JEE PYQ: Hydrocarbons Question 32
Question 32 - 2019 (12 Jan Shift 1)
The major product of the following reaction is:
$\text{CH}_3\text{CH}_2-\text{C}(-\text{H})(-\text{Br})-\text{CH}(-\text{H})(-\text{Br}) \xrightarrow{(i)\ \text{KOH (alc.)}}$ $\xrightarrow{(ii)\ \text{NaNH}_2/\text{in liq. NH}_3}$
(1) $\text{CH}_3\text{CH}=\text{C}=\text{CH}_2$ (allene)
(2) $\text{CH}_3\text{CH}_2\text{CH}(-\text{NH}_2)-\text{CH}_2(-\text{NH}_2)$
(3) $\text{CH}_3\text{CH}=\text{CHCH}_2\text{NH}_2$
(4) $\text{CH}_3\text{CH}_2\text{C}\equiv\text{CH}$ (terminal alkyne)
Show Answer
Answer: (4)
Solution
$\text{CH}_3\text{CH}_2-\text{CHBr}-\text{CH}_2\text{Br} \xrightarrow{(i)\ \text{KOH alc.}} \text{CH}_3\text{CH}_2-\text{CH}=\text{CHBr}$ (vinyl bromide, dehydrohalogenation) $\xrightarrow{(ii)\ \text{NaNH}_2/\text{liq. NH}_3} \text{CH}_3\text{CH}_2-\text{C}\equiv\text{CH}$ (terminal alkyne, second dehydrohalogenation).
BETA
