Question

Explain the products observed in the following reaction of an alcohol with the Lucas reagent.

Short answer

Lucas reagent differentiates the “primary, secondary and tertiary” alcohol present in any chemical sample.

Chemically Lucas reagent is the mixture of concentrated HCl andZnCl₂.

Step-by-step solution

Step 1: Lucas Reagent

Lucas reagent differentiates the “primary, secondary and tertiary” alcohol present in any chemical sample.

Chemically Lucas reagent is the mixture of concentrated HCl andZnCl₂.

Reaction of alcohol with the Lucas reagent

(1R,2R)-1,2-dimethyl cyclohexanol When reacted with Lucas reagent protonation of (1R,2R)-1,2-dimethyl cyclohexanol happen which convert hydroxy group to good leaving group water

Removal of water as an excellent leaving group leads to planar tertiary carbocation formation. The upcoming nucleophile (Cl^- ) can approach from both top and bottom, giving cis (1R, 2R) 1-chloro-1,2-dimethylcyclohexane and trans (1S,1R)-1-chloro-1,2-dimethylcyclohexane isomers as products.

Reaction of alcohol with Lucas reagent