Chemeketa Community College Amides and Amines Chapter 25 Larry Emme Chemeketa Community College

Nitrogen-Containing Compounds The amines and amides are the two major classes of nitrogen-containing compounds. Amines isolated from plants form a group of compounds called alkaloids. Quinine, caffeine Amides are nitrogen derivatives of carboxylic acids. Nylon, proteins

Amides: Nomenclature and Physical Properties

Carboxylic acids react with ammonia to form ammonium salts. When heated, ammonium salts of carboxylic acids lose a molecule of water and are converted to amides:

IUPAC Rules for Naming Amides The IUPAC name is based on the longest carbon chain that includes the amide group. Drop the –oic acid ending from the corresponding IUPAC acid name. Add the suffix –amide.

Naming Amides

Naming Amides When the nitrogen of an amide is connected to an alkyl or aryl group, the group is named as a prefix preceded by the letter N: N,N-dimethylethanamide

Physical Properties of Amides Except for formamide (methanamide), a liquid, all other unsubstituted amides are solids at room temperature. Many are odorless and colorless. Low molar-mass amides are soluble in water, but solubility decreases quickly as molar-mass increases.

The amide functional group is polar, and nitrogen is capable of hydrogen bonding.

Chemical Properties of Amides

Hydrolysis of Amides

Amines: Nomenclature and Physical Properties

IUPAC System for Naming Amines The IUPAC system names simple amines by using the name of the alkane (omitting the final –e) and adding the ending –amine. CH3CH2NH2 ethanamine CH3CH2CH2NH2 1-propanamine

Secondary and tertiary amines are named as N-substituted primary amines by using the longest carbon chain as the parent name.

Common Names of Amines

Heterocyclic Compounds Ring compounds in which the atoms in the ring are not all alike are known as heterocyclic compounds. The most common heteroatoms are oxygen, nitrogen, and sulfur.

Physical Properties of Amines Amines are capable of hydrogen bonding with water. They have odors: Methylamine and ethylamine = strong ammoniacal odor Trimethyamine = ‘fishy’ odor High molar-mass amines = obnoxious odors

Amines are responsible for the strong odors of decaying flesh which are produced by bacterial decomposition. Two of these compounds are actually diamines as shown here. 20 20

Preparation of Amines

Preparation of Amines Alkylation of ammonia and amines Reduction of amides and nitriles Reduction of aromatic nitro compounds

Alkylation of Ammonia and Amines The substitution of alkyl groups for hydrogen atoms of ammonia can be done by reacting ammonia with alkyl halides.

Reduction of Amides

Reduction of Aromatic Nitro Compounds Nitrobenzene is reduced to aniline which is a common aromatic amine. 25 25

Chemical Properties of Amines

Chemical Properties of Amines Alkaline properties of amines Salt formation Formation of amides

Alkaline Properties of Amines Amines are bases and produce OH– ions in water.

Salt Formation An amine reacts with a strong acid to form a salt.

Formation of Amides Amides are produced when primary and secondary amines react with acid chlorides. 30 30

Sources and Uses of Selected Amines

Many antibacterial agents include nitrogen containing compounds such as those shown here. Amines and amides are found in the B-complex vitamins B1 and B3. 32 32

Alkaloids are a class of compounds derived from plants that show biological activity. Procaine is an example of a local anesthetic. An alkaloid like nicotine stimulates the nervous system while the opium alkaloids like methadone and cocaine have morphine-like activity ( i.e. sleep inducing and analgesic properties). 33 33

Amphetamines are a class of compounds that stimulate the central nervous system. Amphetamines like methamphetamine mimics the action of epinephrine which produces a feeling of well-being and increased alertness. 34 34

Barbiturates are a class of compounds that depress the central nervous system. These sedatives contain amide groups. An example is pentobarbital. 35 35

Other examples of drugs containing the amine/amide functional groups include tranquilizers like Valium and antidepressants like Prozac. 36 36

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