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 $S _N 1$
(2013 Main)
(b) Tertiary alcohol by $S _N 1$
(c) Secondary alcohol by $S _N 2$
(d) Tertiary alcohol by $S _N 2$
Show Answer
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.
