Aug 12, 2015

Vinyl chloride is hydrolyzed more slowly than ethyl chloride because the $\text{C-Cl}$ bond in vinyl chloride has some double bond character.

#### Explanation:

There are two reasons for the slow hydrolysis of vinyl chloride.

(a) The carbon atom in vinyl chloride is ${\text{sp}}^{2}$ hybridized.

The $\text{C-Cl}$ bond contains more s character from the $\text{C}$ atom, so the bond is "tighter" and more difficult to break.

(b) The $\text{C-Cl}$ bond in vinyl chloride has some double bond character.

The second structure is a minor contributor but, to the extent that it occurs, it gives some double bond character to the $\text{C-Cl}$ bond.
In ethyl chloride the $\text{C-Cl}$ bond is a pure single bond.