JEE Main2013ChemistryAlcohols Phenols and EthersActual
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:
Options
- ASecondary alcohol by S N 2
- BTertiary alcohol by S N 2
- CSecondary alcohol by S N 1
- DTertiary alcohol by S N 1
Correct answer
D. Tertiary alcohol by S N 1
Step-by-step solution
3° alcohol reacts fastest giving white turbidity immediately on adding Lucas reagent. Reaction takes place through carbocation formation involving S N 1 mechanism. Rate of reaction in this reaction is directly proportional to the stability of the carbocation formed. 3° R-OH(tertiary alcohol) forms 3° carbocation and therefore, the reaction is fastest.