i88 A GENERAL REVIEW OF 



hydroxide gives the excess of the Z-acid found at the end of 

 the process. 



The preparation by Lander (10) of derivatives of benzoyl- 

 acetic acid is referred to in the section dealing with the 

 alkylation of tautomeric compounds. 



PREPARATION OF SUBSTITUTED PROPIONIC ACIDS AND THEIR 



DERIVATIVES 



A simple means of preparing the alkyloxypropionates 

 consists in the alkylation of the lactic esters by the silver 

 oxide method. From methyl Z-lactate, Purdie and Irvine (2) 

 obtained methyl Z-methoxypropionate by the action of silver 

 oxide and methyl iodide, and, substituting ethyl for methyl 

 iodide, they converted ethyl Z-lactate into ethyl Z-ethoxy- 

 propionate. These esters, on hydrolysis, yielded the corre- 

 sponding alkyloxy-acids, and a number of metallic salts of 

 the latter were prepared and examined. Further, the silver 

 salts of these two acids were caused to react with alkyl iodides, 

 and in this way ethyl Z-methoxypropionate and methyl 

 Z-ethoxypropionate were prepared. This series of four esters, 

 two acids and a number of metallic salts, all in active forms, 

 furnished optical data of a nature which was, at the time, 

 much required. With these data the authors were in a position 

 to discuss the effect on the rotation of lactic acid of substitution 

 of alkyl groups for hydrogen in the carboxylic group and in the 

 alcoholic hydroxyl group. The general conclusions arrived 

 at are beyond the scope of this paper. 



It was pointed out in the Introduction that the alkyloxy- 

 esters show, as a rule, considerably greater optical activity 

 than the parent hydroxy-esters. This fact has been usefully 

 employed by Irvine (33) in his resolution of lactic acid. This 

 method of resolution depends on the fact that morphine 

 Z-lactate is much less soluble than the morphine salt of the 

 d-acid. Lactic acid and the lactates are only feebly active 



