Amines and Amides Chapter 16 Pages

Nitrogen Fourth most common atom in living systems. Important component of the structure of nucleic acids, DNA, and RNA Essential to the structure and function of proteins – enzymes and antibodies

Amine Structure Characterized by the presence of an amino group (-NH 2 ) One or more of the hydrogen atoms can be replaced by an organic group.

Amines Organic derivatives of ammonia and, like ammonia, they are basic. Amines are classified according to the number of alkyl groups attached to the nitrogen.

Classification of Amines Primary (1°) – one hydrogen replaced Secondary (2°) – two hydrogens replaced Tertiary (3°) – three hydrogens replaced

Properties of Amines Because nitrogen is more electronegative than hydrogen, the N-H bond is polar. Hydrogen bonding can occur between amines and water. Primary and secondary amines have higher boiling points than tertiary amines because tertiary amines cannot form hydrogen bonds. Small amines (six or fewer carbons) are soluble in water.

Naming Amines - IUPAC Least common system used Parent chain is longest continuous chain to which the amine group is attached. Use a number to indicate the position of the alkane. Add the prefix “amino” to the name of the alkane. If a substituent is present on the nitrogen, it is designated by the prefix N-alkyl.

Naming Amines - IUPAC aminomethaneaminoethane N-methylaminomethaneN-methylaminoethane N,N-dimethylaminomethane

Naming Amines – CA system CA system – Chemical Abstracts system The final –e of the parent name is dropped and the suffix –amine is added. For secondary and tertiary amines, the prefix N-alkyl is added to the parent compound.

methanamineethanamine N-methylmethanamineN-methylethanamine N,N-dimethylmethanamine Naming Amines – CA system

Aromatic Amines Aniline or benzenamine m-toluidine o-toluidine p-toluidine

Other Common Name Amines methylamine ethylamine dimethylamine ethylmethylamine trimethylamine

Amides Products formed in a reaction between a carboxylic acid and an amine. Contains two portions: the carbonyl group from a carboxylic acid and the amino group from the amine Amide Bond

Properties of Amides Most are solids at room temperature Very high boiling points – hydrogen bonding between N-H bond of one amide and the C=O group of the second amide Simpler ones are quite soluble in water Unlike amines, amides are NOT bases

Naming Amides - IUPAC Replace the –oic acid from the carboxylic acid with the ending – amide. Substituents on the nitrogen are placed as prefixes and are indicated by N- followed by the name of the substituent.

Examples Ethanamide Acetamide Propanamide N-methylpropanamide