Chapter 25

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. 25.1Amides: Nomenclature and Physical Properties 25.2Chemical Properties of Amides 25.3Polyamides: Condensation Polymers 25.4Urea 25.5Amines: Nomenclature and Physical Properties 25.6Preparation of Amines 25.7Chemical Properties of Amines 25.8Sources and Uses of Selected Amines Chapter 25 Summary Course Outline 2

3. 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. 3

4. Amides: Nomenclature and Physical Properties Amides are prepared when a carboxylic acid is heated in the presence of ammonia. 4

5. Amides: Nomenclature and Physical Properties Ammonium salts of carboxylic acids can also be converted to amides by heating. 5

6. 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. 6

7. Amides: Nomenclature and Physical Properties IUPAC names for amides are formed from the IUPAC names of carboxylic acids. Here are two examples. 7

8. 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. 8

9. Amides: Nomenclature and Physical Properties The common names for amides are formed from the common names of carboxylic acids. 9

10. Amides: Nomenclature and Physical Properties IUPAC and common names of some amides are on Table 25.1 on the next slide . . . 10

11. 11

12. Your Turn! Write formulas for N-methylpentanamide and N,N-diethyl-2-methylhexanamide. 12

13. Your Turn! Write formulas for N-methylpentanamide and N,N-diethyl-2-methylhexanamide. 13

14. Amides: Nomenclature and Physical Properties Physical Properties of Amides The physical properties of amides are determined largely by hydrogen bonding. 14

15. 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 . . . 15

16. Amides: Nomenclature and Physical Properties Property Description 16

17. Chemical Properties of Amides An important reaction of amides is hydrolysis. Amides undergo acidic and basic hydrolysis producing a carboxylic acid or carboxylate salt. Acidic Hydrolysis Basic Hydrolysis 17

18. Your Turn! Write the equations for the acidic and basic hydrolysis of the following amide. 18

19. Your Turn! Write the equations for the acidic and basic hydrolysis of the following amide. 19

20. Polyamides are condensation polymers that contain repeating amide linkages as shown here. Polyamides: Condensation Polymers 20

21. Polyamides: Condensation Polymers Polyamides are either synthetic like Nylon-66 or are biological like the protein chymotrypsin. The structure of chymotrypsin is shown below. 21

22. Polyamides: Condensation Polymers The structure of synthetic Nylon-66 is shown here. 22

23. 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. 23

24. 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. 24

25. 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). 25

26. Amines: Nomenclature and Physical Properties Examples of primary (1o), secondary (2o) and tertiary (3o) amines are shown here. 26

27. Classify the following amines as 1o, 2o or 3o. Your Turn! 27

28. Classify the following amines as 1o, 2o or 3o. Your Turn! 28

29. 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. 29

30. Amines: Nomenclature and Physical Properties Here are some examples of primary amines. 30

31. 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). 31

32. Amines: Nomenclature and Physical Properties 4. In naming diamines, the final -eof the alkane name is not omitted. 32

33. Amines: Nomenclature and Physical Properties Simple amines are most often referred to by their common names. The common names for aliphatic amines are formed by naming the alkyl group or groups attached to the nitrogen atom, followed by the ending –amine. 33

34. Amines: Nomenclature and Physical Properties The common names of some amines are shown here. 34

35. Amines: Nomenclature and Physical Properties The most important aromatic amine is aniline (C6H5NH2). Derivatives are named as substituted anilines. 35

36. Amines: Nomenclature and Physical Properties When a group is substituted for a hydrogen atom in the ring, the resulting ring substituted aniline is named as we have previously done with aromatic compounds. 36

37. Give names for the following amines. Your Turn! 37

38. Give names for the following amines. Your Turn! 38

39. 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 . . . 39

40. Amines: Nomenclature and Physical Properties Some heterocyclic amines. 40

41. 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. 41

42. 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. 42

43. Amines are prepared by: 1. Alkylation of ammonia and amines 2. Reduction of amides 3. Reduction of nitriles 4. Reduction of aromatic nitro compounds Preparation of Amines 43

44. Preparation of Amines Alkylation of Ammonia and Amines Ammonia can be alkylated producing primary, secondary and tertiary amines in successive reacctions. 44

45. Preparation of Amines Four successive alkylations of ammonia eventually yields a quaternary ammonium salt as seen in the last reaction. 45

46. Preparation of Amines Reduction of Amides Lithium aluminum hydride (LiAlH4) reduces amides to an amines. 46

47. Preparation of Amines Reduction of Nitriles Nitriles are reduced to amines using hydrogen gas and a metal catalyst. 47

48. Preparation of Amines Reduction of Aromatic Nitro Compounds Nitrobenzene is reduced to aniline which is a common aromatic amine. 48

49. Your Turn! Write the structure of an amide and a nitrile that when reduced would form 2-methyl-1-butanamine. 49

50. Your Turn! Write the structure of an amide and a nitrile that when reduced would form 2-methyl-1-butanamine. 50