A student wants to identify the tertiary alcohol among four unlabelled samples using $ZnCl X_{2}$ in concentrated $HCl$ (Lucas reagent) at room temperature, where turbidity appearing immediately indicates a tertiary alcohol. Which sample is most likely to turn turbid immediately?

Abutan-1-ol
B2-methylbutan-2-ol
Cpropan-1-ol
D2-methylpropan-1-ol

Answer: B

Chloride replaces the protonated OH by an SN1 route, whose rate depends on carbocation stability. Only the tertiary alcohol, 2-methylbutan-2-ol, forms a tertiary carbocation fast enough to give the insoluble alkyl chloride at once; the three primary alcohols stay clear at room temperature.

Practice Organic Reaction Mechanisms III: Nucleophilic Substitution More on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

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A student wants to identify the tertiary alcohol among four unlabelled samples using ZnClX2​ in concentrated HCl (Lucas reagent) at room temperature, where turbidity appearing immediately indicates a tertiary alcohol. Which sample is most likely to turn turbid immediately?

Answer: B

More questions on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

A student wants to identify the tertiary alcohol among four unlabelled samples using $ZnCl X_{2}$ in concentrated $HCl$ (Lucas reagent) at room temperature, where turbidity appearing immediately indicates a tertiary alcohol. Which sample is most likely to turn turbid immediately?