Primary amine reacts with carbon disulphide and `HgCl_2` to produce alkyl isothiocyanate. This reaction is

Options

A. Carbylamine reaction
B. Hofmann bromide reaction
C. Perkin reaction
D. Hoffman mustard oil reaction

Explanation

To solve the question regarding the reaction of a primary amine with carbon disulfide and HgCl₂ to produce alkyl isothiocyanate, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The primary amine can be represented as RNH₂, where R is an alkyl group.
- Carbon disulfide (CS₂) is the other reactant.

2. **Reaction of Primary Amine with Carbon Disulfide**:
- When the primary amine reacts with carbon disulfide, it forms a compound known as dithiocarbamic acid. The structure of dithiocarbamic acid can be represented as:
\[ R-NH-C(SH)=S \]
- This compound contains both a thiol (-SH) and a dithiocarbonyl (C=S) group.

3. **Reaction with Mercury(II) Chloride (HgCl₂)**:
- The dithiocarbamic acid then reacts with mercury(II) chloride (HgCl₂). This reaction leads to the formation of alkyl isothiocyanate (R-N=C=S) and mercury(I) chloride (Hg₂Cl₂) as a byproduct.
- The reaction can be summarized as:
\[ R-NH-C(SH)=S + HgCl₂ \rightarrow R-N=C=S + Hg₂Cl₂ + HCl \]

4. **Identify the Product**:
- The product formed, alkyl isothiocyanate, is characterized by the isothiocyanate functional group (N=C=S). This compound is known for its strong mustard-like odor, which is why this reaction is associated with the "Hofmann mustard oil reaction".

5. **Conclusion**:
- The reaction of a primary amine with carbon disulfide and HgCl₂ to produce alkyl isothiocyanate is known as the **Hofmann mustard oil reaction**.

### Final Answer:
The reaction is the **Hofmann mustard oil reaction**.

---