Carbohydrates are polyhydroxy aldehydes or ketones. The most common monosaccharide is D-glucose, which cells use for energy. Carbohydrates are classified as monosaccharides (simple sugars like glucose and fructose), disaccharides (two monosaccharides joined like sucrose), oligosaccharides (3-9 monosaccharides), or polysaccharides (long chains of monosaccharides like starch, cellulose, and glycogen). D-glucose is the primary energy source in animals and plants and is stored as glycogen in animals. Common disaccharides formed from monosaccharides include sucrose from glucose and fructose, lactose from glucose and galactose, and malto

1. Carbohydrates
General molecular formula Cn(H2O)n
Appeared to be hydrates of carbon.
not all carbohydrates have this empirical formula: deoxysugars, aminosugars
Carbohydrate -polyhydroxy aldehyde, ketones.

2. General characteristics
Most carbohydrates are found naturally in bound form rather than as simple sugars
Polysaccharides (starch, cellulose, inulin, gums)
Glycoproteins and proteoglycans (hormones, blood group substances, antibodies)
Glycolipids (cerebrosides, gangliosides)
Glycosides
Nucleic acids

3. Classification of carbohydrates
Monosaccharides
Trioses, tetroses, pentoses, hexoses
Disaccharides
Maltose, sucrose, lactose
Oligosaccharides
3 to 9
Polysaccharides or glycans
Homopolysaccharides
Heteropolysaccharides

4. D-Glucose in Nature
The most abundant carbohydrate is D-glucose.
Cells of organisms oxidize glucose for energy:
In animals excess glucose is converted to a polymer called glycogen.

5. Disaccharides On hydrolysis give two molecules of monosaccharides
E.g
Sucrose (Cane sugar)
Lactose (milk sugar)
Maltose (malt sugar)

6. Polysaccharides
Starch, cellulose, glycogen
On the hydrolysis of each of them, they yields large number of monosaccharides.

7. Monosaccharides
also known as simple sugars
classified by 1. the number of carbons and 2. whether aldoses or ketoses
most (99%) are straight chain compounds
D-glyceraldehyde is the simplest of the aldoses (aldotriose)
all other sugars have the ending ose(glucose, galactose, ribose, lactose, etc…)

8. Monosaccharides
•General formula (CH2O)n
•Triose: n = 3 (e.g., glyceraldehyde)
•Tetrose: n = 4
•Pentose: n = 5 (e.g., ribose)
•Hexose: n = 6 (e.g., glucose)
•Heptose: n = 7

9. CONCEPTS OF ISOMERS Two or more different compounds which contain the same number and types of atoms and the same molecular weights.

10. Stereoisomers: Enantiomers and Diastereomers
Stereoisomers Are not constitutional isomers since they have the constituent atoms connected in the same sequence! They only differ in the arrangement of their atoms in space! Stereoisomers can be subdivided into two categories:
Enantiomers: Are stereoisomers whose molecules are mirror images of each other. (These are like our hands). The molecules of enantiomers are not superimposeable

12. Diastereomers: Are stereoisomers that are not mirror images of each other as indicated in (Fig.).

13. MonosaccharidesRepresented by Fischer projectionsEmil FischerNobel Prize 1902CCHO
CH2OH
H
OH
D-Glyceraldehyde
C
CH2OHCOHOHH

14. D- and L- Notation
 Prior to determination of absolute configurations, the
19th century chemists assigned arbitrary designations
to structures:
HC O
CH2OH
H OH
HC O
CH2OH
HO H
(R)-(+)-glyceraldehyde (S)-(–)-glyceraldehyde
D-glyceraldehyde L-glyceraldehyde

15. D-and L-Notation
If the OH group attached to the bottom-most chirality center is on the right, it is a D-sugar:
The D-or L-together with the common name of the monosaccharide completely describes the structure, since the relative configurations at all chirality centersis implicit in the common name.

16. Aldotetroses
Aldotetroses have two chirality centers
hence 22= 4 stereoisomers:

17. C
CH2OH
H OH
C O
H
H C OH
C
CH2OH
OH H
C O
H
OH C H
these two aldotetroses are enantiomers.
They are stereoisomers that are mirror
images of each other
C O
H
HO C H
HO C H
H C OH
C
CH2OH
H OH
C O
H
HO C H
HO C H
HO C H
C
CH2OH
H OH
these two aldohexoses are C-4 epimers.
they differ only in the position of the
hydroxyl group on one asymmetric carbon
(carbon 4)
Enantiomers and epimers

18. Epimers
A pair of diastereomers that differ only in the configuration about a single carbon atom are said to be epimers.
HOHOHHOHHOHHOHCH2OHHOHOHHOHHOHHOHCH2OHHOHOHHOHHOHHOHCH2OHD(+)-GalactoseD(+)-MannoseD(+)-GlucoseEpimersEpimersDiastereomers

20. POLARIMETER Dextrorotatory -plane polarized light rotated to clockwise (or to the right) Levoratatory -plane polarized light rotated to counterclockwise.

21. POLARIMETRY
Measurement of optical activity in chiral or asymmetric molecules using plane polarized light
Molecules may be chiral because of certain atoms or because of chiral axes or chiral planes
Measurement uses an instrument called a polarimeter

23. polarimetry
Magnitude of rotation depends upon:
1. the nature of the compound
2. the length of the tube (cell or sample container) usually expressed in decimeters (dm)
3. the wavelength of the light source employed; usually either sodium D line at 589.3 nm or mercury vapor lamp at 546.1 nm
4. temperature of sample
5. concentration of analyte in grams per 100 ml

24. []D
T
l x c
 observed x 100
=
D = Na D line
T = temperature oC
 obs : observed rotation in degree (specify solvent)
l = length of tube in decimeter
c = concentration in grams/100ml
[] = specific rotation

25. Specific rotation of various carbohydrates at 20oC
D-glucose+52.7
D-fructose-92.4
D-galactose +80.2
L-arabinose+104.5
D-mannose+14.2
D-arabinose-105.0
D-xylose+18.8
Lactose+55.4
Sucrose+66.5
Maltose++130.4
Invert sugar-19.8
Dextrin+195

26. Most common monosaccharide. Commercially from starch. Mutarotation ---The optical changes of glucose in water solution to constant value 20D= +520 -D -glucose ->D -glucose <-b-D -glucose 20D= 11320D= 5220D= = 19At equilibrium = 35% of -form and 65% of b-form. Glucose (dextrose)

27. MONOSACCHARIDE
Hexoses
1. Glucose(dextrose) ---rotate the polarized light to the right.
OHOHCHHCOHCHHHOHCCH2OHOCOHOOHOHHOCH2OH123456

28. 3.Fructose (levulsoe) ---Rotation in polarimeter is left
D-Fructoseb-D-Fructose-D-Fructose
CH2OHOCH2OHCHOHCOHCHHCOHOCH2OHCHOHCOHCHHCCH2OHCH2OHCHHOHCOHCHHOCOHCH2OHOor

29. b - D - Fructofuranose  - D - Fructofuranose
O
HO
OH
CH2OH
HOCH2 OH
O
HO
OH
HOCH2
CH2OH
OH
Fructose (levulsoe)

30. Hexoses C6H12O6CCCCHOCCH2OHOHHHOHHOHHOHD- Glucose

31. Oxidation reactions
Aldoses may be oxidized to acids
Aldonic acids: aldehyde group is converted to a carboxyl group ( glucose –gluconic acid)
Saccharic acids(glycaric acids) –oxidation at both ends of monosaccharide)
Glucose ----saccharic acid
Galactose ---mucic acid
Mannose ---mannaric acid

32. Oxidation Reactions:1-Nitric acid, HNO3: Nitric acid is a potent oxidizing reagent and will convert both aldehydes into carboxylic acids. This usually results in the conversion of an aldose into a dicarboxylic acid derivative:ose/aric

33. b-Conc. HNO3CCCCHOCCH2OHOHHHOHHOHHOHglucoseconc. HNO3CCCCOOHCCOOHOHHHOHHOHHOHsaccharic acid

34. CCCCH2OHCCH2OHOHHHOHHOHOD- fructoseCOOHCCCOOHOHHHOHmeso-tartaric acidConc. HNO3CH2OHCOOH+ glycollic acid

35. Bromine water
Ose/onic
HOHOHHOHHOHHOHCH2OHD(+)-GlucoseBr2/H2OHOHOHOHOHHOHHOHCH2OHGluconic acid

36. Monosaccharides are further classified as reducing or non-reducing sugars according to their behaviour toward Ag(I) (Tollens’ solution) or Cu(II) (Benedict’s solution). Both Tollens’ and Benedict’s tests are visual tests for aldehyde groups which, when oxidized to carboxylic acids, reduce the silver or copper ions yielding metallic silver metal or red copper(I)oxide precipitates (Fig.).

37. Effect of Ba(OH)2 or Ca(OH)2
The alkaline reaction conditions facilitate the a tautomeric equilibrium between the enol and keto forms of the open-chain structure. Enolization may result in the formation of glucose from fructose, mannose or vice versa.

38. HOHOHOHHHOHHOHCH2OHOHHOHOHHHOHHOHCH2OHD-MannoseD-GlucoseCCHOHOHHHOHHOHCH2OHHOHCOOHHHOHHOHCH2OHHHOHD-Fructose1,2-Enediol

39. Acylation of monosaccharides
Reaction with acetic anhydride: the alcohol groups of sugars react with acetic anhydride to make ester derivatives.

40. Reduction
either done catalytically (hydrogen and a catalyst) or enzymatically
the resultant product is a polyol or sugar alcohol (alditol)
glucose form sorbitol (glucitol)
mannose forms mannitol
fructose forms a mixture of mannitol and sorbitol
glyceraldehyde gives glycerol

41. Reaction of carbonyl groupsCCCCHOCCH2OHOHHHOHHOHHOHD- GlucoseCCCCH2OHCCH2OHOHHHOHHOHHOHsorbitolNa/Hg

42. CCCCH2OHCCH2OHOHHHOHHOHOD- fructoseCCCCH2OHCCH2OHOHHHOHHOHHOHsorbitolNa/HgCCCCH2OHCCH2OHOHHHOHHOHHOH+ mannitol

44. Reaction with HCN give cyanohydrinCCCCHOCCH2OHOHHHOHHOHHOHD- GlucoseCCCCCH2OHOHHHOHHOHHOHGlucose cyanideHCNCNOHH

45. Reaction with hydroxylamineCCCCHOCCH2OHOHHHOHHOHHOHD- GlucoseNH2OH. HClCCCCHCCH2OHOHHHOHHOHHOHGlucose oximeNOH

46. Formation of osazones
once used for the identification of sugars
consists of reacting the monosaccharide with phenylhydrazine
a crystalline compound with a sharp melting point will be obtained
D-fructose and D-mannose give the same osazone as D-glucose
seldom used for identification; we now use HPLC or mass spectrometry

47. Formation of OsazoneC(CHOH)3CHOHOHD- GlucoseCH2OHPhNHNH2C(CHOH)3CH=NHNHPhHOHCH2OHPhNHNH2C(CHOH)3CH=NHNHPhOCH2OHPhNHNH2C(CHOH)3CH=NHNHPhNHNHPhCH2OHOsazoneC(CHOH)3CH2OHOD- fructoseCH2OHPhNHNH2C(CHOH)3CH2OHNHNHPhCH2OHPhNHNH2C(CHOH)3CHONHNHPhCH2OHPhNHNH2

49. Formation (Glycosides).
Acetal derivatives formed when a monosaccharide reacts with an alcohol in the presence of an acid catalyst are called glycosides. "ose" suffix of the sugar name is replaced by "oside", and the alcohol group name is placed first

50. Sucrose
-D-glucopyranosido-b-D-fructofuranoside
b-D-fructofuranosido--D-glucopyranoside
sugar cane or sugar beet
hydrolysis yield glucose and fructose (invert sugar) ( sucrose: +66.5o; glucose +52.5o; fructose –92o)
used pharmaceutically to make syrups, troches

51. Sugar caneSugar beet

52. Sucrose2-0--D-Glucopyranosyl b-D-Fructofuranoside OOHOHHOCH2OHCH2OHOCH2OHOHOOHH123456

53. Lactose
b-D-galactose joined to -D-glucose via b(1,4) linkage
milk contains the and b-anomers in a 2:3 ratio
b-lactose is sweeter and more soluble than ordinary -lactose
used in infant formulations, medium for penicillin production and as a diluent in pharmaceuticals

54. LactosePrincipal sugar in milk OOHOHCH2OHOOHOHCH2OHOOHOH

55. Maltose
2-glucose molecules joined via (1,4) linkage
known as malt sugar
produced by the partial hydrolysis of starch (either salivary amylase or pancreatic amylase)

56. Disaccharides (anydrides of 2 monosaccharides): Maltose: 4-0--D-Glucopyranosyl (1->4) -D- Glucopyranose OOHOHHOCH2OHOOHOHCH2OHOOH

57. Cellobiose4-0-b-D-Glucopyranosyl (1->4)-b-D-Glucopyranose OOHOHHOCH2OHOOHOHCH2OHOOH

58. Sucralfate (Carafate)

59. Polysaccharides
homoglycans (starch, cellulose, glycogen, inulin)
heteroglycans (gums, mucopolysaccharides)
characteristics:
polymers (MW from 200,000)
White and amorphous products
not sweet
not reducing; do not give the typical aldose or ketose reactions)
form colloidal solutions or suspensions

60. Starch
most common storage polysaccharide in plants
composed of 10 –30% -amylose and 70-90% amylopectin depending on the source
the chains are of varying length, having molecular weights from several thousands to half a million

61. The reserve carbohydrate of plants. Occurs as granules in the cell. Made of amylose and amylopectin. Amylose---ploymer of -D-Glucose (1->4) linkage- straight-chain. STARCH OOHOHCH2OHOHOOOOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OH

62. Amylose and amylopectin are the 2 forms of starch. Amylopectinis a highly branched structure, with branches occurring every 12to 30 residues

63. suspensions of amylosein water adopt a helicalconformationiodine (I2) can insert inthe middle of the amylosehelix to give a blue colorthat is characteristic anddiagnostic for starch

64. (in starch) (in cellulose)

65. Cellulose
Polymer of b-D-glucose attached by b(1,4) linkages
Yields glucose upon complete hydrolysis
Partial hydrolysis yields cellobiose
Most abundant of all carbohydrates
Cotton flax: 97-99% cellulose
Wood: ~ 50% cellulose
Gives no color with iodine
Held together with lignin in woody plant tissues

66. POLYSACCHARIDECellulose---polymer of b-D-Glucose (1, 4) linkage. Repeating cellobiose moiety. OOHOHCH2OHOHOOOOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHOOHOHCH2OHn

67. Structure of cellulose

68. Glycogen
also known as animal starch
stored in muscle and liver
present in cells as granules (high MW)
contains both (1,4) links and (1,6) branches at every 8 to 12 glucose unit
complete hydrolysis yields glucose
glycogen and iodine gives a red-violet color
hydrolyzed by both and b-amylases and by glycogen phosphorylase

69. GLYCOGENAnimal starch. -(1 ->4) linkage and -(1 -> 6) linkage12:1

70. RELATIVE SWEETNESS OF DIFFERENT SUGARSSucrose100Glucose74Fructose174Lactose16Invert Sugar126Maltose32Galactose32

71. CARBOHYDRATE DETERMINATION1.Monosaccharides and OligosaccharidesA.Enzymatic Method1.Glucose oxidase2.HexokinaseB.Chromatography Method1.Paper or thin layer chromatography2.Gas chromatography3.Liquid column chromatography2.Polysaccharides

72. Glucose Oxidase System Glucose OxidaseD-Glucose + O2Gluconic Acid + H2O2PeroxidaseH2O2+ 0 -Dianisidine 2 H2O + Oxidized 0-Dianisidine(Colorless) (Brown) OCH3H3COH2NNH2H3COOCH3HNNH

73. Synthetic Sweeteners