Grignard reaction workup to form tertiary alcohol

Steps:

• Cyclohexanone reacts with methylmagnesium bromide (Grignard reagent) to form the magnesium alkoxide intermediate.
• The alkoxide requires hydrolysis to protonate and yield 1-methylcyclohexanol.
• Aqueous NaOH provides the water and base for gentle hydrolysis without degrading the alcohol.
• This completes the synthetic route to the tertiary alcohol.

Why A is correct:

• Aqueous NaOH hydrolyzes the MgBr(OR) adduct to ROH + Mg(OH)Br, standard for isolating alcohols from Grignard products.

Why the others are wrong:

• B: Cold dilute KMnO4 performs syn dihydroxylation on alkenes, irrelevant to alkoxide hydrolysis.
• C: Ethanolic NaOH promotes E2 elimination in alkyl halides, not used for Grignard workup.
• D: Hot concentrated KMnO4 causes oxidative cleavage of alkenes or alcohols, destroying the product.

Final answer: A