In the presence of dry HCl gas, `CH_(3)CHO` condenses with `C_(2)H_(5)OH` to give

Options

A. aldol
B. ethyl acetate
C. acetal
D. polymer

Explanation

To solve the problem of what compound is formed when acetaldehyde (CH₃CHO) condenses with ethyl alcohol (C₂H₅OH) in the presence of dry HCl gas, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants are acetaldehyde (CH₃CHO) and ethyl alcohol (C₂H₅OH).

2. **Understand the Reaction Type**: This reaction is an example of acetal formation. Acetals are formed when a carbonyl compound (like an aldehyde) reacts with alcohol in the presence of an acid catalyst.

3. **Protonation of the Carbonyl Group**: In the presence of dry HCl, the carbonyl oxygen of acetaldehyde gets protonated, making the carbonyl carbon more electrophilic. This step can be represented as:
\[ \text{CH}_3\text{CHO} + \text{H}^+ \rightarrow \text{CH}_3\text{C(OH)}^+ \text{H} \]

4. **Nucleophilic Attack by Ethanol**: The ethyl alcohol (C₂H₅OH) acts as a nucleophile and attacks the protonated carbonyl carbon, leading to the formation of a hemiacetal. This can be represented as:
\[ \text{CH}_3\text{C(OH)}^+ \text{H} + \text{C}_2\text{H}_5\text{OH} \rightarrow \text{CH}_3\text{C(OH)(OC}_2\text{H}_5) \]

5. **Proton Transfer**: A proton transfer occurs within the hemiacetal, stabilizing the structure. This results in the formation of a hemiacetal intermediate.

6. **Formation of Acetal**: The hemiacetal can then react with another molecule of ethanol. The alcohol attacks the hemiacetal, leading to the formation of the acetal and the elimination of water:
\[ \text{Hemiacetal} + \text{C}_2\text{H}_5\text{OH} \rightarrow \text{Acetal} + \text{H}_2\text{O} \]

7. **Final Structure of the Acetal**: The final product is diethyl acetal of acetaldehyde, which can be represented as:
\[ \text{CH}_3\text{C(OC}_2\text{H}_5)_2 \]

### Final Answer:
The compound formed is **Diethyl acetal of acetaldehyde** (or simply, **Acetal**).