Phelps, Palmer and Smillie — Ester Formation. 293 



pressure was collected iirst and afterward purified in the usual 

 manner by treatment with ether. 



From an inspection of the results of Table I it is evident 

 that theoretical yields of succinic ester are obtained with sul- 

 phuric acid as a catalyzer, taking into consideration the loss of 

 ester inherent in the process of recovery. In the case of acid 

 potassium sulphate a greater yield is obtained by an increase, 

 within limits, in the amount of catalyzer. This is shown by 

 comparing (7) with (8). But if the catalyzer is present in 

 larger amount, there tends to be a falling off in the yield, as is 

 shown by comparing (8) with (9). Acid ammonium sulphate 

 accelerates the esterification much more than acid potassium 

 sulphate. An increase in the amount of acid ammonium sul- 

 phate increases the yield of ester. As is shown in experiment 

 (13), acid sodium sulphate under the conditions of this experi- 

 ment gives almost as good results as sulphuric acid alone. 



In Table II are given the results with benzoic acid. It will 

 be seen that acid potassium sulphate does not accelerate the 

 esterification to any great extent, but that an increase in the 

 quantity of the acid sulphate present up to a certain extent in- 

 creases the yield, as appears in experiments (3) and (4) ; how- 

 ever, the presence of a still larger amount of the acid sulphate, 

 as in experiments (5), (6), (7), and (8), seems to hinder the 

 esterification ; the esterification indeed seems to depend on 

 conditions not yet completely understood. In the case of acid 

 ammonium sulphate, it is evident that the yields increase both 

 with the time of reaction and with the concentration of the 

 catalyzer. From a comparison of (10), (11), and (14), in which 

 the time of reaction was approximately the same, it is seen 

 that the yields increase with the concentration of the catalyzer ; 

 and from a comparison of (9) with (10), (11) with (12), and 

 (13) with (14), in each of which the amount of the catalyzer 

 present was the same, it is evident that the yields of ester 

 increase with the time of reaction. With acid sodium sul- 

 phate larger yields are obtained than with corresponding quan- 

 tities of acid ammonium sulphate, but similarly the yields are 

 increased as the reaction time is greater, as shown by comparing 

 (15) with (16), (17) with (18), and (19) with (20), and also as the 

 amount of catalyzer present is greater, as shown by comparing 

 (15), (17) and (19), and further (16), (18) and (20) with each 

 other. It is evident that neither the pyridine nor the aniline 

 acid sulphates accelerate the esterification of benzoic acid to 

 any great extent. 



In comparing these results with the results which were 

 obtained with sulphuric acid alone as a catalyzer in the former 

 paper* in this Journal, it is evident that none of the acid sul- 



* This Journal, xxv, 39. 



