Exams › JEE Advanced › Chemistry
Consider the following sequence of reactions starting from compound X (molecular formula C6H10O): X + (i) CH3MgBr, (ii) H2O -> Q Q + 20% H3PO4, 360 K -> R (major product) Q + conc. HCl -> S (major product) R + HBr / benzoyl peroxide, heat -> U (major product) R + (i) H2/Ni, (ii) Br2/hv -> T (major product) Identify the correct statement(s).
- Q is an alcohol
- S is the major product of dehydration of Q with conc. HCl
- R is an alkene
- U is the major product of anti-Markovnikov addition of HBr to R
Correct answer: Q is an alcohol
Solution
X is cyclohexanone; Grignard addition gives 1-methylcyclohexanol (Q, a tertiary alcohol). H3PO4/360 K dehydrates Q to 1-methylcyclohexene (R, an alkene). Conc. HCl converts Q to 1-chloro-1-methylcyclohexane (S) via SN1 — not dehydration — so option B is wrong. HBr/peroxide on R gives anti-Markovnikov product U (correct, D). Q being an alcohol (A) and R being an alkene (C) and U being anti-Markovnikov (D) are all correct; B is incorrect because S is a substitution product, not a dehydration product.
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