An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism?

Question

An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism? (A) Tertiary alcohol by SN2 (B) Secondary alcohol by SN1 (C) Tertiary alcohol by SN1 (D) Secondary alcohol by SN2

Tardigrade Admin · Accepted Answer

The reaction of alcohol with Lucas reagent is mostly an S N 1 reaction and the rate of reaction is directly proportional to the stability of carbocation formed in the reaction. Since 3° R - OH forms 3° carbocation (most stable), hence it will react fastest.

Q. An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism?

Tertiary alcohol by $S_{N} 2$

Secondary alcohol by $S_{N} 1$

Tertiary alcohol by $S_{N} 1$

Secondary alcohol by $S_{N} 2$

The reaction of alcohol with Lucas reagent is mostly an $S_{N} 1$ reaction and the rate of reaction is directly proportional to the stability of carbocation formed in the reaction. Since $3^{\circ} R - O H$ forms $3^{\circ}$ carbocation (most stable), hence it will react fastest.

Q. An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism?

Tertiary alcohol by SN​2

Secondary alcohol by SN​1

Tertiary alcohol by SN​1

Secondary alcohol by SN​2

The reaction of alcohol with Lucas reagent is mostly an SN​1 reaction and the rate of reaction is directly proportional to the stability of carbocation formed in the reaction. Since 3∘R−OH forms 3∘ carbocation (most stable), hence it will react fastest.

Tertiary alcohol by $S_{N} 2$

Secondary alcohol by $S_{N} 1$

Tertiary alcohol by $S_{N} 1$

Secondary alcohol by $S_{N} 2$

The reaction of alcohol with Lucas reagent is mostly an $S_{N} 1$ reaction and the rate of reaction is directly proportional to the stability of carbocation formed in the reaction. Since $3^{\circ} R - O H$ forms $3^{\circ}$ carbocation (most stable), hence it will react fastest.