Phelps and Tillotson, Jr. — Cyanacetic Ester. 261 



sion by this procedure. From the results given in Table I it 

 is plain that with small amounts of zinc chloride as catalyzer, 

 in the presence of one or two molecules of water, malonic ester 

 may be obtained to the extent of 90 per cent of that theoreti- 

 cally possible, as shown in experiments (1) and (2) of series A. 

 Taking into consideration the loss inherent in the process, we 

 have 9tt per cent accounted for. The loss of 6 per cent is 

 doubtless due to decomposition of malonic ester or acid ester 

 in the presence of water and the large amount of hydrochloric 

 acid. When no water was used, as in the remaining experi- 

 ments of the table, a much larger yield was obtained. Under 

 these circumstances the water necessary for the conversion 

 may have been formed in the secondary reaction between the 

 alcohol and hydrochloric acid in the presence of the catalyzer, 

 water and ethyl chloride being formed. The presence of ethyl 

 chloride was detected in the alcoholic distillates from these 

 experiments. It is also possible that the reaction took a differ- 

 ent course, the imido ester hydrochloride first formed reacting 

 with alcohol to form ammonium chloride and the ortho ester 

 which, in the presence of the large amount of alcohol and the 

 catalyzers, was easily decomposed with the formation of the 

 normal ester and ethyl ether. This same sort of a reaction has 

 been described by Claisen* in the case of acetals, which he 

 finds are easily broken up by catalyzers with the formation of 

 the aldehydes and ether. It is evident from the results 

 obtained in experiments (1) and (2) of series B that the con- 

 version of cyanacetic ester to malonic ester has been nearly 

 quantitative, either because sufficient water has been formed 

 in the secondary reaction mentioned above, or a reaction simi- 

 lar to that pointed out by Claisen has taken place, with the 

 formation of ethyl ether, or both of these actions have gone 

 on simultaneously. That is to say, the water theoretically 

 demanded by the equation for the conversion of cyanacetic 

 ester to malonic ester need not be introduced as such when the 

 conversion is effected by hydrochloric acid in alcoholic solu- 

 tion. Since this is true and since malonic ester is so easily 

 hydrolyzed, the better yields obtained without the use of any 

 water are easily understood. 



Experiment (4) of series A, which was treated in the esteri- 

 fication apparatus in order to complete the esterification of any 

 acid ester that might have been formed, if too much water 

 were present for any reason, shows a slight increase in yield 

 over experiment (3) of series A, which was shaken out 

 directly after saturation with hydrochloric acid and treatment 

 on the return condenser. In experiment (5) of series A, 

 after saturating in the cold with hydrochloric acid, the excess 



* Berichte, xl, 8903. 



