Give IUPAC name of the following compound:
\( CH_3-CH_2-CH_2-CH(Br)-CH(CH_3)-CH_2-CHO \)
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4-Bromo-3-methylheptanal
In an IUPAC name the principal functional group decides the suffix and the numbering. Here it is the aldehyde group, so the name ends in -al, the parent chain must contain the –CHO carbon, and that carbon is always C1. The other groups, bromo and methyl, are prefixes written in alphabetical order.
\( \displaystyle \ce{CH3-CH2-CH2-CH(Br)-CH(CH3)-CH2-CHO} \)
The longest chain through the –CHO carbon has seven carbons, so the parent is heptanal. Counting from the –CHO carbon (C1), the \( \ce{CH2} \) next to it is C2, the carbon with the methyl group is C3, and the carbon with the bromine is C4; C5, C6 and C7 complete the chain. With bromo before methyl in the alphabet, the name is 4-bromo-3-methylheptanal.