Amides and Amines: Organic Nitrogen Compounds

1. Chapter 25 Introduction to General, Organic, and Biochemistry, 10e John Wiley & Sons, Inc Morris Hein, Scott Pattison, and Susan Arena Amides and Amines: Organic Nitrogen Compounds Nylon is one of the materials used to give these colorful sails their strength and durability.

2. Amides: Nomenclature and Physical Properties Amides are neutral nitrogen-containing compounds. They are not acidic or basic (neutral) and exist as molecules both in aqueous solution and as pure substances. These compounds contain carbonyl groups. The carbonyl group is directly connected to a nitrogen atom. 2

3. Amides: Nomenclature and Physical Properties Amides are prepared when a carboxylic acid is heated in the presence of ammonia. 3

4. Amides: Nomenclature and Physical Properties Ammonium salts of carboxylic acids can also be converted to amides by heating. 4

5. Amides: Nomenclature and Physical Properties • IUPAC Rules for Naming Amides • Name the longest continuous carbon chain containing the amide group. The carbonyl carbon atom is the #1 carbon atom. • 2. Drop –oic from the corresponding carboxylic acid and add the suffix –amide. 5

6. Amides: Nomenclature and Physical Properties IUPAC names for amides are formed from the IUPAC names of carboxylic acids. Here are two examples. 6

7. Amides: Nomenclature and Physical Properties 3. Use a capital N (italicized) as the prefix if alkyl groups or other groups are attached directly to the amide nitrogen atom. 7

8. Amides: Nomenclature and Physical Properties The common names for amides are formed from the common names of carboxylic acids. 8

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10. Your Turn! Write formulas for N-methylpentanamide and N,N-diethyl-2-methylhexanamide. 10

11. Amides: Nomenclature and Physical Properties Physical Properties of Amides The physical properties of amides are determined largely by hydrogen bonding. 11

12. Amides: Nomenclature and Physical Properties High water solubility and high melting and boiling are the result of hydrogen bonding. A table summarizing the physical properties of amides is on the following slide . . . 12

13. Amides: Nomenclature and Physical Properties Property Description 13

14. Urea is a simple diamide that is excreted in urine. Urea is the metabolite the body uses to excrete toxic ammonia. Urea Urea is a white solid that melts at 133 C. It is very soluble in water. 14

15. Urea Urea is a common commercial product. It is widely used in fertilizers to add nitrogen to the soil and as a starting material in the production of plastics and barbiturates like barbituric acid. 15

16. Amines: Nomenclature and Physical Properties • Classification of Amines • Amines are basic nitrogen-containing compounds that are derivatives of ammonia. Amines are classified as: • Primary(the nitrogen atom has one hydrocarbon group directly attached) • Secondary(the nitrogen atom has two hydrocarbon groups directly attached) • Tertiary(the nitrogen atom has three hydrocarbon groups directly attached). 16

17. Amines: Nomenclature and Physical Properties Examples of primary (1o), secondary (2o) and tertiary (3o) amines are shown here. 17

18. Classify the following amines as 1o, 2o or 3o. Your Turn! 18

19. Amines: Nomenclature and Physical Properties • IUPAC Rules for Naming Amines • Name the longest continuous carbon chain containing the amine group. The carbon atom attached to the amine group is the #1 carbon atom. • Drop –e from the corresponding alkane and add the suffix –amine. 19

20. Amines: Nomenclature and Physical Properties Here are some examples of primary amines. 20

21. Amines: Nomenclature and Physical Properties 3. Use a prefix with a capital N (italicized) if the amine nitrogen atom has an alkyl group or other group attached (2o and 3o amines). 21

22. Amines: Nomenclature and Physical Properties 4. In naming diamines, the final -eof the alkane name is not omitted. 22

23. Amines: Nomenclature and Physical Properties The most important aromatic amine is aniline (C6H5NH2). Derivatives are named as substituted anilines. 23

24. Give names for the following amines. Your Turn! 24

25. Amines: Nomenclature and Physical Properties Heterocyclic Compounds Heterocyclic compounds are ring compounds which have two or more atoms in the ring that are different. O, N, and S are common heteroatoms found in heterocyclic compounds. Nitrogen-based heterocyclic compounds like those shown on the next slide are found in DNA . . . 25

26. Amines: Nomenclature and Physical Properties Some heterocyclic amines. 26

27. Amines: Nomenclature and Physical Properties Physical Properties of Amines Amines are capable of hydrogen bonding with water. As a result, the aliphatic amines with up to six carbons are quite soluble in water. Methylamine and ethylamine are flammable gases with a strong ammoniacal odor. Trimethylamine has a “fishy” odor. 27

28. Amines: Nomenclature and Physical Properties 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. 28

29. Chemical Properties of Amines • Amines are weak bases. Compare the pH of the following amines with the pH of ammonia. • A 0.1M solution of NH3 has a pH of 11.1 • CH3NH2 is more basic at a pH of 11.8. • An aromatic amine like aniline is less basic at a pH of 8.8. 29

30. Chemical Properties of Amines Amines are much more basic than amides and the body uses this fact to convert toxic ammonia into urea as shown here. 30

31. Sources and Uses of Selected Amines Nitrogen compounds are found throughout the plant and animal kingdoms. Amines, substituted amines, and amides occur in every living cell. Many of these compounds have important physiological effects. 31

32. Sources and Uses of Selected Amines • Biogenic aminesare derived from amino acids and act as neurotransmitters and hormones in animals. • GABA (γ-aminobutyric acid) slows nerve action and can bring relaxation. • Norepinephrine shown below affects our focus and concentration. 32

33. Sources and Uses of Selected Amines Biogenic amines that act as hormones include the “fight-or-flight” hormone epinephrine (also a catecholamine) as well as histamine, an important component in allergic reactions. 33

34. Sources and Uses of Selected Amines Amphetamines are designed to mimic the action of biogenic amines and act as stimulants. They are used to treat depression, narcolepsy, and obesity. The most widely abused amphetamine is methamphetamine, commonly called “speed.” 34

35. Sources and Uses of Selected Amines Barbiturates are another class of drugs that are amines. These drugs are classified as sedatives and depress the activity of brain cells. An example is pentobarbital. 35

36. Sources and Uses of Selected Amines Basic compounds that are derived from plants and show physiological activity are known as alkaloids. These substances are usually amines. Nicotine, an alkaloid derived from tobacco leaves, acts to stimulate the nervous system. 36

37. Sources and Uses of Selected Amines Coffee beans and tea leaves contain caffeine, an alkaloid stimulant. 37

38. Sources and Uses of Selected Amines The opium alkaloids are often called opiates and include both compounds derived from the opium poppy and synthetic compounds that have morphine-like activity. These compounds are sleep-inducing and have analgesic properties. 38

39. Sources and Uses of Selected Amines These drugs are classified as narcotics because they produce physical addiction, and they are strictly regulated by federal law. An example is methadone. 39

40. Sources and Uses of Selected Amines Another common narcotic alkaloid, cocaine, is obtained from the leaves of the coca plant. 40