266 Phelps and Tillotson, Jr. — Cyanacetic Acid. 



ester was much lower. Similarly, in experiments (6), (7), and 

 (8) in which sulphuric acid and absolute alcohol were used, 

 no ammonium salt was precipitated and the ester obtained was 

 evidently pure ethyl cyan acetate. In experiment (6) half a 

 gram of sulphuric acid produces an increase of 31 per cent 

 over experiment (1) in which conditions were the same, except 

 that no catalyzer was present. Two grams of sulphuric acid 

 in experiment (7) further increases the yield to 96*6 per cent, 

 and by increasing the time to two hours, as in experiment (8), 

 97*1 per cent of cyanacetie ester was obtained. Taking into 

 consideration the 2'5 per cent loss inherent in the process, it 

 seems probable that the cyanacetic acid was completely esteri- 

 fied under the conditions imposed in experiment (8). 



The work recorded here has shown that, using alcohol alone, 

 with no catalyzer, 63 per cent of cyanacetic ester may be easily 

 obtained, that the yield is increased by the use of catalyzers 

 and, within limits, increases with the amount of catalyzer used. 

 Increasing the time, as shown in one experiment, also causes a 

 more complete esterification. The use of alcohol containing 

 only 1*25 per cent of hydrochloric acid causes a partial con- 

 version to malonic ester at 100°-110°, while with sulphuric 

 acid as a catalyzer this reaction apparently does not take place. 

 Esterification is more complete when sulphuric acid and abso- 

 lute alcohol are used instead of zinc chloride and alcohol 

 charged with hydrochloric acid, and nearly theoretical yields 

 may be obtained by using two grams of sulphuric acid with 

 200 cm3 of absolute alcohol acting for a period of two hours. 

 Hence, in the preparation of cyanacetic ester, hydrochloric 

 acid may not be used if the temperature is above 100°. If 

 the temperature is lower and if the concentration of the hydro- 

 chloric acid is also low, presumably pure cyanacetic ester may 

 be obtained, but such conditions are neither the best nor the 

 most convenient. Sulphuric acid may, however, be used and 

 pure cyanacetic ester obtained, and that in theoretical amount 

 if proper proportions of reagents and proper conditions as to 

 temperature and time of action are employed. 





