Question

Write the main product formed when propanal reacts with the following reagents: 
H₂N- NH₂  followed by heating with KOH in ethylene glycol.

Answer 1

\[\ce{CH3CH2CHO + H2N - NH2 -> CH3CH2CH = N - NH2 + H2O}\]

This is a nucleophilic addition-elimination process where the carbonyl group (C = O) is replaced with a hydrazone group \[\ce{(C = N - NH2)}\].

The hydrazone is then heated with KOH in ethylene glycol, a strong base under high-temperature conditions. This leads to the loss of nitrogen gas (N₂) and the reduction of the carbon–nitrogen double bond to a C–H bond.

\[\ce{CH3CH2CH = N - NH2 \overset{KOH/ethylene glycol,Δ}{->} CH3CH2CH3 + N2 ↑}\]