Question

Which of the following order is correct for priority of functional group in IUPAC nomenclature?

• (1) –CHO > –COOR > –CO– > –CN > ≡ > –NH$_2$
• (2) –CONH$_2$ > –CN > –CHO > –CO– > –NH$_2$ > ≡
• (3) –CONH$_2$ > –COOR– > –CN > –CHO > –CO– > ≡
• (4) –COOR > –CN > –CONH$_2$ > –CHO > –CO– > ≡

Answer 1

The Correct Option is B

Memory-based rule for IUPAC functional group seniority.

RATIONALE:
The general priority sequence is:
Acids > Acid derivatives > Nitriles > Carbonyls > Alcohols > Amines > Unsaturation.
Detailed: \(-COOH > -SO_3H > -COOR > -COCl > -CONH_2 > -CN > -CHO > >C=O > -OH > -NH_2 > C=C > C \equiv C\).
Evaluating Option (2): Amide \((-CONH_2)\) > Nitrile \((-CN)\) > Aldehyde \((-CHO)\) > Ketone \((-CO-)\) > Amine \((-NH_2)\) > Alkyne \((\equiv)\). This matches the rules.