1-phenyl-2-chloropropane on treating with alc. `KOH` gives mainly

Options

A. 1-phenylpropene
B. 2-phenylpropene
C. 1-phenylpropane-2-ol
D. 1-phenylpropane-1-ol

Answer

To solve the question of what product is formed when 1-phenyl-2-chloropropane is treated with alcoholic KOH, we can follow these steps:

### Step 1: Identify the Reactant
1-Phenyl-2-chloropropane has the structure:
- A phenyl group (C6H5) attached to a carbon (C) which is also attached to a chlorine (Cl) and a propyl group (C3H7). This can be represented as:
```
C6H5
|
CH-CH-CH3
|
Cl
```

### Step 2: Understand the Reaction Conditions
Alcoholic KOH is a strong base that promotes elimination reactions (E1 or E2). In this case, it will lead to the elimination of HCl from the molecule.

### Step 3: Determine Possible Elimination Pathways
When 1-phenyl-2-chloropropane reacts with alcoholic KOH, the elimination can occur in two ways:
1. Elimination of H from the carbon adjacent to the chlorine (C2), leading to the formation of a double bond between C1 and C2.
2. Elimination of H from the carbon adjacent to the phenyl group (C1), leading to the formation of a double bond between C2 and C3.

### Step 4: Draw the Possible Products
1. If H is eliminated from C2:
- Product: **1-phenylpropene** (C6H5-CH=CH-CH3)
2. If H is eliminated from C1:
- Product: **1-phenylpropene** (C6H5-CH2-CH=CH2)

### Step 5: Analyze the Stability of the Products
The product formed from the first pathway (elimination from C2) results in a conjugated system:
- **C6H5-CH=CH-CH3** has a double bond between C1 and C2, which allows for resonance stabilization due to the phenyl group.

The product formed from the second pathway does not have such stabilization:
- **C6H5-CH2-CH=CH2** lacks conjugation.

### Step 6: Determine the Major Product
Due to the stability provided by conjugation in the first product, **1-phenylpropene** (C6H5-CH=CH-CH3) will be the major product formed when 1-phenyl-2-chloropropane is treated with alcoholic KOH.

### Final Answer
The major product formed is **1-phenylpropene**.

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