44 Phelps and Osborne — Esterification of Benzoic Acid. 



made to contain 1*25 per cent of hydrochloric acid by the addi- 

 tion of enough pure, concentrated, aqueous hydrochloric acid 

 is given. The benzoic acid was esterified in the apparatus 

 described above for the experiments recorded in Table I. In 

 experiments (1) to (9) and (19) the ester was purified in the 

 same way as. stated above for the experiments in Table I. 

 In all remaining experiments excepting (10) in which zinc 

 chloride was present in amounts larger than 1 grm., the 

 process of purification was the same excepting that the 

 mass was washed as free from zinc salt as possible by shak- 

 ing in the separating funnel with water before neutralizing 

 with sodium carbonate. In experiment (10) the process of 

 purification was peculiar : after all the alcohol had been driven 

 over into the second flask the mass of material was freed from 

 low-boiling impurities by a vacuum fractionation, then what- 

 ever ester had been produced was distilled into the receiver by 

 heating the 250 cm3 flask to 150° for some time, the ester was 

 extracted with ether from this solution after diluting with 

 water, the extract was fractioned in vacuo, and the ester 

 recovered in this way was weighed. 



It is evident from experiment (10) of Table II that zinc 

 chloride with ethyl alcohol esterifies benzoic acid only in small 

 amount. In presence of hydrochloric acid, however, it tends 

 to make the esterification more complete. In experiment (3) 

 of Table II the presence of 0'5 grm. of zinc chloride so 

 influences the course of action that a yield of benzoic ester 

 greater by 2*8 per cent is obtained in half the time from given 

 amounts of ethyl alcohol and hydrochloric acid than in experi- 

 ment (3) of Table I, where conditions were otherwise similar. 

 In experiment (1) of Table II, in the presence of 1 grm. of 

 zinc chloride, in a little more than half the time and with 

 twenty per cent of the hydrochloric acid, the amount of 

 alcohol being the same, the yield was larger by 1"1 per cent 

 than in experiment (2) of Table I. In experiment (3) of 

 Table II, in the presence of - 5 grm. of zinc chloride and in a 

 little more than half the time, the increase in the yield 

 amounted to 3*8 per cent over that obtained in experiment (2) 

 of Table I under conditions otherwise similar. In experiment 

 (8) of Table II, in which 10 per cent of hydrochloric acid and 

 1 grm. of zinc chloride were used, the amount of alcohol being 

 the same, there is an increase of 6*4 per cent of ester over the 

 amount found in experiment (4) of Table I, although the time 

 is a third less. In experiment (12), in which 10 grm. of zinc 

 chloride were used, the yield is 13 per cent better than in 

 experiment (4) of Table I, made under conditions otherwise 

 similar. A comparison of experiment (15) of Table II with 

 (5) of Table I shows that, with 10 grm. of zinc chloride and 



