In ammonolysis, primary amine is obtained as a major product by taking

Options

A. large excess of alkyl halide
B. large excess of ammonia
C. Both a and b
D. None of the above

Explanation

To solve the question regarding the conditions under which primary amine is obtained as a major product in ammonolysis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ammonolysis**:
Ammonolysis is a reaction where an alkyl halide reacts with ammonia (NH₃) to form amines. The reaction typically follows an SN2 mechanism, where the nucleophile (ammonia) attacks the electrophilic carbon of the alkyl halide.

**Hint**: Recall that SN2 reactions involve a backside attack and result in the inversion of configuration at the carbon center.

2. **Formation of Primary Amine**:
When ammonia reacts with an alkyl halide, it can lead to the formation of a primary amine. For example, if we take methyl chloride (CH₃Cl) and react it with ammonia, we can form methylamine (CH₃NH₂).

**Hint**: Identify the structure of the alkyl halide and the product formed after the nucleophilic attack.

3. **Competing Nucleophiles**:
In the reaction mixture, both ammonia and the primary amine (once formed) can act as nucleophiles. The primary amine can further react with the alkyl halide to form secondary amines.

**Hint**: Consider the role of each nucleophile present in the reaction mixture and how they can participate in further reactions.

4. **Excess of Alkyl Halide**:
If a large excess of alkyl halide is used, once the ammonia is consumed, the primary amine can react with the remaining alkyl halide to form secondary and tertiary amines. This can lead to a lower yield of primary amine.

**Hint**: Think about how the stoichiometry of the reactants affects the formation of products.

5. **Excess of Ammonia**:
To favor the formation of the primary amine, a large excess of ammonia should be used. This ensures that ammonia is in higher concentration compared to the primary amine, thus favoring the SN2 reaction with the alkyl halide.

**Hint**: Remember that increasing the concentration of a reactant in an equilibrium reaction shifts the equilibrium towards the products.

6. **Conclusion**:
Therefore, to obtain primary amine as the major product in ammonolysis, it is essential to use a large excess of ammonia compared to the alkyl halide.

**Final Answer**: A large excess of ammonia is required to obtain primary amine as a major product in ammonolysis.