194 I. K. and 31. A. Plielps — Use of Zinc Chloride. 



h^ 



Art. XX. — The Use of Zinc Chloride in the Esterification 

 of Succinic Acid • by I. K. and M. A. Phelps. 



[Contributions froni the Kent Chemical Laboratory of Yale Univ. — clxii.] 



In a former paper* from this laboratory it has been shown 

 that in the action of succinic acid with ethyl alcohol contain- 

 ing hydrochloric acid to form diethyl succinic ester, the largest 

 yield from a known weight of succinic acid is obtained where 

 maximum dehydration is accomplished. In the work given 

 here the action of zinc chloride in forming diethyl succinic 

 ester in the mixture of succinic acid and ethyl alcohol both 

 with and without the addition of hydrochloric acid is shown. 



The apparatus figured was used in all of the experiments 

 recorded here. Two round bottom flasks of 500 cra3 capacity, each 

 provided with inlet and outlet tubes 

 held in rubber stoppers, were con- 

 nected as shown. Of these, B, con- 

 nected to a condenser through a 

 Hempel columu, carried a thermom- 

 eter, and from flask A an inlet tube 

 adjusted to dip beneath the liquid 

 to the same depth as the thermom- 

 eter. The flask A carried a separa- 

 ting funnel provided with a drying 

 tube, as well as the exit tube to the 

 flask B. In the flask B succinic acid 

 was heated, by means of a bath of 

 acid potassium sulphate, in some ex- 

 periments with a definite amount of 

 absolute alcohol alone, in others with 

 the same amount of absolute alcohol 

 containing hydrochloric acid gas, 



while from the flask A gaseous alcohol in most cases, and in a 

 few cases gaseous alcohol with hydrochloric acid, was driven 

 over into the mixture in B where esterification took place. 

 The crude succinic ester left in flask B was freed from impuri- 

 ties by treating with sodium carbonate solution after first 

 removing the zinc chloride by washing with water. The ester 

 was freed from carbonate by rinsing with distilled water 

 containing sodium chloride. The mass of ester carried mechan- 

 ically with the several wash waters was extracted by shaking- 

 out separately three times with ether. The ether extracts 

 and the succinic ester were gathered in a 250 om3 distilling flask 

 fitted in the usual way for a vacuum distillation with a 100 cm3 

 distilling flask used as a receiver, and, after fractioning off 

 low boiling impurities, largely ether, alcohol, and water, was 

 * This Journal, xxiii, 368. 



