The Carbohydrates

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Title
The Carbohydrates C(H2O)n
Emil Hermann Fischer (1852-1919)
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F-R Convention
The Fischer-Rosanoff Convention
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D/L Series
Fischer-Rosanoff D- and L-Series
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D-Aldohexoses
The D-Aldohexoses
C3
C5
C4
C2
All altruists gladly make gum in gallon tanks
L. Fieser
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Rxn of Aldoses
Reactions of Aldoses
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Osazones
More on Osazones
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F-K and Ruff
Chain Lengthening and Shortening of Aldoses
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D-Series Interrelationship
Interrelationship of the D-Series of Aldoses via
Chain Lengthening and Degradation
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Which one is Glucose?
The Aldohexoses
But which one is ()-glucose?
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Aldaric Acids/Alditols
Rosanoff Formulation of C6 Aldaric Acids and
Alditols
Terminal groups identical CO2H or CH2OH
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Fischer Proof 1
Fischers Proof Part 1
()-Glucose forms an optically active aldaric
acid and optically active alditol.
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Fischer Proof2
Fischers Proof Part 2
()-Glucose and ()-mannose form the same
osazone. If 1, 7, 9, and 15 are not related to
()-glucose, then they are not related to
()-mannose nor are 2, 8, 10, and 16 related to
()-glucose.
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Fischer Proof3
Fischers Proof Part 3
()-Arabinose affords (-)-glucose and (-)-mannose
by Kiliani-Fischer synthesis.
()-Arabinose must be of the opposite series
(D/L)as ()-glucose and have the same absolute
configuration at C3-5 as (-)-glucose and
(-)-mannose.
What is the structure of arabinose?
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F P3, cont

• Arabinose forms an optically active
• aldaric acid (arabinaric acid)
• and optically active alditol
• (arabitol) as its borax complex.

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Fischer Proof4
Fischers Proof Part 4
The pentose ()-xylose affords optically inactive
xylaric acid and optically inactive xylitol as
its borax complex.
Fischer-Kiliani synthesis of ()-xylose leads to
two new hexoses, ()-gulose and ()-idose, both
of which form optically active aldaric acids.

• ()-Xylose must be one of the remaining two
  structures.

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Fischer Proof5
Fischers Proof Part 5
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Fischer Proof5, cont
Fischers Proof Part 5
()-Glucose and (-)-gulose form the same
optically active aldaric acid, glucaric acid.
or
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Fischer Proof5, cont-2
Fischers Proof Part 5

• Mannaric acid is formed from
• a single hexose.

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Fischer Proof6
Fischers Proof Part 6
Just Guess!

• Fischer arbitrarily assigned the D-series to the
  dextrorotatory enantiomer.

• Sixty years later (1951), he was proved correct
  when Bijvoet
• related ()-glucose to ()-tartaric acid.

• Fischer All sugars related to D-()-glucose by
  chemical correlation
• belong to the D-series.

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Fischers Flaw
A Flaw in the Fischer Scheme
Identical Achiral Mucic Acid (An
Aldaric Acid)
"Two aldoses can produce the same dibasic acid
only if they belong to the same stereochemical
family. That this, however, is erroneous as a
general proposition, may be readily seen from
the fact that the two enantiomorphous galactoses
- plainly belong to the opposite families -
yield the same mucic acid. A. M. Rosanoff-1906
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Rosanoffs Wheel
Rosanoffs Reorganization of the Carbohydrates

• Arranged by successive Kiliani
• syntheses

• The D- and L- assignments were
• Fischers based on chemical
• correlation with D-()-glucose,
• an unreliable scheme.

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Evolution of Signage
Evolution of Signage
Optical Activity
Configuration
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D-Aldohexoses
aldotriose
aldotetrose
aldo pentose
aldo hexose
All altruists gladly make gum in gallon tanks
L. Fieser
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Fischer Projections
Fischer Projections of Glucose
form hemiacetals between C5-OH and C1
D-()-Glucose
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Anomers
Fischer Projections of Glucopyranose Anomers
right alpha
left beta
C
HO
C
OH
OH
OH
HO
HO
OH
OH
O
O
CH2OH
CH2OH
b-D-()-Glucopyranose
a-D-()-Glucopyranose
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Haworth
Haworth Projections of Glucopyranose Anomers
up (top) beta
down (bottom) alpha
b-D-()-Glucopyranose
a-D-()-Glucopyranose
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Conformational Glucopyranose
Chair Conformations of Glucopyranose Anomers
b-D-()-Glucopyranose
a-D-()-Glucopyranose
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Old Salt
How an Old Salt Remembers
starboard
port
right
left
fewer letters
more letters
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Mutarotation
Mutarotation of Anomers
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Ring Sizes of Hexoses
Ring Sizes of Hexoses
Hexose Pyranose Form (?/?) Furanose Form
allose 92 8
altrose 70 30
glucose 100(36.5/63.5) lt1
mannose 100(67/33) lt1
gulose 97 3
idose 75 25
galactose 93(27.5/72.5) 7
talose 69 31
fructose 67 33
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Periodic acid
Periodic Acid Cleavage of Carbohydrates as a
Diagnostic Tool
2 CH2O
CH2O HCO2H
Formaldehyde (CH2O) arises from a primary alcohols
Formic acid (HCO2H) arises from a secondary
alcohols
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Periodic Acid Diagnostic
Periodic Acid Cleavage of Carbohydrates as a
Diagnostic Tool
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Periodic on Carbohydrates
Periodic Acid Cleavage of Carbohydrates
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Methylation
Methylation of Pyranoses Pyranosides
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Ring Size
Ring Size of Pyranosides
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Periodic on Glycosides
Periodic Acid Cleavage of Methyl
?-Glucopyranoside
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Enzymes
Enzymatic Cleavage of Glucosides
Methyl ?-D-glucoside
Methyl ?-D-glucoside
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Tollens
The Silver Mirror Test
www.chem-pics.co.uk/download.htm
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Tollens 2
The Silver Mirror Test
Aldoses and ketoses are reducing sugars
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Intro Di- and Polysaccharides
Disaccharides and Polysaccharides
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Sucrose/Olestra
?-D-Glucopyranosyl- ? -D-fructofuranoside
or??-D-Fructofuranosyl-?-D-glucopyranoside
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Woodward
Sucrose is Formed from Glucose and Fructose
This discussion brings to mind a wonderful story
told to me by Professor Harry Wasserman (Yale),
who during the late 1940's was a graduate student
of Professor R. B. Woodward at Harvard.
Apparently Woodward had received a notice of a
1,000 prize for the first person to accomplish a
chemical synthesis of sucrose. He went into the
laboratory and said to his students that all they
had to do was connect two molecules of glucose
together ...and lose a molecule of water and
they would have themselves 1,000. One student,
obviously not overwhelmed by Woodward's stature
in the field even at such a young age, replied
that if you did it that way,
the prize would be 2,000!
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Sucralose
Sucralose
1,6-Dichloro-1,6-dideoxy-ß-D-fructofuranosyl-4-chl
oro-4-deoxy-a-D-galactopyranoside
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Bees Do It
Bees Do It
or H3O
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Cellobiose
Disaccharides-Cellobiose
emulsin,??-glucosidase (termites, ruminants)
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Cellobiose-Str. Proof
Cellobiose-Structure Proof

• hydrolysis ----gt only D-glucose

• emulsin ----gt ?-glucoside

• positive Tollens test ----gt reducing sugar

• shows mutarotation

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Cellobiose-Str. Proof
Cellobiose-Structure Proof
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Maltose
Disaccharides Maltose
Starches poly-?-D-glucosides

• hydrolysis ----gt only D-glucose

• maltase ----gt ?-glucoside

• positive Tollens test ----gt reducing sugar

• shows mutarotation

• differs from cellobiose at the glycosidic
  anomeric center

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Lactose
Disaccharides Lactose
4-O-(?-D-galactopyranosyl)-D-glucose
5 of human and cow milk

• lactose intolerance

• shows mutarotation

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Amygdalin
Disaccharides Amygdalin
Laetrile (laevorotatory mandelonitrile), vitamin
17
Touted in some circles as a treatment for cancer.
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Cellulose Chain Length
Cellulose Chain Length
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Starches Plant Polysaccharides
Starches Plant Polysaccharides
Amylose

• 20 water soluble starch poly
  4-O-(?-D-glucoside)

• forms helical structure blue complex with iodine

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Starches Plant Polysaccharides
Starches Plant Polysaccharides

• permethylation/hydrolysis

• permethylation

Average 20 glucose units /chain
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Diogenes
And Finally, a True Story
In March of 1986 I was in California visiting
several universities. While at Stanford
University, I stopped at the health center to
have a swollen foot examined. The young resident
was very attentive. To assess his
qualifications, I asked him where he had attended
college. M.I.T., he responded. So you must
have had Professor Kemp for organic chemistry, I
countered. Yes, I did, he said. Then I asked,
What D-aldohexose forms the same osazone as
glucose?
I really enjoyed organic chemistry!
Really?
Organic, dont remind me!
An honest man?
I know the mechanism of the aldol condensation.
Wrong chapter!
I know what a Grignard reagent is.
Wrong test!
Wait! Give me some time.
Its only an hour exam.
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Moral
The Moral of the Story
Somewhere,sometimesomeone might ask you this
question.
What D-aldohexose forms the same osazone as
D-glucose?
Your answer will be...
D-Mannose!
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The End
The End