Aldehyde
An aldehyde has the carbonyl group (C=O) mandatorily at the end of the chain — the carbonyl carbon also carries a hydrogen (except in methanal, where it carries two). This differentiates it from a ketone, whose carbonyl sits in the middle of the chain.
General formula
R–CHO
Naming rule
Name = main chain (counting the carbonyl carbon) + suffix -al. No locant needed — the aldehyde carbonyl is always at position 1 by definition.
Examples
| Name | Formula |
|---|---|
| Methanal (formaldehyde) | HCHO |
| Ethanal (acetaldehyde) | CH₃CHO |
| Propanal | C₂H₅CHO |
| Benzaldehyde | C₆H₅CHO |