Identify the end product (C ) in the following sequence :
`C_2H_5-OH overset(SOCl_2)underset("pyridine")(to) A overset(KCN(alc))(to) B overset(H_2O //H^+)(to) C`

Options

A. `C_2H_5- CH_2NH_2`
B. `C_2H_5 - CONH_2`
C. `C_2H_5-COOH`
D. `C_2H_5-NH_2+HCOOH`

Explanation

To solve the problem step by step, we will analyze each reaction in the sequence provided:

### Step 1: Reaction of Ethanol with Thionyl Chloride
- **Starting Compound**: Ethanol (C₂H₅OH)
- **Reagent**: Thionyl chloride (SOCl₂) in the presence of pyridine
- **Reaction**: The hydroxyl group (-OH) in ethanol is replaced by a chlorine atom (Cl) through a nucleophilic substitution reaction (SNI mechanism).

**Product A**: Chloroethane (C₂H₅Cl)

### Step 2: Reaction of Chloroethane with Alcoholic Potassium Cyanide
- **Starting Compound**: Chloroethane (C₂H₅Cl)
- **Reagent**: Alcoholic potassium cyanide (KCN)
- **Reaction**: The chlorine atom in chloroethane is replaced by a cyanide group (CN) through another nucleophilic substitution reaction (SN2 mechanism).

**Product B**: Ethane nitrile (C₂H₅CN)

### Step 3: Hydrolysis of Ethane Nitrile
- **Starting Compound**: Ethane nitrile (C₂H₅CN)
- **Reagent**: Water (H₂O) in acidic conditions
- **Reaction**: Ethane nitrile undergoes hydrolysis to first form an amide (C₂H₅CONH₂), and with further hydrolysis, it converts to a carboxylic acid.

**Final Product C**: Propanoic acid (C₂H₅COOH)

### Summary of the End Product
The end product C after the sequence of reactions is **propanoic acid** (C₂H₅COOH).

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