Question

Which of the following is the correct IUPAC name of given organic compound (X)?

Answer 1

2-(Bromomethyl)-3-methylbut-2-ene

Answer 2

Step 1: Identify the parent chain and unsaturation The longest chain containing the C=C has 4 carbons, so the parent is but‑2‑ene.

Step 2: Number the chain to give substituents the lowest set of locants

• Numbering from the left gives substituents at C2 (methyl) and C3 (bromomethyl): locants {2,3}.
• Numbering from the right gives substituents at C2 (bromomethyl) and C3 (methyl): locants {2,3}.
  Both sets tie (2,3), so we apply the locant–first–substituent alphabetic rule.

Step 3: Alphabetical order of substituents

• “bromomethyl” (B) comes before “methyl” (M), so bromomethyl must have the lower number (2).

Step 4: Assemble the name
2-(Bromomethyl)-3-methylbut-2-ene