide (1 mol.) was added, and the mixture heated on the water bath in a reflux apparatus ; sodium bromide immediately began t o separate, and after about two hours boiling the mixture was neutral. The alcohol mas now distilled off, water added, and the product ext'racted with ether ; the ethereal solution, washed with caustic soda to remove phenol, and afterwards with water, was dried over calcium chloride, evaporated, and the residue distilled. The chief portion boiled between 210 and 230°, but there was a considerable residue, which solidified after a time, and consisted of ethylene di- phony1 ether (see p. 166) ; on redistilling the fraction 210-230', it was fomd that it boiled at 220°, and on standing some time nearly the whole of the distillate solidified to a beautiful white, crystalline mass, melting at 28'.0.2501 gave 0.2305 AgCl. C1 = 22.8. CeH90C1 requires C1 = 22.75 per cent. The crystals are very readily soluble in light petroleum, benzene, Henry (Zoc. c d . ) gives the melting and boiling points and alcohol. of this substance at 25' and 221' ( i 5 4 mni.) respectively. /3-BromethyZ PhenyZ Ether, C6H5*0*CH2*CH2Br. This substance is prepared in a manner exactly similar to the chlorinated derivative, using ethylene dibromide in place of ethylene chlorobromide. During the operation, large quantities of vinylic bro- mide, formed from the ethylene dibromide by the removal of hydrogen bromide by the sodium phenoxide, issue from the condenser, and, owing to t'his secondary action, large quantities of unchanged phenol are found in the product ; as this interferes considerably with the fractionation of the product if it is not entirely removed, care must be taken to wash the ethereal solution repeatedly with dilute soda, until it is quite free from phenol. The product is then frac- tionated under diminished pressure, as the bromide decomposes if distilled under the ordinary pressure.The fraction distilling at166 BENTLEY, HAWORTH, AND PERKlN : 140-150' (at 40 mm.) is colle-cted; the residue which solidifies is described later. On redistillation, the bromide boiled almost con- stantly at 144O (at 40 mm.), and gave the following numbers on analysis. 0.2124 gave 0.1991 AgBr. Br = 39.89. p-Bromethyl pheizyl ether is a white, crystalline substance, melting a t 35'.I t possesses in a very high degree the property of superfusion, a pure sample having been kept liquid in a bottle for several weeks ; on removing the stopper the whole solidified with considerable evoln- tion of heat. The yield of bromide obtained by the above method is about 20 per cent. of the theoretical. fi-Bromethyl phenyl ether was first prepared by Weddige ( J . pr. Chenz., 1881, [el, 24, 242), by the action of ethylene bromide on sodium phenoxide, but the details of the preparation and purifica- tion as given by him are troublesome; 8fter many experiments the abope method of procedure was found to be the most convenient. According to Weddige, the ether melts at 39O, and distils at 240-250°, undergoing decomposition and evolving hydrogen bromide.C,H,OBr requires Br = 39.8 per cent. Ethy Zene Diphenyl Zllher, C6H~*0.CH2*CHz*0CGHJ. The residue left after distillation of the /3-brom- (or p-chlor-) ethyl phenyl ether solidifies to an almost colourless crystalline mass, which can be readily crystallised from light petroleum (b. p. 100-120"), in which it is easily soluble on boiling, but admost insoluble in the cold. After repeated recry stallisation, the product melted at 96O, and gave the following numbers on analysis. 0.1402 gave 0.4025 CO, and 0.0828 H,O. C = 78-29. ; H = 6.56. C,,HI4O2 requires c' = 78.5 ; H = 6-54 per cent.. Burr (Zeit. fiir Cheni., 1869,165), who first prepared this substance, gives the melting point as 98*5O, whereas Lipmann (Zeit.fur Ohem., 1869, 447) states that it melts at 95O. Action of Methylene Chloride and Nethylene Iodide on Sodium Phen- oxide. dfethyzene Dipphenyl Ether, C6H6*O*CH$O*C6HS. These experiments were instituted in the %ope of obtaining chloro- methyl phenyl ether and iodomethyl phenyl ether, substances which were required for a series of synthetical experiments, Methylene iodide, C HJ2, and methylene chloride, CH,Clz, were treated with sodium phenoxide, in proportions theoretically required to form C6H5*O*CH~I and C6H,*O*CH2C1. I n the former case, thery-PHENOXT-DERIVATIVES OF MALONIC ACID, ETC. 167 mixture was heated on the water bath in a reflux apparatus, but when the chloride was used the mixture was heated i n soda-water bottles in boiling water for five hours ; the product was isolated exactly as described in the case of the preparation of /3-hromethyl phenyl ether from ethylene dibromide.I n the present case, however, the sodium phenoxide, curiously enough, acts on one half of the iodide or chloride only, and leaves the other half unchanged ; methylene diphenyl ether being the sole product of the action. This compound is a colour- less, syrupy liquid boiling at 205O, under a pressure of 50 mm. When cooled to Oo i t solidifies to a colourless, cryst(a1line mass, which melts at about 15'. The following numbers were obtained on analysis. 0.1187 gave 0-3377 CO, and 0.0715 H20. C = 77.59; H = 6.69. 0.1523 ,, 0.4334 ,, ,, 0.0810 ,, C = i7.61; H = 5.91, C,,H,,O, requires c! = 78.00 ; R = 6.00 per cent. Attempt.8 were subsequently made to obtain C6H,*O*CH2Br from the compound just described by treating it with hydrogen bromide under various coiiditions, but in t'his we were unsuccessful, as, even when we used the theoretical quantity of hydrogen bromide dissolved in acetic acid, one-half was converted into methylene dibromide and the otlier half remained unchanged. Methylene diphenyl ether has been described by Henry (Ann.Chim. Phys., 1883, [ 5 ] , 30, 269) and by Arnhold (Annulen, 1887, 240, 201) as a liquid boiling at 293-296O. yPhenoxyethy ZmaZonic acid, C6H,0*CH2*CH2*CH( COOH),. This substance is easily prepared as follows :-Ethylic malonate (13 grams) is added to sodium (2 grams) dissolved in alcohol (25 gramP), and the mixture treated with p-bromethyl phenyl ether (14 grams).The whole is then heated on the water bath i n a. reflux apparatus till neutral, after which it is cooled, diluted with water, and the oil which separates extracted with ether ; the ether is evaporated, and the light yellow, oily residue hydrolysed by boiling with alcoholic potash (14 grams) for two hours. The alkaline soh- t,ion is evaporated with water until all the alcohol has been expelled, and is then acidified and extracted with ether; the ethereal solation is dried over calcium chloride, the ether boiled off, and the resulting oil poured into a basin when it quickly solidifies. Finally the sub- stance is puri6ed by cryatallisation from xylene from which it separates in minute needles melting at about 142" with slight evolu- tion of gas. Analyses.0.1168 gave 0.2520 CO, and 0.0586 H20. C = 58-89 ; H = 5.39. CsHaO*CH,~CH,*CH(COOH), requires C = 58.93 j H = 5-35.168 BENTLEE', HAWORTH, AND PERKiN : ~ - P h e ~ z o s ~ e t h y l ~ z a l o n i c acid is sparingly soluble in cold, readily in hot water; i t is very sparingly soluble in benzene, and almost in- solnble in light, petroleum, but it dissolves very easily in alcohol and ethylic acetate, and is fairly soluble in ether. yPhenoxybutyric acid (y-Phenoxyethylac~tic acid), CGHsO.CH2.C Hz* CH z*C 0 0 H. This acid was readily obtained on heating yphenoxyethylmalonic acid a t 150--160° until the rapid evolution of carbon dioxide had slackened, and then finally raising the temperature to 200' for a few minutes ; the residual syrup, which was of a pale brownish colour, solidified to a hard mass on cooling.It was easily purified by re- crystallisation from light petroleum (b. p. 100-120'), from which i t separates in thin plates melting a t 64-65'. 0.1346 gave 0.3282 C02 and 0.0808 H,O. C6H50~CB2*CH,*CH2*COOH requires C = 66.66 ; H = 6.66 per cent. yPlzenoxpbutyiic acid is sparingly soluble in cold water, easily iii hot, and, on cooling, separates in the flocculent condition. It is easily soluble in benzene, ethylic acetate, alcohol, and acetic acid. C = 66.50; H = 6-67. f: Hz* C H2* Q ET2 O-- co ' Butyolactone, A number of experiments were conducted with the object of dis- covering the best possible means of replacing the phenoxy-group in yphenoxybutyric acid by the hydroxy-group ; in this case the y-hy- droxybutyric acid formed would imniedizttely lose water, yielding butyrolnctone. yPhenoxybu tyric acid (25 grams) was gently heated on the water bath with fuming hydrobroniic acid (60 c.c.) i n zt reflus apparatus for about eight hours, and afterwards for the same length of time on the sand bath.On cooling acd diluting with water, a heavy black oil separated which was extracted with pure ether, and the ethereal solution mashed with water. The ethereal solution was then extracted eeveral times with a strong solution of sodium carbonate, the extracts boiled with animal charcoal for 12 hours, and the liquid filtered from the animal charcoal ; the pink filtrate, after being evaporated to a small bulk, was extracted with ether to remove phenol, and then acidified and again extracted repeatedly with pure ether.This ethereal solution was dried over calcium chloride, the ether removed by evaporation, and the residual oil (about 5 grams) fractionated. Practically the whole of the oil distilled between 20k0 and 206' at the atmospheric pressure, and a sample oE the oil boiling a t 205' yielded the following results on ttnalysis. The following method gave the best results.y-PHE~OBf-DERIVBTIVES OF MALOSIC ACID, ETC. 169 0.1020 gave 0.2090 CO, and 0.0646 H20. C = 55.88 ; H = 7.03. C1H60, requires C = 55-81 ; H = 6.97 per cent. The substance lva 8 : there fore, evidently y-butyrolactone, which, according to Fittig and Rocder (Annden, 1885, 227, 22), boils a t 206'. Diphenoxyeth yhzalonic acid, ( C6H50*CH,.CH,),C(COOH),. This acid has been prepared in considerable quantities ; the method me usunlly employed being as follows :-Ethylic malonato (16 grams) is added to sodium (2.3 grams), dissolved in alcohol (30 grams), and the mixture heated with fi-brornethjl phenyl ether (20 grams) on the water bath till neutral; the product is then cooled and again treated with sodiuni (2.3 grams), dissolved in alcohol (30 grams), and p-bromethyl phenyl ether (20 grams), and the mixture once more heated on the water bath till neutral.On adding water, a heavy oil separates; this is extracted with ether, thc ether removed by eva- poration, and the oily residue hydrolysed by boiling with alcoholic potash (17 grams). After removing the alcohol by evaporation with water, the solution is acidified, and the copious white precipitate of crude diphenoxyethylmalonic acid thus produced is collected, washed with water, and dried 011 a porous plate until quite free from oily impurity.It is then purified by recrystallisation from 50 per cent. acetic acid from which it separates in rhombic prisms melting and decomposing a t 150". 0.1266 gave 03098 CO, and 0.6680 H,O. (C6H50*CH2*CH2)2C(COOH), requires C = 66.28 ; H = 5.81 per cent. ~~1ie~zoxyet,72ylmal~~zic acid is nlmost insoluble in cold water, very slightly soluble in hot water or benzene, and almost insolnble in light petroleum; it is moderately soluble in ether, ethylic acetate, and alcohol, aud is extremely soluble in acetic acid. It is reprecipitated by water from its alcoholic and acetic acid solutions. C = 66.44 ; H = 5.96.Diphenoxyethylacetic acid, (C,H,O~CH,*CH,),CH~COOH. This compound was prepared by heating dipheiioxyetbylmalonic acid a t lFOo until carbon dioxide ceased t o be evolved; the brown, syrupy residue solidified completely on cooling, and was readily puri- fied by recrystallisation from light petroleum (b. p. 100-120"), from wvEich it separated in feathery groups, melting a t 88". 0.1054 gave 0.2788 CO, and 0.0625 H,O. (CsH50~CH2~CH2)2C€€~COOH requires C: = 72-00 ; H = 6.66 per cent. D~lzeizoxyethylacetic mid is insoluble in cold, and only sparingly soluble in hot, water ; it is sparingly soluble in cold, light petroleum, C = 72.14; H = 6.59.170 BENTLET, HAWORTH, AND PERKIN : easily in the hot liquid, and very soluble in benzene, ethylic acetate, alcohol, and acetic acid ; its alcoholic and acetic acid solutions yield flocculent precipitates when diluted with water. P-P henox yet hy I- r-ph ydr0s.y butyric ucz'd, OH'' H2* cH2> C H*C 0 0 H.CsH,O*CH,*C H, This substance was obtained accidentally in examining the product formed by heating a sample of crude diphenoxyethylacetic acid in a sealed tube with a solution of hydrogen chloride in acetic acid for some hours at about 130' ; the contents of the tube were diluted with water, and the dark, heavy oil which was precipitated was extracted with ether, the ethereal solution washed repeatedly with water to remove acetic acid, and the ether evaporated. The dark, oily residue was then boiled with a strong solution of sodium carbonate for it considerable length of time, in order to remove chlorine.The alkaline solution was now extracted with ether, to remove phenol, acidified, extracted with ether, and the ethereal solution dried with calcium chloride and filtered ; shortly afterwards it was observed that crystals were separating from the ethereal solution ; these were collected, washed with ether, dried on a porous plate, and recrystal- lised twice from benzene, in which i t dissolves but slightly. I t crptallises in prisms, which melt at 1 1 2 O , but sinter several degrees below this temperature. 0*1083 gave 0.2578 CO, and 0.0716 H,O. C = 64.92 ; H = 7-33. When pure, this substance is almost insoluble in ether, very sparingly soluble in light petroleum, but moderately easily in water. The siher salt, CI2Hl5AgO4, was prepared by precipitating an aqueous solution of the ammonium salt with silver nitrate; it is moderately soluble in hot water, and ci*ystallises on cooling in white tufts.0.1092 gave 0*0358 Ag. Ag = 32.78. C,,H,5AgOa requires Ag = 32.63 per cent. With copper sulphate solution, the aqueous solution of the ammo- nium salt gives a bluish-white precipitate, which dissolves on boiling, and separates out again on cooling, apparently not in the crystalline condition. Lead acetate solution gives 110 precipitate at, first, but, on standing, a white, crystalline salt gradually separates ; this redissolves on boiling, and crystallises out again on cooling. Barium nitrate and calcium chloride give no precipitate with the aqueous solution of the ammonium salt.ry-PHENOST-DERIVATIVES OF MALONIC ACID, ETO.171 Action of /3-Bronzethyl Phenyl Ether on the Sodium Derivatire of Et h y 1 ic Meth y lrnalon ate. Ethylic -pPhenoxyethyl-a-Nethylrnaloiiate, CCH5O*CH2.CHz.C (CH,) (COOCzH5),. This substance is obtained when the bromo- or chloro-ether, C6H~*O*CB2.CH2Br or C,H5*O*CH,*CH2Cl (1 mol.), reacts with the sodium derivative of ethylic methylmalonate (1 mol.) in alcoholic solution. I n the case of the chloride, the action proceeds slowly, six hours boiling being required to complete it, but in the case of the bromide, it sets in on gently warming, and is so vigorous as to main- tain the mixture a t the boiling point for some time ; when the decom- position is complete, wateris added, and the oily product is extracted with ether. The ethereal solution is washed with water, dried over calcium chloride, evaporated, and the residual oil fractionated under reduced pressure, when the bulk of it distils at 230' (45 mm.) as a colourless, thick oil, which, on analysis, gave the following numbers.C = 65.01 ; H = 7-39, C,,H,,06 requires C = 65.3; H = 7.M per cent. 0.1392 gave 0.0927 HzO and 0.3318 CO,. Ethglic y-phenoxyetltyl-a-methylinalonate is a colourless syrup, which, even on long standing, showed no signs of crystallising. During the fractionation of the crude product of the action of pben- oxyethylbromide on ethylic sodiomethylmalonate, a considerable quan- tity of an oil of low boiling point was obtained, which, on subsequent fractionation under the ordinary pressure, was found to contain, besides ethylic methylmalonate, a liquid free from halogen, and boiling a t about 230".In order to free this substance from ethylic methyl- malonate, i t was boiled with excess of alcoholic potash for four or five hours, when a large quantity remained uiisaponitied. Water was added, the oil which was precipitated extracted with ether, the ethereal solution well washed with wat,er, dried, and evaporated. The oily residue thus obtained, when distilled, boiled constantly a t 2YOo under the ordinary pressure. The analytical results agreed w i t h the formula C6H50*CH2*C H,*OC,H5. 0.1502 gave 0.1150 H20 and 0.3974 CO,. /3- Ethoxyethyl phenyE ether is a colourless, mobile oil of penetrating C = 7215; H = 8.50. C,oH,kOz requires C = 72.28 ; H = 8.43 per cent. odour, resembling that of benzyl ethyl ether, C6H5*CHz*OCaH5.yPhenoxyethy1-a-methylmalolzic acid, C~HJO*CH~*CH,.C(CH,) (COOH),. I n order t o prepare t h i s acid, ethylic yphenoxjethyl-a-methyl malonate (50 grams) was boiled with alcoholic potash (50 grams).178 BYSTLEY, HAWORTH, AND PERK1:T : There appeared to be very little action in the cold, but, on gently warming, a large quantity OE an insoluble potassium salt soon sepa- rated ; sufficient water mas added to dissolve nearly the whole of this, and the mixture boiled on the water bath in a refliix apparatus for two or three hours. Water was tlhen added, the alcoliol completely rcmoved by evapomtion on the water bath, the residue dissolved in water, cooled, and acidified with hydrochloric acid ; the crude ~,-phenoxjethyl-a-rnethylmalonic acid, which then separated as a thick, heavy, brown oil, was extracted with pure ether, and the et.herea1 solntion dried over calcium chloride and evaporated.After standing overnight in a vacuum over sulphuric acid, the oil solidified to a, bard crystalline mass, which was readily purified by recrystalii- sation from hot benzene. The followingare the results of the analysis of this substance. 0.1312 gave 010684 HzO and 0.2920 COz. C,,B,,05 requires C = 60.50 ; H = 5.88 per cent. .I-Phenoxyethyl-2-methylmnlonic acid crystallises in colourless prisms which melt a t 125O with decomposition and formation of yphenoxy- cthyl-x-met hylacetic acid and carbon dioxide. It is sparingly soluble in cold water or cold benzene, aiid insoluble in light petroleum, but readiiy soluble in hot water, hot benzene, alcohol, or ether.C = 60.69; H = 5-79. ?~-YhenoxyethyE-x-?izethyZacetic acid, C6H50*CH2*CH2*C H (C H3) *C OOH. This Rubstance was prepared by heating yphenoxyethyl-a-methyl- malonic acid a t 180" until evolution of carbon dioxide had entirely ceased, and then distilling the residual oil under diminished pressure. The whole distilled between 205' and 210' (45 mm.), the correct boil- ing point a t this pressure being 207'. A small portion of the distil- late, which, 011 cooling, soliditied immediately, was recrjstallised from light putroleurn (60-goo), and thus obtained in the form of small, colourless crystals melting a t 80". C = 67.91 ; H = 7-00, 0.1745 gave 0.1100 H,O and 0.4345 GO,. CllHIIOYrequires C = 68.04; H = 7.21 per cent. This acid is readily soluble in alcohol, ether, or benzene, mode- rately so in hot water and light petroleum, but only sparingly in the two last-named solvents in the cold.Silver salt, C6H,0~CHz~CHz~CH(CH,).COOAg.-~~~s was pre- pared by suspending t'he acid i n water and gradually adding ammonia until the whole had dissolved; the solution was then boiled t o get rid of the slight excess of ammonia, and silver nitrate added when the solution was cold. The white, flocculent precipitate thus ob- tained was collected, washed well with water, spread on a porous plate, and dried in a vacuum over snlphuric acid.7-PHENOXT-DERIVATIVES OF MALOXIC ACID, ETC. I 7 3 0.0910 gave 0.0382 H,O and 0.1456 CO,. 0.1298 ,, 0.0467 Ag. Ag = 35.98. This silver salt is somewhat soluble in boiling water, and separates again, in the amorphous condition, on cooling. A neutral solution of t!;e ammonium salt of PI-phenoxyethyl-a-methylacetic acid gives no precipitate with barium or calcium salts, but, on adding lead acetnte, a white, amorphous precipitate is thrown down, which is somewhat soluble in boiling water.With copper salphate a flocculent green precipitate is obtained insoluble in boiling water. C = 43.65; H = 4 66. C,,H,,O,Ag requires C = 43.85 ; H = 4.32; Ag = 335.88 per cent. Action of Brornethyl Phenyl EtJier on E t h y l i c NetJLylncetoncetate. This reaction was carried out as follows. Sodium (4 grams) was dissolved in ethylic alcohol (50 grams), the solution cooled, and a, mixture of ethjlic methylacetoacetate (25 grams) and bromethyl phenyl ether (35 grams) added.In the cold there appeared to be no action, but, on heating on the water bath in a reflux apparatus, sodium bromide quickly separated ; the mixture, which, after boiling for about two hours mas neutral, was poured into water, and the oily prodncts extracted with ether in the usual way. On distilling the dry product under a pressure of 40 mrn. ethylic methylacetoacetate first passed over; the thermometer then rose rapidly, and at 1@5O almost the whole of the new compound distilled. CsH,0*[ICH2],*C(CH~)(CO*CH,).COOC,B, requires C = 68.10 ; H =1 7-55 per cent. Ethylic -,-phenoxyethyl-a-methylacetoacetate is a thick, colonrless oil which, on hydrolysis with strong alcoholic potash, yields rpphen- oxyethyl-a-metbylacetic acid.0.140c) gave 0.0983 H20 and 0.3473 CO,. C = 67-64! ; H = 7.80. Formation of a-Methylbutyrolactone fvow r~-Phenoxyethyl-a-rnethylacetic acid. yPhenoxyethyi-a-methylacetic acid is moderately easily decom- posed by heating with mineral acids with formation of a-melhyl- butyrolactone ; the best results being obtained as follows. The pure acid is heated in sealed tubes with a strong solution of hJdrogen bro- mide in glacial acetic acid for six hours at 100" ; the contents of the tubes are then diluted with water, the products extracted with ether, and after the ethereal extmct has been washed with water until free from acetic acid, the ether is distilled off, and the residue is boiled with potassium carbonate solution for 12 hours. The phenol formed is then removed by means of ether, the aqueous solution concentrated on the water bath, and, afber cooling, acidified and boiled in a reflux174 v-PHENOXY-DERIVATIVES OF MALONIC ACID, ETC.appamtus for two hours, to convert the hydroxy-acid into the lactone. The solution is then repeatedly extracted with pure ether, the ethereal solution dried over calcium chloride, evaporated, and the product distilled. In this way, a colourless, mobile liquid is obtained which boils constantly at 2Olo, and is evidently identical with the a-methylbu tyrolnctone described by Marbnrg (Ber., 1895, 28, 10). a- Meth y I- y -2lromohutyric acid. In order to prepare this substance, pure a-methylbuyrolactone is left for 24 hours at the ordinary temperature in contact with satn- rated aqueous hydrobromic acid ; the product is poured into water, all rise of temperature being carefully avoided, and the liquid rapidly extracted with ether.After washing well with water, the ethereal solution is dried and evaporated, when a brown, oily residue is left, which cannot be purified by distillation, as it decomposes readily on warming; for analysis i t was, therefore, merely Jeft over sulphuric acid in a vacuum for a, short time. 0.2732 gave 0.2840 AgBr. This acid gives off hydrogen bromide: at ordinary temperatures, Br = 44.04. CsH9Br02 requires Br = 44-19 per cent. very probably with formation of a-methylbutyrolactone. Ethylic yBrom-a-methy Zhutyrate, CH2Br*CH2*CH(CH3) *C 00C2H6.- The impure ~-brom-a-metl~ylbutyric acid obtained as described above was dissolved in ethylic alcohol and the solution saturated with dry hydrogen chloride ; after 24 hours, water was added, the ethereal salt extracted with ether, and the ethereal solution, after being well washed with water and sodium carbonate solution, was dried over calcium chloride, and evaporated. I n this case also, the oily residue could not be distilled, for although it did not give off hydrogen bromide so readily in the cold as the acid did, it decomposed rapidly below its boiling point.After standing in a vacuum over sulphuric acid for 12 hours, the bromine was determined. 0.2460 gave 0.2146 AgBr. Br = 37.12. C,H,02Br requires Br = 38-27 per cent. Action of Phosphorus Pentachloride on a-ll.lethyIhutyrolactone. In order to study this decomposition, phosphorus pentachloride (20 grams) was gradually added to a-methylbutyrolactone (10 grams), the mixture being well cooled with water during the addi- tion. When all the pentachloride had been added, and the wholeHAWORTH AND PERKIN: THE PREPARATION OF GLYCOL. 175 allowed to stand for one hour, the action was completed by heating for one hour on the water bath. On subsequently distilling the pro- duct, phosphorus oxychloride passed over first., and then the tempera- ture rose to 1 8 9 O , at which the rest distilled; there was, however, some decomposition accompanied by charring and evolution of hydro- gen chloride. The analysis of the product obtained in this way did not give very good analytical results, although they indicated that the substance was ~-chlor-a-met7~lllbutyryl chloride, CHzC1.C H2*CH (CH,)*COCl; this was borne out by the study of the properties of the chloride. Anilide of ly-Chlor-a-rnethy Ibutyric acid, C HZC1.C H2.C H (CH,) *C 0 *NH*CCHs. This crystalline substance is obtained when tbe product of the action of phosphorus pentachloride on a-methylbutyrolactone is slowly poured into aniline, the mixture being well cooled during the addition. After standing for one hour, the product is poured into water, dilute hydrochloric acid added until the excess of aniline has been removed, and the whole extracted with ether. The ethereal solution, after being washed successively with dilute hydrochloric acid and with water, is evaporated, and the residue left in a vacuum over sulphuric acid until it gradually deposits crystals. These are freed from oily mother liquor on a porous plate, and then recrystallised from light petroleum (b. p. 100-120"). The beautiful white prisms thus obtained melt a t 106'. N = 6-96, 0.1155 gave 7.0 C.C. moist nitrogen at 18' and 753 mm. C11H140ClN requires N = 6.62 per cent. Owens College, Manchester.

ISSN:0368-1645    

DOI:10.1039/CT8966900161

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年代:1896

数据来源: RSC

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HAWORTH AND PERKIN: THE PREPARATION OF GLYCOL. 175 XIX-Note on the Preparation of Glycol. By EDWARD HAWOBTH, B.Sc., and WILLIAM HENRY PERKIN, Jun. IN preparing glycol by the usual method, namely, digesting ethylene dibromide with potassium carbonate solution, evaporating the product nearly to dryness, and extracting the glycol by means of a mixture of ether and alcohol, a very small yield only is obtained, due prin- cipally to the volatility of the glycol with steam, and consequent loss during the evaporation. As we required a considerable quantity of glycol for some synthetical work, we made many experiments with the object of176 HAWORTH AND PERKIN: THE PREPARATION OF GLYCOL. improving the method of preparation, and found that by the followiiig simple modifications of the usual process, the yield may be grmtly increased.I n the first place, potassium carbonate (138 grams) is dissolved i i r water (1 litre), and the solution boiled in a stout, round-bottomed flask with ethylene dibromide (188 grams) in a reflux apparatus, from the top of which a glass tube leads to a couple of wash bottles con- taining bromine. When almost all t,he oily drops have disappeared (which is usually the case after 8-10 hours), the same quantities of potassium carbonate and ethylene dibromide are again added to the solution, and the boiling continued as before; the operation being repeated until 1128 grams of ethylene dibromide have been de- composed. After the third addition of ethylene dibromide, crpstsls of pobassiuni bromide separate on standing over night.These (and those which separate after each succeeding operation) are removed i n the morn- ing, by filtration on a vacuum pump, before the action is again started. The crystal^^ are then washed with absolute methylated spirit, the washings being subsequently used for the isolation of the glycol, as explained below. After the decomposition of the ethylene dibromide is complete, the solution of glycol is heated in an oil bath t o slowly distil off the water, using a colonna to prevent, as far a s possible, loss of glycol by evaporation. When the distillation has continued some time, the liquid begins to bump violently, owing to the separation of potassium bromide, The solution is now cooled, the crystals of potassium bromide removed, as before, and the distillation then continued.All the water which distils over should be carefully preserved for use in a sabsequent preparation. When the solution becomes very viscid, and the tem- perature of the vapour passing over begins to rise, the distilla- tion is stopped, and the residue is mixed with the methylated spirit employed in washing the potassium bromide crystals, as explained above. After standing for some time, the crystals of potassium bromide, which separate in quantity, are removed by filtra- tion on the pump, washed with absolute methylated spirit, and the combined alcoholic extracts concentrated by slow distillation, as before, from a flask fitted with a colonna. The residue is then again treated with absolute methylated spirit, which sepmates more potassium bromide ; this treatment is repeated, now using a mixture of alcohol and ether, until almost the whole of the potassium bromide has been removed. The solvent is then removed by distillation, and the residual glycol fractionated, first under reduced pressnre, and finally at the ordinary pressure.OXIMES OF BENZALDEHPDE AND THEIR DERIVATIVES. 177 The yield of glycol obtained in this way is about 50-60 per cent. of the theoretical, and we have found it practicable in one apparatus to prepare 1 kilu. of glycol in about 10-14 days. During the action, considerable quantities of vinylic bromide are formed ; this is absorbed by the bromine in the wash bottles, and by subsequently treating the product with dilute potash, to remove the excess of bromine, and fractionation, tribromethylene, CH,Br.CHBr,, is readily obtained i n a pure state. Owens College, lMaiac hester .

ISSN:0368-1645    

DOI:10.1039/CT8966900175

出版商:RSC    

年代:1896

数据来源: RSC

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OXIMES OF BENZALDEHPDE AND THEIR DERIVATIVES. 177 XX.--The Oximes of Benzaldehyde aizd their Deri- vatives. * Ry CHARLES M. LUXMOORE, D.Sc. IT is well known that stereochemical explanations of the isomerism amongst compounds where the carbon is doubly linked to nitrogen, have received less unequivocal support from the behaviour of the aldoximes than from that of other oximido-derivatives. Of the latter, the benzeno'id ketoximes may be mentioned as exhibiting in their general deportment a very fair accordance with what stereo- chemical hypotheses would lead us to expect. On the other hand, the fact that the isomeric oximes of the benzenoid aldehydes, on methylation, &c., in the usual manner, yield structurally isomeric derivatives as the principal products, offers a difficulty in the way of regarding them as stereoisomers merely.The remarkable results obtained by Dnnstan and Dymond (Trans,, 1894, 65, 206) by treating paraffinoid aldoximes with phosphorus penta- chloride, may be named as another illustration of the abnormal behaviour of oximido-derivatives containing aldehydic hydrogen. At Professor Dunstan's suggestion I have carried out a series of experiments on the oximes of benzaldehyde, with a view -of throwing further light on the nature of their isomerism, and I now communicate the principal results that have been obtained. Bet Lz-an tial doxirn e . This is most conveniently prepared in the manner described by Beckmann (Ber., 1890, 23, 1684). After being distilled under reduced pressure, the strongly refractive liquid quickly solidifies on * Part of a thesis accepted for the degree of Doctor of Science of the Univereity of London.FOL. LXIX. 0178 LUXMOORE : TEE OXIMES OF BENZALUEHYDE touching it with a crystalline fragment. The melting point of the pure substance recrystallised from light petroleum is 34'; this is readily depressed several degrees by minute traces of impurities (Dnnstan and Luxmoore, Proc., 1894, 253). The boiling point of benz-antialdoxime is as follows (thermomet.er in vaponr)-10 mm., 118-119°; 14 mm., 12.3-12eG; 19 mm., 128-129' ; 31 mm., 138-139' ; 53 mm., 152-153" ; these results are plotted out on the annexed curve. Boiling points of Benz-antialdoxime under reduced pressure. 155 150 145 125 120 115 10 20 30 40 50 60 Pressure in millimetres of merciiry.Whether benzaldoxime is formed in the presence of an excess Bodium hydroxide, according to Beckmann's method, or by shak an aqueous solution of hydroxylamine (made by mixing concentra solutions of hydroxylamitie hydrochloride and sodium carbonate equivalent proportions) with an ethereal solution of benzaldehy of ing ted in .de,AND THEIR DERIVATIVES. 179 only the an ti-modification appears to be formed ; no benz-synaldoxime has been obtained in m y case. Benz-antialdoxime Ht~droc7do~ide.--This is instantly thrown down as a white pulverulent precipitate when dry hydrogen chloride is passed into an ethereal solution of benz-antialdoxime cooled to Oo. It nielts gradually between 103' and 105'. When treated with dilute aqueous ammonia in the presence of broken ice, the oxime collects in oily drops, which are extracted with ether, and the ether allowed to evaporate ; on touching the residue with 8 crystal of benz-antialdoxime it solidifies.The crystals obtained in this manner from the hydro- chloride, prepared a t zero or below, invariably consisted of benz- antialdoxime, mixed with, a t the most, ouly a minute trace of benz-synaldoxime. Be9z.z-synaldozime Hydrochloride.--If hydrogen chloride is passed into an ethereal solution of benz-antialdoxime at the ordinary temperature heat is evolved, and the well-known pearly leaflets of benz-synaldoxime hydrochloride are gradually precipitated. In one experiment, a thermometer, immersed in the solution, rose from 10' to 28'. The same salt is obtained by the action of hydrogen chloride on benz-syn- aldoxime ; purified by recrystallisation from chloroform and light petrolenm i t melts at 66-67', if heated quickly.The difference between the isomeric hjdrochlorides is at once apparent on moistening them with water (or better with aqueous ammonia) ; both are dissociated, but whilst the one at once gives rise to oily drops of benz-antialdoxime, the other undergoes no change in appearance, as the liberated benz-synaldoxime is a white crystalline powder. If the acid is not neutrslised, this, at the ordinary tem- perature, is soon converted into oily drops of benz-antialdoxime ; in the presence of lwoken ice, however, even if it is not neutralised, the synaldoxime can be isolated, only slightly contaminated with its isomer, hy quickly extracting with ether, washing the ethereal solu- tion, and allowing it to evaporate spontaneously.Isomeric Tramformation of the Hydrochlorides.-On attempting to purify benz-antialdoxime hydrochloride by recrystallisation, it was found that by the mere act of dissolution it was converted into the isomeric syn-hydrochloride. A confirmation of this result was found in the obserratioii that an ethereal filtrate from the preparation of benz-antialdoxime hydrochloride at - 1 Oo, when allowed t o evaporate spontaneously, deposited a few crystals of the syn-hyarochloride. Doubt.less, therefore, the formation of benz-synaldoxime hydro- chloride by the action of hydrogen chloride on benz-antialdoxime is always preceded by the formation of the hydrochloride of the latter, and if kept at or below zero only a trace of this can be dissolved by ether, and the remainder is therefore protected from isomeric change ; 0 2180 LUXMOORE : THE OXIMES OF BENZALDEHYDE at higher temperatures it is more readily dissolved, and thus under- goes rapid tranaforma tion into the more stable benz-synaldoxime hydrochloride.Benz-synuldoxime hydrobromide is obtained when dry hydrogen bromide is pmsed into an ethereal solution of benz-antialdoxime cooled below 0". When recrystallised from chloroform and light petroleum, or from acetone and light petroleum, it melts at 7 7 - - 7 8 O , if rapidly heated. It is a white powder, becoming yellow on exposure to light. 0*157 gram required for neutralisation 7.1 C.C. decinormal ammonia. Calculated for C7H6NOH,HBr 7.8 O.C.Bemz-spaldoxirne hydriodide is prepared in the same manner, tbe liquid soon becomes brown from liberated iodine. The hydriodide is unstable, rapidly becoming yellow on exposure to the ail-. 0.224 gram required 8.6 C.C. decinormal ammonia. Calculated for C7H6NOH,HI 9 C.C. Benz-syrzaldoxinie Dihydro3uoride.-When hydrogen flooride is passed into an ethereal or chloroformic solution of benz-antialdoxime, this salt is precipitated. Its melting point lies between 50" and 60°, but it is difficult to determine as it decomposes on heating, and melts gradually. 0.193 gram required 22.9 C.C. decinormal ammonia. Calculated for C7H6NOH,H2F2 23.9 C.C. ; for C7H6NOH,HF 13.7 C.C. These three new halo'id salts all yielded benz-synaldoxime on re- generation, neither a hydrofluoride, hy drodromide, nor hydriodide of benz-antialdoxime could be isolated ; doubtless these derivatives were first formed, but were instantly transformed into salts of benz-syn- aldoxime, although the temperature was below 0".BenzaZdoxime Szdphates.-When benz-antialdoxime is gradually ,dded to strong snlphuric acid, the first portions completely dissolve ; as soon as a molecular proportion (C7H6NOH=121 to €€,SO4= 98) has been added, the temperature rises, and the whole solidifies to a hard, white, deliquescent mass of benz-synaldoxime sulphate. If, however, snlphuric acid and benz-an tialdoxime, both in ethereal solution, are gradually mixed whilst kept i n a freezing mixture of ice and salt, an oil separates which is the sulphate of benz-antialdoxime, since it yields the latter by regeneration, when treated with aqueous ammonia at 0'.This oil quickly solidifies, especially on stirring, while the tempera- ture still remains beIow zero; the solid thus obtained is benz-syn- aldoxime sulphate. 0.124 gram required 11.7 C.C. decinormal ammonia, and yielded 0.627 gram benz-synaldoxime. Calculated for C7H6NOR,H2S04 11.3 C.C. and 0.0681 gram. The assumption of a structural isomerism between the two oximes of benzaldehyde does not lend itself to an explanation either of theAND THEIR DERIVATIVES. 181 readiness with which the oxime of higher melting point is converted by heat or by dilute aqueous acids into its isomer, 01' of the reverse change of the hydrochloride, &c., which takes place even more readily, namely, by mere dissolution.The only structural formulae available for the oximes of benzalde- hyde are C6H5*CH:NOH and C6H5*CH<rH. Adopting these formulre for the oximes melting at 34' and 130' respectively, the changes in question would be expressed by the scheme 0 It is difficult to conceive of any reason why the transformation indicated in the left hand column by which the compound, having the isoxime formula, is very readily converted into the normal oxime should be exactly reversed in the hydrochlorides as indicated by the arrow in the right-hand column. If, on the other hand, the isoxime formula be attributed to a-benzaldoxime and /3-benzaldoxime be regarded a8 the true oxime, a similar scheme, with the arrows reversed, wculd express the facts, and this would be equally difficult t o understand.On a stereochemical hypothesis, it is not difficult to suggest a partial explanation of the fact that t,he lability of the aldoximes is reversed in their salts wibh hydrogen haloids and sulphuric acid. These salts can be conveniently formulated in the plane of the paper consistently with Pickering's theory (Trans., 1893, 63, 1069), and the transformation of the oximes clearly expressed as follows. H - HCl182 LUXMOORE : THE OXIMES OF BENZALDEHYDE We may then suppose that, in the oximes themselves, the attrac- tion of hydroxyl to phenyl is greater than to hydrogen, whilst the addition of the elements of hydrogen chloride, for instance, may disturb this equilibrium, because the directive attraction of hydro- gen for hydroxyl added to that of phenpl fo:.chlorine is greater than that of hIdrogen for chlorine added to that of phenyl for hydrogen. The fact that the hydrobromide and the hydriodide of benz- antialdoxime are less stable than the hydrochloride, suggested that this might be due to the greater mass of the bromine and iodine atoms, and for this reason the action of hydrogen fluoride was tried ; but in this case also a syn-derivatire only was obtained. As this was a dihydrofluoride, the question Cannot be regarded as positively settled. The mass of the radicle X in the anti-aidoxime salt CtjH5.R *H HO*$T-X, H is approximately as follows : HX = H2F2 HCl HBr HI H,SO, X = HF, C1 Br I HSO, Mass of X = 39 35.4 80 127 97 The mass of HF2 would thus put it after C1, but very close; while the mass of HSOa would putl it between Br and I.In neither case is this in accordance with the facts. It is more likely that the greater solubility of tdhe anti-salts that have not been obtained determined their very ready isomeric transformation. The fact, however, that different salts of benz-antialdoxime differ in their degree of stability, suggests that they should be formulated as above, and not with the chlorine, &c., in the median position, H0-y.H. X CsH5* f j *H Although Hantzsch (Bey., 1893, 26, 930) had obtained stereoiso- meric hydrochlorides of anisaldoxime and cnminaldoxime, he repre- sents the oximes of benzaldehyde (G?rund&s, pp. 122, 123) as having one hydrochloride of the formula H*T*CI, with the hydroxyl in the median position.This perhaps is derived from van’t Hoff’s conception of pentad nitrogen as situated at the centre of a cube, the valencies being directed to five of its trihedral angles. Van’t Hoff does no himself, however, seem t o have used this cube for the representation CGH5* fi *H OHAND THEIR DERIVATIVES. 183 of oximido-compounds in which pentad nitrogen may be assumed. The fact that' there are two hydrochlorides corresponding with parent oximes is best represented hy formulae in which the hydroxyl occupies the same position in the oximes themselves and in their Ralts, as used above ; and, so far as it goes, this is in favour of Pickering's hypo- thesis rather than of vnn't Hoff's. N- Meth y 1 bew-antialdoxime . When equal quantitie8 of benz-antialdoxime and methylic bromide dissolved in methylic alcohoi, are heated at 80- -90" for a couple of hours, a hydrobromide of a methyl derivative is obtained which, after recrystallisation from methylic alcohol and ether melts a t 67-67-5" 0.4513 gave 0.3856 AgBr.Br = 36.4. 0.2482 ,, 14.3 C.C. moist nitrogen at 12' and 766.2 mm. N = 6-87, C7H6NO*CH3,HBr requires Br = 37.0 ; N = 6.48 per cent. The hydrobromide is readily hydrolgsed, even by cold water, the odour of benzaldehyde becoming apparent at once on moistening ; it is, therefore, impossible to obtain the base by regeneration in aqueous solution. It was, however, isolated by passing an excess of dry ammonia into an alcoholic solution, precipitating the ammonium bro- mide by ether, and evaporating to dryness in a vacuum without heat, the residue being redissolved in alcohol and ether added, repeat- ing the process until the ammonium bromide was entirely removed ; tbe methyl derivative was finally separated as a colourless oil by the addition of light petroleum.On stirring, this oil solidified to a waxy mass which could readily be broken up into an app:trently amorphons, almost odourless, powder. The substance thus obtained in one experinlent melted gradually between 45-49'. This speci- men was used for a nitrogen determination. 0*3278 gave 29.4 C.C. moist nitrogen a t 13' and 750 mm. N = 10.5. Methylbenzaldovime requires N = 10.37 per cent. The metlijl derivative was hydrolysed by distillation with dilute hydrochloric acid ; from 2.95 grams, about 1.9 grams of benzaldehyde were obtained, besides a residue of 26 grams of benzoic acid formed by R tmospheric oxidation.The hydrochloride obtained weighed 1% granis. The equation, C,H,NO*CH, + H20 + HCI - C6H5*COH + CH3-NH30CI, requires methylhydroxylamine hydrochloride 1.8 grams (found 1.6 grams), benzaldehyde 2-3 grams (found 2.1 grams). The methj lhy droxylamine bydrochloride was purified by recrgstrtllisa- tion from methylic alcohol and ether, and was thus obtained in the form of silky needles which were very hygroscopic, and had a power- ful reducing action on Fehling's solution. The melting point was found to be SO~5--81*O0, which is lower than that recorded for p184 LUXMOORB: THE OXIBllcS OF BENZALDEHYDE xqethylbydroxylamine (82-90°), doubtlee8 thrangh the difficulty of obtaining the crystals quite free from moisture.Since the melting point of the isomeric a-salt is 149', and it has no reducing effect on Fehling's solution, there can be no doubt as to the identity of the The substance was also reduced with hydriodic acid; the hydro- chloride of the base formed was hygroscopic, and had otherwise the properties of methylamine hydrochloride. Converted into the platino- chloride and ignited, 0.3120 gram gave 0.1320 gram platinum = 42.3 per cent. Calculated for metlhylamine platinochloride 41.3 per cent. The new methyl derivative was found to be without constant melting point. A specimen melting, on one occasion, below 68' did not melt, a few days later, below 73'. This was found to be due to the gradual conversion of the substance into the isomeric derivative of benz-synaldoxime.Specimens, after keeping a few days and recrystallking from benzene and light petroleum, showed the correct melting point (81-82'), and had the other properties characteristic of the latter, some of which was prepared for cornparison in the manner described by Goldschmidt (Ber., 1891, 24, 3808). The isomeric change of the new methyl derivative into the N-methyl derivative of benz-synaldoxime takes place spontaneously in a short t'inie, and without heating, so that the melting point of any specimh depends on the length of time since it was prepared from its hydrobromide, which is perfectly &able. The lowest melt- ing point observed is that of 45-49', recorded above ; the melting point of the pure anti-derivative may, however, be lower than this.This readinessof isomeric change confirms the conclusion drawn from th'e products of hydrolysis, that the new derivative is structurally identical with the " nitrogen methyl ether " of benz-sgnddoxime, and has the formula CsH,*CH< I product. N*CHy 0 . That the two snbstances are not identical is shown (1) by the difference in melting point, (2) by the tendency of the anti-derivative ta mperfusion, and (3) especially by the very different behaviour of the two derivatives towards water. As already mentioned, all &tempts to regenerate the new methyl derivative from its hydro- bromide in tbe presence of water failed on account of the great readi- ness with which i t is hydrolysed even by cold water. The methyl derivative itself is also hydrolysed by water wheti freshly prepared, and gives an almost immedide reduction with Fetiling's sdution in the cold, although it loses this property if kept, in consequence of its conversion into the syn-derivative ; the latter, on the contrary, is per- fectly stable towards water and nent~al saline solutionR, being in factAND THEIR DERIVATIVES.185 obtained by the dissocistiou of it8 sodium iodide compound by the action of water or of fiolution of sodium chloride. It must also be observed that the hydrobromide of the new methyl derivative is formed from the anti-oxime under circumshnces in which the syn-oxime cannot exist, whilst the methylimido-derivative of the syn-oxime is obtained in a manner which in no way renders it likely that the latter should be converted into the isomeric benz-rtnti- aldoxime.Methylic iodide, when heated with benz-antiddoxime, also combines with i t to form the corresponding hydriodide ; this generally remm- bles the hydrobromide in its properties, but is veiy difficult to purify in consequence of the readiness with which it becomes coloured by the liberation of iodine. Methylic chloride. on the other hand, does not react with benz-antialdoxime ; neither does ethylic iodide, so that i t has been impossible to obtain an ethyl derivative in this manner.* The hydrobromide of the so-called " nitrogen methyl ether " of benzsynaldoxime mas prepared for the sake of comperison. I t melts at 66-67', that is to say, at almost the same temperature as the hydro- bromide obtained from benz-antialdoxime aiid methylic bromide.As i t was possible this might be the same substance formed by hydrogen bromide having caused isomeric change in the reverse direc- tiou, the regeneration was conducted in the absence of water in the maliner previously described ; the quantity was small, and the whole of the operations were completed in it very short time, so that if the anti-methyl derivative had been the product of regeneration no time was allowed for its isomeric transformation back into the syn-deriva- tive. The crystals of the base thus obtained, after merely draining for a few moments on a tile, and without being recrystallised, melted at 82-83'. Moreover, after boiling with water and cooling, they did not reduce Fehling's solution, showing that they were not hydrolysable by water.Eridently, therefore, they consisted of the nitrogen mekhyl derivative of benx-synaldosime, and the two hydrobromides are distinct substances, though melting at about the same temperatures. It i R well known that in the usual method of methylating benz- antialdoxime by adding sodium methoxide and methylic iodide succes- sively, the action being carried out on a water bath, the methoxy- * There is no record of any previous experiments being made to bring about the addition of the elements of an alkylic haloiid to an oxime by heating them together. An attempt was therefore made to extend this reaction so as to make it available for the preparation of the little known dky1 isoximido-derivatives of the ketoximee, but witliout success. Benzophenoxime heated with methglic iodide at 90' wae not acted on; at a higher temperature, there ww eo much decomposition that the hydriodide of the methyl derivative could not be isolated.Methylamino, how- ever, wa8 obtained on reducing the product of the action, showing that an isoximido- derivative had been formed.186 LUXMOORE : THE OXIMES OF BENZALDEHYDE derivative of benz-antialdoxime, CsH5*CH:NO*CH3, is almost the only product. As i t seemed likely that the preformation of the sodium salt was in a great degree, at any rate, the causeof this, a few experi- ments were made to see whether the new methyl derivative would be obtained if the conditioris of the experiment were slightly altered. To a mixture of methylic iodide with benz-antialdoximc, the calcii- lated quantity of sodiuni methoxide dissolved in methylic alcohol was gradually added in the cold ; the characteristic fruity odour of the oxygen methyl ether was at once apparent.A test portion of the product gave, after boiling with water and cooling, a notable re- duction of Fehling’s solution, due, doubtless, to the presence of the new nitrogen ether. I t was, however, found impoesible to isolate t h i s ; but the isomeric syn-derivative, into which it passed, was separated in the form of its sodium iodide compound. That this was not the first product of the action is proved firstly by the case with which specimens of the product, tested shortly after its formation, were found t o be hydrolysed by water ; and, secondly, because, as was found in a separate experiment, benz-synaldoxime cannot exist i n the presence of methylic iodide, so that a.derivative of the latter oxime could only be formed from an anti-derivative first formed. Altogether, about 10 per cent. of the methyl derivative formed had the isoximido-structure, in other words, about 1 molecule in 10 W R S caught i n the tautomeric form expressed by the formula A review of the alkyl derivatives of thc oximes furnishes conclusive evidence of the existence of isomerism which structural formul~e are insufficient to represent. The benzenoid aldoxiules form two series of alkyl derivatives having the true oximido-structure, :NOH, and yielding identical products of hydrolysis and reduction ; the chief distinctions between the corresponding alkyloxy-derivatives of anti- aud syn-aldoximes lie in their melting and boiling points.The chief products, however, of the action of alkylic iodides and sodium alcoholates on syn-aldoximes are the so-called “ nitrogen ethers,” in which there is evidence of direct linking between alkyl and nitrogen. No evidence of the existence of such isoxiniido-deriva- tives of the antialdoximes has hitherto been forthcoming, the supposed isomeric benzylimido-derivative of furfuraldoxime which Werner (Bey., 1890, 23, 2336) assumed to be an anti-derivative having been shown by Goldschmidt (Ber., 1892, 25, 2573) to be a compouiid of the syn-derivative with water of crystallisation. The methyl derivative obtained from benz-antialdoxime by the action of methylic bromide being structurally identical with that obtained fromAND THEIR DERIVATIVES. 187 benz-synnldoxime by the action of methglic iodide and sodium me th- oxide, completes the set o€ four methyl derivatives obtainable from the oximes of benzaldehyde. Thus there are four distinct series of derivatives, two of which have the oximido- and two the isoximido-structure, whilst one of each pair is an anti- and the other a syn-derivative.For= these four methyl derivatives of the oximes of benzaldehyde, only two structural formula are available. It seems, therefore, necessary toadmit some other cause of isome- rism amongst the alkyl derivativea of the benzenoid aldoximes than can be expressed by structural formulse. Without attempting to draw any definite conclusions as to the exact disposition of the atoms in space, we may accept as a working hypothesis the assumption that the isomerism that cannot be satisfactorily accounted for by diEerent modes of atomic linking is due to a condition of asymmetry in the molecule, the hjdrogen 01’ alkyl being nearer to the aldehydic hydro- gen in the one isomer, and to the phenyl in the other.In true oximido-compounds this will be represented by the following con- figuration forrnulse in the plane of the paper. C6H5* $ *H C6H5. fi *H RO-N N*OR Anti-configuration. Syii -configuration. The same isomerism would obtain amongst the isoximido-com- pounds, which we may expi*ess by the formuls CGH5.C *H CsH5*C.H C6H5*C*H C g H5* C *H RON R*K N-R NOR In. I b. I r a . IIb. O<l or I >O I>O or O<I But the formulae Ia and I b must be taken to be identical, as muet the formuh IIa and I I b , as it is simplest to assume that the oxygen and its two valencies are in the same plane (at right augles to the place of the paper) as that containing the nitrogen and carbon atoms and the four valencies by which they are linked to each other and to oxygen.Whilst it seems clear that stereoisomerism exists amongst the alkyl derivatives of the benzenoki aldoximes, and it is therefore reasonable to admit that it also obtains amongst the oximes themselves, it can- not be denied that this is an incomplete explanation of the isomerism of the two oximes of benzaldehyde, since it fails to account for the fact that the principal products of their methylation in the usual manner have different structures. Hantzsch, indeed, maintains (Gwizdriss der Stereochemie, p.113) that the :NOH formula reyre- sents the normal structure of both oximes, and that the formation of188 LUXMOORE : THE OXIMES OF BENZALDEHYDE isoximido-derivatives is due to the action of water ; and Goldschmidt (Bey., 1891, 24, 2808), in his description of the sodium iodide com- pound fnrmed when benz-synaldoxime, methylic iodide, and sodium methoxide react, gives a very ingenious explanation of the way in which he supposes the isoximido-methyl derivative to be formed from the parent substance supposed to have the normal structure :NOH. But the formula which he gives to the intermediate sodium iodide compound is very improbable, and his explanation cannot be regarded as valid. The fact that, when benz-antialdoxime and methylic bromide are heated together (in the absence of water), the hydro- bromide of the isoximido-methyl derivative is formed, completely disproves this statement o€ Hantzsch's, for it shows that both oximes are very ready to react in the sense of the isoximido-formula, though the benzsynaldoxime does so more readily than its isomer.It seems likely that Goldschmidt's sodium iodide compound is formed by the a,ddition of the elements of methylic iodide to the sodium derivative of the syn:oxime with the isoxime strhcture, in a manner analogous bo the formation of the hydrobromide of the methyl derivative from benz-antialdoxime. If we represent these changes according to positional formub we gct the scheme C6H5*C*H C6H5*C*H CgH5*C*H I >O NCHs I>O + CH& - I>O - H*N H*N*CH3 I Br Benz-antialdoxime Hydrobromide of Methyl derivative (isoxime formula).methyl derivalive. (labile). Benz qnaldoxime (isoxime formula). CgHS*C*H C6*Ha*CaH NaOCH3 + CH,I - I>O - I >O CH,*N*Na CH3N I I Sodium iodide com- Nethyl pound of methyl derivative derivative. (stable). That is, the anti-aldoxime yields a methyl derivative having the syn- configuration, and the syn-aldoxime yields a derivative having the anti-configuration. Although this appears to be supported by the fact that the anti-derivatives generally (exclusive of those containing pentad nitrogen) are Illore stable than the corresponding syn-deriva- tives, nevertheless it is not suBciently certain to justify any change of name, and it will be wise, therefore, to continue to designate these m ethyl derivatives after the parent sldoxime. Acetylbenz-antialdoxime.This substance, prepared by the action of acetyl oxide on crystal-AND THEIR DEECIVATIVES. 189 lised benz-antialdoxime, can be solidified by cooling to -10" and peiyjistently stirring, although it has been described as an oil by previous observers ; it melts between 14" and 16'. That this crys- talline substance was a true derivative of the anti-oxime was estab- lished by regeneration. When dry hydrogen chloride is passed into a cooled ethereal solu- tion of acetylbenz-antialdoxime, benzonitrile is formed, as stated by MinunEi (Gazzetta, 1892,22, ii, 174) ; in many cases benzamide is also obtained, and sometime3 R hydrochloride of benzamide is precipitated, even when every trace of water is most carefully excluded.A number of experiments have been made to elucidate this action, and it has been ascertained that the latter are secondary products. In view of the difficulty of accounting for the formation of benzamide in the ab- sence of moisture, a, direct experiment was made to determine whether the elements of water conld be abstracted from acetic acid by benzonitrile in the presence of hydrogen chloride with the concurrent formation of acetyl chloride or acetyl oxide. The acetic acid used was freed from water by mixing it with excess of acetyl oxide, and repeatedly redistilling till it boiled constantly at 119'. It was then mixed wit,h benzonitrile and ether (distilled over sodium) and dry hydrogen chloride passed in, the whole being allowed to remain for a short time, and then fractionally distilled. Benzttmide (m.p. 128") was obtained equivalent to about half the benzonitrile taken. The early fractions of the distillate appeared to indicate that probably both acetyl chloride and acetyl oxide had been formed. Whilst Minnnni's experimental results are thus confirmed, the con- clusions he draws from them, in opposition to Hantzsch's use of t h e acetyl derivative as a criterion of configuration, do not appear to be adequately supported. As the hydrogen chloride is evidently a potent factor in the action, it would seem reasonable to suppose that a com- pound is at first' formed which is of a very unstable nature, and which, by immediate loss of the elements of hydrogen chloride and hydrogen acetate, yields benzonitrile.Assuming the hydrogen chlo- ride to be added on somewhat in the same way ns in the salts of the oximes, we get the following scheme. -, 7 + fc,H, + HO*CO*CH3, c1 in which the remaining affinities of pentad nitrogen are made use of according to Pickering's theory.190 LUXMOORE : THE OSIMES OF BENZALDEHYDE My attempts to isolate such an intermediate compound have been unsuccessful, and, therefore, it would iiot be proper to lay too much stress on the above explanation ; however, such a compound would, of course, be very unstable, and the above considerations seem SUE- cient to show that Minunni's objection to the stereochemical repre. sentation of the nldoxirnes cannot be maintained by means of this decorn posi tion.Action of Phosphorus Pentachloride on Benzaldoximes. An excess of phosphorus pentachloride was gradually added to an ethereal solution of benz-antialdoxime kept below -8' by a freezing mixture. A small quaiitity of a white powder was precipitated, probably benz-antialdoxime hydrochloride. The orange-coloured liquid was poured into ice-cold water and the mixture distilled ; in the aqueous portion of the distillate, formic acid was identified, an aliquot portion yielding, with mercuric chloride, a precipitate corresponding to 0.03 gram 011 the whole quantity. An oil had also come over which was a mixture of bensaldehyde and benzonitrile ; the latter, when hydrolysed with potassium hydroxide, gave a quantity of a m - monium chloride corresponding to 2.1 grams of benzonitrile on the whole quantity. Hydroxglamine and aniline were identified in the residue from the original distillation.Benz-antialdoxime had thus yielded, under the influence of phosphorus pentachloride, the hydro- lytic products of fornianilide 0.08 gram, and benzonitrile 2.1 grams, and some oxime had been regenerated. Benz-synaldoxime, treated in the same way, gave similar results. 0.06 gram of forrnairilide and 2.3 grams of benzonitrile were obtained besides regenerated oxime. The formation of formanilide as a pro- duct of the action of phosphorus pentachloride on the oximes of benz- aldehyde does not appear to have been noticed by previous workers, but it was, of course, probable considering that the formation of formamide from acetaldoxime had been observed by Dunstaii and Dymond (Zoc.cit.). It is, nevertheless, very difticult to explain this result. In tthe first place it is quite clear that benz-antialdoxime is not in this experiment converted into benz-synaldoxime by the action of hydrogen chloride, for it has been'shown that at these low tempera- tures the anti-hydrochloride suspended in ether is st'able ; moreover, the quantity of hydrochloride precipitated is only very small. If, however, in the experiment with benz-aniialdoxime, it be assumed that either the hydrogen chloride formed, or the phosphorus pentachloride favoiirs the transformation into the synnldoxime, so that the benzo- nitrile is formed as the result of the action of the pentachloride on the latter, then i t would be necessary to make a further assumption that in the experiments wit11 benz-synaldoxime under identical con-AND THEIR DERIVATIVES.191 ditions, the sanie reagent favoured a transformation of part of the synaldoxime into anti-aldoxime which yielded the formanilide. It seems more reasonable to assume that the action of phosphorus pentachloride in some way removes the cause that makes the stereo- isomerism possible, 'For instance, it may combine in a loose way with the oxime, so that the latter ceases to have a double link be- tween carbon and nitrogen, and the action goes on mainly in the sense of the most favoured (syn) configuration, whilst a small pro- portion of the molecules are caught in the less favoured configuration, and undergo the Beckmann transposition, yielding formanilide.Actioqa of Phosphorus l'rickloride on Benz-antiatdoxime. On adding phosphorus trichloride to a cooled ethereal solution of benz-antialdoxime a white precipitate of hydrochloride is thrown down, and the filtrate, having been poured into water and neutra. lised with sodium hydroxide. is found to contain much benzonitrile, but to regenerate a certain quantity of the oxime. By rerersing the process, and adding the oxime to a large excess of phosphorus tri- chloride, less of the hydrochloride is precipitated, but still the ele- ments of hydrogen chloride are eliminated from some of the chlorine compound, so that the product of the action consists of a mixtnre of the very unstable chlorine substitution compound, C,H,*CHNCI, benzoni t-rile, and the excess of phosphorus trichloride.From this mixture it is impossible to isolate the new compound, as there is no means of separating it from the benzonitrile. Its presence was, how- ever, proved by decomposing the phosphorus trichloride with the least possible quantity of water, and then, after distilling off the ether under diminished pressure and extracting the residue with light petroleum, in which hydrogen phosphite is insoluble, the solution thus obtained was freed from the last trace of phosphite compound by shaking wit'h a drop of water ; on now decomposing it by sodium hydroxide, it was found to contain a considerable quantity of chlorine, evidently from the presence of the chloriiie substitutioii compound C,HjCH:HO*N. Benz-antial- doxime, dissolved in a very little ether, was gradually added to a large excess of phosphorus trichloride below 0' ; the precipitate formed, supposed to be the hjdrochloride of the oxime, was filtered off, but after a few minutes i t became liquid, and had the character- istic odonr of benzonitrile.As it seemed likely that this was the compound which it was desired to isolate, and that had thus evolved its hydrogen chloride on exposure, the experiment was repeated using scarcely any ether at all. The precipitate which was formed was set to drain in a beaker well surrounded by a freezing mixture, but it This compound was ultimately obtained as follows.192 OXINES OF BENZALDEHYDE AND THEIR DERIVATIVES. presently bekan to evolve hydrogen chloride with almost explosive violence, and after standing in a desiccator for a short time the re- sidual liquid gave, on hydrolysis, no trace of hydroxylamine, all the oxime having been convert?ed into nitrile. I n these experiments, no hydrogen chloride was evolved while the oxime was being added to the phosphorus trichloride, and no hydrochloride of the oxime was formed.The chlorine substitution compound of benz-antialdoxime, C~H,*CK:NCI, is therefore a white solid, neady insoluble in phosphorus trichloride, moderately soluble in ether. In the pure state it decomposes into beiizonitrile and hydrogen chloride below Oo, but can be kept for a short time in dilute solution. Action of Phosphorus Tricldoride on Be?az-synaldozinze. When phosphorus trichloride is added to an ethereal solution of benz-synaldoxime a t -loo, half of the oxime is instantly converted into benzonitrile, the other half being converted into the hydrochloride by the hydrogen chloride which i8 eliminated. If the filtered liquid is poured into water, no oxime is regenerated. Thus the compound formed by the substitution of chlorine for hydroxyl in benz-synald- oxime is so unstable as to be incapable of existence; it instantly decomposes into benzonitrile and hydrogen chloride, and although the latter combines with more oxime, if any is present, to form the hydrochloride, this has no share in effecting the decomposition. This was proved by adding benz-synaldoxime in small portions to a large excess of phosphorus trichloride ; hydrogen chloride was freely evolved, and only a comparatively small quantity of hydrochloride was precipitated. This experiment was carried out so a8 to be strictly comparable with that in which the chlorine substitution compound was obtained from hnz-antiddoxime, but no corresponding derivative cauld be obtained. It evidently breaks up at the moment of its formation. Evidently this difference of behaviour between the two oximes when treated with phosphorus trichloride, confirms the configuration formule assigned to them. 06H5* 8 *H C6H6* # OH HO*N N-OH Benz-antialdoxime, m. p. 34'. Benz-synaldoxime, m. p. 130". This investigation was carried out at the Research Laboratory of the Pharmaceutical Society, and I desire to express my warmest thanks to Professor Dunstan, not only for many valuable suggestions, but also very especially for his kind and unfailing encouragement.

ISSN:0368-1645    

DOI:10.1039/CT8966900177

出版商:RSC    

年代:1896

数据来源: RSC