Alkoxide ion formation

Alkoxide ion formation is important as a means of generating a strong nucleophile that will readily form C-O bonds in SN2 reactions. Thus ethanol reacts very slowly with methyl iodide to give methyl ethyl ether, but sodium ethoxide in ethanol solution reacts quite rapidly ... 

There are a number of claims4 40 51,69,150,247,268-274 for the isolation of bimolecular ethers from various other heterocyclic cations although the structures of these products have rarely been unambiguously established. The reaction mechanism outlined for the formation of 114 probably does occur in other heterocyclic systems, particularly in those cases in which alkoxide ion formation from the pseudobase readily occurs. Solubility considerations may dictate the precipitation of the bimolecular ether rather than the pseudobase from basic aqueous solutions containing relatively high concentrations of the heterocycle. However, such bimolecular ether formation will usually be in direct competition with the pseudobase disproportionation reaction (Section V,D) which shows the same pH dependence. 

Subsequent propagation may occur by nucleophilic displacement involving a new alkoxide ion formation in each addition ... 

---