139
6
industrial interest because it can be
polymerized into the biodegradable
thermoplastic polylactic acid (PLA). It is
also being investigated whether it can be
dehydrated to acrylic acid.
5 Among the chemical conversion of
monosaccharides, the dehydration of
hexoses to 5-hydroxymethylfurfural (HMF)
is of great importance. This “platform
chemical” can be converted into numerous
derivatives, e.g. 2,5-bis(hydroxymethyl)
furan, 2,5-furandicarboxylic acid and
levulinic acid. Due to their two functional
groups, these substances can be used
as monomers for biopolymers. The
dehydration of pentoses leads to furfural,
which also has an extensive downstream
chemistry.
5 Carboxylic acids, e.g. gluconic acid and
glucuronic acid, are formed by oxidation
of monosaccharides.
5 Hydrogenation of sugars leads to sugar
alcohols. Glucose becomes sorbitol,
fructose becomes mannitol. Both serve as
artificial sweeteners. Sorbitol is also the
starting compound for the synthesis of
l-ascorbic acid, vitamin C.
5 Glucose can be converted into alkyl
polyglucosides (APG) by glycosidation
with fatty alcohols. They are important
non-ionic surfactants consisting
exclusively of renewable raw materials.
They are very skin-friendly and
completely biodegradable.
5 Esterification of sugar leads to sugar
esters, which can also be used as active
washing substances.
5 By amination of glucose with
methylamine in the presence of
hydrogen, N-methylglucamine is formed,
which reacts with fatty acid esters to form
fatty acid N-methylglucamide. These
glucamides are also easily degradable
surfactants.
5 Disaccharides include sucrose,
isomaltulose, lactose (“milk sugar”) and
maltose (“malt sugar”).
5 The most important disaccharide in terms
of quantity, sucrose, is obtained from sugar
cane or sugar beet. Sucrose is isolated in
sugar factories by extraction with hot water
occurs in cereals and many plant tubers, such
as potatoes or tapioca (7 Chap. 8).
5 Chitin consists of N-acetylglucosamine
units, which (as in cellulose) are linked by a
β-(1,4)-glycosidic bond to each other. This
polysaccharide occurs in the shells of crustaceans. Chitosan is formed by splitting off the
acetyl group (7 Chap. 9).
5 Glycogen is the storage carbohydrate in the
animal organism and is stored especially in
the liver, but also in the muscles. Its structure
is similar to that of starch, but it has a larger
number of α (1,6)-glycosidic branches.
5 Pectins are found in numerous fruits, stems
and tubers. They consist of galacturonic acid
units (or their methyl esters), which are (as
in starch) linked via an α-(1,4)-glycosidic
bond to each other. They can form gels and
are therefore used for the production of jellies
and jams.
5 We already introduced the polysaccharide
inulin at the beginning of the discussion on
fructose. It is the reserve carbohydrate in
the root tubers of dahlias and artichokes.
It consists of fructose units linked via
β-(1,2)-glycosidic bonds, with one glucose
unit as the terminal group.
5 The chemical industry also produces a
number of other oligo- and polysaccharides,
such as cyclic cyclodextrins, which consist of
several glucose units. These compounds are
discussed together in 7 Chap. 10.
Summary (Take-Home Messages)
5 Carbohydrates or “saccharides” have
the general molecular formula C n (H 2 O) n .
They are divided into mono-, oligo- and
polysaccharides.
5 Monosaccharides are polyhydroxyaldehydes or -ketones with three to six
carbon atoms. Typical representatives
are the aldohexose glucose and the
ketohexose fructose. In addition to
their linear form, they also exist in cyclic
hemiacetal and hemiketal structures.
5 Monosaccharides undergo a number
of fermentative reactions. These
include the transformation to lactic
acid, 3-hydroxypropionic acid, succinic
acid, itaconic acid and glutamic acid.
In particular, lactic acid is of great
6.4 · Outlook on Further Oligo- and Polysaccharides
6
industrial interest because it can be
polymerized into the biodegradable
thermoplastic polylactic acid (PLA). It is
also being investigated whether it can be
dehydrated to acrylic acid.
5 Among the chemical conversion of
monosaccharides, the dehydration of
hexoses to 5-hydroxymethylfurfural (HMF)
is of great importance. This “platform
chemical” can be converted into numerous
derivatives, e.g. 2,5-bis(hydroxymethyl)
furan, 2,5-furandicarboxylic acid and
levulinic acid. Due to their two functional
groups, these substances can be used
as monomers for biopolymers. The
dehydration of pentoses leads to furfural,
which also has an extensive downstream
chemistry.
5 Carboxylic acids, e.g. gluconic acid and
glucuronic acid, are formed by oxidation
of monosaccharides.
5 Hydrogenation of sugars leads to sugar
alcohols. Glucose becomes sorbitol,
fructose becomes mannitol. Both serve as
artificial sweeteners. Sorbitol is also the
starting compound for the synthesis of
l-ascorbic acid, vitamin C.
5 Glucose can be converted into alkyl
polyglucosides (APG) by glycosidation
with fatty alcohols. They are important
non-ionic surfactants consisting
exclusively of renewable raw materials.
They are very skin-friendly and
completely biodegradable.
5 Esterification of sugar leads to sugar
esters, which can also be used as active
washing substances.
5 By amination of glucose with
methylamine in the presence of
hydrogen, N-methylglucamine is formed,
which reacts with fatty acid esters to form
fatty acid N-methylglucamide. These
glucamides are also easily degradable
surfactants.
5 Disaccharides include sucrose,
isomaltulose, lactose (“milk sugar”) and
maltose (“malt sugar”).
5 The most important disaccharide in terms
of quantity, sucrose, is obtained from sugar
cane or sugar beet. Sucrose is isolated in
sugar factories by extraction with hot water
occurs in cereals and many plant tubers, such
as potatoes or tapioca (7 Chap. 8).
5 Chitin consists of N-acetylglucosamine
units, which (as in cellulose) are linked by a
β-(1,4)-glycosidic bond to each other. This
polysaccharide occurs in the shells of crustaceans. Chitosan is formed by splitting off the
acetyl group (7 Chap. 9).
5 Glycogen is the storage carbohydrate in the
animal organism and is stored especially in
the liver, but also in the muscles. Its structure
is similar to that of starch, but it has a larger
number of α (1,6)-glycosidic branches.
5 Pectins are found in numerous fruits, stems
and tubers. They consist of galacturonic acid
units (or their methyl esters), which are (as
in starch) linked via an α-(1,4)-glycosidic
bond to each other. They can form gels and
are therefore used for the production of jellies
and jams.
5 We already introduced the polysaccharide
inulin at the beginning of the discussion on
fructose. It is the reserve carbohydrate in
the root tubers of dahlias and artichokes.
It consists of fructose units linked via
β-(1,2)-glycosidic bonds, with one glucose
unit as the terminal group.
5 The chemical industry also produces a
number of other oligo- and polysaccharides,
such as cyclic cyclodextrins, which consist of
several glucose units. These compounds are
discussed together in 7 Chap. 10.
Summary (Take-Home Messages)
5 Carbohydrates or “saccharides” have
the general molecular formula C n (H 2 O) n .
They are divided into mono-, oligo- and
polysaccharides.
5 Monosaccharides are polyhydroxyaldehydes or -ketones with three to six
carbon atoms. Typical representatives
are the aldohexose glucose and the
ketohexose fructose. In addition to
their linear form, they also exist in cyclic
hemiacetal and hemiketal structures.
5 Monosaccharides undergo a number
of fermentative reactions. These
include the transformation to lactic
acid, 3-hydroxypropionic acid, succinic
acid, itaconic acid and glutamic acid.
In particular, lactic acid is of great
6.4 · Outlook on Further Oligo- and Polysaccharides