368 Phelps and Hubbard — Esterification of Succinic Acid. 



Akt. XXXVI. — On the Ester if cation of Succinic Acid / by 

 I. K. Phelps and J. L. Hubbakd. 



[Contributions from the Keut Chemical Laboratory of Yale Univ. — clvii.] 



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

 that succinic acid analytically pure may be prepared from suc- 

 cinic ester by hydrolysis in presence of a small amount of 

 nitric acid ; and, further, that the acid prepared in this way is 

 of a decidedly higher degree of purity than that of the socalled 

 chemically pure acid of commerce. This paper concerns the 

 study of certain conditions under which the preparation of the 

 pure diethyl ester, C 2 H 4 (COOC„H 5 ) 2 , is readily made and, also, 

 certain conditions under which the esterification of the acid 

 seems to be almost quantitatively complete. 



The reaction for the formation of an ester from an alcohol 

 and an acid with the elimination of water is a common 

 example of what is termed a reversible reaction. In order to 

 avoid reversion of the reaction various methods of dehydration 

 have been made use of in the processes brought out for the 

 formation of esters. This seems to have been accomplished 

 most successfully by Fischerf and Speier, although as early as 

 1864 Carey Lea X showed that in the esterification of oxalic 

 acid there in an advantage in acting upon the acid in a tube 

 with gaseous alcohol, in comparison with the usual method of 

 esterification by heating oxalic acid with alcohol. Fischer and 

 Speier have shown that when one part by weight of acid and 

 three, four, or five parts of absolute alcohol containing one or 

 three per cent of hydrochloric acid are boiled on a return con- 

 denser for four hours, the product poured into cold water after 

 distilling off half to three quarters of the excess of alcohol, the 

 aqueous mixture shaken out with ether, the ethereal extract 

 dried, and fractioned, gives of the ester a yield which is con- 

 sidered good when compared with the amount obtainable by 

 other methods. While this procedure generally gives good 

 yields when used for the esterification of organic acids, the 

 esterification of each individual acid must, nevertheless, be 

 studied by itself in detail ; for, as Fischer has stated, the best 

 yields in given cases are obtained by varying the general pro- 

 cedure. 



In Fischer's procedure for the preparation of the ethyl ester 

 of succinic acid the absolute alcohol is a solvent for succinic 

 acid and its esters. It is, also, a dehydrating agent. But inas- 

 much as the water remains with the alcohol and the esters, it 



* This Journal, xxiii, p. 211. 



f Berichte der Chem. Ges., xxviii, 3252, 1895. 



JThis Journal [2], xxxix, 210. 



