JEE Main 2022 · 25 Jun · Shift 1 · Chemistry Q78

← JEE Main 2022 · 25 Jun · Shift 1

ChemistrySingle correct+4 / -1Question 78 of 90

The reaction of $\mathrm{R\text{-}\overset{\displaystyle O}{\overset{\|}{C}}\text{-}NH_2}$ with bromine and KOH gives $\mathrm{RNH_2}$ as the end product. Which one of the following is the intermediate product formed in this reaction ?

\mathrm{R\text{-}CO\text{-}NH\text{-}Br}

\mathrm{R\text{-}NH\text{-}Br}

\mathrm{R\text{-}N=C=O}

\mathrm{R\text{-}CO\text{-}NBr_2}

Answer and worked solution

Official answer: C

Hofmann bromamide reaction. $\mathrm{RCONH_2\rightarrow RCONHBr\rightarrow}$ (loss of HBr, migration of R to N) $\mathrm{R\text{-}N=C=O}$ , which hydrolyses to $\mathrm{RNH_2+CO_2}$ . Among the intermediates the isocyanate is the key one asked for.

(C)

Topics:Amines Acid derivatives

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JEE Main 2022 · 25 Jun · Shift 1, Chemistry question 78