PURDIE'S REACTION 209 



By substituting isopropyl iodide for ethyl iodide in the above 

 reaction, and using benzene as a solvent, a mixture of un- 

 changed benzoin, benzaldehyde, isopropyl benzoate, and the 

 isopropyl ether of benzoin resulted. 



Under improved conditions, however, it is possible by 

 this process to convert benzoin practically quantitatively 

 into an ether. Thus Irvine and Weir (40) effected the com- 

 plete solution of the benzoin by adding acetone to the methyl 

 iodide used, and by then proceeding with the alkylation in 

 the usual manner obtained benzoin methyl ether in a purer 

 state than the material prepared by Fischer's hydrochloric 

 acid method. 



Similarly Irvine and McNicoll (43) have succeeded in 

 eliminating those secondary reactions which Lander found 

 to accompany the formation of benzoin ethyl ether. The 

 materials here used were benzoin (1 mol.), silver oxide (3 mols.), 

 and ethyl iodide (9 mols.), dry ether being added until the boil- 

 ing-point of the solution was reduced to 50 C. During the 

 heating at this temperature the benzoin slowly passed into 

 solution, and, after further heating at a slightly higher 

 temperature, was converted into the benzoin ether. The yield 

 was somewhat greater than 70 per cent, of the benzoin used. 



The methylation of o-dimethoxybenzoin has been shown 

 by Irvine (5 and 11) to proceed with perfect smoothness. 

 The benzoin (1 mol.) is dissolved in excess of methyl iodide, 

 and silver oxide (3 mols.) is gradually added. Gentle reaction 

 takes place and is completed by 30 minutes' heating on 

 the steam-bath. The product is extracted with ether and 

 recrystallised from carbon bisulphide. In this way pure 

 o-dimethoxybenzoin methyl ether is obtained in almost 

 quantitative yield. The corresponding hydrobenzoin is in- 

 soluble in methyl iodide, and, in the absence of a solvent, 

 resists alkylation by the silver oxide method. If hydro- 

 benzoin itself, however, be brought into solution by the 

 addition of acetone to the methyl iodide, vigorous action occurs 



2D 



