Monobromination of 2-methylbutane gives how many distinct isomers? (A) One (B) Two (C) Three (D) Four

To determine how many distinct isomers can be formed from the monobromination of 2-methylbutane, we first need to understand the structure of the compound and the nature of bromination. 2-methylbutane is a branched alkane with the molecular formula C5H12. When we perform monobromination, we are replacing one hydrogen atom with a bromine atom, which can occur at different positions on the carbon chain, leading to various isomers.

Analyzing the Structure of 2-Methylbutane

2-methylbutane has the following structure:

• It consists of a four-carbon chain (butane) with a methyl group attached to the second carbon.

Identifying Possible Bromination Sites

When we consider bromination, we can replace a hydrogen atom at different positions:

• At the terminal carbon (C1)
• At the second carbon (C2)
• At the third carbon (C3)
• At the fourth carbon (C4)

Distinct Isomers from Each Bromination Site

Let’s evaluate the distinct isomers formed by bromination at each of these positions:

• Bromination at C1: This leads to 1-bromo-2-methylbutane.
• Bromination at C2: This results in 2-bromo-2-methylbutane, which is unique due to the presence of the bromine on a tertiary carbon.
• Bromination at C3: This gives us 3-bromo-2-methylbutane, which is also distinct.
• Bromination at C4: This leads to 1-bromo-3-methylbutane, another unique isomer.

Counting the Distinct Isomers

From our analysis, we can summarize the distinct isomers formed from the monobromination of 2-methylbutane:

• 1-bromo-2-methylbutane
• 2-bromo-2-methylbutane
• 3-bromo-2-methylbutane
• 1-bromo-3-methylbutane

Thus, we find that there are a total of four distinct isomers that can be produced through the monobromination of 2-methylbutane.

Final Answer

The correct choice is (D) Four.