Question

Which chloride is the most reactive towards aqueous NaOH?
A. Methyl chloride
B. Chlorobenzene
C. Vinyl chloride
D. Benzyl chloride

Answer 1

Hint: Carbon Chlorides react with sodium hydroxide to form alcohols and sodium chloride. For a chloride to be more reactive towards aqueous NaOH, the bond between carbon and chlorine must be weak. Find the chloride with the weakest carbon-chlorine bond out of the given chlorides and that will be the most reactive one towards NaOH.

Complete step by step answer:
We are given to find the most reactive chloride towards aqueous NaOH from among the given options.
The first one is Methyl chloride. The molecular formula of methyl chloride is $C{H_3}Cl$. Methyl chloride reacts with sodium hydroxide to form Methyl alcohol and Sodium chloride. Methyl chloride is also known as chloromethane.
$C{H_3} - Cl + NaOH \to C{H_3} - OH + NaCl$
The second one is the Chlorobenzene. The molecular formula of Chlorobenzene is ${C_6}{H_5}Cl$. Chlorobenzene reacts with Sodium hydroxide (at 623 K temperature and 300 atmospheric pressure) to form Sodium phenoxide and hydrochloric acid which on further hydrolysis produces Phenol.
${C_6}{H_5} - Cl + NaOH\xrightarrow[{300atm}]{{623k}}{C_6}{H_5}ONa + HCl\xrightarrow{{{H^ + }}}{C_6}{H_5}OH\left( {Phenol} \right)$
The third one is Vinyl chloride. Vinyl chloride is also known as chloroethene. The molecular formula of vinyl chloride is $C{H_2} = CH - Cl$. Vinyl chloride reacts with sodium hydroxide to form Vinyl Alcohol and Sodium chloride.
$C{H_2} = CH - Cl + NaOH \to C{H_2} = CH - OH + NaCl$
The fourth one is Benzyl chloride. Benzyl chloride reacts with sodium hydroxide on hydrolysis gives benzyl alcohol and Sodium chloride. This reaction follows the ${S_N}2$ mechanism.
${C_6}{H_5} - C{H_2} - Cl + NaOH\xrightarrow{{{H^ + }}}{C_6}{H_5} - C{H_2} - OH + NaCl$
In the above four chlorides, the bond present between carbon and chlorine is the weakest in methyl chloride as it readily reacts with sodium hydroxide and the reaction is called nucleophilic substitution reaction where hydroxyl ion is replaced by chloride ion.

The correct option is Option A.

Note:
Alkyl chlorides are different from benzyl chlorides. The C-Cl bond in alkyl chlorides is very weak compared to C-Cl bonds in benzene chlorides. Chlorobenzene is not the same as benzyl chloride as the difference between them is the functional group attached to benzene.
Here, the substituent is the carbon atom.