The major product obtained when - Butane is treated with bromine in the presence of light is

Options

A. `CH_(3)-CH_(2)-CH_(2)-CH_(2)-Br`
B.
C.
D.

Answer

To determine the major product obtained when butane is treated with bromine in the presence of light, we will follow these steps:

### Step 1: Understand the Structure of Butane
Butane (C4H10) has the following structure:
- CH3-CH2-CH2-CH3

### Step 2: Identify the Reaction Conditions
The reaction involves bromine (Br2) in the presence of light. The light causes the Br2 molecule to undergo homolytic cleavage, producing two bromine radicals (Br•).

### Step 3: Identify the Types of Hydrogen Atoms in Butane
In butane, there are two types of hydrogen atoms:
1. Terminal hydrogens (attached to the CH3 groups)
2. Internal hydrogens (attached to the CH2 groups)

### Step 4: Radical Formation
When a bromine radical (Br•) reacts with a hydrogen atom in butane, it can abstract a hydrogen atom, leading to the formation of a butyl radical. This can occur at either of the two types of hydrogen atoms.

### Step 5: Determine Possible Radicals
1. If Br• abstracts a hydrogen from a terminal carbon (CH3), we get a primary radical:
- CH3-CH2-CH2-•CH3 (1° radical)
2. If Br• abstracts a hydrogen from an internal carbon (CH2), we get a secondary radical:
- CH3-CH•-CH2-CH3 (2° radical)

### Step 6: Analyze Radical Stability
Radicals are stabilized by the number of adjacent hydrogen atoms (alpha hydrogens):
- The primary radical (1°) has 2 alpha hydrogens.
- The secondary radical (2°) has 5 alpha hydrogens.

Since the secondary radical is more stable due to having more alpha hydrogens, it will be the major product.

### Step 7: Product Formation
Once the more stable radical is formed, it will react with another bromine radical (Br•) to form the final product:
- The major product will be 2-bromobutane.

### Final Answer
The major product obtained when butane is treated with bromine in the presence of light is **2-bromobutane**.

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