General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 18 Amines and Amides 18.1 Amines Lectures © 2013 Pearson Education, Inc.

Amines Amines are derivatives of ammonia (NH3). In the IUPAC name for amines, the e in the corresponding alkane name is replaced with amine. When the amine has a chain of three or more carbon atoms, it is numbered to show the position of the –NH2 group and any other substituents. 2 2

Guide to IUPAC Naming of Amines 3 3

Naming the Longest Carbon Chain Name the longest carbon chain bonded to the N atom by replacing the e of its alkane name with amine. Here, the longest carbon chain bonded to the N atom has four carbon atoms, which is named by replacing the e in the alkane name with amine to give butanamine. 4 4

Numbering the Carbon Chain The N atom in the amine group is attached to carbon 1 of butanamine. 5 5

Alkyl Groups Attached to the N Atom Any alkyl group attached to the N atom is indicated by the prefix N- and the alkyl name, which is placed in front of the amine name. Alkyl groups attached to the N atom are listed alphabetically. The IUPAC name is N-methyl-1-butanamine. 6 6

Naming Common Amines Common amines are named with common names as alkylamines. List the names of the alkyl groups bonded to the N atom in alphabetical order in front of amine. Ethylamine Dimethylamine Ethyldimethylamine 7 7

Learning Check Give the common and IUPAC names, and classify each as primary, secondary, or tertiary. 8 8

Solution A. STEP 1 Name the longest carbon chain bonded to the N STEP 1 atoms as alkanamines by replacing e of the STEP 1 alkane name with amine. STEP 2 Number the carbon chain to show the position of STEP 2 the amine group and any substituents. Propanamine CH3—CH2 —CH2—NH2 3 2 1 Propylamine (common), 1° 1-Propanamine (IUPAC) 9 9

Solution (continued) B. STEP 1 Name the longest carbon chain bonded to the N STEP 1 atoms as alkanamines by replacing e of the STEP 1 alkane name with amine. STEP 2 Number the carbon chain to show the position of STEP 2 the amine group and any substituents. ethanamine 10 10

Solution (continued) B. STEP 3 In a secondary or tertiary amine, use the prefix STEP 3 N- to name groups attached to the N atom. Ethyldimethylamine (common), N,N-Dimethylethanamine (IUPAC), 3° 11 11

Naming Compounds with Two Functional Groups When a compound contains more than one functional group, we need to identify which group is used as the name of the compound and which group is named as the substituent. According to the IUPAC rules, an oxygen-containing group will have priority over an —NH2 group. As a result, the —NH2 group is named as the substituent, amino. 12 12

Aromatic Amines The amine of benzene is called aniline. may have alkyl groups attached to N that use the prefix N- and the alkyl name. 13 13

Learning Check Give the common and IUPAC names for each of the following: A. B. C. 14 14

Solution A. B. C. Ethylmethylamine(common); N-methylethanamine Butylethylmethylamine (common); N-ethyl-N-methyl-1-butanamine Aniline C. 15 15

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. 16 16

Please insert Figure of hydrogen bonds here; Properties of Amines Amines contain polar N—H bonds, which allow primary and secondary amines to form hydrogen bonds with water. Nitrogen is not as electronegative as oxygen, which results in weaker hydrogen bonds as compared to those found in alcohols. Please insert Figure of hydrogen bonds here; Pg 646 17 17

Solubility in Water Amines are soluble in water if they have 1 to 6 carbon atoms. Generally, 1° amines are most soluble while 3° amines are least soluble because the N atom in smaller amines forms hydrogen bonds with the polar O—H bond in water. 18 18

Learning Check Consider the following compounds: 1) CH3—CH2—CH2—NH2 2) CH3—CH2—NH—CH3 3) CH3—CH2—CH2—CH3 A. Which compound has the highest boiling point? B. Which compound(s) is/are soluble in water? 19 19

Solution Consider the following compounds: 1) CH3—CH2—CH2—NH2 2) CH3—CH2—NH—CH3 3) CH3—CH2—CH2—CH3 A. Which compound has the highest boiling point? B. Which compound(s) is/are soluble in water? 20 20

Heterocyclic Amines A heterocyclic amine is a cyclic organic compound. has a five- or six-atom ring. contains one or more nitrogen atoms. 21 21

Heterocyclic Amines in Nature such as purine and pyrimidine rings are found in DNA and RNA. like piperidine, are found in black pepper. with two or three double bonds, have aromatic properties similar to benzene. 22 22

Learning Check Identify the following heterocyclic amines: A. B. C. 23

Solution Identify the following heterocyclic amines: A. B. C. Piperidine Pyrrolidine Pyrrole 24 24

Alkaloids Alkaloids are physiologically active nitrogen-containing compounds. produced by plants. used as stimulants, anesthetics, and antidepressants. often habit forming. Nicotine is an alkaloid. 25 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 26

Alkaloids Related to Morphine such as morphine and codeine, are produced by the poppy and have been used for centuries as painkillers. such as heroin and codeine, are modifications of morphine. 27 27

Synthesizing Drugs: Pharmacology Areas of pharmacology research design drugs, such as procaine, lidocaine, and Demerol, that retain some of the characteristics of alkaloids. modify the structures of cocaine and morphine to produce anesthesia, but without the addictive side effects. 28 28

Amides In amides, an amino group(–NH2) replaces the –OH group of carboxylic acids. 29 29

Naming Amides: IUPAC In both the IUPAC and the common names of amides, amides are named by dropping the -ic acid or -oic acid ending of the corresponding carboxylic acid and adding the suffix amide. 30 30

IUPAC Names of Amides Write the IUPAC name for STEP 1 Determine the alkane name of the carbon chain in the carboxyl portion and replace e with amide. butanamide STEP 2 Name each substituent on the N atom using the prefix N- and the alkyl name. N-ethylbutanamide 31 31

Examples of IUPAC and Common Names N-Methylethanamide (IUPAC) N-Methylacetamide (common) N-Ethylpropanamide (IUPAC) N-Ethylpropionamide (common) CH3—C H2—C—N—CH2—CH3 O ║ H — 32 32

Learning Check Write the IUPAC name for the following: CH3—CH2—CH2—CH2—C—N—CH2—CH3 O ║ CH2—CH3 │ 33 33

N,N-diethylpentanamide Solution STEP 1 Determine the alkane name of the carbon chain in the carboxyl portion and replace e with amide. pentanamide STEP 2 Name each substituent on the N atom using the prefix N- and the alkyl name. N,N-diethylpentanamide 34 34

Aromatic Amides The amide of benzene is named benzamide. 35 35

Learning Check Draw the condensed structural formulas of the following amides. A. pentanamide B. N-methylbutyramide 36 36

Solution Draw the condensed structural formulas of the following amides. A. pentanamide B. N-methylbutyramide 37 37

Classification of Amides Amides are classified according to the number of carbon atoms bonded to the nitrogen atom. Primary (1) Secondary (2) amide Tertiary (3) amide 38 38

Learning Check Give the common and IUPAC names for the following amides, and classify them as primary, secondary, or tertiary. A. B. 39 39

Solution Give the common and IUPAC names for the following amides, and classify them as primary, secondary, or tertiary. A. B. Butryamide (common) butanamide (IUPAC) primary (1) N-Ethyl-N-methylacetamide (common) (3) N-ethyl-N-methylethanamide (IUPAC), tertiary 40 40

Melting Points of Amides that are primary and secondary, form hydrogen bonds and have high melting points. that are tertiary (no H on N), do not form hydrogen bonds and have lower melting points. Insert table 18.2 here, Pg 657 41 41

Solubility of Amides in Water Primary, secondary, and tertiary amides with 1 to 5 carbon atoms form hydrogen bonds with water. are soluble in water. 42 42

Some Amides in Health and Medicine (continued) 43 43

Neurotransmitters A neurotransmitter is a chemical compound that transmits an impulse from a nerve cell to a target cell, such as another nerve cell, a muscle cell, or a gland cell. 44

Amine Neurotransmitters: Acetylcholine Neurotransmitters contain N atoms as amines and alkyl ammonium ions. Acetylcholine (ACh) was the first neurotransmitter to be identified. Neurotransmitters communicate between the nervous system and the muscle. When stimulated, it releases into the synapse where it binds to muscle cell receptors causing the muscles to contract. Please insert acetylcholine to acetate reaction here (Pg 662) 45

Dopamine Dopamine is produced in the nerve cells of the midbrain and acts as a natural stimulant to give us energy and feelings of enjoyment. Cocaine and amphetamine block the reuptake of dopamine resulting in a longer lifetime in synapse. 46

Norepinephrine and Epinephrine Norepinephrine (noradrenaline) and epinephrine (adrenaline) are hormonal neurotransmitters that play a role in sleep, attention and focus, and alertness. Epinephrine is synthesized from Norepinephrine. Both are normally produced in the adrenal glands. Both are highly produced during the fight-or-flight response. 47

Serotonin Serotonin helps us relax, sleep deeply and peacefully, think rationally, and it provides us a feeling of well-being and calmness. Serotonin is synthesized from the amino acid tryptophan. Low serotonin levels may be associated with depression, anxiety disorders, etc. Prozac and Paxil (antidepressant drugs) are selective serotonin reuptake inhibitors (SSRIs). 48

Histamine Histamine is synthesized in the nerve cells in the hypothalamus from the amino acid, histidine. is produced by the immune system in response to pathogens and invaders, or injury. When histamine combines with histamine receptors, it produces allergic reactions. 49

Amino Acid Neurotransmitters Glutamate is the most abundant neurotransmitters in the nervous system. stimulates the synthesis of nitrogen oxide (NO). Too much glutamate in the spinal cord causes degeneration of nerve cells (known as Lou Gehrig’s disease). 50