Question

Schiff’s base is formed by the reaction of aldehyde with:

• A. Ammonia
• B. Amines
• C. Hydrazine
• D. Phenyl hydrazine

Hint:

For Schiff’s base formation:

- Requires aldehyde/ketone and primary amine.

- Produces an imine (\({C=N}\)).

- Differentiate from hydrazones formed with hydrazine derivatives.

Answer 1

The Correct Option is B

A Schiff’s base, or imine, is characterized by a carbon-nitrogen double bond (\({C=N}\)) formed through a condensation reaction. We need to identify the correct reagent that reacts with an aldehyde to produce this compound.
Step 1: Reaction mechanism 
An aldehyde (\({RCHO}\)) reacts with a primary amine (\({R'NH_2}\)) to form a Schiff’s base: \[ {RCHO + R'NH_2 -> RCH=NR' + H_2O} \] The amine’s nitrogen attacks the electrophilic carbonyl carbon, followed by dehydration to form the imine. 
Step 2: Analyze options 
- (A) Ammonia: Forms unstable intermediates like aldehyde ammonias, not Schiff’s bases. 
- (B) Amines: Primary amines form Schiff’s bases, correct. 
- (C) Hydrazine: Produces hydrazones (\({RCH=NNH_2}\)), a different compound. 
- (D) Phenyl hydrazine: Forms phenylhydrazones (\({RCH=NNHC6H5}\)), not Schiff’s bases. 
Step 3: Conclusion 
Schiff’s base is formed with primary amines, matching option (B).