Give the following conversion acetaldehyde `rarr` alanine.

Explanation

To convert acetaldehyde (CH3CHO) to alanine (C3H7NO2), we can follow these steps:

### Step 1: Nucleophilic Addition of Hydrogen Cyanide
- **Reaction**: Acetaldehyde reacts with hydrogen cyanide (HCN).
- **Mechanism**: The cyanide ion (CN-) acts as a nucleophile and attacks the carbonyl carbon of acetaldehyde. The oxygen atom of the carbonyl group gains a negative charge, leading to the formation of a cyanohydrin.

**Equation**:
\[ CH_3CHO + HCN \rightarrow CH_3C(OH)(CN) \]

### Step 2: Formation of an Amine
- **Reaction**: The cyanohydrin formed in Step 1 is treated with ammonia (NH3).
- **Mechanism**: The amine group (NH2-) from ammonia attacks the carbon atom that is bonded to the hydroxyl group (OH) and the cyanide group (CN). A water molecule is eliminated in this process.

**Equation**:
\[ CH_3C(OH)(CN) + NH_3 \rightarrow CH_3C(NH_2)(CN) + H_2O \]

### Step 3: Acidic Hydrolysis
- **Reaction**: The product from Step 2 undergoes acidic hydrolysis.
- **Mechanism**: The cyanide group (CN) is converted to a carboxylic acid (COOH) through hydrolysis. The reaction involves the addition of water and the presence of an acid catalyst.

**Equation**:
\[ CH_3C(NH_2)(CN) + H_2O \rightarrow CH_3C(NH_2)(COOH) \]

### Final Product
- The final product is alanine (C3H7NO2), which has the structure:
\[ CH_3CH(NH_2)COOH \]

### Summary of the Reaction Steps
1. **Nucleophilic addition of HCN to acetaldehyde** to form a cyanohydrin.
2. **Reaction with ammonia** to form an intermediate amine.
3. **Acidic hydrolysis** of the intermediate to convert the cyanide to a carboxylic acid, yielding alanine.