AMIDES

Amides In amides, an amino group replaces the –OH group of carboxylic acids. O O || || CH3 — C — OH CH3 — C — NH2

Preparation of Amides Amides are produced by reacting a carboxylic acid with ammonia or an amine (1° or 2°). O O   CH3—C—OH + NH3 CH3—C—NH2 + H2O O O   CH3—C—OH + CH3—NH2 CH3—C—NH—CH3 + H2O

Naming Amides Amides are named as alkanamides. In the IUPAC and common names, the –oic acid or -ic acid endings are replaced by –amide. O  Methanamide (IUPAC) H—C—NH2 Formamide (common) O  Propanamide (IUPAC) CH3—CH2—C —NH2 Propionamide (common)

Naming Amides with N Groups An alkyl group bonded to the N atom is named as N-alkyl in front of the amide name. O  CH3—C—NH —CH3 N-methylethanamide (IUPAC) N-methylacetamide (common) O CH3   CH3—CH2—C —N —CH3 N,N-dimethylpropanamide N,N-dimethylpropionamide

Aromatic Amides The amide of benzene is named benzamide.

Amides in Health and Medicine Urea is the end product of protein metabolism. Saccharin is an artificial sweetener. Some amides such as phenobarbital, Nembutal and Seconal are barbiturates. Acetaminophen is used to reduce fever and pain.

Classification of Amides Amides are classified according to the number of carbon atoms bonded to the nitrogen atom. O H || | CH3—C—N—H Primary (1°) amide O H CH3—C—N—CH3 Secondary (2°) amide O CH3 CH3 —C—N—CH3 Tertiary (3°) amide

Amides in Health and Medicine

Physical Properties of Amides Hydrogen bonds form in primary and secondary amides, but not tertiary amides. The melting points of primary amides are higher than secondary amides, which have higher melting points than tertiary amides. All amides can form hydrogen bonds with water. Amides with 1–5 carbon atoms are soluble in water.

Hydrogen Bonding of Amides || CH3—C—N—H | H Hydrogen bonding occurs between primary amides. H

Reactions of Amides Amides undergo: Acid hydrolysis to produce a carboxylic acid and ammonium salt. Base hydrolysis to produce the salt of a carboxylic acid and an amine or ammonia.

Hydrolysis Reactions || CH3—C—OH + NH4+Cl- || CH3—C—NH2 acid hydrolysis O || CH3—C—OH + NH4+Cl- O || CH3—C—NH2 CH3—C—O-Na+ + NH3 HCl + H2O NaOH base hydrolysis