12.2 : アルデヒドの IUPAC 命名法

IUPAC names of aldehydes are obtained by replacing the final -e of the longest –CHO group containing the parent hydrocarbon with ‑al.

In acyclic aldehydes, parent chain numbering begins from the aldehydic carbon. However, due to the terminal position of the aldehyde group, the locant value of this carbon is not part of the name.

In cyclic compounds comprising the aldehyde group directly attached to a ring system, ‘carbaldehyde’ is suffixed to the parent name.

The ring carbon adjacent to the aldehydic carbon is considered carbon-1, and the numbering continues in the direction that gives a lower value to the next substituent on the ring.

If a molecule has multiple functional groups, it is named based on the priorities of the different groups.

For instance, if the aldehyde group is part of the parent chain containing a higher priority group, it is prefixed as ‘oxo’ to the parent name.

However, if the aldehyde group is not part of the parent chain, the prefix ‘formyl’ is used with the parent name.