Which one of the following on reduction with lithium aluminium hydride yields a secondary amine?

Which one of the following on reduction with lithium aluminium hydride yields a secondary amine?
  1. Methyl isocyanide
  2. Acetamide
  3. Methyl cyanide
  4. Nitroethane

Solution

Reduction of alkyl isocyanides in presence of $\mathrm{LiAlH}_{4}$ yields secondary amines containing methyl as one of the alkyl group.
$\mathrm{R}-\mathrm{N} \equiv \mathrm{C}+4[\mathrm{H}] \frac{\mathrm{LiAlH}_{4}}{\longrightarrow} \mathrm{R}-\mathrm{NH}-\mathrm{CH}_{3}$
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$ $2^{\circ} \mathrm{amine}$
e.g., $\mathrm{CH}_{3}-\mathrm{N} \geqslant \mathrm{C}+4[\mathrm{H}] \stackrel{\mathrm{LiAlH}_{4}}{\longrightarrow} \mathrm{CH}_{3}-\mathrm{NH}-\mathrm{CH}_{3}$
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$ dimethyl amine
whereas, alkyl cyanides give $1^{\circ}$ amine on reduction. .

Asked in: JEE-TOPICTESTS-CHEMISTRY

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