Phelps and Osborne — Esterification of Benzoic Acid. 39 



Aet. II. — On the Esterification of Benzoic Acid; by 

 I. K. and M. A. Phelps, and R. W. Osbokne. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — clxviii.] 



It has been stated by Fischer and Speier* that benzoic acid 

 heated in certain proportions on a return condenser for some 

 hours with ethyl alcohol containing one or three per cent of 

 hydrochloric acid gives either 64*5 per cent or 76 per cent of 

 the ethyl benzoic ester theoretically possible, the amount 

 obtained being increased by the presence of the larger amount 

 of hydrochloric acid. By the use of 10 grm. of sulphuric 

 acid with 100 cm3 of ethyl alcohol and 50 grm. of benzoic acid 

 Fischer and Speier were able on heating for three hours to 

 obtain nearly 90 per cent, of ester ; and they gave it as their 

 opinion that by increasing the amount of alcohol used nearly 

 quantitative amounts of ester should be formed. Goldschmidtf 

 and Kailan^: have measured the rate of esterification under 

 certain conditions of benzoic acid with ethyl alcohol and 

 hydrochloric acid, but, so far as we are aware, no one has 

 shown any method of predicting the yield when a large per- 

 centage of ethyl benzoic ester is to be obtained. In a former 

 paper§ from this laboratory a procedure has been outlined by 

 which succinic ethyl ester can be obtained in almost quantita- 

 tive amounts from succinic acid by leading alcoholic vapor 

 charged with dry hydrochloric acid from one flask into a 

 second flask, heated at 100° to 110°, containing the succinic 

 acid with some of the alcoholic mixture. In somewhat later 

 work I from this laboratory it has been shown that succinic 

 acid in the presence of zinc chloride is esterified much more 

 rapidly by the alcoholic mixture. This esterification was made 

 in flasks specially arranged as illustrated in that paper. 



In the work given here, with the arrangement of flasks 

 referred to above, the esterification of benzoic acid has been 

 studied under the conditions recorded in the table ; first with 

 ethyl alcohol alone, then with ethyl alcohol containing zinc 

 chloride, then with ethyl alcohol containing hydrochloric 

 acid, then with the same mixture in the presence of zinc 

 chloride, and, finally, with ethyl alcohol containing sulphuric 

 acid. 



The pure benzoic acid of commerce was used in all of the 

 work recorded here. The alcohol was either the alcohol of 

 commerce 88"8 per cent, or alcohol made as free from water as 

 possible by repeated distillations from calcium oxide. The sul- 



*Berichte, xxviii, 3252. flbid., xxviii, 3218. 



X Monatscheft f . Chemie, xxvii, 543. 



§This Journal, xxiii, 368. |lbid., xxiv, 194. 



