See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Concept: The transformation converts 1-(hydroxymethyl)cyclohexan-1-ol (a 1,2-diol equivalent on a tertiary carbon bearing a primary hydroxymethyl group) into cyclohexanol. This requires removal of the -CH2OH group and retention of the ring OH. Step 1 - Identify the substrate: The starting material is 1-(hydroxymexthyl)cyclohexan-1-ol, which has a tertiary OH on the cyclohexane ring and a primary -CH2OH group on the same carbon. This is a 1,2-diol (vicinal diol) if we consider the two carbons: C1 of the ring (bearing OH) and the exocyclic CH2 (bearing OH). Step 2 - Apply HIO4 (periodic acid): HIO4 cleaves vicinal diols (1,2-diols) oxidatively. When applied to 1-(hydroxymethyl)cyclohexan-1-ol, the C1-C(exocyclic) bond is cleaved. The tertiary carbon bearing OH becomes a ketone (cyclohexanone), and the -CH2OH becomes formaldehyde (HCHO). Step 3 - Apply LiAlH4: LiAlH4 is a strong reducing agent that reduces ketones to secondary alcohols. Cyclohexanone is reduced to cyclohexanol. Step 4 - Overall sequence: HIO4 cleaves the diol to give cyclohexanone + HCHO, then LiAlH4 reduces cyclohexanone to cyclohexanol. This matches option (b). Why other options fail: - Option (a): H+/delta alone causes dehydration, and Zn(Hg)/HCl is Clemmensen reduction (removes C=O completely to CH2, not useful here for making cyclohexanol from this substrate via this pathway). - Option (c): HIO4 gives cyclohexanone, then H+/delta would cause dehydration or other acid-catalyzed reactions, not reduction to cyclohexanol. - Option (d): H+/delta first would dehydrate the diol (elimination), not cleave to give cyclohexanone cleanly; subsequent HIO4 on an alkene gives different products. Therefore, the correct answer is B.