Hydrolysis of Cyanides Nitriles

The carbon-nitrogen triple bond of organic cyanides can be hydrolyzed to a carboxyl group. The reaction requires either acid or base. In acid, the nitrogen atom of the cyanide is converted to an ammonium ion. 

In base, the nitrogen is converted to ammonia and the organic product is the carboxylate salt, which must be neutralized in a separate step to give the acid. 

First let us consider some reactions we have learned. Addition reactions (catalytic hydrogenation and Diels-Alder reactions, for example) do not create any by-products. The same can be said for isomerization reactions. Such reactions are said to be atom economical —all of the atoms in the reactants appear in the product. On the other hand, eiimination reactions and substitution reactions necessariiy produce by-products. This does not mean that they are bad, but if a synthesis can be devised that focuses on addition and isomerization reactions, iess attention wiii have to be devoted to disposing of, or deveioping uses for, by-products. 

Some other generai strategies for the deveiopment of green chemistry are to use cataiysts to accomplish reactions (rather than stoichiometric reagents), to minimize the use of heavy metais as stoichiometric oxidants (for 

The mechanism of nitrile hydrolysis involves acid or base promoted addition of water across the triple bond. This gives an intermediate imidate that tautomerizes to an amide. The amide is then hydrolyzed to the carboxylic acid. The addition of water to the nitrile resembles the hydration of an alkyne (eq. 3.52). The oxygen of water behaves as a nucleophile and bonds to the electrophilic carbon of the nitrile. Amide hydrolysis will be discussed in Section 10.20. 

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