PURDIE'S REACTION 185 



minimum amount of the hot solvent and to add the silver 

 oxide and alkyl iodide in small, aliquot quantities. 



The preparation of dimethyl <?-dimethoxysuccinate (8) 

 from methyl tartrate may be taken as a typical case of 

 alkylation in the absence of a solvent. Methyl tartrate 

 (1 mol.) is dissolved in methyl iodide (6 mols.), and dry silver 

 oxide (3 mols.) is added in small quantities at a time. The 

 reaction mixture is contained in a flask under a reflux con- 

 denser. The reaction, which is spontaneous and at first violent, 

 is moderated by dipping the flask into cold water. Finally, 

 when spontaneous action has ceased, the reaction is com- 

 pleted by heating the flask on a steam-bath for two or three 

 hours. The product is then extracted by boiling ether, and 

 the oil remaining after the removal of the solvent by distil- 

 lation crystallises on nucleation. The silver residues are 

 practically entirely composed of silver iodide, and the yield 

 of dimethyl rf-dimethoxysuccinate is almost quantitative. 



It has already been mentioned that the alkyl iodides are 

 the most suitable halides for this reaction. Of the iodides, 

 methyl and ethyl iodides are most conveniently used, as the 

 reaction is usually more complete with these than with the 

 higher iodides (Lander (4) ). The explanation of this fact is 

 given in the discussion of the mechanism of the reaction. 



The possibility of oxidation occurring during alkylation 

 by means of silver oxide and alkyl iodides must not be lost 

 sight of. The liability to oxidation depends on the conditions 

 under which the experiment is carried out, and by considera- 

 tion of these conditions may be almost entirely avoided. 



It is not intended, in this paper, to give an exhaustive 

 account of all the applications which have been made of the 

 silver oxide reaction, as such an undertaking would involve 

 a detailed description of the chemical research work in St. 

 Andrews during the past thirteen years. A glance at the index 

 to the literature will serve to show how numerous and varied 

 have been the applications of the reaction, and further, that 



2A 



