Question

Gem dihalide on hydrolysis gives:
a.) vicinal diol
b.) geminal diol
c.) carbonyl compound
d.) carboxylic acid

Answer 1

Hint: Geminal dihalide hydrolysis is an organic reaction in which the gem-halide reacts with water or undergo hydrolysis in an alkaline medium. There are two products which can be formed.

Complete step by step solution: Geminal dihalides are dihalogen compounds in which both the halogen atoms are attached to the same carbon atom.
For example, Ethylidene dichloride

Suppose, there is a geminal dihalide $$C{H}_{3}CH{(Cl)}_2$$ is present, the hydrolysis of gem-halides takes place in alkaline medium. So, we will hydrolyse it in the presence of aqueous NaOH/KOH.
On hydrolysis, both of the chlorine group will be replaced by hydroxyl group (OH),

$$C{H}_{3}CH{(OH)}_2$$ will be formed.

As both the hydroxyl groups are present on the same carbon, this compound is not stable. So, water acts as a leaving group i.e. $$H_{2}O$$ will be removed.
Thus, forming an aldehyde group $$C{H}_{3}CHO$$, this compound is called acetaldehyde. But this is the case when gem-dihalide is present at the terminal position.
$$C{H}_{3}CH{(Cl)}_2\underset{aq}{\overset{KOH}{\to }}C{H}_{3}CH{(OH)}_2\to C{H}_{3}COH+H_{2}O$$
Now, let's take a compound $$C{H}_{3}C{(Cl)}_{2}C{H}_3$$, on hydrolysis the chlorine groups will be replaced by hydroxyl groups, $$C{H}_{3}C{(OH)}_{2}C{H}_3$$will be obtained.
Similarly, as the previous example, this compound will also be unstable, thus water will act as a leaving group.
Thus, forming a keto or carbonyl group $$C{H}_{3}COC{H}_3$$, this compound is called acetone.

$$C{H}_{3}C{(Cl)}_{2}C{H}_3\underset{aq}{\overset{KOH}{\to }}C{H}_{3}COC{H}_3+2KCl+H_{2}O$$

Therefore, from the above statements we can conclude that the correct option is (c).

Note: Geminal dihalides are prepared by reacting a non-enolizable aldehyde and/or ketone with phosgene or thionyl chloride in the presence of an organic-phosphorus compound.