which of the following does not react with `HNO_2`

Options

A. `CH_3 CONH_2`
B. `(CH_3)_3 C(NO_2)`
C. `(C_2H_5)_2 NH`
D. `CH_(3)CH_(2)NH_(2)`

Answer

To determine which of the given compounds does not react with HNO2 (nitrous acid), we need to analyze the structure of each compound and identify whether they contain an amine group (–NH2) that can participate in the reaction with HNO2.

### Step-by-Step Solution:

1. **Understand the Reaction of HNO2 with Amines:**
- HNO2 reacts differently with primary (1°), secondary (2°), and tertiary (3°) amines.
- **Primary amines (1°)** react with HNO2 to produce nitrogen gas (N2).
- **Secondary amines (2°)** react to form nitrosamines, which are typically insoluble oils.
- **Tertiary amines (3°)** react to form ammonium salts.

2. **Analyze Each Option:**
- **Option 1: CH3CONH2 (Acetamide)**
- This compound contains an amine group (NH2) and is classified as a primary amine. It will react with HNO2 to produce nitrogen gas.

- **Option 2: CH3C(NO2)CH3 (Nitroalkane)**
- This compound has a nitro group (NO2) instead of an amine group. Since it lacks an amine group, it will not react with HNO2.

- **Option 3: C2H5-NH (Ethylamine)**
- This is a primary amine (1°) and will react with HNO2 to produce nitrogen gas.

- **Option 4: CH3CH2NH2 (Ethylamine)**
- This is also a primary amine (1°) and will react with HNO2 to produce nitrogen gas.

3. **Conclusion:**
- The compound that does not react with HNO2 is **Option 2: CH3C(NO2)CH3** (Nitroalkane), as it does not contain an amine group.

### Final Answer:
**The compound that does not react with HNO2 is CH3C(NO2)CH3.**