Write the structural formula of the following and indicate primary, secondary or tertiary amines:
(i) (N-Methyl) butan-2-amine (ii) 3-(N-ethylamino) butan-1-ol
(iii) N-ethyl-N-methylpropanamine (iv) Dibenzylamine

Explanation

To solve the question, we will write the structural formulas for each of the given amines and classify them as primary, secondary, or tertiary amines.

### (i) (N-Methyl) butan-2-amine
1. **Identify the structure**: Butan-2-amine indicates that the amine group (-NH2) is on the second carbon of a butane chain.
2. **Add the N-methyl group**: Since it is N-methyl, one hydrogen atom of the nitrogen is replaced by a methyl group (-CH3).
3. **Draw the structure**:
- The butane chain: CH3-CH(NH(CH3))-CH2-CH3
- The nitrogen is attached to one methyl group and one hydrogen, making it a secondary amine.
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