The product of above reaction is: $CH\equiv CH+H_{2}O\xrightarrow[333K]{Hg^{2+}/H^{+}}$

Question

Accepted Answer

The reaction given is the hydration of acetylene ($CH\equiv CH$) in the presence of mercuric ion ($Hg^{2+}$) and an acidic medium ($H^{+}$) at 333 K. This reaction is a classic example of the addition of water to an alkyne, specifically acetylene, to form an aldehyde.

1. **Explanation for Option 4 ($CH_{3}-CHO$):**
   - The reaction involves the addition of water to acetylene. In the presence of $Hg^{2+}$ and $H^{+}$, acetylene undergoes hydration to form an enol intermediate. This enol is unstable and tautomerizes to form an aldehyde.
   - The enol formed from acetylene is vinyl alcohol ($CH_2=CHOH$), which quickly tautomerizes to acetaldehyde ($CH_3CHO$). This tautomerization is driven by the stability of the carbonyl group in the aldehyde.
   - Therefore, the product of the reaction is acetaldehyde, which corresponds to Option 4 ($CH_{3}-CHO$).

2. **Explanation for why other options are incorrect:**
   - **Option 1 ($CH_{3}CH_{2}OH$):** This option suggests the formation of ethanol. However, the hydration of acetylene does not lead to the formation of an alcohol directly. The reaction conditions favor the formation of an aldehyde, not an alcohol.
   - **Option 2 (HCHO):** This option suggests the formation of formaldehyde. Formaldehyde is not formed in this reaction because the hydration of acetylene leads to the formation of a two-carbon compound, acetaldehyde, not a one-carbon compound like formaldehyde.
   - **Option 3 ($CH_{3}-C(=O)-CH_3$):** This option suggests the formation of acetone. Acetone is a ketone, and the hydration of acetylene does not produce a ketone. The reaction specifically leads to the formation of an aldehyde, acetaldehyde, due to the nature of the tautomerization process.

In conclusion, the correct product of the reaction is acetaldehyde ($CH_{3}-CHO$), which is why Option 4 is the correct answer.