Major product of the following reaction
`CH_(3)-CH_(2)-Broverset(KCN)tounderset(H_(2)O)overset(overline(O)H)tounderset(Delta)overset(PCl_(5))to` product

Options

A. `CH_(3)-CH_(2)-Cl`
B. `H_(3)C-CH_(2)-underset(O)underset(||)(C)-Cl`
C. `CH_(3)-CH_(2)-CN`
D. `CH_(3)-underset(O)underset(||)(C)-NH_(2)`

Answer

To determine the major product of the given reaction sequence, we will break down the steps involved in the reaction of ethyl bromide with KCN, followed by the treatment with OH- and H2O, and finally with PCl5 under heating.

### Step-by-Step Solution:

1. **Identify the Reactants**:
The starting compound is ethyl bromide (CH3CH2Br).

2. **Reaction with KCN**:
Ethyl bromide reacts with potassium cyanide (KCN). The cyanide ion (CN-) acts as a nucleophile and attacks the carbon atom bonded to the bromine atom, leading to the substitution of bromine with the cyanide group.
- **Reaction**:
\[ CH3CH2Br + KCN \rightarrow CH3CH2CN + KBr \]
- **Product**: Ethyl cyanide (CH3CH2CN).

3. **Hydrolysis with OH- and H2O**:
The ethyl cyanide then undergoes hydrolysis in the presence of hydroxide ions (OH-) and water (H2O). This process converts the nitrile (CN) group into a carboxylic acid, which can further be converted into an alcohol.
- **Reaction**:
\[ CH3CH2CN + H2O + OH^- \rightarrow CH3CH2COO^- + OH^- \rightarrow CH3CH2OH + CN^- \]
- **Product**: Ethanol (CH3CH2OH).

4. **Reaction with PCl5**:
The final step involves treating the alcohol (ethanol) with phosphorus pentachloride (PCl5) under heating. This reaction converts the alcohol into an alkyl chloride.
- **Reaction**:
\[ CH3CH2OH + PCl5 \rightarrow CH3CH2Cl + POCl3 + HCl \]
- **Product**: Ethyl chloride (CH3CH2Cl).

5. **Final Product**:
The major product of the entire reaction sequence is ethyl chloride (chloroethane).

### Conclusion:
The major product of the reaction sequence is **ethyl chloride (CH3CH2Cl)**.

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