Fill in the blanks.
In Hell-Volhard-Zelinsky reaction, the carboxylic acids are halogenated at ______ position by using _______ and ______.

Options

A. `alpha`, NaOH, iodine
B. `alpha`, phosphorus, halogen
C. `beta`, phosphorus, `H_(2)O`
D. `beta, PCl_(5),NaOH`

Answer

**Step-by-Step Solution:**

1. **Understanding the Hell-Volhard-Zelinsky Reaction**: This reaction is a method for halogenating carboxylic acids. It specifically involves the introduction of a halogen atom into the molecule.

2. **Identifying the Position of Halogenation**: In the Hell-Volhard-Zelinsky reaction, the halogen is introduced at the alpha position of the carboxylic acid. The alpha position refers to the carbon atom adjacent to the carboxyl group (-COOH).

3. **Identifying the Reagents Used**: The reaction requires specific reagents. The main reagents involved are:
- A phosphorus compound (commonly phosphorus tribromide, PBr3, or phosphorus trichloride, PCl3).
- A halogen (such as bromine or chlorine).

4. **Filling in the Blanks**: Based on the above understanding, we can fill in the blanks:
- The carboxylic acids are halogenated at **alpha** position by using **phosphorus** and **halogen**.

**Final Answer**: In Hell-Volhard-Zelinsky reaction, the carboxylic acids are halogenated at **alpha** position by using **phosphorus** and **halogen**.

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