Overview of common functional groups

This image provides you with an overview of the most common functional groups in organic chemistry. You can read more about each of the functional groups below the image.

• Alkane: A hydrocarbon that has no functional groups. Alkanes are named with the suffix -ane, e.g. butane.

• Alkene: A hydrocarbon that has at least one C-C double bond. The double bond is nucleophilic, which makes the alkenes substrates in electrophilic addition reactions. Alkenes are named with the suffix -ene, e.g. butene.

• Alkyne: A hydrocarbon that has at least one C-C triple bond. The triple bond is nucleophilic, which makes the alkynes substrates for electrophilic addition reactions. If the alkyne is terminal, the proton is slightly acidic and acetylide anions can be formed. Alkynes are named with the suffix -yne, e.g. butyne.

• Arene: Also called aromatics, are hydrocarbons that contain at least one phenyl group. Aromatic rings have a high electron density and are nucleophilic, which makes them substrates for electrophilic aromatic substitution. Aromatics can contain other functional groups and are named with the prefix phenyl- or with the suffix -benzene, e.g. phenylamine and chlorobenzene.

• Haloalkane: A compound that contains a halogen (main group VII in the periodic table) substituent. The halogens are more electronegative than carbon, and are good leaving groups, making haloalkanes good substrates for S_N1/S_N2 and E1/E2 reactions. Haloalkanes are named with a derivation of the prefix halo-, e.g. bromobutane.

• Aldehyde: A compound that contains a C-O double bond, where one of the substituents on the carbon atom is a hydrogen atom and the other is a carbon atom. The C=O bond is polarized towards oxygen, making the carbon atom electrophilic and thus aldehydes are substrates for nucleophilic addition reactions. Aldehydes are named with the suffix -al, e.g. butanal.

• Ketone: A compound that contains a C-O double bond, where both of the substituents on the carbon atom are carbon atoms. The C=O bond is polarized towards oxygen, making the carbon atom electrophilic and thus ketones are substrates for nucleophilic addition reactions. Ketones are named with the suffix -one, e.g. butanone.

• Alcohol: A compound with a hydroxy (-OH) substituent to saturated carbon. Alcohols can be deprotonated to create a good nucleophile, or protonated to transform the -OH into a good leaving group (OH₂), thereby making the alcohols suitable substrates for S_N1/S_N2 and E1/E2 reactions. Alcohols are named with the suffix -ol, e.g. butanol. Note that a hydroxy (-OH) group on an aromatic ring yields the functional group phenol, which has slightly different reaction properties.

• Ether: A compound that contains a C-O-C bond. Ethers are generally not very reactive and are often used as solvents. Ethers are named with the suffix ether, e.g. diethyl ether.

• Amine: A compound that contains an amino substituent. The amine can be primary (R-NH₂), secondary (R-NHR') or tertiary (R-NR'R''). Amines are alkaline and often used as bases or nucleophiles. Amines are named with the suffix amine, e.g. triethyl amine.

• Carboxylic acid: A compound with a -COOH substituent. Carboxylic acids and their derivatives (below) can be transformed into each other through nucleophilic substitution reactions. Carboxylic acids are named with the suffix -oic acid, e.g. butanoic acid.

• Acid anhydride: A compound with a -COOCO- component. Acid anhydrides are derivatives of carboxylic acids, structurally resembling two carboxylic acids that have been merged with the elimination of a water molecule. Acid anhydrides are named with the suffix -oic anhydride, e.g. butanoic anhydride.

• Ester: A compound with a -COOR substituent. Esters are derivatives of carboxylic acids, structurally resembling a carboxylic acid that has been merged with an alcohol by the elimination of a water molecule. Esters are named with -yl -oate, e.g. butyl butanoate.

• Amide: A compound with a -CONHR substituent. Amides are derivatives of carboxylic acids, structurally resembling a carboxylic acid that has been merged with an amine by the elimination of a water molecule. Amides are named with the suffix amide, e.g. butanamide.

• Acyl halide: A compound with a -COX substituent, where the X is a halogen. Acid halides are derivatives of carboxylic acids, where the hydroxy substituent has been replaced with a halogen atom. Acyl halides are named with the suffix -oyl halide, e.g. butanoyl chloride.