Carbohydrates are the hydrates of carbonCx(H2O)y as named erlier. These are made ofCarbon, Hydrogen and Oxygen

Carbohydrates are often refered asSaccharides (Saccharum = sugar) because ofsweet taste of its simpler members.

But higher membranes are not sweet intaste.

Starch

Hydrolysis

Chemically carbohydrates are defined as thepolyhydroxy aldehydes or polyhydroxyketones or substances which produce thesecompounds on hydrolysis .

Monosaccharide:Simplest carbohydrate which cannot befurther hydrolysed

glyceraldehyde Glucose Fructose

Monosaccharide may be Aldoses or Ketosesbased on the fuctional group present

Aldoses Ketoses

Monosaccharide may be trioses, tetroses,pentoses or hexose based on the number ofcarbon atoms in a molecule.

trioses hexosestetrose Pentose

Oligosaccharide:Carbohydrate which can be furtherhydrolysed to get two or fewmonosaccharide molecules

Disaccharide-glucose Tetra saccharide stachyose

Trisaccharide raffinose

Polysaccharide:Carbohydrate which can be furtherhydrolysed to get two or fewmonosaccharide molecules Eg Starch,Cellulose, Glycogen.

Reducing sugars Sugars which reduces Tollens’s reagentand Fehling ‘s solution Eg Glucose, Fructose, maltose

Non-reducing sugars Sugars which do not reduces Tollens’s

and Fehling ‘s solution Eg Sucrose

Sugars

Carbohydrate

Non-SugarsPolysaccharidesoligosaccharidesMonosaccharides

Aldoses Ketoses Disaccharides TetrasaccharidesTriaccharides

It is aMonosaccharideSugarA DextroseAldoseHexoseGrape SugarTwo isomers α-D-Glucoseβ-D-Glucose

1. Elemental qualitative analysis – CHO2. Quantitative analysis – C6H12O6

3. Parent carbon chain- Hexane is formedwhen treated with HI/Red P

4. Aq. Solution is neutral so –COOH group isabsent.

One mole of glucose react with onemole of HCN to form glucocyanohydrin.Condenses with one mole ofhydroxylamine to give glucose oxime.This shows that Glucose contain eitheraldehydic ( -CHO) or (–C=O)ketonicgroup

5. With Br water it gives Gluconic acid

It reduces Tollen’s reagentIt reduces Fehling’s solutionShows that -CHO group is present in glucose

6. Position of aldehyde groupthe above reaction we get compoundwith same carbon atoms. This impliesthat –CHO group is at the end.

7. Number of –OH groupIn presence of pyridine acetylation takesplace with 5 moles of acetic anhydride

8. Position of –OH groupIf two –OH groups were on the samecarbon atom molecule becomesunstable but Glucose is very stablecompound. Shows that 5 –OH groupsare on different carbon.

9. Based on this Baeyer in 1870 suggested

In 1886 Killiani confirmed by synthesis

2,3,4,5,6-pentahydroxyhexanal

But Glucose dose not react with Schiff’s reagent, Sodiumbisulphite and grignard reagent. This shows that –CHOgroup is not free for many reaction. ThereforeFischer suggested the following ring structure

Alcoholic –OH group 5th carbon attacks the carbonylcarbon to form hemiacetal

This leads to formation of C1 as assymetric . If it has –OHgroup on right side is called α-Glucose, If it has –OHgroup on left side is called β-Glucose

Fischer structure does not exactly indicate the specialarrangement of atoms so W.N Haworth suggested

3D model called Haworth Projection formula.

Convertion

α-D-(+) glucopyranose β-D-(+) glucopyranose

It is aMonosaccharideSugarA DextroseKetoseHexoseFruit SugarTwo isomers α-D-Fructoseβ-D-Fructose

1. Elemental qualitative analysis – CHO2. Quantitative analysis – C6H12O6

3. Parent carbon chain- Hexane is formedwhen treated with HI/Red P

4. Aq. Solution is neutral so –COOH group isabsent.

One mole of fructose react with onemole of HCN to form cyanohydrin.Condenses with one mole ofhydroxylamine to give oxime. Thisshows that fructose contain eitheraldehydic ( -CHO) or (–C=O)ketonicgroup

5. With HNO3 it gives tartaric acid andGlycollic acid

It reduces Tollen’s reagentIt reduces Fehling’s solutionShows that -CHO group is present in glucose

6. Position of ketone groupthe above reaction we get compoundwith different carbon atoms. This impliesthat –C=O group is at the 2nd position.

7. Number of –OH groupIn presence of pyridine acetylation takesplace with 5 moles of acetic anhydride

8. Position of –OH groupIf two –OH groups were on the samecarbon atom molecule becomesunstable but Glucose is very stablecompound. Shows that 5 –OH groupsare on different carbon.

9. Baeyer suggested structure

1,3,4,5,6-pentahydroxyhexa-2-one

But Glucose dose not react with Schiff’s reagent, Sodiumbisulphite and grignard reagent. This shows that –CHOgroup is not free for many reaction. ThereforeFischer suggested the following ring structure

Alcoholic –OH group 5th carbon attacks the carbonyl (2nd )to form hemiketal

This leads to formation of C2 as assymetric . If it has –OHgroup on right side is called α-Fructose, If it has –OH group on left side is called β-fructose

Fructofuranase

Fructopyranaose

Fischer structure does not exactly indicate the specialarrangement of atoms so W.N Haworth suggested

3D model called Haworth Projection formula.

Convertion

α-D-(+) glnoseucopyra β-D-(+) glucopyranose

Maltose

1,4 linkage between Alpha Glucose and Alpha Glucoseto form glycosidic linkage

1,2 linkage between Alpha Glucopyranose and beta-fructofuranose to form glycosidic linkage

Sucrose

Polysaccharides

Glycogen