Question

$R-OH+HX\to R-X+H_{2}O$ In the above reaction, the reactivity of different alcohols is

• A. Tertiary > Secondary > Primary
• B. Tertiary < Secondary < Primary
• C. Tertiary < Secondary > Primary
• D. Secondary < Primary < Tertiary

Answer 1

The correct option is A Tertiary > Secondary > Primary

$R-OH+HX\to R-X+H_{2}O$
When alcohols react with halogen acids, alkyl halides are formed. Generally, reaction takes place via $S{N}_1$ mechanism.
In the first step protonation of alcohol takes place. In the second step carbocation is formed. In the third step attack of nucleophile occurs.

As we know tertiary carbocation is the most stable followed by secondary and primary carbocation, reactivity order will be in the order tertiary > secondary > primary. Hence, option (a) is correct.