Alcohols and Ethers - Result Question 10
13. 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) Secondary alcohol by $S _N 1$
(b) Tertiary alcohol by $S _N 1$
(c) Secondary alcohol by $S _N 2$
(d) Tertiary alcohol by $S _N 2$
(2013 Main)
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Answer:
Correct Answer: 13. (b)
Solution:
- 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 $3^{\circ}$ $R$ - $OH$ forms $3^{\circ}$ carbocation (most stable), hence it will react fastest.
BETA
