Which is the correct IUPAC name of the compound, $CH_3CH=CHC(Br) (CH_3)_2$?

4-Bromo-4-methylpent-2-ene

The correct answer is Option (1) → 4-Bromo-4-methylpent-2-ene

To determine the IUPAC name, follow these standardized rules:

1. Identify the Longest Carbon Chain:

The longest continuous chain containing the double bond has 5 carbon atoms, making the parent alkane pentane. Since there is a double bond, the suffix is -ene.

2. Number the Chain:

Number the chain from the end that gives the double bond the lowest possible number.

• Numbering from left to right: The double bond starts at C2.

• Numbering from right to left: The double bond starts at C3.

• Therefore, we number from left to right.

3. Locate Substituents:

Using the left-to-right numbering:

• The double bond is at position 2.

• There is a Bromine atom (bromo) at position 4.

• There is a Methyl group ($-CH_3$) at position 4.

4. Assemble the Name:

Alphabetize the substituents (Bromo comes before Methyl) and combine them with the parent chain name.

• Substituents: 4-Bromo-4-methyl

• Parent: pent-2-ene

Final IUPAC Name: 4-Bromo-4-methylpent-2-ene