Synthesis of Nitriles
Nitriles are formed by an SN2 reaction between a bromide and sodium cyanide
Reactivity of Nitriles
The carbon in a nitrile is electrophilic because a resonance structure can be drawn which places a positive charge on it. Because of this the triple bond of a nitrile accepts a nucleophile in a manner similar to a carbonyl.
Hydrolysis of Nitriles
Nitriles can be converted to carboxylic acid with heating in sulfuric acid. During the reaction an amide intermediate is formed.
Reduction of Nitriles
Nitriles can be converted to 1° amines by reaction with LiAlH4. During this reaction the hydride nucleophile attacks the electrophilic carbon in the nitrile to form an imine anion. Once stabilized by a Lewis acid-base complexation the imine salt can accept a second hydride to form a dianion. The dianion can then be converted to an amine by addition of water.
Going from reactants to products simplified
1) Nucleophilic Attack by the Hydride
2) Second nucleophilic attack by the hydride.
3) Protonation by addition of water to give an amine
Addition of Grignard Reagents
Grignard reagents can attack the electophillic carbon in a nitrile to form an imine salt. This salt can then be hydrolyzed to become a ketone.
1) Nucleophilic Attack by the Grignard Reagent
4) Nucleophilic attack by water
5) Proton Transfer
6) Leaving group removal
Prof. Steven Farmer (Sonoma State University)