HVZ reaction is specific for -

Options

A. Replacement of `beta-`hydrogens
B. Replacement of `alpha-`hydrogens
C. Replaceent of `beta-`carbons
D. Replacement of `alpha-`carbons

Answer

**Step-by-Step Solution:**

1. **Understanding the HVZ Reaction**: The Hell-Wolhard-Zelinsky (HVZ) reaction is a chemical reaction that involves the halogenation of carboxylic acids. It specifically targets the alpha-hydrogen of the carboxylic acid.

2. **Reactants Involved**: In the HVZ reaction, we start with a carboxylic acid (RCH2COOH) and halogens (like Cl2 or Br2) in the presence of red phosphorus.

3. **Mechanism of the Reaction**:
- The reaction proceeds by the halogenation of the alpha position (the carbon adjacent to the carboxylic acid group).
- The red phosphorus acts as a reducing agent, facilitating the halogenation process.

4. **Formation of Alpha Halo Carboxylic Acids**: The result of the HVZ reaction is the formation of alpha halo carboxylic acids (RCHXCOOH), where X is the halogen (Cl or Br). The alpha-hydrogen is replaced by a halogen atom.

5. **Example**: For example, if we take butanoic acid (CH3CH2COOH):
- First, with Br2 and red phosphorus, the alpha-hydrogen is replaced, resulting in CH3CHBrCOOH (2-bromobutanoic acid).
- If the reaction is repeated, we can replace another alpha-hydrogen, yielding CH3CBr2COOH (2,2-dibromobutanoic acid).

6. **Conclusion**: The HVZ reaction is specific for carboxylic acids, particularly focusing on the halogenation of the alpha-hydrogen to form alpha halo carboxylic acids.

**Final Answer**: The HVZ reaction is specific for carboxylic acids.

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