What is the IUPAC name of the compound H3C-CH(CH3)-CH(Br)-CH2-CH3?

The given compound is:

The longest continuous carbon chain is 5 carbons long. This makes the parent alkane pentane.

• There is a methyl ($\text{CH}_{3}$) group.
• There is a bromo ($\text{Br}$) group.

Let's consider numbering from both ends:

• Numbering from left to right:

  $$\text{C}^{1}\text{H}_{3}-\text{C}^{2}\text{H}(\text{CH}_{3})-\text{C}^{3}\text{H}(\text{Br})-\text{C}^{4}\text{H}_{2}-\text{C}^{5}\text{H}_{3}$$

  The methyl group is at carbon 2. The bromo group is at carbon 3. The set of locants is (2, 3).

• Numbering from right to left:

  $$\text{C}^{5}\text{H}_{3}-\text{C}^{4}\text{H}_{2}-\text{C}^{3}\text{H}(\text{Br})-\text{C}^{2}\text{H}(\text{CH}_{3})-\text{C}^{1}\text{H}_{3}$$

  The bromo group is at carbon 3. The methyl group is at carbon 4. The set of locants is (3, 4).

Comparing the two sets of locants, (2, 3) is lower than (3, 4). Therefore, we number the chain from left to right.

• Bromo ($\text{Br}$) comes before Methyl ($\text{CH}_{3}$).

The bromo group is at position 3.
The methyl group is at position 2.
The parent chain is pentane.

The full name of the compound is: