Hydrolysis of Nitriles

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Nitriles are hydrolysed in basic medium to carboxylic acids.

Preparation of carboxylates from nitriles

Therefore, the introduction of a nitrile group, by nucleophilic substitution (SN) with cyanide on a compound bearing a good leaving group, is an excellent method to obtain a carboxylic acid.

A halide R–X with cyanide gives the nitrile R–CN, which is hydrolysed (HO⁻, then H₃O⁺) to R–COOH

Remember that nucleophilic substitution reactions cannot always be achieved, depending on the structure of the R group.

Click here to recall how the aliphatic SN worked.

An aldehyde with cyanide gives a cyanohydrin, whose hydrolysis gives an α-hydroxy acid

Another interesting possibility is the formation of a cyanohydrin by addition of cyanide to an aldehyde. Subsequent hydrolysis of the nitrile gives α-hydroxy acids.

Click here to recall what a cyanohydrin is.

Click here to preview the mechanism of nitrile hydrolysis, which belongs to the next chapter.