What is the final product of the following reaction sequence?
cyclohexanol ` overset((i) conc. H_2 SO_4//Delta ) overset((ii) NB S//C Cl_4 //hv)underset((iv) Br_2//40^@ C) underset((iii) Alc KOH//Delta ) to `

Options

A.
B.
C.
D.

Explanation

To determine the final product of the reaction sequence involving cyclohexanol, we will break down each step of the reaction.

### Step 1: Dehydration of Cyclohexanol
- **Reaction**: Cyclohexanol reacts with concentrated H₂SO₄ and heat (Δ).
- **Mechanism**:
1. The hydroxyl group (-OH) of cyclohexanol is protonated by H₂SO₄, forming a better leaving group (water).
2. Water leaves, forming a carbocation.
3. A double bond forms as a hydrogen atom from an adjacent carbon atom is eliminated, resulting in the formation of cyclohexene.

**Product after Step 1**: Cyclohexene

### Step 2: Bromination using NBS
- **Reaction**: Cyclohexene reacts with NBS (N-Bromosuccinimide) in the presence of CCl₄ and light (hv).
- **Mechanism**:
1. NBS generates a bromine radical.
2. The bromine radical abstracts a hydrogen from the cyclohexene, forming a cyclohexyl radical.
3. The cyclohexyl radical then reacts with another bromine radical, resulting in the formation of bromocyclohexane.

**Product after Step 2**: Bromocyclohexane

### Step 3: Elimination using Alcoholic KOH
- **Reaction**: Bromocyclohexane reacts with alcoholic KOH and heat (Δ).
- **Mechanism**:
1. The alcoholic KOH acts as a base, abstracting a hydrogen atom from the carbon adjacent to the bromine.
2. This leads to the elimination of bromine and the formation of a double bond, resulting in the formation of a conjugated diene.

**Product after Step 3**: 1,3-Cyclohexadiene

### Step 4: Bromination of the Diene
- **Reaction**: 1,3-Cyclohexadiene reacts with Br₂ at 40°C.
- **Mechanism**:
1. The diene acts as a nucleophile and attacks the bromine molecule, forming a cyclic bromonium ion.
2. The bromide ion then attacks the more substituted carbon, leading to the formation of a dibrominated product.

**Final Product**: 1,4-Dibromocyclohexane

### Summary of the Reaction Sequence:
1. Cyclohexanol → Cyclohexene (dehydration)
2. Cyclohexene → Bromocyclohexane (bromination)
3. Bromocyclohexane → 1,3-Cyclohexadiene (elimination)
4. 1,3-Cyclohexadiene → 1,4-Dibromocyclohexane (bromination)

### Final Answer:
The final product of the reaction sequence is **1,4-Dibromocyclohexane**.

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