252 Phelps and Tillotson, Jr. — Malonic Acid. 



the time during which it is allowed to act, produces a more 

 complete esterification of malonic acid. Larger amounts of 

 zinc chloride up to 10 grm. appear to increase the yield as in 

 experiments (1), (4) and (IT) of Table I, while the use of 5 grm. 

 of sulphuric acid seems to possess no advantage over 2 grm., as 

 is shown in experiments (1) and (7) of series B in Table II. 

 Under similar conditions, however, 2 grm. of sulphuric acid 

 with 200 cm3 of absolute alcohol running for one hour and fifteen 

 minutes in experiment (1) of series A in Table II gives a yield 

 of malonic ester nearly equal to that produced by 1 grm. of zinc 

 chloride and 300 cm3 of alcohol, charged with 1*25 per cent 

 hydrochloric acid and running for 50 minutes, in experiment 

 (12) of Table I, or to that produced in experiment (17) of 

 Table I by 10 grm. of zinc chloride and 200 Gm3 of alcohol 

 charged with 1*25 per cent hydrochloric acid. 



Finally it has been shown that by allowing malonic acid and 

 absolute alcohol to react in the form of apparatus described, a 

 yield of malonic ester, equal to the best described in the litera- 

 ture, may be obtained, while by treating for a long time with 

 alcohol charged with hydrochloric acid increases the yield over 

 twenty per cent. The presence of sulphuric acid or of zinc 

 chloride and alcohol charged with hydrochloric acid permits 

 the action to proceed in a shorter time. The best yields of 

 malonic ester were obtained by causing the esterification to 

 proceed as far as possible at a temperature below that at which 

 the malonic acid decomposes. This was accomplished, as 

 described above, by heating an alcoholic solution of malonic 

 acid with sulphuric acid on a water bath at 50° for eight hours, 

 and treating the residue obtained in this manner with a fresh 

 portion of alcohol for a period of two hours. By following 

 this procedure, a yield of 96*1 per cent of malonic ester was 

 obtained, with only 2*1 per cent lost, either through decom- 

 position of the acid, or acid ester, or by volatilization of the 

 ester. 



