JEE PYQ: Hydrocarbons Question 25
Question 25 - 2020 (07 Jan Shift 1)
What is the product of following reaction?
Hex-3-ynal $\xrightarrow{(i)\ \text{NaBH}_4}$ $\xrightarrow{(ii)\ \text{PBr}_3}$ $\xrightarrow{(iii)\ \text{Mg/ether}}$ $\xrightarrow{(iv)\ \text{CO}_2/\text{H}_3\text{O}^+}$
(1) A carboxylic acid with intact triple bond (long chain)
(2) A carboxylic acid with reduced triple bond
(3) A carboxylic acid with triple bond preserved
(4) A different carboxylic acid
Show Answer
Answer: (4)
Solution
Hex-3-ynal $\xrightarrow{\text{NaBH}_4}$ Hex-3-yn-1-ol (aldehyde reduced to alcohol, triple bond preserved) $\xrightarrow{\text{PBr}_3}$ 1-bromohex-3-yne $\xrightarrow{\text{Mg/ether}}$ Grignard reagent $\xrightarrow{\text{CO}_2/\text{H}_3\text{O}^+}$ Hept-4-ynoic acid (carboxylic acid with triple bond intact).
BETA
