Which of the following statements is not correct ?

Options

A. `2`-chloroethanol is more acidic than ethanol
B. Sodium metal may be used to remove the last traces of `H_(2)O` from benzene as well as from ethanol.
C. Pentan-`3-ol` reacts with `HBr` to give a mixture of `3-` and `2`-bromopentanes. The exact composition of the mixture depends upon whether gaseous or aqueous `HBr` is used.
D. The same mixture of `2`-chloropentane `(A)` and `3`-Chloropentane `(B)` is obtained when either `2-` or `3`-chloropentane is in contact with `ZnCl_(2)` dissolved in conc.`HCl`.

Answer

B

Explanation

`Na` metal may be used to remove the last traces of `H_(2)O` from `C_(6)H_(6)` but from `C_(2)H_(5)OH` because `C_(2)H_(5)OH` is acidic enough to react with `Na` while benzenes is inert :
`2C_(2)H_(5)OH + 2Na rarr 2 C_(2)H_(5)overset(-)ONa^(+) + H_(2)`
(1) The electron withdrawing `Cl` declocalozes the negative charge of `Cl larr CH_(2)CH_(2) larr O^(-)` by induction making it (more stable) and hence a weaker base than `CH_(3)CH_(2)O^(-)`. Thus , 2-chloroethanol is more acidic
(3) Pentan -`3-ol(a 2^(@)ROH)` can undergo both `S_(N)1` and `S_(N)2` nucleophilic substitution . `3`-Bromopentane results from `S_(N)2` attack by `Br^(-)` on the `2^(@)C`:

The `S_(N)1` pathway leaves a `2^(@)C^(+)` that also gives `3`-bromopentane :
`CH_(3)CH_(2)underset(OH)underset(|)(CH)CH_(2)CH_(3) underset((ii)-H_(2)O) overset((i)H^(+)) rarr CH_(3)CH_(2)overset(+)underset(Br)underset(darr)underset(CH_(3)CH_(2)CHCH_(2)CH_(3))underset(darr Br^(-))((CH)CH_(2)CH_(3))`
But , in addition , the `2^(@)C^(+)` undergoes a hydride `( :H^(-))` shift to give some `2`-bromopentane.

In gaseous `HBr` , carbocation may not form.
(4) `ZnCl_(2)` is a Lewis acid that enhances formation carbocations from `RX`:

`underset(2-"chloropentane")(2CH_(3)underset(CI)underset(|)(CH)CH_(2)CH_(2)CH_(3))overset(ZnCI_(2))hArr 2CH_(3)overset(+)(CH)CH_(2)CH_(2)CH_(3)C^(2)R^(+)`
`underset(3-"chloropentane")(2CH_(3)CH_(2)underset(CI)underset(|)(CH)CH_(2)CH_(3))overset(ZnCI_(2))hArr 2CH_(3)CH_(2)overset(+)CH_(2)CH_(3)C^(3)R^(+)`
The `C^(2)R^(+)` from `2`-chloropentane is in rapid equilibrium with the `C^(3)R^(+)` from `3`-chloropentane , via hydride shift. Thus , the same equilibrium mixture results from either isomeric chloride when the mixture of carbocations accepts a `Cl^(-)` from `ZnCl_(4)^(2-)` :