An interesting result of the unimportance of the nucleophile to the rate (and therefore the usefulness) of an SN1 reaction is that very poor nucleophiles indeed may react in the absence of anything better. Nitriles, for example, are very poorly basic and nucleophilic because the lone pair of electrons on the nitrogen atom is in a low-energy sp orbital. However, if t-butanol is dissolved in a nitrile as solvent and strong acid is added, a reaction does take place. The acid does not protonate the nitrile, but does protonate the alcohol to produce the t-butyl cation in the usual first step of an SN1 reaction. This cation is reactive enough to combine with even such a weak nucleophile as the nitrile.

The resulting cation is captured by the water molecule released in the fi rst step and an exchange of protons leads to a secondary amide. The overall process is called the Ritter reaction and it is one of the few reliable ways to make a C–N bond to a tertiary centre.

مواضيع ذات صلة

The nucleophile in SN1 reactions

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