We established earlier that in an SN1 reaction the nucleophile is not important with regard to rate. The rate-determining step of the reaction is loss of the leaving group, so good and bad nucleophiles all give products. We don’t need to deprotonate the nucleophile to make it more reactive (water and hydroxide work just as well as each other) and this means that SN1 reactions are often carried out under acidic conditions, to assist departure of a leaving group. Compare, for example, these typical conditions used to make a methyl ether and a tert butyl ether. The methyl ether is made,  using methyl iodide in an SN2 reaction. It needs a good nucleophile, so the alcohol is deprotonated to make an alkoxide with sodium hydride in DMF, which, is a good solvent for SN2 reactions. The tert-butyl ether on the other hand is made simply by stirring the alcohol with tert-butanol and a little acid. No base is needed, and the reaction proceeds rapidly to give the tert-butyl ether.

مواضيع ذات صلة

A very bad nucleophile in a good SN1 reaction: the Ritter reaction

Epoxides as electrophiles

Ethers as electrophiles

Substituting alcohols with the Mitsunobu reaction

Nucleophilic substitutions on alcohols: how to get an OH group to leave

A closer look at electronic effects

The effect of solvent

A closer look at steric effects

Adjacent C=C or C=O π systems increase the rate of SN2 reactions

An adjacent C=C π system stabilizes a carbocation: allylic and benzylic carbocations

Alkyl substituents stabilize a carbocation

Shape and stability of carbocations