What will be the final product when elthyl benzene is treated with the reeagent listed, below?
(P)NBS, peroxide, heat (Q)alcoholic KOH, `(/_\)`
( R ) `B_(2)H_(6)` (S) `H_(2)O_(2),HO_(Θ)`

Options

A. `Ph-CH_(2)-CH_(2)-OH`
B. `PH-underset(Br)underset(|)CH-H_(2)-OH`
C. `PH-overset(OH)overset(|)CH-CH_(3)`
D. `Ph-underset(OH)underset(|)CH-CH_(2)Br`

Answer

To determine the final product when ethylbenzene is treated with the reagents listed, we will analyze each step sequentially.

### Step 1: Reaction with NBS, Peroxide, and Heat (Reagent P)
- **Reaction**: Ethylbenzene (C6H5CH2CH3) is treated with NBS (N-bromosuccinimide) in the presence of peroxide and heat.
- **Mechanism**: NBS will brominate the benzylic position (the carbon adjacent to the benzene ring). The reaction will replace one hydrogen atom from the benzylic carbon with a bromine atom.
- **Product**: The product after this step will be benzyl bromide (C6H5CHBrCH3).

### Step 2: Reaction with Alcoholic KOH (Reagent Q)
- **Reaction**: The benzyl bromide obtained from the previous step is treated with alcoholic KOH.
- **Mechanism**: Alcoholic KOH promotes a dehydrohalogenation reaction, where the bromine atom and a hydrogen atom from the adjacent carbon are eliminated, forming a double bond.
- **Product**: The product after this step will be styrene (C6H5CH=CH2).

### Step 3: Reaction with B2H6 (Reagent R)
- **Reaction**: Styrene is then treated with diborane (B2H6).
- **Mechanism**: Diborane adds across the double bond in an anti-Markovnikov manner, resulting in the formation of a trialkylborane intermediate.
- **Product**: The product after this step will be a trialkylborane (C6H5CH2CH2B).

### Step 4: Reaction with H2O2 and HO- (Reagent S)
- **Reaction**: The trialkylborane is then treated with hydrogen peroxide (H2O2) in the presence of a hydroxide ion (HO-).
- **Mechanism**: This reaction leads to the oxidation of the boron atom to an alcohol group.
- **Product**: The final product will be phenethyl alcohol (C6H5CH2CH2OH).

### Final Product
The final product after all the reactions is phenethyl alcohol (C6H5CH2CH2OH).

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