Common Organic Functional Groups
The essential organic functional groups with their general formulas, naming conventions, and representative examples. Fundamental to understanding organic chemistry nomenclature.
Functional Groups and Their Suffixes
General formula, IUPAC suffix, and a worked example for each common functional group.
| Alkane | CₙH2ₙ+2 | -ane | Ethane | C2H6 |
| Alkene | CₙH2ₙ | -ene | Ethene (ethylene) | C2H4 |
| Alkyne | CₙH2ₙ-2 | -yne | Ethyne (acetylene) | C2H2 |
| Alcohol | R–OH | -ol | Ethanol | C2H5OH |
| Aldehyde | R–CHO | -al | Ethanal (acetaldehyde) | CH3CHO |
| Ketone | R–CO–R' | -one | Propanone (acetone) | CH3COCH3 |
| Carboxylic acid | R–COOH | -oic acid | Ethanoic acid (acetic acid) | CH3COOH |
| Ester | R–COO–R' | -oate | Ethyl ethanoate | CH3COOC2H5 |
| Amine | R–NH2 | -amine | Methylamine | CH3NH2 |
| Amide | R–CONH2 | -amide | Ethanamide (acetamide) | CH3CONH2 |
| Ether | R–O–R' | prefix: alkoxy- | Diethyl ether | C2H5OC2H5 |
| Haloalkane | R–X (X = F, Cl, Br, I) | prefix: fluoro-, chloro-, bromo-, iodo- | Chloromethane | CH3Cl |
| Thiol | R–SH | -thiol | Ethanethiol | C2H5SH |
| Nitrile | R–C≡N | -nitrile | Ethanenitrile (acetonitrile) | CH3CN |
Important Notes
- R represents any alkyl group (hydrocarbon chain). R' represents a second, possibly different alkyl group.
- IUPAC priority order (highest to lowest): carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > thiol > amine > alkene > alkyne > alkane.
- The highest-priority group determines the suffix; lower-priority groups are named as prefixes.
- The general formulas CₙH₂ₙ (alkene) and CₙH₂ₙ₋₂ (alkyne) apply to acyclic hydrocarbons with exactly one double or one triple bond; rings or additional unsaturation change the hydrogen count.
- Aldehydes always occur at the end of a carbon chain (terminal); ketones occur within the chain (internal).
- Common names are shown in parentheses. IUPAC names should be used for formal nomenclature.
- Naming follows IUPAC 2013 Recommendations for the Nomenclature of Organic Chemistry.