48 Phelps and Osborne — Esterifieation of Benzoic Acid. 



water. This was done in experiment (3) of Table L, (14) of 

 Table II, and (16) of Table III. 



Special tests were made to ascertain whether the ester might 

 contain condensation products. The boiling point observed on 

 redistillation of the ester obtained in experiment (8) of Table II 

 was found to be constant within two-tenths of a degree. There 

 was no evidence of condensation products of higher boiling 

 point in the material remaining in the flask from which the 

 ester was distilled. Nor were indications of material of differ- 

 ent character obtained in redistilling the combined products of 

 all remaining experiments recorded in this paper. The experi- 

 ence was similar when the crude ester produced in presence of 

 25 grm. of zinc chloride was distilled at once after shaking 

 with water in a separating funnel. Seventy-five grams of 

 redistilled ethyl benzoic ester boiling within two-tenths of a 

 degree were treated for three-quarters of an hour in the 

 apparatus for esterifieation, in presence of 25 grm. of zinc 

 chloride with 200 c ' ma of absolute alcohol containing 1*25 per 

 cent of hydrochloric acid, and then recovered in the usual way. 

 The recovered product weighed 74*7 grm., and upon redistilla- 

 tion it appeared to be pure ethyl benzoate. 



It is evident that in esterifying benzoic acid by the use of 

 ethyl alcohol and hydrochloric acid, or ethyl alcohol and zinc 

 chloride with hydrochloric acid, the amount of' ethyl benzoate 

 produced will, naturally, vary with the proportions of the 

 reagents used and with the time during which the action takes 

 place. Further, with the time of action given and such pro- 

 portions as are here used, if the conditions as to the amount of 

 alcohol in the first place, the amount of either hydrochloric 

 acid, zinc chloride and hydrochloric acid, or sulphuric acid in 

 the second case, and the length of time of the action in the 

 third case are considered by themselves, it appears that, within 

 limits, an increase in the proportion of any allows a falling off 

 in the proportion of any other of these. Finally, it is plain 

 that with certain proportions of reagents and sufficient time of 

 action, a quantitative yield, or nearly such, of ethyl benzoic 

 ester is easily obtainable. In our experiments the yield of 

 ester never exceeded 90 per cent when benzoic acid, alcohol, 

 and hydrochloric acid" were the reagents. The theoretical 

 yield was obtained when 50 grm. of benzoic acid and 2 grm. 

 of sulphuric acid were treated for three hours with 200 cm3 of 

 absolute alcohol, or for four hours with 400 cm3 of absolute 

 alcohol charged with 1-25 per cent of hydrochloric acid and 

 10 grm. of zinc chloride. 



