Addition of Grignard Reagents to Nitriles

The imine formed by nucleophilic addition of the Grignard reagent to the nitrile is normally not isolated but is hydrolyzed directly to a ketone. The overall sequence is used as a means of preparing ketones. 

Write an equation showing how you could prepare ethyl phenyl ketone from propanenitrile and a Grignard reagent. What is the structure of the imine intermediate  

Organolithium reagents react in the same way and are often used instead of Grignard reagents. 

Nitriles are readily identified by absorption due to —C N stretching in the 2210-2260 cm region. 

NMR Chemical-shift differences in their H NMR spectra aid the stracture determination of esters. Consider the two isomeric esters ethyl acetate and methyl propanoate. 

The carbon-nitrogen triple bond of nitriles is much less reactive toward nucleophilic addition than is the carbon-oxygen double bond of aldehydes and ketones. Strongly basic nucleophiles such as Grignard reagents, however, do react with nitriles in a reaction that is of synthetic value  

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The Addition of Grignard Reagents to Nitriles and Isocyanates Alkyl,oxo-de-nitrilo-tersubstitution (Overall transformation)... 

Ketones can be prepared by addition of Grignard reagents to nitriles, followed by hydrolysis of the initially formed imine anion. Many ketones have been made in this manner, though when both R groups are alkyl, yields are not high. Yields... 

You have, in fact, already met an imine hydrolysis at the end of Chapter 12 we talked about the addition of Grignard reagents to nitriles. The product is an imine that hydrolyses in acid solution to ketone plus ammonia. 

Addition of Grignard reagents to nitriles gives ketones, after work-up. 

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