Key points from the chart
- The chart shows 40 functional groups in organic chemistry, each with its structure, its naming rule and an example compound.
- The groups are colour coded by the atoms they contain: hydrocarbons, halogens, oxygen, nitrogen, sulfur and phosphorus. Groups with two kinds of heteroatom have a two coloured ring.
- R stands for the rest of the molecule and X for any halogen atom. Numbered R groups (R1 to R4) can differ from each other.
- Most examples are two carbon compounds, so the naming endings can be compared directly: ethane, ethene, ethyne, ethanol, ethanal, ethanoic acid.
- Compound Interest says this expanded chart has almost double the groups of its original 2014 version, 40 against 21 [1].
Functional groups chart in text
Title: Functional groups in organic chemistry. Compound Interest logo, top right.
Intro text: Functional groups are the characteristic groups in organic molecules that give them their reactivity. In the formulae below, R represents the rest of the molecule and X represents any halogen atom.
Legend: Hydrocarbons (dark grey), Halogen-containing groups (green), Oxygen-containing groups (red), Nitrogen-containing groups (blue), Sulfur-containing groups (orange), Phosphorus-containing groups (purple).
The 40 groups, in the chart’s order (four rows of ten, left to right). The structures are drawn as skeletal formulas on the graphic and are written here as condensed formulas. The last column is read from each formula and matches the colour of its ring.
| # | Functional group | Structure (as drawn) | Naming | Example | Atoms besides C and H |
|---|---|---|---|---|---|
| 1 | Alkane | R1-CH2-CH2-R2 | -ane | ethane | none |
| 2 | Alkene | R1R3C=CR2R4 | -ene | ethene | none |
| 3 | Alkyne | R1-C≡C-R2 | -yne | ethyne | none |
| 4 | Arene | R-C6H5 (benzene ring) | -yl benzene | ethyl benzene | none |
| 5 | Haloalkane | R-X | halo- | chloroethane | halogen |
| 6 | Alcohol | R-OH | -ol | ethanol | O |
| 7 | Aldehyde | R-C(=O)-H | -al | ethanal | O |
| 8 | Ketone | R1-C(=O)-R2 | -one | propanone | O |
| 9 | Carboxylic acid | R-C(=O)-OH | -oic acid | ethanoic acid | O |
| 10 | Acid anhydride | R1-C(=O)-O-C(=O)-R2 | -oic anhydride | ethanoic anhydride | O |
| 11 | Acyl halide | R-C(=O)-X | -oyl halide | ethanoyl chloride | O, halogen |
| 12 | Ester | R1-C(=O)-O-R2 | -yl -oate | ethyl ethanoate | O |
| 13 | Ether | R1-O-R2 | -oxy -ane | methoxyethane | O |
| 14 | Epoxide | three membered C-C-O ring with R1 to R4 | -ene oxide | ethene oxide | O |
| 15 | Amine | R1-N(R2)(R3) | -amine | ethanamine | N |
| 16 | Amide | R-C(=O)-NH2 | -amide | ethanamide | N, O |
| 17 | Nitrate | R-O-N+(=O)-O- | -yl nitrate | ethyl nitrate | N, O |
| 18 | Nitrite | R-O-N=O | -yl nitrite | ethyl nitrite | N, O |
| 19 | Nitrile | R-C≡N | -nitrile | ethanenitrile | N |
| 20 | Nitro | R-N+(=O)-O- | nitro- | nitromethane | N, O |
| 21 | Nitroso | R-N=O | nitroso- | nitrosoethane | N, O |
| 22 | Imine | R1R2C=N-R3 | -imine | ethanimine | N |
| 23 | Imide | R2-C(=O)-N(R1)-C(=O)-R3 | -imide | succinimide | N, O |
| 24 | Azide | R-N=N+=N- | -yl azide | phenylazide | N |
| 25 | Cyanate | R-O-C≡N | -yl cyanate | methyl cyanate | N, O |
| 26 | Isocyanate | R-N=C=O | -yl isocyanate | methyl isocyanate | N, O |
| 27 | Azo compound | R1-N=N-R2 | azo- | azoethane | N |
| 28 | Thiol | R-SH | -thiol | methanethiol | S |
| 29 | Sulfide | R1-S-R2 | sulfide | dimethyl sulfide | S |
| 30 | Disulfide | R1-S-S-R2 | disulfide | dimethyl disulfide | S |
| 31 | Sulfoxide | R1-S(=O)-R2 | sulfoxide | dimethyl sulfoxide | S, O |
| 32 | Sulfone | R1-S(=O)2-R2 | sulfone | dimethyl sulfone | S, O |
| 33 | Sulfinic acid | R-S(=O)-OH | -sulfinic acid | benzenesulfinic acid | S, O |
| 34 | Sulfonic acid | R-S(=O)2-OH | -sulfonic acid | benzenesulfonic acid | S, O |
| 35 | Sulfonate ester | R1-S(=O)2-O-R2 | -yl sulfonate | methylmethanesulfonate | S, O |
| 36 | Thiocyanate | R-S-C≡N | thiocyanate | ethyl thiocyanate | S, N |
| 37 | Isothiocyanate | R-N=C=S | isothiocyanate | ethyl isothiocyanate | S, N |
| 38 | Thial | R-C(=S)-H | -thial | ethanethial | S |
| 39 | Thioketone | R1-C(=S)-R2 | -thione | propanethione | S |
| 40 | Phosphine | R1-P(R2)(R3) | phosphane | methylphosphane | P |
Footer: www.compoundchem.com. © Andy Brunning/Compound Interest 2024. Creative Commons Attribution-NonCommercial-NoDerivatives licence.
What a functional group does
The OpenStax organic chemistry textbook defines a functional group as a group of atoms within a molecule that has a characteristic chemical behaviour, and says a given functional group behaves in nearly the same way in every molecule it is part of [2]. That is why chemists sort organic compounds into families by functional group: an alcohol such as ethanol and a much larger alcohol share much of their chemistry because both carry an OH group.
Compound Interest makes the same point: all carbon based molecules contain functional groups, some more than one, and these give molecules their particular reactivity, so molecules with a certain group can be predicted to react in similar ways [1].
Reading the naming column
The naming column shows the suffix or prefix each group adds to a compound’s name. Endings such as -ol, -al, -one and -oic acid replace the -e of the parent alkane, so ethane becomes ethanol, ethanal and ethanoic acid. Some groups are named with a prefix instead (halo-, nitro-, nitroso-, azo-), and several sulfur groups are named as separate words (dimethyl sulfide, dimethyl sulfoxide). The examples on the chart use systematic names; some have common names, for example ethanoic acid is better known as acetic acid and propanone as acetone.
Notes on this infographic
- Versions. Compound Interest first published a functional groups chart in 2014 and an expanded 40 group edition in February 2020 [1]. The image on this page carries a 2024 copyright line and is the same file now shown on that Compound Interest post.
- Not exhaustive. Compound Interest says the chart does not claim to include every functional group [1].
- Formulas in text. Wedge and hash bonds (amine, epoxide, phosphine) and the ring drawings cannot be shown in plain text, so the table gives simplified condensed formulas.
Questions about functional groups
What are functional groups in organic chemistry?
They are groups of atoms within a molecule that have a characteristic chemical behaviour, and they behave in nearly the same way in every molecule they appear in [2]. The chart’s own definition is the characteristic groups in organic molecules that give them their reactivity.
Why are functional groups important in organic chemistry?
Because they decide how a molecule reacts. Knowing a molecule’s functional groups lets chemists predict that it will react in similar ways to other molecules with the same group [1][2], and the groups are the basis for how organic compounds are classified and named.
How many functional groups are there in organic chemistry?
The Compound Interest chart shows 40 functional groups, almost double the 21 in its original 2014 version [1]. The expanded 40 group edition was first published in February 2020 [1]. Compound Interest says the chart does not claim to include every functional group [1], so 40 is the number on this chart rather than a complete total.
What are the name endings for alcohols, aldehydes and ketones?
Alcohols end in -ol, aldehydes in -al and ketones in -one, so the chart's examples are ethanol, ethanal and propanone. These endings replace the -e of the parent alkane, as does -oic acid for carboxylic acids, giving ethanoic acid. Some groups use a prefix instead, such as halo-, nitro- and azo-. Ethanoic acid is better known as acetic acid and propanone as acetone.
Sources
- Compound Interest (Andy Brunning), Organic functional groups chart, expanded edition (21 February 2020, image updated 2024).
- LibreTexts Chemistry, Organic Chemistry (OpenStax), 3.1 Functional Groups.
Last reviewed 30 October 2026
