In Gabriel synthesis, halide may be:

Options

A. benzyl halide
B. alkyl halide
C. both (a) and (b)
D. tertiary alkyl halide

Explanation

**Step-by-Step Solution:**

1. **Understanding Gabriel Synthesis**: Gabriel synthesis is a method used to synthesize primary amines. It involves the use of phthalimide as a starting material.

2. **Formation of Potassium Phthalimide**: The process begins with phthalimide reacting with a strong base, typically potassium hydroxide (KOH) in an alcoholic solution. This reaction results in the formation of potassium phthalimide.

3. **Reaction with Alkyl Halide**: The potassium phthalimide then reacts with an alkyl halide. Common alkyl halides used in this reaction include methyl iodide (CH3I) or ethyl bromide (C2H5Br). The halide can be either an alkyl halide or a benzyl halide.

4. **Formation of Primary Amine**: Upon reaction with the alkyl halide, the potassium phthalimide undergoes nucleophilic substitution, leading to the formation of a primary amine. After hydrolysis, the product is a primary amine along with phthalic acid.

5. **Types of Halides**: In Gabriel synthesis, the halides that can be used are:
- **Alkyl Halides**: These include compounds like methyl iodide or ethyl bromide.
- **Benzyl Halides**: These include compounds like benzyl chloride or benzyl bromide.
- **Aryl Halides**: These cannot be used because they do not undergo nucleophilic substitution effectively.

6. **Conclusion**: Therefore, the halides that may be used in Gabriel synthesis are both benzyl halides and alkyl halides.

**Final Answer**: In Gabriel synthesis, the halide may be either a benzyl halide or an alkyl halide.

---