When excess of chlorine is passed through acetic acid in presence of red phosphorus, it forms

Options

A. Acetyl chloride
B. Chloral
C. Trichloroacetic acid
D. Methyl chloride

Answer

To solve the question regarding the reaction of acetic acid with excess chlorine in the presence of red phosphorus, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are acetic acid (CH₃COOH) and chlorine (Cl₂), with red phosphorus (P) acting as a catalyst.

2. **Understand the Reaction Type**:
- This reaction is an example of alpha halogenation, specifically the Hell-Walden-Zelinski reaction, which involves the substitution of alpha-hydrogens in carboxylic acids by halogens.

3. **Recognize the Role of Red Phosphorus**:
- Red phosphorus facilitates the reaction by generating reactive halogen species that can replace the alpha-hydrogens.

4. **Determine the Alpha-Hydrogens**:
- In acetic acid, the alpha-hydrogens are the hydrogen atoms attached to the carbon adjacent to the carboxylic acid group (COOH). In CH₃COOH, there are three alpha-hydrogens.

5. **Reaction with Excess Chlorine**:
- When acetic acid is treated with excess chlorine, all three alpha-hydrogens will be replaced by chlorine atoms.

6. **Write the Product**:
- The product formed after the substitution of all three alpha-hydrogens with chlorine will be trichloroacetic acid (CCl₃COOH).

7. **Final Product Identification**:
- The final product is identified as trichloroacetic acid, which is characterized by having three chlorine atoms attached to the alpha position of the acetic acid structure.

### Final Answer:
The product formed when excess chlorine is passed through acetic acid in the presence of red phosphorus is **trichloroacetic acid (CCl₃COOH)**.

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