Test Index

MHTCET 10 May 2024 Shift 2 Paper

Question : 84 of 150

Marks: +1, -0

Which of the following is Mendius reduction?

$\mathrm{R}-\mathrm{CONH}_{2} \xrightarrow[\Delta]{B_{2}, \mathrm{KOH}_{(\mathrm{aq})}} \mathrm{R}-\mathrm{NH}_{2}$
$\mathrm{R}-\mathrm{NH}_{2} \xrightarrow{\mathrm{RX} \text { (excess) }} \mathrm{R}_{4} \mathrm{NX}$
$\mathrm{R}_{4} \mathrm{NX} \xrightarrow[\Delta]{\text { Moist } \quad \mathrm{Ag}_{2} \mathrm{O}}$ Alkene $+\mathrm{R}_{3} \quad \mathrm{~N}$
$\mathrm{R}-\mathrm{CN} \underset{\text { or } \quad \mathrm{LiAlL}_{4}}{\mathrm{Na} / 2 C_{2} \mathrm{OH}} \mathrm{R}-\mathrm{CH}_{2} \mathrm{NH}_{2}$

Validate

Solution:

Concept:

Mendius reduction is the conversion of a nitrile (

\mathrm{R{-}CN}

) into a primary amine using a reducing agent.

Explanation:

In Mendius reduction, the

- \mathrm{C}{\equiv}\mathrm{N}

group is reduced to

- \mathrm{CH}_{2}\mathrm{NH}_{2}

The commonly used reagents are sodium in ethanol (

\mathrm{Na}/C_{2}\mathrm{H}_{5}\mathrm{OH}

) or lithium aluminium hydride (

\mathrm{LiAlH}_{4}

This reaction adds four hydrogen atoms across the triple bond of the nitrile.

The balanced transformation is:

\mathrm{R{-}CN} + 4[\mathrm{H}] \xrightarrow[\text{Na/C}_2\mathrm{H}_5\mathrm{OH}\ \text{or}\ \mathrm{LiAlH}_4]{} \mathrm{R{-}CH}_2\mathrm{NH}_2

Among the given options, only option D shows this nitrile-to-amine reduction.

Options A, B, and C describe Hoffmann bromamide degradation, exhaustive alkylation, and Hofmann elimination respectively, which are not Mendius reduction.

Answer:

Option D is the correct answer.

Go to Question:

Prev Question

Next Question