Question
An unknown alochol is treated with the "Lucas reagent" to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism :
BITSAT
Chemistry
Alcohols Phenols and Ethers
2024
BITSAT 2024 (Memory Based Paper 1)
BITSAT Chemistry Question (2024) — Solution
Options
- A. secondary alcohol by S _ N 1
- B. tertiary alcohol by S _ N 1
- C. secondary alcohol by S _ N 2
- D. tertiary alcohol by S _ N 2
Answer
B. tertiary alcohol by S _ N 1
Step-by-step solution
The reaction of alcohol with Lucas reagent is mostly an S _ N 1 mechanism reaction and the rate of reaction is directly proportional to the carbocation stability formed in the reaction, hence tertiary alcohol will react fastest.
Related: Chemistry — Alcohols Phenols and Ethers · All PYQ Banks