Chapter 15 Amines 15.1 Amines 15.2 Naming Amines 15.3 Physical Properties of Amines 1
Amines Amines are organic compounds in which one or more H in ammonia, NH 3, is replaced with alkyl or aromatic groups. H H H H N H CH 3 N H CH 3 N CH 3 ammonia 2
Classification of Amines Amines are classified as primary, secondary, or tertiary. In a primary (1 ) amine, one carbon group is bonded to the nitrogen atom. A secondary (2 ) amine has two carbon groups. A tertiary (3 ) amine has three carbon groups. H CH 3 CH 3 CH 3 N H CH 3 N H CH 3 N CH 3 1 2 3 3
Models of Amines The threedimensional models show the shapes of amine molecules with one or more alkyl groups bonded to the nitrogen atom. 4
Common Names of Amines Simple amines are named as alkylamines. The alkyl groups bonded to the N atom are listed in alphabetical order in front of amine. CH 3 CH 2 NH 2 CH 3 NH CH 3 Ethylamine Dimethylamine CH 3 CH 3 N CH 2 CH 3 Ethyldimethylamine 5
IUPAC Names of Amines In the IUPAC system, amines are named as alkanamines. The e in the alkane name of the longest chain is changed to amine. The chain is numbered to locate the amine group and substituents. NH 2 CH 3 CH 2 NH 2 CH 3 CH CH 3 Ethanamine 2-Propanamine 6
Naming Secondary and Tertiary Amines Each alkyl groups bonded to the N atom is named as N-alkyl groups in front of the amine name for the longest chain. HN CH 3 CH 3 CH 2 CH 2 NH CH 3 CH 3 CH CH 2 CH 3 N-Methyl-1-propanamine N-Methyl-2-butanamine 7
Learning Check Give the common and IUPAC names and classify as primary, secondary, or tertiary: A. CH 3 CH 2 CH 2 NH 2 CH 3 B. CH 3 CH 2 N CH 3 8
Solution A. CH 3 CH 2 CH 2 NH 2 1-propylamine, 1-propanamine, 1 CH 3 B. CH 3 CH 2 N CH 3 ethyldimethylamine, N,N-dimethylethanamine, 3 9
Learning Check Write a structural formula for A. 2-pentanamine B. N-methyl-1-butanamine 10
Solution A. 2-pentanamine NH 2 CH 3 CH CH 2 CH 2 CH 3 B. N-methyl-1-butanamine CH 3 CH 2 CH 2 CH 2 NH CH 3 11
Aromatic Amines The amine of benzene is named aniline. NH 2 NH 2 NH CH 3 Cl Aniline 3-Chloroaniline N-Methylaniline 12
Boiling Points of Amines, Alcohols, and Alkanes The boiling points of amines are higher than alkanes, but lower than alcohols of similar mass. 13
Boiling points of some common amines are shown in the Table 15.1 14
Hydrogen Bonding for Amines The polar N-H bond provides hydrogen bonding in 1 and 2 amines, but not 3. However, the N-H bonds in amines are not as polar as the O-H bonds in alcohols. 15
Solubility in Water Amines with 1-5 carbon atoms are soluble in water. The N atom in amines forms hydrogen bonds with the polar O-H bond in water. 16
Learning Check Consider the following compounds: 1) CH 3 CH 2 CH 2 NH 2 2) CH 3 CH 2 NH CH 3 3) CH 3 CH 2 CH 2 CH 3 A. Which compound has the highest boiling point? B. Which compound is soluble in water? 17
Solution Consider the following compounds: 1) CH 3 CH 2 CH 2 NH 2 2) CH 3 CH 2 NH CH 3 3) CH 3 CH 2 CH 2 CH 3 A. Which compound has the highest boiling point? 1) CH 3 CH 2 CH 2 NH 2 B. Which compound is soluble in water? 1) CH 3 CH 2 CH 2 NH 2 2) CH 3 CH 2 NH CH 3 18
15.4 Basicity of Amines Like ammonia, amines are weak bases in water. NH 3 + H 2 O NH 4+ + OH ammonium hydroxide CH 3 NH 2 + H 2 O CH 3 NH 3+ + OH methylammonium hydroxide 19
15.5 Amine Salts An amine salt: Forms when an amine is neutralized by acid. Is named by replacing the amine part of the name with ammonium followed by the name of the negative ion. CH 3 NH 2 + HCl CH 3 NH 3+ Cl Methylamine methylammonium chloride 20
Properties of Amine Salts Amine salts are: Solids at room temperature. Soluble in water and body fluids. The form used for drugs. 21
Cocaine Cocaine is sold illegally as an amine salt. Cocaine is reacted with NaOH to produce the free amine form known as crack. 22
Heterocyclic Amines In a heterocyclic amine, a five- or six-atom ring contains one or more nitrogen atoms. N N H Pyrrolidine N H Pyrrole N H Imidazole N N N N N N H Piperidine Pyridine Pyrimidine N Purine N H 23
Names and structures of several heterocyclic nitrogen compounds are given in Table 15.2. 24
Alkaloids Alkaloids are: Physiologically active nitrogen-containing compounds. Produced by plants. Used as stimulants, anesthetics, and antidepressants. Often habit forming. 25
Caffeine Caffeine: Is a stimulant of the central nervous system. Is found in coffee beans, tea, chocolate, and soft drinks. Contains an imidazole ring. 26
Nicotine Nicotine: Increases the adrenaline level in the blood. Causes addiction to tobacco. Contains a pyrrolidine ring. N CH 3 27
Alkaloids Related to Morphine Alkaloids such as morphine and codeine are produced by the poppy. For centuries, morphine and codeine have been used as painkillers. Heroin is a modification of morphine. Methadone 28
Pharmacology An area of research in pharmacology is to design drugs with some of the characteristics of alkaloids. The structures of cocaine and morphine are modified to produce anesthesia, but without the addictive side effects. 29
Pharmacology Parts of the morphine structure that produce anesthesia are found in procaine, lidocaine, and demerol. 30
Learning Check Identify the heterocyclic amine in serotonin. HO CH 2 CH 2 NH 2 N H serotonin 31
Solution Identify the heterocyclic amine in serotonin. HO CH 2 CH 2 NH 2 N H Indole 32