Which of the following sequence of reactions (reagent ) can be used for the conversion of `C_6H_5CH_2CH_3` into `C_6H_5CH=CH_3`

Options

A. `SOCl_2 , H_2O`
B. `SO_2Cl_2 , alc.KOH`
C. `Cl_2//hv , H_2O`
D. `SOCl_2` , alc. KOH

Explanation

To convert `C6H5CH2CH3` (ethylbenzene) into `C6H5CH=CH3` (styrene), we can follow these steps:

### Step 1: Chlorination
First, we need to introduce a chlorine atom into the molecule. This can be done by reacting ethylbenzene with thionyl chloride (SOCl2) under high temperature. The reaction will convert the `CH2` group into a `CHCl` group.

**Reaction:**
\[ C6H5CH2CH3 + SOCl2 \rightarrow C6H5CHClCH3 + HCl + SO2 \]

### Step 2: Elimination Reaction
Next, we will perform an elimination reaction to remove the chlorine and a hydrogen atom from the adjacent carbon. This can be achieved through an E2 elimination mechanism. We will use a strong base, such as sodium ethoxide (NaOEt), to facilitate this elimination.

**Reaction:**
\[ C6H5CHClCH3 + NaOEt \rightarrow C6H5CH=CH3 + NaCl + EtOH \]

### Final Product
After the elimination reaction, we obtain the desired product, `C6H5CH=CH3` (styrene).

### Summary of Reagents Used:
1. Thionyl chloride (SOCl2) at high temperature.
2. Sodium ethoxide (NaOEt) for the elimination step.

### Final Answer
The correct sequence of reactions to convert `C6H5CH2CH3` into `C6H5CH=CH3` is:
1. `C6H5CH2CH3 + SOCl2 (high temperature) → C6H5CHClCH3`
2. `C6H5CHClCH3 + NaOEt → C6H5CH=CH3`