178 A GENERAL REVIEW OF 



action of alkyl iodides on silver salts of hydroxy-acids, certain 

 anomalous results were obtained. The ethereal tartrates 

 prepared in this way, for instance, displayed abnormally 

 high rotations, and it was ascertained that alkyloxy-derivatives 

 were produced during the reaction. In endeavouring to ob- 

 tain evidence of the production of these alkyloxy-derivatives, 

 Purdie and Pitkeathly (1) found that the reaction between 

 silver malate and isobutyl iodide gave rise to very little 

 ethereal salt but to free malic and isobutoxy-succinic acids, 

 and further, that isopropyl isopropoxysuccinate was formed 

 during the interaction of isopropyl iodide and silver tartrate. 

 Consideration of these results led to further experiments. 

 Ethyl malate, ethyl iodide, and litharge, when heated together, 

 showed no interaction, but on substituting mercuric oxide 

 for litharge, a product which was more active than ethyl 

 malate was obtained. Finally, when silver ox^de was added 

 to a solution of ethyl malate in isopropyl iodide, a vigorous 

 reaction was found to ensue. A closer study of the reaction 

 was now made ; the materials used were ethyl malate, ethyl 

 iodide, and silver oxide in the proportions calculated on the 

 assumption that the reaction proceeds according to the 

 following equation : 



OH . C 2 H 3 (COOEt) 2 +2EtI+Ag 2 = 

 OEt . C 2 H 3 (COOEt) 2 +EtOH+2AgI. 



From the reaction mixture pure ethyl Z-ethoxysuccinate 

 was isolated and its optical activity was found to agree with 

 that of the ester prepared from the active acid previously 

 obtained by resolution of the racemic acid (Trans., 1895, 

 67, 972). The value of the reaction was further exemplified 

 by ethylating ethyl tartrate by treating it with silver oxide 

 and ethyl iodide in a similar manner ; the product of the 

 reaction was ethyl rf-diethoxysuccinate. All previous at- 

 tempts to alkylate the alcoholic hydroxyl groups of tartaric 

 acid had been unsuccessful. It is thus seen that the discovery 



