PURDIE'S REACTION 217 



oxide and methyl or ethyl iodides react energetically immedi- 

 ately on coming into contact with one another, with evolution 

 of much heat. Such, however, is not the case ; Lander (4) 

 found that with either iodide the reaction is slow, and he 

 considers that interaction with the formation of ethers depends 

 upon the presence, or initial formation, of small quantities of 

 alcohol or water : 



Ag 2 0+2C 2 H 5 OH = 2C 2 H 5 OAg+H 2 

 C 2 H 5 OAg+C 2 H 5 I = (C 2 H 5 ) 2 0+AgI. 



Purdie and Bridgett (20) record similar observations. Dry 

 silver oxide shows no apparent change when heated with 

 excess of methyl iodide, but when dry methyl alcohol is present 

 the reaction starts immediately on warming and then proceeds 

 spontaneously. In the course of two hours' heating on the 

 water-bath, 35*5 per cent, of the silver oxide was converted 

 into silver iodide in the former case, while in the latter 88 per 

 cent, underwent the same change. The authors are of the 

 opinion that in the absence of every trace of moisture and 

 alcoholic substance, silver oxide and methyl iodide would not 

 interact, and they share Lander's view that the Wurtz syn- 

 thesis of ethers can only occur in the presence of traces of 

 moisture which act catalytically in producing alcohols, these 

 being afterwards alkylated. The statements which have been 

 given are necessary in order to explain the apparent anomaly 

 that silver oxide and an alkyl iodide should etherify a hydroxyl 

 group in a compound rather than interact with one another 

 with the formation of simple ethers. The anomaly is non- 

 existent, since the statement of Wurtz is inaccurate. It must 

 be remembered, however, that water is formed during alkyla- 

 tion by means of silver oxide and alkyl iodides, and that loss 

 of the alkylating materials will therefore occur owing to simple 

 ether formation in the manner mentioned above. If an 

 alcoholic solvent is employed, the loss of the alkylating reagents 

 is considerable. The necessity for the employment of a large 



2 E 



