2-methylbutane on reacting with bromine in the presence of sunlight gives mainly

Options

A. 1-bromo-3-methylbutane
B. 2-bromo-3-methylbutane
C. 2-bromo-2-methylbutane
D. 1-bromo-2-methylbutane

Answer

To solve the question regarding the reaction of 2-methylbutane with bromine in the presence of sunlight, we can follow these steps:

### Step 1: Identify the Reactants
The reactant is 2-methylbutane (C5H12) and bromine (Br2). The presence of sunlight indicates that the reaction will proceed via a free radical mechanism.

**Hint:** Identify the reactants in the reaction and note the conditions (sunlight) that suggest a free radical mechanism.

### Step 2: Write the Reaction
When 2-methylbutane reacts with bromine in the presence of sunlight, a bromination reaction occurs. The general reaction can be represented as:
\[ \text{2-methylbutane} + \text{Br}_2 \xrightarrow{\text{sunlight}} \text{bromo derivatives} + \text{HBr} \]

**Hint:** Write the overall reaction to visualize the transformation of reactants to products.

### Step 3: Understand the Mechanism
The reaction proceeds through three main steps: initiation, propagation, and termination.

1. **Initiation:** Bromine undergoes homolytic fission to form two bromine radicals.
\[ \text{Br}_2 \rightarrow 2 \text{Br}^\cdot \]

2. **Propagation:** The bromine radical reacts with 2-methylbutane to form an alkyl radical. The most stable radical will be favored. In this case, the tertiary radical (2-bromo-2-methylbutane) is formed because it is the most stable.
\[ \text{Br}^\cdot + \text{2-methylbutane} \rightarrow \text{2-bromo-2-methylbutane} + \text{HBr} \]

3. **Termination:** Radicals combine to form stable products, but the main product from this reaction is the one formed during propagation.

**Hint:** Break down the mechanism into initiation, propagation, and termination to understand how the products are formed.

### Step 4: Identify the Major Product
From the propagation step, the major product formed is 2-bromo-2-methylbutane. This is because the tertiary radical formed during the reaction is more stable than secondary or primary radicals.

**Hint:** Focus on the stability of the radicals formed during the reaction to determine which product is the major one.

### Step 5: Analyze the Options
The options provided are:
1. 1-bromo-3-methylbutane
2. 2-bromo-3-methylbutane
3. 2-bromo-2-methylbutane
4. 1-bromo-2-methylbutane

The correct answer is **2-bromo-2-methylbutane**, as it is the main product formed from the reaction.

**Hint:** Compare the products formed with the options given to select the correct answer.

### Final Answer
The main product formed when 2-methylbutane reacts with bromine in the presence of sunlight is **2-bromo-2-methylbutane**.

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