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Home , Aldose, Carbohydrate, Erythrose, Furanose, Glyceraldehyde, Hexose

Carbohydrates – polyhydroxyaldehydes or polyhydroxy- of formula (CH2O)n, or compounds that can be hydrolyzed to them. (aka or saccharides) – that cannot be hydrolyzed to simpler carbohydrates; eg. or . – carbohydrates that can be hydrolyzed into two units; eg. , which is hydrolyzed into glucose and fructose. – carbohydrates that can be hydrolyzed into a few monosaccharide units. – carbohydrates that are are polymeric sugars; eg or . – polyhydroxyaldehyde, eg glucose – polyhydroxyketone, eg fructose , , , , etc. – carbohydrates that contain three, four, five, six, etc. per molecule (usually five or six); eg. Aldohexose, ketopentose, etc. Reducing – a that is oxidized by Tollen’s, Fehling’s or Benedict’s solution. Tollen’s: Ag+  Ag (silver mirror) Fehling’s or Benedict’s: Cu3+ (blue)  Cu2+ (red ppt) These are reactions of and alpha-hydroxyketones. All monosaccharides (both and ) and most* disaccharides are reducing sugars. *Sucrose (table sugar), a , is not a . Glucose (a monosaccharide) : chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + starch (+)-glucose (+)-glucose glycogen (+)-glucose (+)-glucose or aminoacids respiration

(+)-glucose + 6 O2 6 CO2 + 6 H2O + energy * CH2CHCH O an aldotriose OH OH

CHO CHO H OH HO H

CH2OH CH2OH D-(+)-glyceraldehyde L-(-)-glyceraldehyde

D & L are used to relate configuration of the chiral center most removed from the reducing group ( C=O ). If the -OH is on the right in the , then it is D, if the -OH is on the left, then it is L aldotetroses * * CH2CHCHCH O OH OHOH

CHO CHO H OH HO H H OH HO H CH OH CH2OH 2 D- L-erythrose

CHO CHO H OH HO H HO H H OH

CH2OH CH2OH L- D-threose * * * * (+)-glucose? An aldohexose CH2CHCHCHCHCH O (1902) OH OHOHOHOH Four chiral centers, 24 = 16 stereoisomers

CHO

OH?

CH2OH CHO CHO CHO CHO CHO CHO H OH HO H HO H H OH H OH HO H H OH HO H H OH HO H HO H H OH H OH HO H H OH HO H H OH HO H H OH HO H H OH HO H H OH HO H

CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH

CHO CHO CHO CHO CHO CHO HO H H OH H OH HO H HO H H OH HO H H OH H OH HO H H OH HO H H OH HO H HO H H OH HO H H OH H OH HO H H OH HO H H OH HO H

CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH

CHO CHO CHO CHO H OH HO H HO H H OH HO H H OH HO H H OH HO H H OH HO H H OH H OH HO H H OH HO H

CH2OH CH2OH CH2OH CH2OH Ruff degradation – a series of reactions that removes the reducing ( C=O ) from a sugar and decreases the number of chiral centers by one; used to relate configuration.

CHO CO2H Br H OH 2 H OH H OH H OH H2O CH2OH CH2OH Ca2+

CO2 CHO H2O2 H OH H OH + H OH CH2OH Fe3 CH2OH D-(+)-glyceraldehyde Kiliani-Fischer synthesis. A series of reactions that extends the carbon chain in a carbohydrate by one carbon and one chiral center.

C N C N COOH COOH CHO HCN H OH HO H + + H ,H2O H OH HO H H OH H OH H OH H OH H OH CH2OH CH2OH CH2OH CH2OH CH2OH separable CHO O C H OH Na(Hg) H OH H OH H OH CH OH 2 H2C O -H2O lactone – stereoisomers that differ only in configuration about one chiral center.

CHO CHO H OH HO H HO H HO H H OH H OH H OH H OH

CH2OH CH2OH D-glucose D-

epimers CHO H OH HO H H OH H OH Exists only in solution. There are two : CH2OH o (+)-glucose α-glucose m 146 [α] = +112.2 β-glucose m 150o [α] = +17.5

In each mutarotates to an equilibrium with [α] = +52.7 (63.6% β / 36.4% α) CHO OH OH H H OH H H O H O HO HO H HO HO H HO OH H OH H OH H OH H OH H OH H H CH2OH alpha-(+)-glucose beta-(+)-glucose

CH OH 2 CH2OH O H H H O OH OH H OH H OH OH OH H H OH H OH Addition of alcohols to aldehydes/ketones:

O OH OR' C + R'OH R C H R C H R H OR' OR' geminal geminal / diether reducing! non-reducing! CHO OH OH H H OH H H O H O HO HO H HO HO OH HO H H OH H OH H OH H H H OH H OH CH2OH

nucleophilic addition of -OH on carbon 5 to the

HOH CHO H O CH O HO H OH HO H H OH H OH HO H H OH HO H α H OH H OH H OH HOH2C H HOH CH OH 2 OH H O HO HO OH β rotate C-5 OH to rear H OH H H HOH HOH H O H O HO HO HO H HO OH H OH H OH H OH H H

alpha hemiacetal beta

O D-glucopyranoses

4H- H H H OH HOHO O HO O HO H HO HO H H OH H H H OH H OH

alpha form beta furanose form

D-glucofuranoses O HOH HOH H O H O HO HO HO H HO OH H OH H OH H OH H H

alpha beta

- epimers at C-1

chair conformations - alpha has one group axial beta has all groups equatorial in solution to 63.6% beta/36.4% alpha CH2OH O CH OH OH CH2OHO 2 HO H CH2OHO H OH H OH H OH

H OH H OH H CH2OH OH H OH H CH2OH

alpha-D-fructofuranose D-fructose beta-D-fructofuranose acetal OH H HOH H O CH3OH H HO O HO OH HO H HCl HO OCH3 OH H OH H H H H

methyl beta-D-

(glucoside - glucose acetal) non-reducing, does not muta- rotate Disaccharides: (+)- “ sugar” two glucose units (alpha) (+)- two glucose units (beta) (+)- “ sugar” & glucose (+)-sucrose “table sugar” glucose & fructose HOH H O HO two glucose units HO H OH H OH H alpha C-1 to C-4 H H O O HO OH H OH H H (+)-maltose reducing sugar

HOH HOH H O HO H O two glucose units HO O H OH HO OH beta C-1 to C-4 H H H OH H H

(+)-cellobiose reducing sugar HOOH HOH galactose beta C-1 H O H H O to C-4 glucose HO O H OH HO OH H H H OH H H (+)-lactose reducing sugar

HOH H O H

O

HO 2

HO H H

H C glucose alpha C-1 OH H H O to beta C1 fructose O H OH CH OH acetal 2 non-reducing HO H (+)-sucrose Polysaccharides starch cellulose Starch 20% (water soluble) 80% (water insoluble)

amylose + H2O  (+)-maltose

(+)-maltose + H2O  (+)-glucose starch is a poly glucose (alpha-glucoside to C-4)

O O O O O O O O

O O O O O O O O Amylopectin + H2O  (+)-maltose

(+)-maltose + H2O  (+)-glucose Also a polyglucose, but branched every 20-25 units:

O O O O O O

O O O O O O

CH2 O O O O O O O O

O O O O O O O O Cellulose is a polyglucose with a beta-linkage: O O

O O

O O

O O

O O

O O

O O

O O