1212 RUHEMANN: THE ACTION OF ETHYL CXXIL-The Action of Ethyl Chloyofumarate on Monoalkylmalonic Esters. By SIEUFRIED RUHEMANN. THIS investigation was undertaken with the view of preparing alkyl derivatives of aconitic acid, and to study them on the same lines as aconitic acid itself. Although the action of ethyl chlorofumarate on the sodium derivative of ethyl malonate does not yield ethyl carboxy- aconitate but ethyl trimethylenetetracarboxylate, nevertheless such a transformation of the unsaturated grouping into trimethylene com- pounds is excluded if, instead of ethyl malonate, its monoalkyl deriv- atives are used. Their sodium compounds react, indeed, with ethyl chlorofumarate according to the equation : It*CNa(CO,Et), + CO,Et*CCl:CH*CO,Et = R*C(CO,Et),*C( C0,Et): CH*CO,Et + NaCI, but the yield of the homologues of ethyl carboxyaconitate is small.The quantity depends on the nature of the alkyl group in the substi- tuted malonic ester, and decreases as the size of the radicle increases. Thus, on treatment of ethyl chlorofumarate with ethyl sodiomethyl- malonate, 50 per cent. of ethyl methylcarboxyaconitate are produced, but the yields are as small as 6 per cent. on using the phenyl or benzyl derivatives of malonic ester. As yet, I have only examined in detail the hydrolysis of ethyl phenylcarboxyaconitate, and have found that a substance of the formula C,,H,O, is formed which is the anhydride of a dicarboxylic acid. It is neutral t o litmus, it melts on heating with water to an oil which slowly dissolves, giving an acid solution; from this, on cooling, the greater part of the anhydride separates out again. The alkaline solu- tion of the substances is not attacked by potassium permanganate and the anhydride does not form an additive compound with bromine.These facts lead to the conclusion that the product is not an unsatur- ated compound, but a derivative of trimethylene. The following twoCHLOROFUMARATE ON MONOALKYLMALONIC ESTERS. 1213 formula are the only ones possible which agree with its mode of forma- tion from ethyl phenylcarboxyaconitate : (1) A C,H,* C-CO (’) H2C--CH* GO \/ 0 C,H,*CH (1) (3)H$!--$!H(2) /\ >o. (3) (2) ( l ) oc co The result of the action of sodium amalgam on the anhydride proves formula (2) to be correct. Under the influence of the reducing agent, the anhydride, besides being transformed into the corresponding acid, unites with two atoms of hydrogen :and yields a dicarboxylic acid identical with Zelinsky and Buchstab’s s-phenylmethylsuccinic acid, C6H5*CH(C0,H)*CH(CH,)*C02H (Ber., 1891, 24, 1876). The form- ation of this acid from the anhydride C,,H,O, can only take place with a compound of formula (2).I t further follows that the trimethylene ring does not open up between the carbon atoms 1 and 2, as might be expected, but between the atoms 1 and 3. EXPERIMENTAL. The method which z‘ have used for the preparation of the homologues of ethyl carboxyaconitate is as follows. The monoalkylmalonic ester (1 mol.) is mixed with a solution of sodium (I at.) in absolute alcohol, and then ethyl chlorofumarate (1 mol.) is added.The mixture becomes warm and turns a deep yellow or brown; it is heated on the water- bath for about 6 hours, the alcohol distilled off as far as possible, the residue poured into water, and the solution acidified with dilute sulph- uric acid and extracted with ether, The oil which remains after evaporation of the ether is subjected t o fractional distillation in a vacuum. The larger portion passes over at a low temperature and is a mixture of the unchanged esters; from the portion of higher boiling point, the product of the reaction is obtained pure after 2 or 3 distil- lations. Ethyl Methylcarboxyaconitate, CH, C(C02*C2H5)2*C( GO,- C,H,) : CH*C?0,*C2H5. This ester is formed from ethyl methylmalonate and ethyl chloro- fumarate in the manner described above; it is a yellow oil which boils at 302-204O under 16 mm, pressure.On analysis : 0.2004 gave 0.4088 CO, and 0.1260 H,O. C= 55.63 ; H== 6.98. C,,H,,O, requires C = 55.81 ; H = 6.98 per cent.1214 RUHEMAPL”: THE ACTION OF ETHYL Ethyl Ethylcarboxyaconitate, C2H5* C (CO,. C,H,),*C( CO,*C,H,) :CH*CO,* C,H,. The yield of this substance from ethyl ethylmalonate and ethyl chlorofumarate is very small; it is a viscous oil, which distils at 205-207O under 14 mm. pressure, 0.2015 gave 0.4190 CO, and 0*1280 H,O. C- 56.71 ; HI 7.15. CI7H,,0, requires C = 56.98 ; H = 7-26 per cent. On analysis : Ethyl Benxy Ecarbox yacon;t ate, C,H,* CH,* C( C02*C2H,),~C(C0,*C2H5): CH* CO,*C,H,. On boiling the mixture of ethyl benzylmalonate and ethyl chloro- fumarate with a solution of sodium in alcohol, the liquid turns blue, The quantity of ethyl bensylcarboxyaconitate which is.formed amounts to 6 per cent.The yield is about the same, if, instead of ethyl chlorofumarate, ethyl acetylenedicarboxylate is heated with ethyl benzylmalonate and dry sodium ethoxide for several hours on the water-bath, The product of the reaction is a very viscous oil which boils at 245-246’ under 15 mm. pressure. On analysis : 0.2016 gave 0.4633 CO, and 0.1197 H,O. C = 62.67 ; K = 6.60. Alcoholic potash readily acts on the ester ; a yellow solid is precip- itated, and the liquid turns deep red. On adding dilute sulphuric acid t o the aqueous solution of the product of hydrolysis, carbon dioxide is evolved, and the organic acid separates as a very viscous oil.I have not obtained it in a pure state, but the following analysis of the silver salt, prepared from the oil, and dried at loo’, indicates it to be a tricarboxylic acid : C2,H,,0, requires C = 62.86 ; H = 6.67 per cent. 0.2773 left, on ignition, 0,1515 Ag. Ag=54*63, C1,H,OGAg, requires Ag = 55-38 per cent. Ethyl P~snylcarboxyaconitate, C6H,*C(C02~C,H,),-C(C02*C2H,):CH*C0,*C,H,, Ethyl phenylmalonate, which is required for the formation of the ester, was prepared, according to W. Wislicenus’ directions (Ber., 1894, 27, 1091), by heating ethyl phenyloxaloacetate, the product of the action of sodium ethoxide, on a mixture of ethyl oxalate and ethyl phenylacetate ; its boiling point was found to be 158-150’ under 10 mm. pressure, as compared with 170-17Z0 under 14 mm.pressure given by Wislicenus. The ester, on treatment with ethyl chlorofumarate andCRLOROFUMARATE ON MONOATJKYLMALONIC ESTERS. 1215 a solution of sodium in absolute alcohol, as in the previous cases, yields e thy1 phenylcarboxyaconitate. On analysis : 0*2195 gave 0.4992 CO, and 0.1270 H,O. C21H,G0, requires c = 62.07 ; I3 = 6.40 per cent. With the view of improving the yield of this ester, which is only 6 per cent., I have modified the action between ethyl phenylmalonate and ethyl chlorofumarate by using absolute ether and dry sodium ethoxide. The ethoxide dissolves and the solution turns deep red. After allowing to stand for a day, evaporating the ether and fraction- ating the oil which remains behind, the same result as in the previous case is obtained.Nor is the yield increased if, instead of ethyl chlorofumarate, ethyl acetylenedicarboxylate is mixed with ethyl phenylmalonate and the mixture heated with dry sodium ethoxide on the water-bath. The fact that in the first method the alcoholic solution becomes neutral, although a quantity of the esters of phenyl- malonic and chlorofumaric acids remains unaltered, seems to indicate that the ethoxide forms an additive compound with ethyl phenyl- carboxyaconitate. This view is in harmony with the following result : on distillation of the products of the reaction, a small quantity of an oil passes over at a temperature beyond the boiling point of ethyl phenylcarboxyaconitate, whilst a tarry residue remains behind in the flask. Anhydride of Phen yltiaimeth ylenedicarboxylic Acid, C= 62*02; H=6*42.The hydrolysis of the ester is complete after 2 hours' boiling with alcoholic potash on the water-bath, The alcohol is distilled off and the residue dissolved in water; on adding an excess of dilute sulphuric acid to the solution, carbon dioxide is evolved and a solid gradually separates out, The filtrate from it, on extraction with ether, furnishes a further crop of the substance. It crystallises from dilute alcohol in colourless needles which melt at 99'. On analysis : 042058 gave 065297 CO, and Oa0830 H,O. C,,H,O, requires C = 70.21 ; H = 4'26 per cent, The rsubatance is readily soluble in alcohol, ether, or benzene, and these solutions are neutral to litmus; on boiling with water, it melts and very slowly dissolves, yielding an acid solution from which, on cooling, the larger portion of the original substance crystalliaes.These facts indicate that the compound is the anhydride of n dicarb oxylic acid and that this acid is transformed into its anhydride with the greatest ease. The salts of the acid, however, are stable; I have examined those with silver and lead. C = 70.19 ; H= 4.48,1216 THE ACTION OF ETFIYL CHLOROFDMARATE. The siZver salt is obtained as a white precipitate by boiling the anhydride with dilute ammonia and adding silver nitrate to the soh- tion thus produced. It is stable to light, and can be dried at 100'. On analysis : 0.3640 left, on ignition, 0.1870 Ag. Ag=51*37. The lead salt is formed as a crystalline solid by dissolving the anhydride in boiling water and adding lead acetate.For analysis, it was washed with water, then with alcohol, in order to free it from unaltered anhydride, and dried at looo : C1,H80,Ag2 requires Ag = 51.43 per cent. 0.3920 gave 0.2875 PbSO,. P b = 50.12. C,,H,O,Pb requires P b = 50.36 per cent. s-Phenylmethylsuccinic Acid, C,H5*CH(C0,H)*CH(CH,)*C0,H. The reduction of the compound C,,H,O, is effected in alkaline solution by sodium amalgam. The anhydride is insoluble in cold potash, but on boiling it gradually dissolves. The solution is allowed t o assume the temperature of the room, and is then agitated with an excess of sodium amalgam (24 per cent.). After standing overnight, the liquid is decanted from the mercury and mixed with an excess of dilute sulphuric acid, when a colourless substance gradually separates.This is readily soluble in alcohol or ether, but only sparingly so in boiling water, from which, on cooling, it crystallises in plates melting a t 192-193O. On analysis : 0.2033 gave 0.4743 GO, and 0.1085 H20. C= 63-62 ; H= 5.92. As has been mentioned in the introduction, this substance is s-phenylmethylsuccinic acid. Zelinsky and Buchstab (Zoc. cit.) obtained it by hydrolysing the product of the interaction of ethyl sodiocyano- acetate and ethyl a-bromophenylacetate with potassium hydroxide and heating the tricarboxylic acid thus formed with dilute sulphuric acid. The acids are identical because their melting points are the same and because they are transformed into anhydrides with identical properties. The anhydride is formed from the acid at the temperature of the fusing point.Zelinsky and Buchstab distilled it under the ordinary pressure, when it passed over between 310' and 320'; I find that, on heating in a vacuum, it distils at a constant temperature of 184O under 10 mm. pressure as a colourless oil which, like Zelinsky and Buchstab's anhydride, is transformed back into the dicarboxylic acid by boiling water. I have, moreover, examined the following salts of g-phenylmethylsuccinic acid, C1,Hl2O, requires C = 63.46 ; H = 5.77 per cent.SOLUBILITY OF MANNITOL, PICRIC ACID, AND ANTHRACENE. 1217 The silver salt is precipitated by adding silver nitrate to the neutral solution of the acid in ammonia; it is not changed by light or by dry- ing at 1009 On analysis : 0.3910 left, on ignition, Og2000 Ag. Cl1H1,O,Ag, requires Ag = 5 1.1 8 per cent. The bad salt is formed as a white precipitate, insoluble in water, on 0.2680, dried at looo, gave 0.1970 PbSO,. Pb = 50.23. Ag=51*15. mixing aqueous solutions of the acid and lead acetate. On analysis : C,,H,,O,Pb requires Pb = 50.12 per cent. The barium salt separates in colourless needles on adding barium chloride to the neutral solution of the acid in ammonia. The salt, when dried a t looo, contains 2 mols. H,O, as indicated by the follow- ing determination : 0-2215 gave 0,1356 BaSO,. Ba= 35.96. The barium salt, although sparingly soluble in water, slowly crys- tallises from its aqueous solution. The solution has to be evaporated until the salt begins to come down, and the process of concentration and filtration frequently to be repeated when this mode of purification is adopted. C,,H1,0,Ba,2H,0 requires Ba = 36.14 per cent. GONVILLE AND CAIUS COLLEGE, CAMBRIDGE.