Question

In IUPAC names the correct order of decreasing priority of functional groups is:

• A. \(-CONH_2>C=O>-CHO>-NH_2>-C \equiv C-\)
• B. \(-CONH_2>-COOCH_3>-CHO>-NH_2>-OH\)
• C. \(-CONH_2>-CHO>C=O>-NH_2>-C \equiv C-\)
• D. \(-CONH_2>-CHO>-CN>-NH_2>-C \equiv C-\)

Answer 1

The Correct Option is D

To determine the order of decreasing priority of functional groups in IUPAC nomenclature, we need to refer to the rules provided by IUPAC for functional group hierarchy. Higher priority functional groups are named as suffixes, while lower priority groups are named as prefixes. Here's a brief explanation of the functional groups given in the question and their priority:

1. \(-CONH_2\) (Amide): Amides generally have a high priority due to their nitrogen and oxygen content and are one of the principal functional groups for suffix naming.
2. \(-CHO\) (Aldehyde): Aldehydes have a high priority and are typically ranked above several other functional groups due to their characteristic carbonyl oxygen.
3. \(-CN\) (Nitrile): Nitriles are also significant functional groups and have a higher priority than amines.
4. \(-NH_2\) (Amine): Amines, containing nitrogen but lacking the carbonyl group, have a moderate priority.
5. \(-C \equiv C-\) (Alkyne): Alkynes have a lower priority compared to the above groups because they are just hydrocarbons.

Based on the standard priority order in IUPAC nomenclature, the correct decreasing order of priority among the given functional groups is:

• \(-CONH_2\)
• \(-CHO\)
• \(-CN\)
• \(-NH_2\)
• \(-C \equiv C-\)

Therefore, the correct option is:

\(-CONH_2>-CHO>-CN>-NH_2>-C \equiv C-\)

. This choice reflects the chemical understanding and precedence of industrial and educational systems regarding organic chemistry.