2. Carbohydrates – polyhydroxyaldehydes or polyhydroxy-
ketones of formula (CH2O)n, or compounds that can be
hydrolyzed to them. (aka sugars or saccharides)
Monosaccharides – carbohydrates that cannot be hydrolyzed
to simpler carbohydrates; eg. Glucose or fructose.
Disaccharides – carbohydrates that can be hydrolyzed into
two monosaccharide units; eg. Sucrose, which is hydrolyzed
into glucose and fructose.
Oligosaccharides – carbohydrates that can be hydrolyzed into
a few monosaccharide units.
Polysaccharides – carbohydrates that are are polymeric
sugars; eg Starch or cellulose.
3. Aldose – polyhydroxyaldehyde, eg glucose
Ketose – polyhydroxyketone, eg fructose
Triose, tetrose, pentose, hexose, etc. – carbohydrates that
contain three, four, five, six, etc. carbons per molecule
(usually five or six); eg. Aldohexose, ketopentose, etc.
4. Reducing sugar – a carbohydrate 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 aldehydes and alpha-hydroxyketones.
All monosaccharides (both aldoses and ketoses) and most*
disaccharides are reducing sugars.
*
Sucrose (table sugar), a disaccharide, is not a reducing sugar.
11. Ruff degradation – a series of reactions that removes the
reducing carbon ( C=O ) from a sugar and decreases the
number of chiral centers by one; used to relate configuration.
CHO
H OH
CH2OH
H OH
CO2H
H OH
CH2OH
H OH
Br2
H2O
CO2
H OH
CH2OH
H OH
Ca2+
H2O2
Fe3
+
CHO
CH2OH
H OH
D-(+)-glyceraldehyde
12. Kiliani-Fischer synthesis. A series of reactions that extends the
carbon chain in a carbohydrate by one carbon and one chiral
center.
CHO
H OH
CH2OH
HCN
C
H OH
CH2OH
H OH
C
HO H
CH2OH
H OH+
N N
H+,H2O
COOH
H OH
CH2OH
H OH
COOH
HO H
CH2OH
H OH
diastereomers
separable
C
H OH
H2C
H OH
O
O
lactone
Na(Hg)
CHO
H OH
CH2OH
H OH
-H2O
13. Epimers – stereoisomers that differ only in configuration about
one chiral center.
CHO
OHH
HHO
OHH
OHH
CH2OH
D-glucose
CHO
HHO
HHO
OHH
OHH
CH2OH
D-mannose
epimers
14. CHO
OHH
HHO
OHH
OHH
CH2OH
(+)-glucose
Exists only in solution. There are two
solids:
α-glucose m 146o
[α] = +112.2
β-glucose m 150o
[α] = +17.5
In water each mutarotates to an
equilibrium with [α] = +52.7
(63.6% β / 36.4% α)
16. R
C
H
O
+ R'OH R C H
OH
OR'
R C H
OR'
OR'
hemiacetal
geminal
ether/alcohol
reducing!
acetal
geminal
diether
non-reducing!
Addition of alcohols to aldehydes/ketones:
25. O
H
HO
H
HO
H
OHH
H
OH
glucose alpha C-1
to beta C1 fructose
O
HO
H
H
HO
H
H
OHH
OH
O
H
O
H
HO
H
H
OHH
OH
OH galactose beta C-1
to C-4 glucose
reducing sugar(+)-lactose
O
O
CH2OH
CH2OH
H
H
OH
HO
H
(+)-sucrose
acetal
non-reducing
26. Polysaccharides
starch
cellulose
Starch 20% amylose (water soluble)
80% amylopectin (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