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Question
Write the main product formed when propanal reacts with the following reagents:
H2N- NH2 followed by heating with KOH in ethylene glycol.
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Solution
\[\ce{CH3CH2CHO + H2N - NH2 -> CH3CH2CH = N - NH2 + H2O}\]
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.
\[\ce{CH3CH2CH = N - NH2 \overset{KOH/ethylene glycol,Δ}{->} CH3CH2CH3 + N2 ↑}\]
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\ce{(CH3)3C-C-CH3}\\
\phantom{....}||\\
\phantom{....}\ce{O}
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||\\
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| (i) |  |
| (ii) |  |
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