Question

Lucas reagent reacts fastest with

• A. butanol-1
• B. butanol-2
• C. 2-methyl-propanol-2
• D. 2-methyl-propanol-1

Answer 1

Answer: (C)

The order of reactivity with alcohols with lucas reagent is
$3^{\circ }>2^{\circ }>1^{\circ }$
$\therefore$ Lucas reagent reacts fastest with $3^{\circ }$ alcohol.
(a) $\underset{\text{butanol - 1 (1∘ alcohol)}}{C{H}_3-C{H}_2-C{H}_2-C{H}_{2}OH}$
(b) $\underset{\text{butanol-1 (2∘ alcohol)}}{C{H}_3-C{H}_2-\stackrel{\underset{|}{O}H}{C}H-C{H}_3}$
(c) $\underset{\text{2 - methyl 2 - propanol (3∘ alcohol)}}{C{H}_3-\underset{\stackrel{|}{O}H}{\stackrel{\underset{|}{C}{H}_3}{C}}-C{H}_3}$
(d) $\underset{\text{2 - methyl 1- propanol (1∘ alcohol)}}{C{H}_3-\stackrel{\underset{|}{C}{H}_3}{C}H-C{H}_{2}OH}$
$\therefore$ choice (c) is the answer as it is $3^{\circ }$ alcohol and rate of reaction is fastest for $3^{\circ }$ alcohol.