272 Phelps and Tillotson, Jr. — Malonic Acid or its Ester. 



the case of experiment (4) of series A, by adding a solution of 

 sodium acetate in excess, testing the disappearance of aciditv 

 of the solution with logwood paper. The slightly lower yield 

 would indicate that sodium cyanacetate had been formed from 

 the sodium acetate and the free cyanacetic acid present. 



Some loss always occurred during the distillation of the 

 alcohol from the alcoholic solution of cyanacetic acid. The 

 alcoholic distillates, averaging 500 cm3 , from live experiments 

 not recorded in the table but made by the procedure described, 

 were separately distilled through a Hempel column to small 

 volume and the remainder heated at 60°, under diminished 

 pressure, till the manometer registered 15 mm . The weighed 

 residues were combined and esterified. From the weight of 

 cyanacetic ester so obtained it was found that when 500 cm3 of 

 alcohol, containing some water, were distilled at 60° under 

 diminished pressure, from a solution containing about 180 grm. 

 of cyanacetic acid, there also distilled 7*1 grm. of cyanacetic ester, 

 which is equivalent to 10 grm. of malonic ester, or three per 

 cent for each experiment. It has been shown in a former 

 paper* that the loss of malonic ester, inherent in the process 

 employed for the conversion of cyanacetic ester to malonic 

 ester, was about three grams for seventy grams of malonic 

 ester, or 4 # 3 per cent. If these constant losses be considered, 

 it is evident that the results shown in the table are approxi- 

 mately 7'3 per cent lower than the amount of malonic ester 

 which would have been obtained had there been no loss during 

 the process. 



From the experiments in series A, in which potassium 

 cyanide of 96-98 per cent purity was used in excess, the results 

 are as good as those in series B, in which pure cyanide of 

 commerce containing ammonia was employed, and even as 

 good as those in series C, in which cyanide free from ammo- 

 nia and cyanate was made use of, other conditions being the 

 same. Thus it would seem that if the potassium cyanide is in 

 excess, impurities in the cyanide to the extent of three or four 

 per cent do not materially affect the reaction with sodium 

 chloracetate. 



In experiment (2) of series C there was much evolution of 

 carbon dioxide when sodium carbonate was added in the pro- 

 cess of recovery of the pure ester. This was presumably due to 

 the excess of sulphuric acid which was added previously to lib- 

 erate the cyanacetic acid. Too large an excess is not desirable, 

 as it retards esterification, either by holding back water or by 

 forming water and ethyl ether in reacting with alcohol at the 

 temperature 100°-110°, at which esterification took place. The 

 slight variations in yield among otherwise similar experiments 

 may be due to variations in the excess of sulphuric acid present. 



* This Journal, xxvi, 260. 



