Which of the following is a `3^0` amine?

Options

A. 1-methyl cyclohexylamine
B. Triethylamine
C. tert-butyl amine
D. N-methyl aniline

Explanation

To determine which of the given compounds is a tertiary amine, we need to analyze each option based on the structure of the amine and the number of carbon atoms bonded to the nitrogen atom.

### Step-by-Step Solution:

1. **Understanding Tertiary Amines**:
- A tertiary amine is defined as an amine in which the nitrogen atom is bonded to three carbon atoms and has no hydrogen atoms directly attached to it.

2. **Analyzing Option 1: 1-Methylcyclohexylamine**:
- The structure consists of a cyclohexane ring with a methyl group (CH3) and an amine group (NH2).
- The nitrogen in this compound is bonded to one carbon from the cyclohexane and has two hydrogen atoms.
- Therefore, this is a **primary amine**.

3. **Analyzing Option 2: Triethylamine**:
- The structure consists of a nitrogen atom bonded to three ethyl groups (C2H5).
- Since nitrogen is connected to three carbon atoms and has no hydrogen atoms directly attached, this qualifies as a **tertiary amine**.

4. **Analyzing Option 3: Tertiary Butylamine**:
- The structure consists of a tertiary butyl group (C4H9) connected to an amine group (NH2).
- Here, nitrogen is bonded to only one carbon atom from the butyl group and has two hydrogen atoms.
- Thus, this is a **primary amine**.

5. **Analyzing Option 4: N-Methyl Aniline**:
- The structure consists of a benzene ring with an NH2 group and a methyl group (CH3) attached to the nitrogen.
- The nitrogen is bonded to one carbon from the benzene ring and one from the methyl group, along with one hydrogen atom.
- Therefore, this is a **secondary amine**.

6. **Conclusion**:
- After analyzing all options, the only compound that qualifies as a tertiary amine is **Triethylamine** (Option 2).

### Final Answer:
The correct answer is **Option 2: Triethylamine**.

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