Question

\(X\) is the product obtained by hydrolysis of prop-1-yne in the presence of mercuric sulphate under dilute acidic medium. \(Y\) is obtained by the reaction of ethanenitrile with methyl magnesium bromide in dry ether followed by hydrolysis. IUPAC name of product obtained from \(X\) and \(Y\) in presence of barium hydroxide followed by heating is :

• A. 2-Methylpent-4-en-3-one
• B. 4-Methylpent-3-en-2-one
• C. 4-Methylpent-1-ene
• D. 2-Methylpent-3-one

Answer 1

The Correct Option is B

Concept: Terminal alkynes undergo hydration (HgSO\(_4\)/H\(_2\)SO\(_4\)) giving ketones via keto–enol tautomerism. Step 1: {Find product \(X\)} \[ CH_3-C\equiv CH \] Hydration gives: \[ CH_3COCH_3 \] Thus \(X =\) acetone (propanone). Step 2: {Find product \(Y\)} \[ CH_3CN + CH_3MgBr \] After hydrolysis: \[ CH_3COCH_3 \] Thus \(Y =\) acetone. Step 3: {Reaction between \(X\) and \(Y\)} Two acetone molecules undergo aldol condensation in presence of \(Ba(OH)_2\). Intermediate: \[ \text{diacetone alcohol} \] On heating (dehydration): \[ \text{mesityl oxide} \] IUPAC name: \[ 4\text{-Methylpent-3-en-2-one} \]