1. n § 24.1 Nomenclatuur and Structure (page 1235) Polyfunctional Natural Products: Carbohydrates Chapter 24 The two enantiomers of the simplest sugar, glyceraldehyde. Fig. 24.1 C x (H 2 O) y Hydrated carbon!

2. n § 24.1 Nomenclatuur and Structure (page 1235) Polyfunctional Natural Products: Carbohydrates Glyceraldehyde is an aldotriose because it has a three- carbon backbone and an aldehyde group. Fig. 24.2 Problem 24.1* Generalize from the definition of a triose to generate the structures of an aldotetrose and an aldopentose.

3. n § 24.1 Nomenclatuur and Structure (page 1236) Polyfunctional Natural Products: Carbohydrates Aldo sugars are written with the aldehyde group at the top and the primary alcohol at the bottom. In this scheme, called a Fischer projection, horizontal bonds are taken as coming toward the viewer and vertical bonds as retreating. If the OH adjacent to the primary alcohol at the bottom is on the right, the sugar is a member of the D series. If it is on the left, it is in the L series. Fig. 24.3

4. n § 24.1 Nomenclatuur and Structure (page 1237) Polyfunctional Natural Products: Carbohydrates There is no relation between D and L and the sign of optical rotation, (+) and (-). Fig. 24.4

5. n § 24.1 Nomenclatuur and Structure (page 1237) Polyfunctional Natural Products: Carbohydrates Problem 24.2 Write three-dimensional representations for the following molecules.

6. n § 24.1 Nomenclatuur and Structure (page 1237) Polyfunctional Natural Products: Carbohydrates Problem 24.3 Write Fischer projections for the molecules in Figure 24.6

7. n § 24.1 Nomenclatuur and Structure (page 1237) Polyfunctional Natural Products: Carbohydrates The four aldotetrosesFig. 24.8 The four D-aldopentosesFig. 24.9 2 2 stereoisomers both D and L isomers shown 2 3 stereoisomers only D- diastereoisomers shown!

8. n § 24.1 Nomenclatuur and Structure (page 1238) Polyfunctional Natural Products: Carbohydrates The eight D-aldohexosesFig. 24.10 2 4 stereoisomers only D- diastereoisomers shown!

9. n § 24.1 Nomenclatuur and Structure (page 1238) Polyfunctional Natural Products: Carbohydrates D-Fructose, a common ketohexose.Fig. 24.10

10. n § 24.1 Nomenclatuur and Structure (page 1238) Polyfunctional Natural Products: Carbohydrates Problems 24.4 + 24.5 Problem 24.6 Treatment of D-glucose with sodium borohydride (NaBH 4 ) gives D- glucitol (sorbitol), C 6 H 14 O 6. Show the structure of D-glucitol and write a brief mechanism for this simple reaction

11. n § 24.1 Nomenclatuur and Structure (page 1239) Polyfunctional Natural Products: Carbohydrates Although reduction with sodium borohydride, followed by hydrolysis, proceeds normally to give an alcohol, neither NMR or IR reveals large amounts of an aldehyde in the starting material.Fig. 24.12 Why?

12. n § 24.1 Nomenclatuur and Structure (page 1239) Polyfunctional Natural Products: Carbohydrates Intramolecular hemiacetal formation is analogous to hydration and intermolecular hemiacetal formation. Five- and six-membered ring hemiacetals are easily made, and are often more stable than their open forms.Fig. 24.13

13. n § 24.1 Nomenclatuur and Structure (page 1240) Polyfunctional Natural Products: Carbohydrates Intramolecular hemiacetal formation is analogous to hydration and intermolecular hemiacetal formation. Five- and six-membered ring hemiacetals are easily made, and are often more stable than their open forms.Fig. 24.13 Example

14. n § 24.1 Nomenclatuur and Structure (page 1241) Polyfunctional Natural Products: Carbohydrates In an aldohexose, intramolecular hemiacetal formation results in a furanose (five-membered ring) or pyranose (six-membered ring)Fig. 24.14

15. n § 24.1 Nomenclatuur and Structure (page 1241) Polyfunctional Natural Products: Carbohydrates Fischer projections for D-glucofuranose and D-glucopyranoseFig. 24.5

16. n § 24.1 Nomenclatuur and Structure (page 1242) Polyfunctional Natural Products: Carbohydrates If two compounds are in equilibrium, irreversible reaction of the minor partner can result in complete conversion into a product. As long as the equilibrium exists, the small amount of the reactive molecule will be replenished as it is used up.Fig. 24.16

17. n § 24.1 Nomenclatuur and Structure (page 1242) Polyfunctional Natural Products: Carbohydrates Intramolecular hemiacetal formation results in two C(1) stereoisomers called anomers.Fig. 24.17 On the same side as attacking OH, is  -anomer! On the opposite side as attacking OH, is  -anomer!

18. n § 24.1 Nomenclatuur and Structure (page 1245) Polyfunctional Natural Products: Carbohydrates The first step in creating a three-dimensional drawing is rotation around the indicated carbon-carbon bond. This motions generates a new Fischer projection.Fig. 24.19

19. n § 24.1 Nomenclatuur and Structure (page 1245) Polyfunctional Natural Products: Carbohydrates Next, tip the molecule over in clockwise fashion to produce a flat Haworth formFig. 24.20 Problem 24.9 Draw the flat, Haworth form of the  -anomer.

20. n § 24.1 Nomenclatuur and Structure (page 1245) Polyfunctional Natural Products: Carbohydrates Now let the flat, Haworth form relax to a chair. Don’t forget that there are always two possible chair forms.Fig. 24.21 Problem 24.10* Follow this same procedure for the  -anomer.

21. n § 24.1 Nomenclatuur and Structure (page 1246) Polyfunctional Natural Products: Carbohydrates Problem 24.11 Transform the Fischer projection into a three-dimensional picture of D-mannopyranose

22. n § 24.2 Reactions of Sugars (page 1246) n § 24.2a Mutarotation of Sugars Polyfunctional Natural Products: Carbohydrates In water the  -anomer is converted into the  - anomer and visa versa. Explain!

23. n § 24.2 Reactions of Sugars (page 1246) n § 24.2a Mutarotation of Sugars Polyfunctional Natural Products: Carbohydrates The  - and  -anomers can equilibrate through the small amount of the open form present at equilibriumFig. 24.22

24. n § 24.2 Reactions of Sugars (page 1247) n § 24.2a Mutarotation of Sugars Polyfunctional Natural Products: Carbohydrates Problem 24.12* Write a mechanism for the acid-catalyzed mutarotation of D-glucopyranose (in 3-dimensional structures!)

25. n § 24.2 Reactions of Sugars (page 1246) n § 24.2b Isomerization of Sugars in Base Polyfunctional Natural Products: Carbohydrates In base, D-glucose equilibrates with D-mannose and D-fructose, a keto sugar.Fig. 24.23 Explain!

26. n § 24.2 Reactions of Sugars (page 1248) n § 24.2b Isomerization of Sugars in Base Polyfunctional Natural Products: Carbohydrates A mechanism of the equilibration of D-Glucose and D-mannose involves formation of an enolate followed by reprotonationFig. 24.24 Lobry de Bruijn-Alberda van Ekenstein reaction!

27. n § 24.2 Reactions of Sugars (page 1248) n § 24.2b Isomerization of Sugars in Base Polyfunctional Natural Products: Carbohydrates Protonation on oxygen generates a double enol, which can lead to D- fructose (or the D-aldohexoses, D-glucose, and D-mannose).Fig. 24.25

28. n § 24.2 Reactions of Sugars (page 1249) n § 24.2c Reduction Polyfunctional Natural Products: Carbohydrates Reduction of D-glucose proceeds through the small amount of the open, aldo form present at equilibrium. As the open form is used up, it is regenerated through equilibration with the pyranose form.Fig. 24.26

29. n § 24.2 Reactions of Sugars (page 1249) n § 24.2c Reduction Polyfunctional Natural Products: Carbohydrates Problem 24.15* Reduction of D-altrose with sodium borohydride in water gives an optically active molecule, D-altritol. However, the same procedure aplied to D-allose gives an optically inactive, meso hexa-alcohol. Explain.

30. n § 24.2 Reactions of Sugars (page 1250) n § 24.2d Oxidation Polyfunctional Natural Products: Carbohydrates Oxidation of an aldohexose with bromine in water gives an aldonic acid in which the end groups are still different.Fig. 24.27 Aldonic acid

31. n § 24.2 Reactions of Sugars (page 1250) n § 24.2d Oxidation Polyfunctional Natural Products: Carbohydrates Problem 24.16 Write a mechanism for this oxidation. Hint for the first step: What reaction is likely between an aldehyde and water?

32. n § 24.2 Reactions of Sugars (page 1250) n § 24.2d Oxidation Polyfunctional Natural Products: Carbohydrates Problem 24.17 Examination of the NMR and IR spectra of typical aldonic acids often shows little evidence for the carboxylic acid group. Explain this odd behavior.

33. n § 24.2 Reactions of Sugars (page 1251) n § 24.2d Oxidation Polyfunctional Natural Products: Carbohydrates Oxidation with nitric acid generates an aldaric acid in which the end groups are both carboxylic acids. Figure 24.28 Aldaric acid

34. n § 24.2 Reactions of Sugars (page 1251) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Treatment of a sugar with methyl iodide and silver oxide leads to methylation at every free hydroxyl group in the molecule. Figure 24.29 Formation of ethers via Sn2 process! Williamson ether synthesis!!

35. n § 17.10 Synthesis of Ethers from Alkoxides (pag 845) Polyfunctional Natural Products: Carbohydrates Alkoxides can displace halides in an S N 2 reaction to make ethers. This reaction is the Williamson ether synthesis. Figure 17.56 Formation of ethers via Sn2 process! Williamson ether synthesis!!

36. n § 17.10 Synthesis of Ethers from Alkoxides Polyfunctional Natural Products: Carbohydrates Alkoxides can displace halides in an S N 2 reaction to make ethers. This reaction is the Williamson ether synthesis. Figure 17.56 Formation of ethers via Sn2 process! Williamson ether synthesis!!

37. n § 24.2 Reactions of Sugars (page 1251) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates A similar process can be carried out in base with a Williamson ether synthesis. Notice in this example that neither the existing ether at C(1) nor the pyranose ring connection is disturbed in the benzylation. Figure 24.30 Formation of ethers via Sn2 process! Williamson ether synthesis!!

38. n § 24.2 Reactions of Sugars (page 1251) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates ?

39. n § 24.2 Reactions of Sugars (page 1251) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates All the free hydroxyl groups can be esterified with acetic anhydride. Figure 24.30 Formation of poly esters!

40. n § 24.2 Reactions of Sugars (page 1253) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates ?

41. n § 24.2 Reactions of Sugars (page 1253) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Treatment with dilute HCl and alcohol converts only the OH at the anomeric position [C(1)] into an acetal called a glycoside. Figure 24.32 Acetal function!

42. n § 24.2 Reactions of Sugars (page 1253) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Treatment with dilute HCl and alcohol converts only the OH at the anomeric position [C(1)] into an acetal called a glycoside. Figure 24.32 Glycoside! Why only methoxylation at the C-1 position?

43. n § 24.2 Reactions of Sugars (page 1253) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Although all OH groups can be reversibly protonated, loss of only the anomeric OH leads to a resonance-stabilized cation. Addition of alcohol at this position gives the glycoside. Figure 24.33

44. n § 24.2 Reactions of Sugars (page 1253) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Although all OH groups can be reversibly protonated, loss of only the anomeric OH leads to a resonance-stabilized cation. Addition of alcohol at this position gives the glycoside. Figure 24.33

45. n § 24.2 Reactions of Sugars (page 1254) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Methyl  - and methyl  -D-glucopyranosides.Figure 24.34

46. n § 24.2 Reactions of Sugars (page 1254) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates ?

47. n § 24.2 Reactions of Sugars (page 1254) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Hydrolysis of the fully methylated compounds leads to a hemiacetal in which only the methoxyl group at the anomeric position [C(1)] has been converted into an OH.Figure 24.35

48. n § 24.2 Reactions of Sugars (page 1254) n § 24.2e Ether and Ester formation Polyfunctional Natural Products: Carbohydrates Problem 24.18* Explain carefully why it is only the acetal methoxyl group that is converted into a hydroxyl group.

49. n § 24.2 Reactions of Sugars (page 1255) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates What product would you expect from the above reaction?

50. n § 24.2 Reactions of Sugars (page 1255) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates What product would you expect from the above reaction?

51. n § 24.2 Reactions of Sugars (page 1255) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates The small amount of free aldehyde present at equilibrium accounts for phenylhydrazone formation at C(1).Figure 24.36

52. n § 24.2 Reactions of Sugars (page 1256) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates Problem 24.14 Write a mechanism for the above reaction.

53. n § 24.2 Reactions of Sugars (page 1256) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates The actual reaction is far more complicated!

54. n § 24.2 Reactions of Sugars (page 1256) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates Osazone formation involves conversion of C(2) as well as C(1) into phenylhydrazones. Figure 24.37

55. n § 24.2 Reactions of Sugars (page 1256) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates How come?

56. n § 24.2 Reactions of Sugars (page 1256) n § 24.2f Osazone Formation Polyfunctional Natural Products: Carbohydrates The C(1) phenylhydrazone is an imine and therefore in equilibrium with an enamine. This enamine is also an enol.Figure 24.38

57. Polyfunctional Natural Products: Carbohydrates Reaction of the ketone with phenylhydrazine leads to a new phenylhydrazone that can eliminate aniline to give a new imine. Reaction with a third equivalent of phenylhydrazine leads to the osazone.Figure 24.39

58. Polyfunctional Natural Products: Carbohydrates An osazone can be formed from two different aldo sugars that are stereoisomeric at C(2). The stereochemistry at C(2) is destroyed in the reaction. Figure 24.40 n § 24.2 Reactions of Sugars (page 1257) n § 24.2f Osazone Formation Attention!!!!

59. Polyfunctional Natural Products: Carbohydrates n § 24.2 Reactions of Sugars (page 1257) n § 24.2g Methods of Lengthening and Shortening Chains in Carbohydrates

60. Polyfunctional Natural Products: Carbohydrates n § 24.2 Reactions of Sugars (page 1257) n § 24.2g Methods of Lengthening and Shortening Chains in Carbohydrates

61. Polyfunctional Natural Products: Carbohydrates A modern version of the Kiliani-Fischer synthesis generates two new sugars, each one carbon longer than the starting sugar.Figure 24.41 Kiliani-Fischer Synthesis

62. Polyfunctional Natural Products: Carbohydrates n § 24.2 Reactions of Sugars (page 1259) n § 24.2f Methods of Lengthening and Shortening Chains in Carbohydrates Problem 24.20 Apply the Kiliani-Fischer synthesis to D- glyceraldehyde. What new sugars are formed? It is not necessary to write mechanisms for the reactions.

63. Polyfunctional Natural Products: Carbohydrates n § 24.2 Reactions of Sugars (page 1259) n § 24.2f Methods of Lengthening and Shortening Chains in Carbohydrates Problem 24.21 The following two sugars are produced by Kiliani-Fischer synthesis from an unknown sugar (Fig. 24.42). What is the structure of that unknown sugar?

64. Polyfunctional Natural Products: Carbohydrates The Ruff degradation The Ruff degradation shortens the starting sugar by one carbon. It is the original aldehyde carbon that is lost!Figure 24.43 n § 24.2 Reactions of Sugars (page 1259) n § 24.2f Methods of Lengthening and Shortening Chains in Carbohydrates

65. Polyfunctional Natural Products: Carbohydrates The Ruff degradation shortens the starting sugar by one carbon. It is the original aldehyde carbon that is lost!Figure 24.43 Mechanism complicated! n § 24.2 Reactions of Sugars (page 1259) n § 24.2f Methods of Lengthening and Shortening Chains in Carbohydrates

66. Polyfunctional Natural Products: Carbohydrates n § 24.2 Reactions of Sugars (page 1260) n § 24.2f Methods of Lengthening and Shortening Chains in Carbohydrates The Wohl degradation also shortens sugars by loss of the aldehyde carbon. Figur e 24.43 The Wohl degradation

67. Polyfunctional Natural Products: Carbohydrates n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1262) His starting point: Arabinose The natural sugar arbitrarily assumed to be the D- enantiomer Accomplished by Emil Fischer in 1891 The first step in Emil Fischer’s determination of the structure of glucose. The Kiliani-Fischer synthesis applied to D-arabinose leads to D-glucose and D- mannose, which must share the partial structures shown.Figure 24.48

68. Polyfunctional Natural Products: Carbohydrates n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1263) Second step: Determining the configuration of C(2) in arabinose by oxidation Oxidation of D-arabinose leads to an optically active diacid, which shows that the OH at C(2) in D-arabinose is on the left.Figure 24.49 Only an optically active product formed

69. Polyfunctional Natural Products: Carbohydrates n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1263) Current knowledge about the structures of D-arabinose, D-glucose and D-mannose What we now know about the structures of D-arabinose, D-glucose, and D- mannose. Only the configuration at C(3) of D-arabinose, which becomes C(4) in D-glucose and D-mannose, is left to be determined.Figure 24.50

70. Polyfunctional Natural Products: Carbohydrates Third step: Determining the configuration of C(4) in glucose en mannose by oxidation Figure 24.51 If true than both diacids should be optically active upon oxidation with nitric acid! Assumption: OH on the right!

71. Polyfunctional Natural Products: Carbohydrates Third step: Determining the configuration of C(4) in glucose en mannose by oxidation Figure 24.51 If true than both diacids should be optically active upon oxidation with nitric acid!

72. Polyfunctional Natural Products: Carbohydrates Third step: Determining the configuration of C(4) in glucose en mannose by oxidation However, if the unknown OH is on the left, one possible diacid is meso, not optically active.Figure 24.52 If true than only one acid should be optically active! Assumption: OH on the left!

73. Polyfunctional Natural Products: Carbohydrates Third step: Determining the configuration of C(4) in glucose en mannose by oxidation However, if the unknown OH is on the left, one possible diacid is meso, not optically active.Figure 24.52 If true than only one acid should be optically active!

74. Polyfunctional Natural Products: Carbohydrates Conclusion: OH on the right! If the last unknown OH is on the rigtht, two optically active diacdis are produced on oxidation with nitric acid. This result matches the experimental results. Figure 24.51 Experimental Result: Both sugars gave an optically active diacid!

75. Polyfunctional Natural Products: Carbohydrates Now we know the structure of D-arabinose, L-arabinose, and the two structures (A and B) shared by D-glucose and D-mannose. We do not know which structure belongs to D-glucose and which to D-mannose Figure 24.53 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1265)

76. Polyfunctional Natural Products: Carbohydrates Oxidation with nitric acid renders the ends of a sugar equivalent. Both the aldehyde end and the primary alchohol end are converted into the same group, a carboxylic acid. Figure 24.54 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266) Two different sugars may give the same aldaric acid when oxidized!

77. Polyfunctional Natural Products: Carbohydrates n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266) Two different sugars may give the same aldaric acid when oxidized! Experimentally: Glucose gives an aldaric acid that is also obtained by oxidation of another sugar named L-Gulose

78. Polyfunctional Natural Products: Carbohydrates If D-glucose has the structure A, oxidation of another sugar, L-gulose, can give the same aldaric acid. Note in this case that the L-gulose is drawn with the CH 2 OH at the top and the CHO at the bottom. Figure 24.55 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266)

79. Polyfunctional Natural Products: Carbohydrates However, there is no sugar other than B that can give this aldaric acid. As this fact does not match the experimental results, D-glucose must have structure A. Figure 24.56 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266) If glucose would have structure B only glucose would yield this aldaric acid!

80. Polyfunctional Natural Products: Carbohydrates However, there is no sugar other than B that can give this aldaric acid. As this fact does not match the experimental results, D-glucose must have structure A. Figure 24.56 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266) However, this is not true! Conclusion: Glucose has structure A!

81. Polyfunctional Natural Products: Carbohydrates However, there is no sugar other than B that can give this aldaric acid. As this fact does not match the experimental results, D-glucose must have structure A. Figure 24.56 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1266) This outcome also reveals the structure of L-Gulose!

82. Polyfunctional Natural Products: Carbohydrates Now we know the structures of these aldohexoses and aldopentoses. Figure 24.57 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1267) Structures unraveled sofar!

83. Polyfunctional Natural Products: Carbohydrates D-Arabinose and D-ribose give the same osazone, and therefore can differ only at C(2). The structure of D-ribose is therefore known. L-Ribose is simply the mirror image of the D- isomer.Figure 24.58 n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1268)

84. Polyfunctional Natural Products: Carbohydrates n § 24.4 The Fischer Determination of the Structures of D-Glucose (and the 15 other Aldohexoses (page 1268) In a similar way the structures of all the other aldopentoses and aldohexoses were established. See Figures 24.59, 24.60, 24.61 and 24.62

85. Polyfunctional Natural Products: Carbohydrates n § 24.5 Something more: Di- and Polysaccharides (page 1270) A disaccharide How can this structure be unraveled? Examples: Disaccharides: sucrose, lactose, maltose, Polysaccharide: cellulose

86. Polyfunctional Natural Products: Carbohydrates n § 24.5 Something more: Di- and Polysaccharides (page 1270) In acid, (+)-lactose is hydrolyzed to D-glucose and D-galactose.Figure 24.63 Hydrolysis shows the individual monosaccharides!

87. Polyfunctional Natural Products: Carbohydrates Hydrolysis in dilute acid means that there must be a glycosidic linkage in (+)-lactose Figure 24.64

88. Polyfunctional Natural Products: Carbohydrates The remaining questions about the structure of (+)- lactose. Figure 24.65 n § 24.5 Something more: Di- and Polysaccharides (page 1271)

89. Polyfunctional Natural Products: Carbohydrates The acid group in lactobionic acid marks the position of the aldehyde in (+)- lactose. As hydrolysis of lactobionic acid gives a gluconic acid (not a galactonic acid), it is glucose that has the free aldehyde in (+)- lactose. Figure 24.66

90. Polyfunctional Natural Products: Carbohydrates The acid group in lactobionic acid marks the position of the aldehyde in (+)- lactose. As hydrolysis of lactobionic acid gives a gluconic acid (not a galactonic acid), it is glucose that has the free aldehyde in (+)- lactose. Figure 24.66 We still don’t know which OH is making the connection!!!

91. Polyfunctional Natural Products: Carbohydrates The position of the OH used to attach glucose to C(1) of galactose can be determined through a series of methylation and hydrolysis experiments. Figure 24.67 Methylation!

92. Polyfunctional Natural Products: Carbohydrates The position of the OH used to attach glucose to C(1) of galactose can be determined through a series of methylation and hydrolysis experiments. Figure 24.67 Methylation! Not methylated

93. Polyfunctional Natural Products: Carbohydrates A Fischer projection for (+)-lactose.Figure 24.67 n § 24.5 Something more: Di- and Polysaccharides (page 1274) Problem 24.23 Make a good three-dimensional drawing of (+)-lactose

94. Polyfunctional Natural Products: Carbohydrates n § 24.5 Something more: Di- and Polysaccharides (page 1271) No aldehyde oxidation with Br 2 /H 2 O possible!!! -> A nonreducing sugar Sucrose Suggest a basic structural feature for such a sugar

95. Polyfunctional Natural Products: Carbohydrates In nonreducing sugars, there is no free aldehyde group. Attachment must be between both C(1) atoms. Sucrose is an example. Figure 24.69 n § 24.5 Something more: Di- and Polysaccharides (page 1271) Sucrose No aldehyde oxidation with Br 2 /H 2 O possible!!! -> A nonreducing sugar

96. Polyfunctional Natural Products: Carbohydrates Cellulose and amylose Figure 24.70 n § 24.5 Something more: Di- and Polysaccharides (page 1276) Polysaccharides

97. Polyfunctional Natural Products: Carbohydrates n § 24.5 Something more: Di- and Polysaccharides n Problems 24.24; 24.25 n § 24.8 Additional Problems (page 1279) n Problems 24.27; 24.28; 24.29; 24.30; 24.31; 24.32; 24.33; 24.34; 24.37; 24.38; 24.39; 24.40; 24.42; 24.43; 24.44; 24.46; 24.48