JEE Advanced 2015 · Paper 2 · Chemistry Q38

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ChemistryMultiple correct+4 / -2Question 38 of 60

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In the following reactions
$\ce{C8H6}\xrightarrow[\ce{H2}]{\text{Pd-BaSO}_4}\ce{C8H8}\xrightarrow[\text{ii. }\ce{H2O2},\ \ce{NaOH},\ \ce{H2O}]{\text{i. }\ce{B2H6}}\mathbf X$
$\ce{C8H6}\xrightarrow{\ce{H2O},\ \ce{HgSO4},\ \ce{H2SO4}}\ce{C8H8O}\xrightarrow[\text{ii. }\ce{H+},\text{ heat}]{\text{i. EtMgBr, }\ce{H2O}}\mathbf Y$

The major compound Y is

Answer and worked solution

Official answer: D

HgSO₄/H₂SO₄ hydration of phenylacetylene gives acetophenone (C₈H₈O).
EtMgBr gives $\ce{PhC(OH)(CH3)CH2CH3}$ .
H⁺, heat dehydrates it to the most substituted, conjugated alkene: $\ce{PhC(CH3)=CHCH3}$ .

(D)

Topics:Alkynes Nucleophilic addition Elimination reactions

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JEE Advanced 2015 · Paper 2, Chemistry question 38