Which of the following will not undergo HVZ reaction ?

Options

A. Propanoic acid
B. Ethanoic acid
C. 2 - Methylpropanoic acid
D. 2, 2 - Demethylpropanoic acid

Explanation

To determine which of the given carboxylic acids will not undergo the HVZ (Hell-Volhard-Zelinski) reaction, we need to analyze the structures of each acid and check for the presence of alpha-hydrogen atoms. The HVZ reaction occurs only in carboxylic acids that contain alpha-hydrogen atoms.

### Step-by-Step Solution:

1. **Identify the Carboxylic Acids**: The question provides us with four carboxylic acids:
- Propanoic acid (C2H5COOH)
- Ethanoic acid (CH3COOH)
- 2-Methyl propanoic acid (C3H7COOH)
- 2,2-Dimethyl propanoic acid (C5H10O2)

2. **Draw the Structures**:
- **Propanoic Acid**: CH3CH2COOH
- It has 2 alpha-hydrogens (from the CH2 group).
- **Ethanoic Acid**: CH3COOH
- It has 3 alpha-hydrogens (from the CH3 group).
- **2-Methyl Propanoic Acid**: (CH3)2CHCOOH
- It has 1 alpha-hydrogen (from the CH group).
- **2,2-Dimethyl Propanoic Acid**: (CH3)3C-COOH
- It has no alpha-hydrogen atoms (the carbon attached to the carboxylic acid has no hydrogen atoms).

3. **Analyze the Presence of Alpha-Hydrogens**:
- Propanoic acid: 2 alpha-hydrogens → Can undergo HVZ reaction.
- Ethanoic acid: 3 alpha-hydrogens → Can undergo HVZ reaction.
- 2-Methyl propanoic acid: 1 alpha-hydrogen → Can undergo HVZ reaction.
- 2,2-Dimethyl propanoic acid: 0 alpha-hydrogens → Cannot undergo HVZ reaction.

4. **Conclusion**: Since the HVZ reaction requires the presence of alpha-hydrogen atoms, the carboxylic acid that will not undergo the HVZ reaction is **2,2-Dimethyl Propanoic Acid**.

### Final Answer:
**2,2-Dimethyl Propanoic Acid will not undergo HVZ reaction.**

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