Question

The correct set of reagents which convert acetylene to but-$2$-enal are

• A. $H _{2} SO _{4}, NaOH$
• B. $H _{2} O / Hg ^{2+} / H ^{+}$, dil $. NaOH$
• C. $H _{2} O / H ^{+}$, conc $NaOH$
• D. $H _{2} O , KMnO _{4} OH ^{-}$

Answer 1

Answer: (B)

Acetylene is $(H C \equiv C H)$, using $H_{2} O / H g^{2+} / H^{+}$dil. $NaOH$, we get but- $2$ -enal as follows.
$H _{3} C - HC = CH \rightarrow CHO$
$H C \equiv C H \xrightarrow {H _{2} O / Hg ^{2+} / H ^{+}, \text{dil}. NaOH}H _{3} C \rightarrow \underset{\text{but-2-enal
(Product)}}{HC = CH \rightarrow CHO}$