Of the following reactions, how many reaction, are used for the preparation of amines?
`R - overset(overset(O)(||))C - NH_(2) overset(LiAlH_(4) ) (to)`

Explanation

To solve the question regarding the preparation of amines from the given reaction involving an amide and lithium aluminium hydride (LiAlH4), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reaction involves an amide (R - C(=O) - NH2) and lithium aluminium hydride (LiAlH4).

2. **Understand the Role of LiAlH4**:
Lithium aluminium hydride is a strong reducing agent. It is commonly used to reduce carbonyl compounds, including amides, to amines.

3. **Reduction of Amide**:
When an amide is treated with LiAlH4, it undergoes reduction. The carbonyl group (C=O) of the amide is reduced to a methylene group (CH2), resulting in the formation of a primary amine (RCH2NH2).

4. **Reaction Mechanism**:
- The first step involves the nucleophilic attack of the hydride ion (H-) from LiAlH4 on the carbonyl carbon of the amide.
- This leads to the formation of a tetrahedral intermediate.
- Upon further reaction and work-up (usually with water), the intermediate collapses to form the primary amine.

5. **Generalization for Other Amines**:
- If a secondary amide (R1C(=O) - NR2) is used, the same reducing agent can yield a secondary amine (R1CH2NR2).
- Similarly, a tertiary amide can yield a tertiary amine.

6. **Conclusion**:
Since the reaction of amides with lithium aluminium hydride can produce primary, secondary, and tertiary amines, we conclude that this reaction is indeed used for the preparation of amines.

### Final Answer:
Yes, the reaction of amides with lithium aluminium hydride is used for the preparation of amines.