Amine produced by the Hoffmann degradation of benzamide is

Options

A. Secondary amine
B. Aliphatic amine
C. Tertiary amine
D. Aromatic amine

Answer

To determine the amine produced by the Hoffmann degradation of benzamide, we can follow these steps:

### Step 1: Identify the starting compound
The starting compound is benzamide, which has the structure:
\[ \text{C}_6\text{H}_5\text{C(O)NH}_2 \]
This can be represented as:
\[ \text{Ph-C(=O)-NH}_2 \]
where "Ph" represents the phenyl group (C6H5).

**Hint:** Remember that benzamide is an amide derived from benzoic acid.

### Step 2: Understand the Hoffmann degradation process
In the Hoffmann degradation, benzamide is treated with bromine (Br2) in a basic medium (like NaOH). The first step involves the formation of N-bromo-benzamide.

**Hint:** The reaction occurs in a basic medium, which facilitates the formation of the N-bromo derivative.

### Step 3: Formation of N-bromo-benzamide
The hydroxide ion (OH-) removes the acidic hydrogen from the amide nitrogen, resulting in the formation of an anion:
\[ \text{Ph-C(=O)-NH}^- \]
This anion then reacts with Br2 to form N-bromo-benzamide:
\[ \text{Ph-C(=O)-NBr} \]

**Hint:** The presence of bromine introduces a good leaving group (Br) that will facilitate the next steps.

### Step 4: Elimination of bromine and formation of isocyanate
In the next step, the N-bromo-benzamide undergoes elimination of bromide ion (Br-) to form an isocyanate intermediate:
\[ \text{Ph-N=C=O} \]

**Hint:** The elimination of Br- leads to the formation of a highly reactive isocyanate.

### Step 5: Hydrolysis of isocyanate
The isocyanate can then be hydrolyzed in an acidic medium (H3O+) to yield an amine and carbon dioxide:
\[ \text{Ph-N=C=O} + H_2O \rightarrow \text{Ph-NH}_2 + CO_2 \]
This results in the formation of aniline (C6H5NH2).

**Hint:** Hydrolysis of isocyanates typically produces primary amines.

### Conclusion
The amine produced by the Hoffmann degradation of benzamide is aniline (C6H5NH2), which is a primary aromatic amine.

**Final Answer:** The amine produced by the Hoffmann degradation of benzamide is aniline (C6H5NH2).