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 regarding the reaction of 1-phenyl-2-chloropropane with alcoholic KOH, we will follow these steps:

### Step 1: Identify the Structure of 1-Phenyl-2-chloropropane
1-Phenyl-2-chloropropane has the following structure:
- The phenyl group (C6H5) is attached to the first carbon.
- The second carbon has a chlorine atom (Cl) attached to it.
- The third carbon is a methyl group (CH3).

The structure can be represented as:
```
C6H5
|
CH2-CH-CH3
|
Cl
```

### Step 2: Understand the Reaction with Alcoholic KOH
When an alkyl halide like 1-phenyl-2-chloropropane reacts with alcoholic KOH, a dehydrohalogenation reaction occurs. This reaction involves the elimination of a hydrogen halide (HCl in this case) to form an alkene.

### Step 3: Determine the Mechanism of Elimination
In the elimination reaction:
- The hydrogen atom is removed from the beta carbon (the carbon adjacent to the one with the halogen).
- The halogen (Cl) is removed from the alpha carbon (the carbon with the halogen).

### Step 4: Identify the Beta Carbons
In 1-phenyl-2-chloropropane, there are two beta carbons:
1. The carbon adjacent to the phenyl group (C2).
2. The carbon that is part of the methyl group (C3).

### Step 5: Analyze the Stability of the Carbocation
When the elimination occurs, a carbocation intermediate is formed. The stability of this carbocation is influenced by resonance from the phenyl group:
- The carbocation formed by removing H from the beta carbon adjacent to the phenyl group (C2) is more stable due to resonance stabilization.

### Step 6: Write the Product of the Reaction
The elimination will predominantly occur from the more stable carbocation, leading to the formation of:
- 1-phenylpropene (C6H5-CH=CH-CH3).

### Step 7: Conclusion
The main product formed when 1-phenyl-2-chloropropane reacts with alcoholic KOH is **1-phenylpropene**.

### Final Answer
1-phenylpropene is the main product.

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