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19.6 Structures and Names of Amides

19.7 Hydrolysis of Amides

Chapter 19 Amines and Amides

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In amides, an amino group replaces the –OH group of carboxylic acids.

O O || ||

CH3—C—OH CH3—C—NH2

Amides

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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

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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

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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

Naming Amides with N Groups

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Aromatic Amides

The amide of benzene is named benzamide.

C

O

NH2

Benzamide

C

O

NH CH3

N methylbenzamide -

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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

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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.

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Amides in Health and Medicine

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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.

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Hydrogen Bonding of Amides O

||CH3—C—N—H

| H Hydrogen bonding occurs

between primary amides. O ||

CH3—C—N—H |

H

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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.

Reactions of Amides

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acid hydrolysis O ||

O CH3—C—OH + NH4+Cl–

|| HCl + H2O CH3—C—NH2

NaOH O ||

CH3—C—O– Na+ + NH3

base hydrolysis

Hydrolysis Reactions