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Amines and Amides. Chapter 16 Pages 439-465. 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.
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Amines and Amides Chapter 16 Pages 439-465
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 (-NH2) • 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 aminomethane aminoethane N-methylaminomethane N-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.
Naming Amines – CA system methanamine ethanamine N-methylmethanamine N-methylethanamine N,N-dimethylmethanamine
Aromatic Amines Aniline or benzenamine o-toluidine p-toluidine m-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