26 c!#$%&’!()*...26.4 isomerizations of monosaccharides epimers figure 26.4 isomerization of...
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C!"#$%&'"!()*26
SUCROSE
26.3 CHIRALITY OF MONOSACCHARIDES
CHO
C OHH
CH2OH
(R)-glyceraldehyde[!]D = + 13.5o
CHO
OHH
CH2OH
Fischer projection25
CH2OH
C O
C HHO
C
C
OHH
CH2OH
OHH
D-fructose
CH2OH
O
HHO
OHH
CH2OH
OHH
Fischer projection
CHO
C OH
C HHO
C
C
HHO
CH2OH
OHH
D-galactose
Fischer projection
H
CHO
OH
HHO
HHO
CH2OH
OHH
H
carbonyl group at top carbonyl near top
26.3 CHIRALITY OF MONOSACCHARIDESAldoses
CHO
(CH2OH)n
C OHH
CH2OH
a D aldose
CHO
(CH2OH)n
C HHO
CH2OH
an L aldose
CHO
HHO
CH2OH
CHO
OHH
CH2OH
mirror plane
D-ribose
CH2OH
C O
C HHO
C
C
OHH
CH2OH
OHH
D-fructose
CHO
C OHH
C OHH
CH2OH
D-glyceraldehyde D-glucose
CHO
C OH
C HHO
C
C
OHH
CH2OH
OHH
HCHO
C OHH
C
C
OHH
CH2OH
OHH
26.3 CHIRALITY OF MONOSACCHARIDESAldoses
D-allose
CHO
OH
OHH
OHH
CH2OH
OHH
H
D-altrose
CHO
H
OHH
OHH
CH2OH
OHH
HO
D-glucose
CHO
OH
HHO
OHH
CH2OH
OHH
H
D-mannose
CHO
H
HHO
OHH
CH2OH
OHH
HO
Aldohexoses
D-gulose
CHO
OH
OHH
HHO
CH2OH
OHH
H
D-idose
CHO
H
OHH
HHO
CH2OH
OHH
HO
D-galactose
CHO
OH
HHO
HHO
CH2OH
OHH
H
D-talose
CHO
H
HHO
OHHO
CH2OH
OHH
HO
D-erythrose
CHO
C OHH
CH2OHD-glyceraldehyde
CHO
OHH
CH2OH
OHH
Aldotriose
D-arabinose
CHO
HHO
OHH
CH2OH
OHH
D-lyxose
CHO
HHO
HHO
CH2OH
OHH
D-threose
CHO
HHO
CH2OH
OHHAldotetroses
D-ribose
CHO
OHH
OHH
CH2OH
OHH
D-xylose
CHO
OHH
HHO
CH2OH
OHH
Aldopentoses
Figure 26.1 Structures of D-Aldoses
26.3 CHIRALITY OF MONOSACCHARIDESAldoses
Figure 26.2 Enantiomeric Relationship of D- and L-Monosaccharides!e D- and L-monosaccharides have reversed, mirror image configurations at every chiral center.
mirror
D-glucose
CHO
OH
HHO
OHH
CH2OH
OHH
H
Determines D configuration
D-gluco configuration
D-glucose
CHO
H
OHH
HHO
CH2OH
HHO
HO
Determines L configuration
L-gluco configuration
26.3 CHIRALITY OF MONOSACCHARIDESKetoses
D-erythulose
CH2OH
C O
CH2OHdihydroxyacetone
CH2OH
C
C
O
CH2OH
OHH
Ketotriose
Ketotetrose
D-ribulose
CH2OH
C O
C
C
OHH
CH2OH
OHH
D-xylulose
Ketopentoses
CH2OH
C O
C
C
HHO
CH2OH
OHH
D-sorbose D-psicose D-fructose
CH2OH
C O
C HHO
C
C
HHO
CH2OH
OHH
D-tagatose
CH2OH
C O
C OHH
C
C
HHO
CH2OH
OHH
CH2OH
C O
C OHH
C
C
OHH
CH2OH
OHH
CH2OH
C O
C HHO
C
C
OHH
CH2OH
OHH
Ketohexoses
Figure 26.3 Structures of D-2-Ketoses
26.3 CHIRALITY OF MONOSACCHARIDESLess Common Monosaccharides
D-apiose
CHO
OHH
CH2OH
OHHOCH2
(a 3-ketopentose)
CH2OH
C OH
C
C
O
CH2OH
OHH
H
2-deoxy-D-ribose
CHO
C HH
C
C
OHH
CH2OH
OHH
D-2-glucosamine
CHO
C NH2
C HHO
C
C
OHH
CH2OH
OHH
H
N-acetyl-D-2-glucosamine
CHO
C NH
C HHO
C
C
OHH
CH2OH
OHH
H C CH3
O
26.4 ISOMERIZATIONS OF MONOSACCHARIDESEpimers
D-galactose
CHO
OH
HHO
HHO
CH2OH
OHH
H
D-glucose
CHO
OH
HHO
OHH
CH2OH
OHH
H
D-mannose
CHO
H
HHO
HHO
CH2OH
OHH
HO
C-4 epimers
C-2 epimers
1 11
22 2
333
4 4 4
5 5 5
6 6 6
CHO
C OHH
R
CHO
C HHO
Repimer 1 epimer 2
C
COHH
R OH
enediol(E and Z)
26.4 ISOMERIZATIONS OF MONOSACCHARIDESEpimers
Figure 26.4 Isomerization of Aldoses via an Enediol Intermediate
enediolD-glucose
CHO
OH
HHO
OHH
CH2OH
OHH
H
D-mannose
C
HHO
HHO
CH2OH
OHH
C OHH
OHCHO
H
HHO
OHH
CH2OH
OHH
HO
not chiral
26.4 ISOMERIZATIONS OF MONOSACCHARIDESInterconversion of Aldoses and Ketoses
CHO
C OHH
R
CH2OH
C O
R(an aldolse) (a ketose)
C
COHH
R OH
(an enediol)
D-fructose-6-phosphate
CH2OH
O
HHO
OHH
CH2OPO32-
OHH
D-glucose-6-phosphate
CHO
OH
HHO
OHH
CH2OPO32-
OHH
Hglucose-6-phosphateisomerase
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALS
O
H
HO
H
HO
H
OHOHH
H
OH
OH
H
HO
OH
H
OH
HHH
O
OH
D-glucose !-D-glucopyranose
+O
H
HO
OH
H
OH
HHH
OH
OH
"-D-glucopyranose
OO
furan pyran
COHO
H
CO
HH
O
5-hydroxypentanal
or
O
OH
H
K = 20CO
H
OHCO
HH
O
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALS
C-1 CHO group
C-5 hydroxyl group
C-1
C-5 hydroxyl groupbond formation gives hemiacetal
rotation around C-3 C-4 ! bond
D-glucose
C-1 axial OH
!-D-glucopyranose "-D-glucopyranose
C-1 equatorial OH
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALS
!-D-fructofuranose
OH
CH2OH
H
HOH2C
H OH
HO HO
D-fructose
CH2OH
H
HOH2C
H OH
HO HOH
O+
"-D-fructofuranose
CH2OH
OH
H
HOH2C
H OH
HO HO
Table 26.1Composition of Monosaccharides at Equilibrium in Solution (in percent)Monosaccharide Pyranose Furanose
! " ! "D-glucose 36 64D-mannose 67 32 0.8 0.2D-galactose 31 69D-allose 18 70 5 7D-altrose 27 40 20 13D-idose 38 38 10 14D-talose 40 29 20 11D-arabinose 63 34 2 1D-ribose 20 56 6 18D-xylose 27 63D-fructose 2 66 7 25
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALS
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALSHaworth Projection Formulas
Figure 26.5 Haworth Projections of a Pyranose and a Furanose
OH
HOOH
H
CH2OH
HOH
HH
OH
Haworth projection of !-D-glucopyranose
OHOH2C
HH
OH
HO
H
CH2OH
OH
Haworth projection of "-D-fructofuranose
The C-6 CH2OH group is "up" in a Haworth projection of a D-pyranose or D-furanose.
The "-hydroxy group at C-1 is"down" in a Haworth projection of an "-D-pyranose or furanose. It is "up" in the ! anomer.
26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALSMutarotation
O
H
HO
H
HO
H
OHOHH
H
OH
OH
H
HO
OH
H
OH
HHH
O
OH
D-glucose!-D-glucopyranose
crystalize frommethanol
!-D-glucopyranosemp 146o
[!]D = + 112.2o
O
H
HO
OH
H
OH
HHH
OH
OH
"-D-glucopyranose
crystalize fromacetic acid
"-D-glucopyranosemp 150o
[!]D = + 18.7o
26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESReduction of Monosaccharides
D-glucitol (D-sorbitol) (an alditol)
CH2OH
C OH
C HHO
C
C
OHH
CH2OH
OHH
H
reduced
O
H
HO
H
HO
H
OHOHH
H
OHOH
H
HO
OH
H
OH
HH
OH
D-glucose!-D-glucopyranose
NaBH4
C
H
O
OHH
HO
OH
H
OH
HH
OH
D-glucitol
COH
HH
26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESOxidation of Monosaccharides
D-gluconic acid(an aldonic acid)
CO2H
C OH
C HHO
C
C
OHH
CH2OH
OHH
H
oxidized
O
H
HO
H
HO
H
OHOHH
H
OHOH
H
HO
OH
H
OH
HH
OH
D-glucose!-D-glucopyranose
[O]
C
H
O
OHH
HO
OH
H
OH
HH
OH
D-gluconic acid
C
OH
O
26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESOxidation of Monosaccharides
D-glucaric acid(an aldaric acid)
CO2H
C OH
C HHO
C
C
OHH
CO2H
OHH
H
oxidized
oxidized
O
H
HO
H
HO
H
OHOHH
H
OHOH
H
HO
OH
H
OH
HH
OH
D-glucose!-D-glucopyranose
[O]
C
H
O
1o alcohol
OHH
HO
OH
H
OH
HH
C
D-glucaric acid
C
OH
O
OHO
26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESOxidation of Monosaccharides
O
H
HO
H
HO
H
OHOHH
H
OH
!-D-glucopyranose
NADP+-dependentdehydrogenase
1o alcohol
O
H
HO
H
HO
H
OHOHH
H
CO2H
D-glucuronic acid
26.7 GLYCOSIDES
OH
C OR'R
H(a hemiacetal)
+ R'OHH+
OR'
C OR'R
H
+ OHH
(an acetal)
OH
C OR'R
H(a hemiketal)
+ R'OHH+
OR'
C OR'R
H
+ OHH
(a ketal)
O
H
HO
H
HO
H
HOHH
OCH3
OH
methyl !-D-glucopyranoside
!-glycosidic bond
aglycone
26.7 GLYCOSIDES
O
H
HO
H
HO
H
HOHH
OH
O
H
HO
H
HO
H
HOHH
OH
resonance-stabilized oxocarbocation intermediate
O
H
HO
H
HO
H
HOHH
OH
OH
!-D-glucose
H+O
H
HO
H
HO
H
HOHH
O
OH
H
H
O
H
HO
H
HO
H
HOHH
OH
-HOH
26.7 GLYCOSIDESFigure 26.7 Formation of ! and " Glysosides
O
H
HO
H
HO
H
HOHH
OH
CH3OH
O
H
HO
H
HO
HH
OHH
OH
OCH3
H
-H+
O
H
HO
H
HO
HH
OHH
OH
OCH3
methyl !-D-glycopyranoside
HOCH3
O
H
HO
H
HO
HOCH3
OHH
OH
H
H
O
H
HO
H
HO
HOCH3
OHH
OH
Hmethyl "-D-glycopyranoside
-H+
26.8 DISACCHARIDESMaltose
O
H
HO
H
HO
H
OHH
OH
O
H
O
H
H
HOH
OHH
OH
H
OH!-(1,4') glycosidic bond
4-O-(!-D-glucopyranosyl)-"-D-glucopyranose (maltose)
"-anomer of glucose,the agylcone.
26.8 DISACCHARIDESMaltose
Figure 26.8 Molecular Model of Maltose.!e monosaccharide unit on the left is the hemiacetal of the !-D-glucopyranosyl unit. It is linked by an !-(1,4’) glycosidic bond to "-D-glucopyranose, the aglycone. !e oxygen atom of the glycosidic bond is approximately in the center of the structure, between the two rings. It is projected down, axial, and therefore !. It is linked to C-4 of the aglycone, and so the link is axial-equatorial.
4-O-(!-D-glucopyranosyl)-"-D-glucopyranose (maltose)
"-D-glucopyranose unit,the aglycone
"-equatorial hydroxyl group
!-D-glucopyranosylunit
!-axial oxygen of (1,4’)-gycosidic bond
26.8 DISACCHARIDESCellobiose
O
H
HO
H
HO
H
OHH
OH
H
O
!-(1,4') glycosidic bond
4-O-(!-D-glucopyranosyl)-!-D-glucopyranose (cellobiose)
O
H
HHO
H
HOH
OH
HOH
!-anomer of glucose,the agylcone.
!-D-glucopyranosyl unit
26.8 DISACCHARIDESCellobiose
Figure 26.9 Molecular Model of Cellobiose!e monosaccharide unit on the left is the !-D-glucopyranosyl portion of cellobiose. It is linked by a !-(1,4’) glycosidic bond to !-D-glucopyranose, the aglycone. !e oxygen atom of the glycosidic bond is approximately in the center of the structure, between the two rings. It is projected up, equa-torial, and therefore it is !. It is linked to C-4 of the aglycone, and so the link is equatorial-equatorial.
4-O-(!-D-glucopyranosyl)-!-D-glucopyranose (cellobiose)
!-D-glucopyranosylunit
!-D-glucopyranoseunit, the aglycone
!-equatorial hydroxyl group
!-glycosidic bond
1 4’
26.8 DISACCHARIDESLactose
O
H
HO
H
HO
H
OHH
OH
H
O
!-(1,4') glycosidic bond
4-O-(!-D-glucopyranosyl)-!-D-glucopyranose (cellobiose)
O
H
HHO
H
HOH
OH
HOH
!-anomer of glucose,the agylcone.
!-D-glucopyranosyl unit
26.8 DISACCHARIDESLactose
O
HO
H
H
HO
H
OHH
OH
H
O
!-(1,4') glycosidic bond
4-O-(!-D-galactopyranosyl)-!-D-glucopyranose (lactose)
O
H
HHO
H
HOH
OH
HOH
!-anomer of glucose,the agylcone.
!-D-galactopyranosyl unit
C-4 epimer of glucose
26.8 DISACCHARIDESLactose
Figure 26.10 Molecular Model of Lactose!e monosaccharide unit on the left is the !-D-galactopyranosyl portion of cellobiose. It is linked by a !-(1,4’) glycosidic bond to !-D-glucopyranose, the aglycone. Galactose is the C-4 epimer of glucose. !us, the hydroxyl group at C-4, which is equatorial in glucose, is axial in galactose.
4-O-(!-D-galactopyranosyl)-!-D-glucopyranose (lactose)
!-D-galactopyranosylunit
!-D-glucopyranoseunit, the aglycone
!-equatorial hydroxyl group
!-glycosidic bond
C-4 epimer of glucose, axialhydroxyl group
1 4’
26.8 DISACCHARIDESSucrose
O
H
HO
H
HO
H
OHH
OH
O
H
!-anomer of glucose
!-D-glucopyranosyl-"-D-fructofuranoside (sucrose)
"-anomer of fructose
CH2OHH
HOH2C
H OH
HO HO
(1,2')-glycosidic bond
Figure 26.11 Molecular Model of Sucrose!e monosaccharide unit on the left is the !-D-galactopyranosyl portion of sucrose. It is linked by a (1,2’) glycosidic bond to "-D-fructofuranose. !us, the anomeric carbons of the monomers are linked by a glycosidic bond. Sucrose is an acetal. !erefore, it is a nonreducing sugar.
26.8 DISACCHARIDESSucrose
!-D-glucopyranosyl-"-D-fructofuranoside (sucrose)
!-D-glucopyranosylunit
"-D-fructofuranoseunit
"
!1
2’
26.9 POLYSACCHARIDES
O
HO
HO
HO
O O
HO
HO
HO
O O
HO
HO
HO
O O
HO
HO
HO
O
!-(1,4')-glycosidic bonds
cellulose
O
HO
HO
HOO
O
O
O
OO
O
HOHO
HOHO
HOHO
OH
OH
OH
amylose
"-(1,4')-glycosidic bonds
O
HO
HO
HOO
O
O
O
OO
O
HOHO
HOHO
HOHO
OH
O
OH
amylopectin (or glycogen)
"-(1,4')-glycosidic bonds
O
HO
HO
"-(1,6')-glycosidic bonds at branch points
Figure 26.12 Structures of Polysaccharides
26.9 POLYSACCHARIDES
Trisaccharide segment of amylose
!-(1,4’)-glycosidic bonds4’
!-D-glucopyranosyl groups
4’ 4’
1
1
1! !
Figure 26.13 Three !-D-Glucopyranosyl Groups in AmyloseWhen we say that a polymer is “linear” we mean that the polymer contains no branches. Amylose coils into a helix.
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESPeriodate Oxidation
vicinal diol in monosaccharide
C
C
OHH
OHH
HIO4 C
C
OH
OH+
aldehyde or ketone
aldehyde or ketone
vicinal diol at 1o alcohol
R
C
C
OHH
H
OHH
HIO4
R
C
C
OH
H
OH+
an aldehyde
formaldehyde
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESPeriodate Oxidation
(an aldose)
OC
C
H
R
OHH
HIO4
OH
C
C
OH
R
OH+
formic acid
(an aldehyde)+ H2O
OH
C
C
OHH
OHH
(a ketose)
CH2OH
C
C
O
R
OHH
HIO4 CH2 Oformaldehyde
+ H2O
CH2OH
C
C
OHHO
R
OHH
OC
C
OH
R
OHH +
(a carboxylic acid)
HC
R
OHIO4
OC
C
OH
R
OHH + O C O
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESOxidation and Optical Activity
D-galactose
CHO
OH
HHO
HHO
CH2OH
OHH
H
HNO3
CO2H
OH
HHO
HHO
CO2H
OHH
H
optically inactive aldaric acid
plane of symmetry
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESFormation of Osazones
CHO
C
(CH2OH)n
CH2OH
(an aldose)
OHH NH2NHC6H5
CH
C
(CH2OH)n
CH2OH
NHNHC6H5
NHNHC6H5
(an osazone)
CH2OH
C
(CH2OH)n
CH2OH
(a ketose)
O NH2NHC6H5
CH
C
(CH2OH)n
CH2OH
NHNHC6H5
NHNHC6H5
(an osazone)
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESChain Extension of Aldoses
D-ribose
CHO
OHH
OHH
CH2OH
OHH
D-allose
CHO
OH
OHH
OHH
CH2OH
OHH
H
D-altrose
CHO
H
OHH
OHH
CH2OH
OHH
HO
+
oxidation
D-aldaric acid(optically inactive)
CO2H
OH
OHH
OHH
CO2H
OHH
H
(+)-D-altraric acid
CO2H
H
OHH
OHH
CO2H
OHH
HO
oxidation
26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESChain Shortening of Aldoses
(one diastereomer)
CHO
C
C
OHH
R
OHH
NH2OH
CH
C
C
OHH
R
OHH
NOH
(an oxime)
Ac2O
C
C
C
OAcH
R
OAcH
N
C
C
C
OAcH
R
OAcH
N
CH3O
C
C
C
OHH
R
OHH
N
CH3O C
C
OH
R
OHH+ CH3OH+CN
26.11 DETERMINATION OF RING SIZE
OCH3H
CH2OH
H OH
OH HO
methyl !-D-ribofuranoside
HO
H
HO
OH
H
H
OHOCH3
H
methyl !-D-ribopyranoside
OCH3H
CH2OH
H OH
OH HO
methyl !-D-ribofuranoside
HIO4
- OC C
HOCH2
H CHO CHO
HOCH3
dialdehyde product
O
H
HO
OH
H
H
OHOCH3
H
methyl !-D-ribopyranoside
IO4-
O
dialdehyde product
+ HCO2HC H
C OCH3
OH
O
H
O
H
HO
H
HO
H
OHH
OH
OH
H
!-D-glucopyranose
(CH3)2SO4O
H
CH3O
H
CH3O
H
OCH3H
OCH3
OCH3
H
methyl 2,3,4,6-tetra-O-methyl-!-D-glucopyranoside
O
H
CH3O
H
CH3O
H
OCH3H
OCH3
OH
H
2,3,4,6-tetra-O-methyl-!-D-glucopyranose
H3O+
26.11 DETERMINATION OF RING SIZE
26.11 DETERMINATION OF RING SIZE
2,3,4,6-tetra-O-methyl-D-glucose
CHO
C OCH3
C HCH3O
C
C
OCH3H
CH2OCH3
OHH
H
oxidation
CO2H
C OCH3
C HCH3O
C
CO2H
OCH3H
H
dicarboxylic acid product
26.12 CHEMICAL DETERMINATION OF DISACCHARIDE STRUCTURE
OO
OHOCH2
HOOH
OH
HO
HO
OHHOCH2
(CH3)2SO4
lactose
OO
OCH3OCH2
OOCH3
OCH3
CH3O
CH3O
OCH3
CH3OCH2
octamethyllactose
CH3
OO
OCH3OCH2
OOCH3
OCH3
CH3O
CH3O
OCH3
CH3OCH2
CH3
H3O+ OOH
OCH3
CH3O
OCH3
CH2OCH3
+O
OH
OCH3
CH3O
CH2OCH3
HO
2,3,4,6-tetra-O-methyl-D-galactose 2,3,6-tri-O-methyl-D-glucoseoctamethyllactose
26.13 HUMAN BLOOD GROUP ANTIGENS
O
OH
H
OH
H
H
NHOH
H
N-acetylgalactosamine (GalNAc)
CCH3O
O
H
HO
OH
H
H
NHOH
H
N-acetylglucosamine (GlcNAc)
CCH3O
OH OH
O
H
CH3
OH
H
H
OHH
OH
6-deoxy-a-L-galactose (a-L-fucose)
OH
H
26.13 HUMAN BLOOD GROUP ANTIGENS
OO
O
O
HO
OH
!-GalNAcOH
OHOH
OO
HO
HOCH2
NHC
CH3
O
!-GlcNAc
Gal
NHC
O
CH3OCH3
OHOH
OH
"-L-fucose
Type A
Oprotein
OO
O
O
HO
OH
GalOH
OHOH
OO
HO
HOCH2
NHC
CH3
O
!-GlcNAc
Gal
HO
OCH3
OHOH
OH
"-L-fucose
Type B
Oprotein
HOO
O
OHOH
OO
HO
HOCH2
NHC
CH3
O
!-GlcNAc
galactose
OCH3
OHOH
OH
"-L-fucose
Type O
Oprotein
26.13 HUMAN BLOOD GROUP ANTIGENS
Type O Blood Group Antigen
!-D-galactopyranosyl
"-L-fucopyranosyl!-GlcNAc group
1
2’
1
"-(1,2’)-glycosidic bond
!-(1,4’)-glycosidic bond
1
6
6
6
2
4’
"
!
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