1. Carbohydrates

2. Carbohydrates - Definition
Carbohydrates are polyhydroxy aldehydes, or ketones or substances that hydrolyze  polyhydroxy aldehydes & ketones.
They usually contain H & O in the same ratio as in H2O (2:1).
Thus, the name “carbohydrates” indicates that these compounds are “hydrates of carbon”.
Carbohydrates have the general formula:
Cx(H2O)Y where X = Y e.g. hexoses C6(H2O)6

4. Monosaccharides Aldoses are monosaccharides with an aldehydic
Three carbons = Triose
Four carbons = Tetrose
Five carbons = Pentose
Six carbons = Hexose
Aldoses are monosaccharides with an aldehydic
group & many hydroxyl (-OH) groups
Ketoses are monosaccharides with a ketonic
group & many hydroxyl (-OH) groups

7. Most important Physical Properties
Solubility:
Monosacch are sol in cold water & hot alcohol.
Gums are sol in water & insoluble in alcohol.
Inulin, starch, pectin, mucilage & glycogen are more sol in hot than cold water & insol in alcohol.
Pentosans, galactans, mannans & hemicelluloses are insol in cold & hot water but sol in dilute alkalis.
Cellulose is insol in all the previous solvents.

8. Optical activity
Polarimetry = Measurement of optical activity for chiral or asymmetric molecules using plane of polarized light
Instrument: “polarimeter”
Specific rotation is either (+) = dextrorotatory (d) or (-) = levorotatory (l)
Optical Activity Optical activity is the ability of a chiral molecule to rotate the plane of plane-polairsed light, measured using a polarimeter.  A simple polarimeter consists of a light source, polarising lens, sample tube and analysing lens.
When light passes through a sample that can rotate plane polarised light, the light appears to dim because it no longer passes straight through the polarising filters.  The amount of rotation is quantified as the number of degrees that the analysing lens must be rotated by so that it appears as if no dimming of the light has occurred.   Measuring Optical Activity
When rotation is quantified using a polarimeter it is known as an observed rotation, because rotation is affected by path length (l, the time the light travels through a sample) and concentration (c, how much of the sample is present that will rotate the light).  When these effects are eliminated a standard for comparison of all molecules is obtained, the specific rotation, [a].
[a] = 100a / cl    when concentration is expressed as g sample /100ml solution Specific rotation is a physical property like the boiling point of a sample and can be looked up in reference texts.    Take a look at a problem. Enantiomers will rotate the plane of polarisation in exactly equal amounts (same magnitude) but in opposite directions.
Dextrorotary designated as d or (+), clockwise rotation (to the right) Levorotary designated as l or (-), anti-clockwise rotation (to the left) If only one enantiomer is present a sample is considered to be optically pure.  When a sample consists of a mixture of enantiomers, the effect of each enantiomer cancels out, molecule for molecule. For example, a 50:50 mixture of two enantiomers or a racemic mixture will not rotate plane polarised light and is optically inactive.  A mixture that contains one enantiomer excess, however, will display a net plane of polarisation in the direction characteristic of the enantiomer that is in excess.
Determining Optical Purity
The optical purity or the enantiomeric excess (ee%) of a sample can be determined as follows:
Optical purity = % enantiomeric excess = % enantiomer1 - % enantiomer2                      = 100 [a]mixture / [a]pure sample
ee%  =  100 ([major enantiomer] - [minor enantiomer]) / ([major enantiomer] + [minor enantiomer])
where [major enantiomer] = concentration of the major enantiomer           [minor enantiomer] = concentration of the minor enantiomer
Look at some problems like these more in depth. Diasteromeric substances can have different rotations both in sign and in magnitude. 

9. Optical activity is the ability of a chiral molecule to rotate the plane of plane-polairsed light, measured using a polarimeter. 
Polarized light =Light that is reflected or transmitted through certain media so that all vibrations are restricted to a single plane.

10. Mutarotation Mutarotation [α]°C = [α]°C = [α]°C [α]°C [α]°CD D
[α]°C D
[α]°C
[α]°C
At equilibrium = +52.5° D

11. Cyclic Structure of Monosaccharides
Hemiacetal Formation
anomer
anomer
The specific rotation of pure a-D-glucose or b-D-glucose
changes over time to reach an equilibrium (mutarotation)

12. Mutarotation
Glucose (Glc) exists in 2 pure forms ( &  anomers): -glucose: specific rotation (D): +112o, -glucose: D +18.7o.
When either form of Glc ( &  ) is allowed to stand in aq solution, D of solution is slowly changed to o this due to interconversion between - & - anomers.
“Mutarotation” = change in optical rotation, observed on standing, in a sugar solution & produced as a result of equilibration between the 2 anomers ( & ) and the aldehydic form.

14. Anomeric centre (alpha and beta)
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This page has been approved by the Responsible Curator as essentially complete. CAZypedia is a living document, so further improvement of this page is still possible. If you would like to suggest an addition or correction, please contact the page's Responsible Curator directly by , or using this form. Author: Stephen Withers
Responsible Curator: Spencer Williams
The anomeric centre of a sugar is a stereocentre created from the intramolecular formation of an acetal (or ketal) of a sugar hydroxyl group and an aldehyde (or ketone) group. The two stereoisomers formed from the two possible stereochemistries at the anomeric centre are called anomers. They are diastereoisomers of one another.
The configuration at the anomeric centre (that derived from the carbonyl carbon) is denoted alpha- (α-) or beta- (β-) by reference to the stereocentre that determines the absolute configuration. In a Fischer projection, if the substituent off the anomeric centre is on the same side as the oxygen of the configurational (D- or L-) carbon, then it is the α--anomer. If it is directed in the opposite direction it is the β-anomer.
Example 1. Fischer projections and Haworth conformational projections of L-arabinose.
Example 2. Fischer projections and Haworth conformational projections of D-fructose. In the case of D-hexopyranoses drawn in the 'usual' Haworth projection, the α-D-anomer is the isomer with the anomeric substituent on the opposite face to the C5 (hydroxymethyl) substitutent, ie directed ‘down’; the β-D-anomer is that with the anomeric substituent being on the same face as the C5 hydroxymethyl substitutent, ie directed up. For L-hexoses the α-L-anomer has the anomeric group pointing up; the β-L-anomer has this group pointing down.
Example 3. Fischer projections and Haworth conformational projections of D-glucose. References
Robert V. Stick, Spencer J. Williams. Carbohydrates. Amsterdam; Elsevier, ISBN: [StickWilliams2009]

15. Carbohydrates Chemistry

16. D & L Notation
D & L indicate the configuration of the –OH group on the chiral carbon farthest away from the carbonyl group i.e. next to the bottom carbon atom
If the –OH group points to the right, it is a D-isomer
If it points to the left, it is L-isomer
The D form is the isomer usually found in nature.
Configuration of glyceraldehyde:
The simplest monosaccharide, which contains only one chiral center, is glyceraldehyde & it exists in 2 enantiomeric (21 = 2) mirror image forms

17. The D- family of aldohexoses:
D (+) glucose has 4 chiral centers & exists as 24 = 16 (2n, n=4) possible stereoisomers (8 for the D & 8 for the L series).

18. Cyclic Structures Structural Biochemistry/Carbohydrates/Aldoses
An Aldose contains an aldehyde with two or more hydroxyl groups attached; one of the hydroxyl groups is at end opposite to the aldehyde. An Aldose is a type of monosaccharides, which is a chiral molecule that plays a key role in the development of nucleic acids. The two simplest forms of Aldoses are L- and D-Glyceraldehydes, which are three-carbon structures that each contain one aldehyde and two hydroxyl groups. The L and D symbols apply to the two different configurations of the asymmetric carbon farthest from the aldehyde group.
D-Ribose
In the figure below, the common D-aldose sugars are shown:
D-Aldoses containing three, four, five and six carbon atoms
Family Tree of D-Aldoses.jpg
The Aldoses: triose, tetroses, pentoses, and hexoses
Hemiacetal
The carbonyl group in aldehydes and ketones may react with one molecule of alcohol to form a hemiacetal. The ‘-OR’ group in alcohol attacks the carbonyl carbon in aldehydes or ketones, thus breaking the ‘C-O’ double bond. Proton transfer either intramolecularly or via solvent completes the reaction. Hemiacetal formation may be either acid or base catalyzed. Under acidic condition, however, the carbonyl group may react one more time when alcohol is in excess to form an acetal. The following two diagrams depict an example of hemiacetal and acetal found in carbohydrates.
The red arrows shown in the Fischer projection of a glucose molecule demonstrate the brief overview of mechanism for the hemiacetal formation. The (*) mark on the oxygen of aldehyde indicates the position of the oxygen after the ring formation, while the numbers on each stereocenters indicate the position of each carbon.
HemiacetalFormation
Ring formation
Most of the sugars form cyclic rings, which are more stable than the open chain form. To enable ring formation, the aldehyde can react with an alcohol to form a hemiacetal. Carbohydrates may form either five or six membered rings depending on which hydroxyl group undergoes the hemiacetal formation. A five membered ring is called furanose, while a six membered ring is called pyranose. Furanoses form when the hydroxyl group on C4 reacts with the carbonyl group, while pyranoses form when the hydroxyl group on C5 reacts. This forms the intramolecular hemiacetal in the ring structure. In carbohydrates, the hemiacetal/acetal carbon (C1) in cyclic form is called the anomer. This carbon may be labeled as α or β depending on the position of the (*)-labeled oxygen in the figure. If the (*)-labeled oxygen in the picture is above the ring, the anomeric carbon is labeled as β. If below, it is labeled as α. The following is the formation of a five membered ring by a glucose molecule:

19. Cyclic Structures Monosaccharides with 5 & 6 carbon atoms form cyclic
The hydroxyl group on C-5 reacts (addition reaction 
hemiacetal) with the aldehyde group or ketone group
at C-1 or C-2

20. Cyclic Structures

21. Linear & cyclic structures of glucose

22. Abbreviated structures of a-D-glucose
 anomer
Haworth Structure for D-Glucose
–OH groups on the right (C-2, C-4) Down
–OH groups on the left (C-3)  UP
–OH group at C-1 has 2 possibilities:
Down   anomer & Up   anomer

24. Conclusion: Pyranose & Furanose Structures of Monosaccharides
Hexoses do not exist most of the time as straight chain aldehydes or ketones but many evidences indicate the presence of an equilibrium between a straight chain & a cyclic structure.
Reaction between the aldehyde or keto group & the hydroxyl group at C-5 or C-4 result in hemiacetal formation & the cyclic structure is either pyranose (C1-C5) or furanose (C1- C4) or (C2-C5, in case of ketoses).

25. (α) D-glucopyranose (exists as hemiacetal).
e.g.
(α) D-glucopyranose (exists as hemiacetal).
(β) D-glucopyranose (exists as hemiacetal).
(β) D-fructofuranose (exists as hemiketal).

26. Reactions of
Monosaccharides

27. Oxidation reactions
Oxidation of aldoses may result into 3 types of acids
CHO COOH
■ Aldonic acids:
Aldehydic group oxidised  carboxyl group (COOH)
glucose  gluconic acid
■ Uronic acids:
Aldehydic group is maintained intact & 1ry alcoholic gp (at C-6 in Glc) oxidised  COOH
glucose  glucuronic acid
galactose  galacturonic acid
■ Aldaric acids:
Oxidation at both ends of the monosaccharide
Glucose  Saccharic or glucaric acid
Galactose  Mucic acid

28. Oxidation The aldehyde groups can be oxidized by Br2
Ketones and alcohols cannot be oxidized by Br2

29. A strong oxidizing agent such as HNO3 can oxidize the
aldehyde and the alcohol groups

30. Preparation of the Calcium D-Gluconate for the Ruff Degradation

31. Importance of Gluconates
Mineral gluconate salts are used as nutritional supplements (nutraceuticals) & in case of mineral deficiency as they are more easily adsorbed than other mineral salts. Examples:
Calcium Gluconate (Monohydrate) - USP
Calcium Gluconate (Anhydrous) - USP
Copper Gluconate- USP
Ferrous Gluconate – USP
Magnesium Gluconate - USP
Manganese Gluconate (Anhydrous) - USP
Potassium Gluconate (Anhydrous) - USP
Zinc Gluconate - USP

32. Reduction reactions
■ Either done catalytically (hydrogen & a catalyst) or enzymatically
■ The resultant product is a polyol or sugar alcohol (alditol)
■ Glucose  Sorbitol (glucitol)
■ Mannose  Mannitol
■ Fructose  Mannitol + Sorbitol
■ Galactose  Dulcitol

34. Sugar alcohols are very useful intermediates
Mannitol is used as osmotic diuretic
Mannitol hexanitrate used as vasodilator
Osmotic diuretics are freely filterable, low molecular weight substances that due to their limited reabsorption and small size create an osmotic force in the tubular fluid sufficient to retard the reabsorption of fluids and solutes (notably NaCl) along the nephron. Thus, osmotic diuresis results in urinary loss of water and sodium.
Mannitol might inhibit paracellular reabsorption of water and sodium chloride in the proximal tubules by reducing the osmotic driving force. We examined this hypothesis in anesthetized dogs. Bicarbonate reabsorption was kept constant by sodium bicarbonate infusion, and transcellular sodium chloride reabsorption was inhibited by ethacrynic acid. The glomerular filtration rate (GFR) was varied by altering renal perfusion pressure. Mannitol infusion reduced sodium chloride reabsorption from 62 +/- 5% to 33 +/- 5% of the filtered load. The calculated increase in reabsorbate osmolality, averaging 82 +/- 6 mOsm/kg H2O, was due to sodium bicarbonate and equalled the increase in plasma osmolality. Mannitol concentration averaged 81 +/- 7 mM in plasma and 101 +/- 12 mM in urine. A linear relationship between reabsorption and GFR (glomerulo-tubular balance) was maintained over the same range of GFR before and after mannitol infusion. Mannitol infusion reduced sodium chloride reabsorption from 2.6 to 1.4 moles for each mole of sodium bicarbonate reabsorbed. During mannitol infusion, acetazolamide inhibited sodium bicarbonate reabsorption as in control experiments, but reduced sodium chloride reabsorption less. We conclude that reduced water reabsorption increases sodium bicarbonate concentration in the paracellular fluid as much as mannitol concentration is raised in the plasma and glomerular filtrate. Along the proximal tubules, net osmotic force is progressively reduced as mannitol concentration rises, accounting for reduced water and sodium chloride reabsorption.
PMID: 

35. ■ Sorbitol is a mild laxative ■ Sorbitol is dehydrated 
1,4,3,6-dianhydro-D-sorbitol
(isosorbide) used as nitrate in
treatment of angina

36. Reaction with phenylhydrazine (Osazone)
An aldose reacts with 3 molecules ofNH2NHph phenylhydrazine  crystalline phenylosazone.(condensation, dehydrogenation, oxidation then condensation)
This results in loss of the chiral center at C-2.
The C-2 epimers glucose & mannose  same osazone as fructose, the ketohexose at C-2
Maltosazone
Lactosazone
Glucosazone
Galactosazone

37. The reaction is stepwise
First phenylhydrazine is involved in oxidizing the alpha carbon to a carbonyl group, and the second phenylhydrazine involves in removal of one water molecule with the formyl group of that oxidized carbon and forming the similar carbon nitrogen bond. The alpha carbon is attacked here because its more reactive than the others.

38. Osazone Formation Aldoses and ketoses react with three equivalents of
phenylhydrazine

39. Action of mineral acids:
Treatment with hot conc mineral acid (HCl or H2SO4) leads to dehydrated sugars (Deh-Sug).
Pentoses and methylpentoses + HCL give furfural & methylfurfural, while hexoses give hydroxymethylfurfural.
The formation of furfural derivatives is the basis of the color reactions used for qualitative and quantitative determination of monosaccharides by coupling with phenolic compounds or amines.
Examples:
Molisch’s test: Dehydrated Sugar + phenol e.g. -naphthol.
Seliwanoff’s test: Dehydrated Sugar + resorcinol.
Bial’s test: Dehydrated Sugar + orcinol.
Aniline acetate paper test: Dehydrated Sugar + amine e.g. aniline.

40. Furfural is an organic compound derived from a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latinword furfur, meaning bran, referring to its usual source.

41. Seliwanoff's test with fructose as example

42. Reaction with oxidizing cations:
All monosaccharides and reducing disaccharides (i.e all sugars containing free hemiacetal or hemiketal groups) are readily oxidized by metal ions such as Cu+2 e.g. Fehling’s and Benedict’s reagents, Bi+3 and Hg+2 in alkaline medium.
This reaction is used for identification and quantification of reducing sugars.

43. Reduction of Fehling's solution: Reducing sugar Cu2+ + e- Cu2O ¯
Molisch's test:
Reduction of Fehling's solution:
Reducing sugar
Cu2+ + e Cu2O ¯
The compound to be tested is added to the Fehling's solutionand the mixture is heated. Aldehydes are oxidized, giving a positive result, but ketones do not react, unless they are alpha-hydroxy-ketones. ... Fehling's test can be used as a generic test for monosaccharides and other reducing sugars (e.g., maltose).
Osazone test:
C=O + phenyl hydrazine
Phenyl hydrazone
Phenyl hydrazone + 2 phenyl hydrazine
osazone

46. Monosaccharides
A) Pentoses: arabinose, xylose, apiose

47. Monosaccharides - Pentoses
D-Apiose
(branched sugar)
 -D-Xylose
(wood sugar)
-L-Arabinose
(Pectin sugar)
Name
Obtained by hydrolysis of the flavone glycoside, apiin, present in the leaves & seeds of parsley
Obtained by hydrolysis of polysaccharides in:
Corncobs
Bran
Straw
woody material
Gums
Pectic substances
Hemicelluloses
Source
Structural comparison to cellulose. Unlike cellulose, hemicellulose (also a polysaccharide) consists of shorter chains – 500–3,000 sugar units as opposed to 7,000–15,000 glucose molecules per polymer, as seen in cellulose. In addition,hemicellulose is a branched polymer, while cellulose is unbranched.
Gum arabic
Parsley
Corncobs
Wheat bran

48. B) Hexoses (Aldohexoses)

49. -D-Glucose
(dextrose, grape sugar, blood sugar)

50. Preparation: Uses of glucose:
D-Glucose is commercially prepared from starch by acid hydrolysis using dil HCl:
Uses of glucose:
As nutrient by mouth, enema, or
As IV injection (dextrose or dextrose /saline).
- Commercially in the manufacture of candy, carbonated beverages, ice cream, bakery products & in the canning industry.

51. Liquid glucose Colorless, sweet, & H2O-miscible syrupy liquid.
Prepared by partial acid hydrolysis of starch using dil HCl & heating. (20Min.)
Consists of a mixture of glucose, maltose,
dextrin & water.
Used as sweetening agent, as substitute
for sucrose and as an excipient in massing pills.

52. Ketohexoses (Fruit sugar) Source:
Fructose, D-fructose, levulose, -D(-) fructofuranose
(Fruit sugar)
Source:
It is found free in honey & in fruits juices, or as constituent of polysaccharide e.g. inulin.

53. Preparation of fructose
■ From glucose:
By the action of NaOH (epimerization)
■ From sucrose:
After inversion of aqueous solutions of sucrose then separation of fructose from glucose by treatment with Ca(OH)2 (Ca fructosate precipitate)
■ From Inulin: by acid hydrolysis.
A fructosan polymer characteristic of certain plants of family Asteraceae e.g. Jerusalem artichoke & chicory
epimerization (countable and uncountable, plural epimerizations)
(chemistry) The process of forming an epimer by changing one asymmetric centre in a compound that has more than one

54. Uses of fructose
As food for diabetics (in emergencies of diabetic acidosis) & in infant feeding formulae (being more easily digested than glucose).
Diabetic ketoacidosis (DKA) is a potentially life-threatening complication in patients with diabetes mellitus. It happens predominantly in those with type 1 diabetes, but it can occur in those with type 2 diabetes under certain circumstances. DKA results from a shortage of insulin; in
response the body switches to burning fatty acids and producing acidic ketone bodies that cause most of the symptoms and complications.[1]
DKA may be the first symptom of previously undiagnosed diabetes, but it may also occur in people known to have diabetes as a result of a variety of causes, such as inter current illness or poor compliance with insulin therapy.Vomiting, dehydration, deep gasping breathing, confusion and occasionally coma are typical symptoms. DKA is diagnosed with blood and urine tests; it is distinguished from other, rarer forms of ketoacidosis by the presence of high blood sugar levels. Treatment involves intravenous fluids to correct dehydration, insulin to suppress the production of ketone bodies, treatment for any underlying causes such as infections, and close observation to prevent and identify complications
The metabolism of fructose is largely insulin-independent, although the ultimate fate of fructose carbons is determined by the presence or the absence of insulin.
Clinical and experimental work has suggested that fructose may exert beneficial effects as a component of the diet for patients with mild and well-balanced diabetes.
Fructose is absorbed slowly from the gut, and does not induce drastic changes in blood sugar levels.
Secondly, fructose is metabolized by insulin-independent pathways in the liver, intestinal wall, kidney and adipose tissue.
As a consequence of the rapid and efficient utilization of fructose, it has been used widely for intravenous feeding in medicine and surgery. However, it has been shown that the rapid infusion of large amounts of fruetose may cause accumulation of lactic acid in the extracellular fluid. The possibility of lactate acidosis, with concomitant impairment of the acid-base balance, already disturbed, constitutes a relative contraindication to the use of intravenous fructose in the treatment of diabetic ketoacidosis.
Fructose is known to accelerate ethanol metabolism in the liver. No well-documented reports on the use of fructose in the treatment of ethanol intoxication have been published, although it has recently been suggested that fructose might be of value in the treatment of delirium tremens.
Fructose may be less cariogenic than sucrose, at least in short-term experiments. Long-term trials are lacking, and thus the potential advantages of fructose in preventive odontology have not been determined.
Fructose does not seem to have any side-effects when used in reasonable amounts. However, it has been reported that the administration of fructose in large amounts induces hyperlipidemia both in man and in experimental animals. Earlier suggestions concerned with the atherogenic properties of fructose have recently been challenged. The apparent increase in the incidence of coronary disease among sucrose users seems to be a statistical artefact, caused by the increased ingestion of coffee and soft drinks by cigarette smokers.

55. Deoxy sugars (Desoxy sugars)

56. -L-Rhamnose (6-deoxy-L-mannose)
6-Deoxy-hexoses (Methyl pentoses or hexomethyloses)
-L-Rhamnose (6-deoxy-L-mannose)

57. 2,6-Deoxy-hexoses Test for 2,6-Deoxy sugar, Keller Killiani
D-Digitoxose: a component of the sugar part of Digitalis glycosides (digitoxin, gitoxin and digoxin).
D-Cymarose: 3-methyl ether of digitoxose and is found in cymarin (Strophanthus glycoside).
L-Oleandrose: obtained from oleandrin (Nerium oleander glycoside).
1 g powder in 10ml 70% alcohol is boiled for 2-3 min.5ml water and 5ml strong lead acetate solution is added to the filtrate.The clear filtrate is treated with equal volume of chloroform and evaporated.The extract is dissolved in glacial acetic acid and on cooling 2drops of ferric chloride is added.These contents are transferred to 2ml conc.sulphuric acid. A reddish brown layer acquires bluish green coplor appears due to presence of digitoxose.
Test for 2,6-Deoxy sugar, Keller Killiani
Gives intense blue color develops at the surface between the two layers

59. Disaccharides →4 = refers to OH at carbonnumber-4 → glycosidic bond
■ Formed of 2 monosaccharides through a
glycosidic bond  acetal linkage
■ Through OH of anomeric carbon and any other OH
■ In the reaction there is loss of elements of H2O
■ Anomeric carbon gets fixed / locked into either α or β configuration (can’t mutarotate)
e.g. a (1→4) linkage
a = configuration of the anomeric carbon
1 =OH at the anomeric carbon number-1
→4 = refers to OH at carbonnumber-4 → glycosidic bond
In chemistry vicinal (from Latin vicinus = neighbor), abbreviated vic, describes any two functional groups bonded to two adjacent carbon atoms (i.e., in a 1,2-relationship). For example, the molecule 2,3-dibromobutane carries two vicinal bromine atoms and 1,3-dibromobutane does not.
Likewise in a gem-dibromide the prefix gem, an abbreviation of geminal, signals that both bromine atoms are bonded to the same atom (i.e., in a 1,1-relationship). For example, 1,1-dibromobutane is geminal. While comparatively less common, the term hominal has been suggested as a descriptor for groups in a 1,3-relationship.[1]
Like other such concepts as syn, anti, exo or endo, the description vicinal helps explain how different parts of a molecule are related to each other either structurally or spatially. The vicinal adjective is sometimes restricted to those molecules with two identical functional groups. The term can also be extended to substituents on aromatic rings.
See also[edit]

60. Non-reducing disaccharides
Sucrose (Saccharose, Table sugar, Cane Sugar, Beet sugar), commercially obtained from sugar cane or sugar beet
Fehling's is always prepared fresh in the laboratory. It is made initially as two separate solutions, known as Fehling's A and Fehling's B. Fehling's A is a blue aqueous solution ofcopper(II) sulfate, while Fehling's B is a clear solution of aqueous potassium sodium tartrate (also known as Rochelle salt) and a strong alkali (commonly sodium hydroxide).
Equal volumes of the two mixtures are mixed to get the final Fehling's solution, which is a deep blue colour. In this final mixture, aqueous tartrate ions from the dissolved Rochelle salt chelate to Cu2+ (aq) ions from the dissolved copper(II) sulfate, as bidentate ligands giving the bistartratocuprate(II)4- complex as shown below. The tartarate ions, by complexing copper prevent the formation of Cu(OH)2 from the reaction of CuSO4.2H2O and NaOH present in the solution.
Fehling's can be used to determine whether a carbonyl-containing compound is an aldehyde or a ketone. The bistartratocuprate(II) complex in Fehling's solution is an oxidizing agent and the active reagent in the test. The compound to be tested is added to the Fehling's solution and the mixture is heated. Aldehydes are oxidized, giving a positive result, but ketones do not react, unless they are alpha-hydroxy-ketones. The bistartratocuprate(II) complex oxidizes the aldehyde to a carboxylate anion, and in the process the copper(II) ions of the complex are reduced to copper(I) ions. Red copper(I) oxide then precipitates out of the reaction mixture, which indicates a positive result i.e. that redox has taken place (this is the same positive result as with Benedict's solution). A negative result is the absence of the red precipitate; it is important to note that Fehling's will not work with aromaticaldehydes; in this case Tollens' reagent should be used.
Fehling's test can be used as a generic test for monosaccharides. It will give a positive result for aldose monosaccharides (due to the oxidisable aldehyde group) but also for ketosemonosaccharides, as they are converted to aldoses by the base in the reagent, and then give a positive result.[2] For this reason, Fehling's reagent is sometimes referred to as a general test for monosaccharides.
Fehling's can be used to screen for glucose in urine, thus detecting diabetes. Another use is in the breakdown of starch to convert it to glucose syrup and maltodextrins in order to measure the amount of reducing sugar, thus revealing the dextrose equivalent (DE) of the starch sugar.
Formic acid (HCOOH - methanoic acid) also gives a positive Fehling's test result, as it does with Tollens' test and Benedict's test also. This is because it is readily oxidizable tocarbon dioxide and water.
Safety[edit]
Sodium hydroxide is caustic at high concentrations and precautions should be taken as such not to come into direct contact with it. Copper(II) sulfate is also toxic if ingested.[2]
Images[edit]
The aldehyde form of glucose
[CuII(tartrate)2]4− complex
Crystal structure of thecopper(I) oxide precipitate
Fehling test, left side negative, right side 

61. Hydrolysis of sucrose
-The enzymatic (-glucosidase & invertase) or dil acid hydrolysis of sucrose is called “inversion” due to the fact that:
The sign of rotation being changed from (+) in the original solution of
sucrose into (-) in the hydrolyzed solution,
the process is called inversion

62. A) From sugar-cane B) From sugar beet (Saccharum officinarum)
Preparation of Sucrose
A) From sugar-cane
(Saccharum officinarum)
B) From sugar beet
(Beta vulgaris)

63. Sugar cane
Sugar beet

64. Preparation from sugar-cane (Saccharum officinarum)
Alkalinize the juice of sugar cane with Ca(OH)2 (to neutralize the plant acids & avoid hydrolysis)
Heat to coagulate proteins, which are skimmed
Filter & concentrate
Leave to crystallize  raw sugar.
The dark syrup left after second crystallization is called molasses OR blackstrap after third crystallization
The raw sugar is refined by decolorization with charcoal & is recrystallized after concentration under vacuum.

65. Seliwanoff’s test is a chemical test which distinguishes between aldose andketose sugars. Ketoses are distinguished from aldoses via their ketone/aldehydefunctionality. If the sugar contains a ketone group, it is a ketose and if it contains an aldehyde group, it is an aldose. This test is based on the fact that, when heated, ketoses are more rapidly dehydrated than aldoses. It is named afterTheodor Seliwanoff, the chemist that first devised the test.
Seliwanoff-Reaction
The reagents consist of resorcinol and concentrated hydrochloric acid:
The acid hydrolysis of polysaccharides and oligosaccharides yields simpler sugars followed by furfural.[1]
The dehydrated ketose then reacts with the resorcinol to produce a deep cherry red color. Aldoses may react slightly to produce a faint pink color.
Fructose and sucrose are two common sugars which give a positive test. Sucrose gives a positive test as it is a disaccharide consisting of fructose and glucose.
References[edit]
Jump up^ Abramoff, Peter; Thomson, Robert (1966). An experimental approach to biology. WH Freeman & Company, San Francisco. p. 47.
Seliwanoff, Theodor (1887). "Notiz über eine Fruchtzuckerreaction". Berichte der deutschen chemischen Gesellschaft20: 181. doi: /cber
Katoch, Rajan ( ). Analytical Techniques in Biochemistry and Molecular Biology. p. 71. ISBN 
Chawla ( ). Practical Clinical Biochemistry: Methods and Interpretations. p. 35. ISBN 
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Categories: Reagents for organic chemistry

66. Uses of Sucrose ■ Nutrients and demulcent
■ In the preparation of syrups and molasses
■ In moderate aq conc solution , sucrose is bacteriostatic & used as preservative (66%w/v).
■ It masks disagreable taste in tablets & pills
■ It retards oxidation in certain preparations.
■ It is used as excipient for tablets
■ In preparation of dextran (a polysaccharide used as plasma substitute) by action of certain bacteria
excipient
   
ex·cip·i·ent
  [ik-sip-ee-uhnt]  Show IPA
noun Pharmacology .a pharmacologically inert, adhesive substance, as honey, syrup, orgum arabic, used to bind the contents of a pill or tablet.

67. Molasses
Molasses is a thick, brown to deep black, honey-like substance made when cane or beet sugar is processed by boiling to crystallize sucrose. It is used as a sweetener and food supplement in many countries.
Nutritional Profile
Molasses is an excellent source of manganese, copper, iron, calcium, potassium and magnesium. In addition, blackstrap molasses is a good source of vitamin B6 and selenium.
Nutrients in Blackstrap Molasses of 2 tsp (13.67 grams)
Nutrient % Daily Value
Mg 18%, Cu 14%, Fe 13.2%, Ca 11.7%, K 9.7%,Mn 7.3%, vit B 65%, Se 3.4%, Calories (32) 1%

68. Trehalose (Glc-1-1-Glc)
In mushrooms: contains up to %.
The linkage between the two anomeric carbons of the two glucose units (C1-C1)     none reducing.
Uses
As sweetener and stabilizer in food industry.
Stabilizing cell membranes and has a suppressive effect on osteoporosis development.

69. Reducing disaccharides
The reducing properties of disaccharides are due to the presence of free hemiacetal group in their molecule.
Reducing dihexoses are classified according to the site (or position) of the linkage into:
C1-C3, C1-C4 & C1-C6 dihexoses.
The most common are those of the C1-C4 group e.g. maltose & lactose.

70. C-4 Dihexoses Maltose (malt sugar) Glc-1-4-Glc maltase 2 glc Source
In malt and germinating cereals and by partial acid hydrolysis of starch or dextrin or by action of -maltase enzyme.
Structure
Properties
It exists in two anomeric forms α-maltose and β-maltose, which undergo mutarotation.
Reduction: + ve Fehling’s soln and –ve Barfoed’s soln.
It forms osazone (rosettes of plates or broad needles).

71. Lactose (milk sugar) Gal-1-4 Glc + β- galactosidases 
 -Galactose + -Glucose
Source
Lactose is the principal sugar of
mammalian milk.
Obtained from whey (a by-product of cheese manufacture) after concentration, upon which deposits of lactose crystallize out.
Properties
+ve Fehling’s but –ve Barfoed’s solution.
Characteristic osazone (needles aggregated in clusters or tufts).
Uses
Nutrient in infant foods, since it is less sweet than sucrose and more easily digested.
Inert diluent for other drugs.
Whey or milk serum is the liquid remaining after milk has been curdled and strained.

72. Cellobiose Glcβ 1- 4Glc + β -glucosidases (emulsin)  β-Glc + Glc
Source
Obtained from cellulose (cotton fibre or filter paper) by either careful acid hydrolysis or by the action of cellulase enzyme.
Structure
It consists of two glucose units,
linked by β linkage.

73. Turanose Gentiobiose C-3 Dihexoses C-6 Dihexoses
It is obtained from the trisaccharide melezitose by careful acid hydrolysis.
Glc-1- 3 β -Frc + β -glucosidases (emulsin)  -Glc + β-Frc
C-6 Dihexoses
Gentiobiose
It is obtained from the trisaccharide gentianose, but also occurs in some glycosides, e.g. amygdalin.
Glc-1- 6 β Glc + β -glucosidases (emulsin)  β-Glc + Glc

74. Trisaccharides: Raffinose, Gentianose Tetrasaccharides: Stachyose
Raffinose (melitriose or gossypose)
Gal  (1-6)- glc  -(1-2) -D-frc
Raffinose is a non-reducing trisaccharide
Found in beet, cottonseed & soybean
Tetrasaccharides: Stachyose
In the tubers of Stachys tuberifera (Japanese artichoke) and soybean.
It is a non-reducing sugar.
On complete acid hydrolysis it yields D-fructose, D-glucose and two molecules of D-galactose.

76. Examples of Oligosaccharides in Foods
Arabinoxylan-oligosaccharides (derived from cereal grains)
Fructo-oligosaccharides (FOS) or oligofructose (Jerusalem artichokes, onions, canned foods)
Galacto-oligosaccharides (GOS): raffinose, stachyose and verbascose (in beans, peas, lentils, cabbage, whole grains), soybean oligosaccharides in soy, and trans-galactooligosaccharides (TOS),
Gentio-oligosaccharides (produced from pustulan)
Gluco-oligosaccharides (produced from sucrose)
Human milk oligosaccharides (HMO) (human breast milk)
Isomalto-oligosaccharides or IOS (produced from starch)
Lactosucrose (produced from lactose and sucrose)
Maltotriose (produced from starch during digestion, found in liquid glucose, brown rice syrup)
Mannan-oligosaccharides or MOS (artificially produced)
Melibiose-derived oligosaccharides
N-acetylchito-oligosaccharides (derived from chitosan)
Pectic oligosaccharides (derived from pectin)
Xylo-oligosaccharides (produced from corncob and birch wood)
Oligosaccharides are often added to commercial foods as sweeteners or fiber.