S3.2.2 Functional groups

Alkyl

Saturated hydrocarbons with C–C single bonds.

General formula: C_nH_2n+2.

Reactions: Combustion, Free radical substitution.

Alkenyl

Unsaturated hydrocarbons with C=C double bonds.

General formula: C_nH_2n.

Reactions: Combustion, Electrophilic addition, Reduction to alkanes.

Alkynyl

Unsaturated hydrocarbons with C≡C triple bonds.

General formula: C_nH_2n-2.

Reactions: Combustion, Electrophilic addition.

Aldehyde

Carbonyl group (C=O) bonded to H.

General formula: C_nH_2nO.

Reactions: Oxidation to acids, Reduction to primary alcohols (HL only).

Ketones

Carbonyl group (C=O) bonded to two R groups.

General formula: C_nH_2nO.

Reactions: Reduction to secondary alcohols (HL only).

Esters

COO group between two alkyl groups.

General formula: C_nH_2nO₂.

Formed by alcohol + acid, undergo hydrolysis.

Ethers

Oxygen atom bonded to two alkyl groups.

General formula: C_nH_2n+2O

No reactions in IB syllabus.

Hydroxyl

Contain -OH (hydroxy) group.

General formula: C_nH_2n+2O.

Reactions: Combustion, Oxidation, Esterification.

Carboxyl

Contain COOH (carboxy) group.

General formula: C_nH_2nO₂.

Reactions: With alcohols to form esters, Reduction (HL only).

Nitriles

Contain C≡N triple bond.

General formula: C_nH_2n+1N.

Reactions not covered in IB.

Amines

Contain -NH2 or N bonded to alkyl groups.

General formula: C_nH_2n+3N.

Act as Brønsted and Lewis bases.

Amides

Contain CONH2 group.

General formula: C_nH_2n+1NO.

Reactions not covered in IB.

Phenyl

Aromatic compounds with phenyl group.

Benzene molecule minus a hydrogen atom

Reactions (HL): Reduction of nitrobenzene.

Halogenoalkanes

Alkane with halogen (F, Cl, Br, I).

General formula: C_nH_2n+1X.

Reactions: Nucleophilic substitution.