Acid Derivatives

Nitriles to Ketones and Aldehydes

In this conversion series, we mention how nitriles can be converted to ketones and aldehydes. Nitriles are converted to ketones by both Grignard and organolithium reagents:

 

 

The new C-C bonds are formed by nucleophilic addition of the organometallic reagents to the polar C-N triple bond. After protonation of the resulting anion, an imine is formed, which is then hydrolyzed to a ketone.

 

 

Notice that this is different from the Grignard reaction of aldehydes, ketones, esters, and acid chlorides where the major product was an alcohol.

The reason for this difference is that the negatively charged imine cannot go another nucleophilic addition since that would place two negative charges on the nitrogen.

 

The mechanisms of the nitrile reaction with Grignard and organolithium are covered in a separate post. 

 

Nitriles to Aldehydes

Nitriles can be converted to aldehydes by a reduction with DIBAL or hydrolysis using SnCl2 catalyst with HCl (Stephen aldehyde synthesis).

 

 

Notice that the reaction of nitriles with a stronger reducing agent LiAlH4, yields primary amines.

Both of these mechanisms are covered in detail here.

 

 

Organic Chemistry Reaction Maps

Never struggle again to figure out how to convert an alkyl halide to an alcohol, an alkene to an alkyne, a nitrile to a ketone, a ketone to an aldehyde, and more! The comprehensive powerfull Reaction Maps of organic functional group transformations are here!

 

Check Also

 

Share Your Thoughts, Ask that Question!