Question

The reagents/ chemicals X and Y that convert cyanobenzene to Schiff's base are

• A. DIBAL-H, H\(_2\)O, NH\(_2\)OH
• B. DIBAL-H, H\(_2\)O, Aniline
• C. LAH, CH\(_3\)OH
• D. H\(_3\)O\(^+\), Aniline

Hint:

DIBAL-H is a useful reagent for reducing nitriles to imines.

Answer 1

The Correct Option is B

A Schiff base is a compound with the general structure R\(_1\)R\(_2\)C=NR\(_3\), where R\(_3\) is an aryl or alkyl group, but not a hydrogen. They are formed by the reaction of a primary amine with an aldehyde or ketone. Cyanobenzene has the structure \[\text{C}_6 \text{H}_5 \text{C} \equiv \text{N}.\]Diisobutylaluminium hydride (DIBAL-H) is a reducing agent. It will reduce the nitrile group (-C\( \equiv \)N) in cyanobenzene to an imine group (-CH=NH): \[\text{C}_6 \text{H}_5 \text{C} \equiv \text{N} \xrightarrow{\text{DIBAL-H, H}_2 \text{O}} \text{C}_6 \text{H}_5 \text{CH} = \text{NH}.\]Then, the imine will react with aniline (C\(_6\)H\(_5\)NH\(_2\)) to form a Schiff base: \[\text{C}_6 \text{H}_5 \text{CH} = \text{NH} + \text{C}_6 \text{H}_5 \text{NH}_2 \rightarrow \text{C}_6 \text{H}_5 \text{CH} = \text{N} \text{C}_6 \text{H}_5 + \text{NH}_3.\]