In the given reaction `C_6H_5-CH=CH-CH_3+HCl rarr[X]` [X] will be

Options

A. `C_6H_5-overset(Cl) overset(|)(CH)-CH_2-CH_3`
B. `C_6H_5-CH_2-overset(Cl)overset(|)(CH)-CH_3`
C. `Cl-C_6H_4-CH=CH-CH_3`
D. `C_6H_5-CH=CH-CH_2Cl`

Answer

To determine the product [X] formed from the reaction of the compound \( C_6H_5-CH=CH-CH_3 \) with HCl, we can follow these steps:

### Step 1: Identify the Reaction Type
The reaction involves an alkene (the double bond between carbon atoms) reacting with HCl. This is an electrophilic addition reaction.

### Step 2: Protonation of the Alkene
In the presence of HCl, the double bond will react with HCl. The first step is the protonation of the alkene. The double bond can either attack the hydrogen ion (H⁺) from HCl at carbon 1 or carbon 2.

1. **If H⁺ adds to carbon 1**:
- The structure becomes:
\[ C_6H_5-CH^+-CH_2-CH_3 \]
- This forms a carbocation at carbon 1.

2. **If H⁺ adds to carbon 2**:
- The structure becomes:
\[ C_6H_5-CH_2-CH^+-CH_3 \]
- This forms a carbocation at carbon 2.

### Step 3: Stability of Carbocations
Next, we need to evaluate the stability of the two possible carbocations formed:

- **Carbocation at Carbon 1**:
- This carbocation is stabilized by resonance with the benzene ring. The positive charge can be delocalized over the aromatic system, making it more stable.

- **Carbocation at Carbon 2**:
- This carbocation is less stable because it is only stabilized by hyperconjugation from the adjacent alkyl group (methyl group). The positive charge is localized and not delocalized.

### Step 4: Nucleophilic Attack
Since the carbocation at carbon 1 is more stable, it is the favored intermediate. The next step is the attack of the chloride ion (Cl⁻) on the carbocation:

- The chloride ion will attack the more stable carbocation (at carbon 1), resulting in the formation of the product.

### Step 5: Final Product
The final product [X] will be:
\[ C_6H_5-CH(Cl)-CH_2-CH_3 \]
This can be represented as:
\[ C_6H_5-CHCl-CH_2-CH_3 \]

### Conclusion
Thus, the product [X] formed from the reaction of \( C_6H_5-CH=CH-CH_3 \) with HCl is \( C_6H_5-CHCl-CH_2-CH_3 \).

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