Chloromethane on treatment with excess of ammonia yields mainly

Options

A. N,N-dimethylmethanamine

B. N-methylmethanamine `(CH_3-NH-CH_3)`
C. methanamine `(CH_3NH_2)`
D. mixture containing all these in equal proportion.

Explanation

To solve the question, "Chloromethane on treatment with excess of ammonia yields mainly," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this reaction are chloromethane (CH₃Cl) and ammonia (NH₃).

2. **Understand the Reaction Type**: This reaction is a nucleophilic substitution reaction. Chloromethane has a chlorine atom that acts as a leaving group, while ammonia acts as a nucleophile due to the lone pair of electrons on the nitrogen atom.

3. **Reaction Mechanism**:
- In the presence of excess ammonia, the lone pair of electrons on the nitrogen atom of ammonia will attack the carbon atom of chloromethane.
- The carbon atom has a partial positive charge because of the electronegativity of chlorine, making it susceptible to nucleophilic attack.

4. **Formation of the Transition State**:
- As ammonia attacks the carbon atom, a transition state is formed where the bond between carbon and chlorine is breaking while the bond between carbon and nitrogen is forming.
- This is characteristic of an SN2 reaction mechanism.

5. **Product Formation**:
- After the transition state, the chlorine atom leaves as chloride ion (Cl⁻), and ammonia forms a bond with the carbon atom, resulting in the formation of methylamine (CH₃NH₂).
- Additionally, hydrochloric acid (HCl) is formed as a by-product when the chloride ion reacts with a hydrogen atom from ammonia.

6. **Final Products**:
- The main product of the reaction is methylamine (CH₃NH₂), and the by-product is hydrochloric acid (HCl).

### Conclusion:
The main product obtained from the reaction of chloromethane with excess ammonia is **methylamine (CH₃NH₂)**.

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