Which of the following reaction has the correct major product .

Options

A.
B.
C.
D.

Explanation

To determine which of the reactions has the correct major product, we will analyze each reaction step by step.

### Step 1: Analyze the First Reaction
- **Reactant**: 2,3-fluoro-3-methylpentane
- **Reagent**: Ethoxide (a strong base)
- **Mechanism**: Elimination reaction (E2)
- **Product Formation**: Ethoxide abstracts a proton from the less substituted carbon, leading to the formation of the less substituted alkene. The elimination of HF occurs.
- **Major Product**: The product formed is the less substituted alkene.

### Step 2: Analyze the Second Reaction
- **Reactant**: 2,3-dimethylpentane
- **Reagent**: Ethoxide
- **Mechanism**: Elimination reaction (E2)
- **Product Formation**: Ethoxide abstracts a proton from the more substituted carbon, leading to the formation of the more substituted alkene.
- **Major Product**: The product formed is the more substituted alkene.

### Step 3: Analyze the Third Reaction
- **Reactant**: A brominated compound (not specified)
- **Reagent**: Water
- **Mechanism**: Substitution reaction (SN1)
- **Product Formation**: The reaction forms a carbocation intermediate. A hydride shift occurs to stabilize the carbocation, leading to the formation of a tertiary carbocation. The hydroxide ion then attacks the tertiary carbon center.
- **Major Product**: The product formed is a hydroxy compound, not an elimination product.

### Step 4: Analyze the Fourth Reaction
- **Reactant**: 2-bromo-3,3,4-trimethylpentane
- **Reagent**: Bulky base
- **Mechanism**: Elimination reaction (E2)
- **Product Formation**: The bulky base abstracts a proton from the less hindered carbon, leading to the formation of the corresponding alkene. The bulky base prevents the formation of the more substituted alkene.
- **Major Product**: The product formed is the less substituted alkene due to steric hindrance.

### Conclusion
- **Correct Major Products**:
- Reaction 1: Correct (less substituted alkene)
- Reaction 2: Correct (more substituted alkene)
- Reaction 3: Incorrect (substitution product)
- Reaction 4: Correct (less substituted alkene)

Thus, the reactions with correct major products are **1, 2, and 4**.

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