122
Chapter 6 · Sweet Chemistry - Mono- and Disaccharides
6
It can be chemically produced via the corresponding bromine derivative; however,
the enzymatic variant with microorganisms
is much more economical. The non-toxic,
easily degradable compound can be used as
an insecticide, herbicide and plant growth
regulator.
So far, we have taken a closer look at the dehydration of hexoses. Very similar reactions can
also be carried out with pentoses, which are easily
accessible from hemicelluloses. . Figure 6.9
shows the dehydration to furfural and the resulting derivatives.
Furfural is produced worldwide in a quantity of 300,000 t a −1 . Since it can be obtained
from hemicelluloses, which are waste products
from cellulose production, it is similarly inexpensive to petrochemical base chemicals. Important derivatives of furfural are briefly described
below:
5 Catalytic hydrogenation of furfural leads
to furfuryl alcohol. Typical hydrogenation
catalysts are copper chromite, Raney nickel
or Raney cobalt as well as platinum catalysts.
Furfuryl alcohol is an important substrate for
fragrances and other fine chemicals, but also
for furan resins. The further hydrogenation
of furfuryl alcohol leads to tetrahydrofurfuryl
alcohol or 2-methyl-THF.
5 Furfurylamine, which is used for the production of pharmaceuticals and pesticides, is
formed by reductive amination of furfurals.
5 5-Hydroxymethylfurfural (HMF, . Fig. 6.7)
can be produced by reaction with formaldehyde.
5 Catalytic decarbonylation of furfural leads to
furan, which can be further hydrogenated to
tetrahydrofuran (THF), an important solvent
and monomer building block for polytetrahydrofuran.
5 Catalytic oxidation of furfural with oxygen or
hydrogen peroxide yields furan-2-carboxylic
acid (furoic acid), an important starting
material for pharmaceuticals and fragrances.
Oxidation Reactions
In addition to dehydration, oxidation of monosaccharides is an interesting option for derivatization. . Figure 6.10 shows some important
carboxylic acids accessible from glucose.
Levulinic acid is referred to as a “platform chemical” because it is the starting compound for
numerous interesting derivatives. . Figure 6.8
shows some of its derivatives.
Levulinic acid itself is used as a solvent or
food additive. It is also used for coatings, antifreeze and as a raw material for plasticizers,
resins and pharmaceuticals. Because of its two
functional groups, follow-up chemistry, often to
cyclic compounds, is important:
5 Catalytic hydrogenation of levulinic acid
leads via 4-hydroxypentanoic acid to
γ-valerolactone(GVL), an important solvent
for paints, adhesives and insecticides.
Further, hydrogenation leads to 1,4-pentanediol (PDO), which can be dehydrated to
2-methyltetrahydrofuran (MTHF). The latter
is currently being discussed as a fuel or fuel
additive.
5 Esterification of levulinic acid is carried out,
e.g. with methanol, ethanol, n-butanol or
phenol. Typical catalysts are sulfuric acid,
polyphosphoric acid, ion exchange resins or
acidic molecular sieves. Levulinic acid esters
are used as flavors, plasticizers or solvents.
The use as oxygen-containing octane boosters
in fuels is also being discussed.
5 If levulinic acid is heated to its boiling point
(245 °C) in the presence of an acid and the
resulting water is removed by distillation,
angelica lactone is formed. Its reaction with
alcohols leads again to the levulinic acid
esters, its hydrogenation to γ-valerolactone.
5 Oxidation of levulinic acid, e.g. with oxygen
in the gas phase or with hydrogen peroxide
in the liquid phase, leads to succinic acid
(7 Sect. 6.3.1), which is also used in foods as a
flavor enhancer and acidifier. 1,4-butanediol,
THF and γ-butyrolactone are accessible via
succinic acid esters. The diacid is also discussed as monomer for biobased polyamides
and polyesters.
5 Levulinic acid and its esters can easily
undergo condensation reactions, e.g. with
aldehydes and ketones. The reaction of the
acid with formaldehyde leads to α-methylene-γ-valerolactone (MVL), a new acrylic
monomer based on renewable raw materials.
5 An important amine derivative of levulinic
acid is 5-aminolevulinic acid (ALA), an
intermediate product in porphyrin synthesis.
Chapter 6 · Sweet Chemistry - Mono- and Disaccharides
6
It can be chemically produced via the corresponding bromine derivative; however,
the enzymatic variant with microorganisms
is much more economical. The non-toxic,
easily degradable compound can be used as
an insecticide, herbicide and plant growth
regulator.
So far, we have taken a closer look at the dehydration of hexoses. Very similar reactions can
also be carried out with pentoses, which are easily
accessible from hemicelluloses. . Figure 6.9
shows the dehydration to furfural and the resulting derivatives.
Furfural is produced worldwide in a quantity of 300,000 t a −1 . Since it can be obtained
from hemicelluloses, which are waste products
from cellulose production, it is similarly inexpensive to petrochemical base chemicals. Important derivatives of furfural are briefly described
below:
5 Catalytic hydrogenation of furfural leads
to furfuryl alcohol. Typical hydrogenation
catalysts are copper chromite, Raney nickel
or Raney cobalt as well as platinum catalysts.
Furfuryl alcohol is an important substrate for
fragrances and other fine chemicals, but also
for furan resins. The further hydrogenation
of furfuryl alcohol leads to tetrahydrofurfuryl
alcohol or 2-methyl-THF.
5 Furfurylamine, which is used for the production of pharmaceuticals and pesticides, is
formed by reductive amination of furfurals.
5 5-Hydroxymethylfurfural (HMF, . Fig. 6.7)
can be produced by reaction with formaldehyde.
5 Catalytic decarbonylation of furfural leads to
furan, which can be further hydrogenated to
tetrahydrofuran (THF), an important solvent
and monomer building block for polytetrahydrofuran.
5 Catalytic oxidation of furfural with oxygen or
hydrogen peroxide yields furan-2-carboxylic
acid (furoic acid), an important starting
material for pharmaceuticals and fragrances.
Oxidation Reactions
In addition to dehydration, oxidation of monosaccharides is an interesting option for derivatization. . Figure 6.10 shows some important
carboxylic acids accessible from glucose.
Levulinic acid is referred to as a “platform chemical” because it is the starting compound for
numerous interesting derivatives. . Figure 6.8
shows some of its derivatives.
Levulinic acid itself is used as a solvent or
food additive. It is also used for coatings, antifreeze and as a raw material for plasticizers,
resins and pharmaceuticals. Because of its two
functional groups, follow-up chemistry, often to
cyclic compounds, is important:
5 Catalytic hydrogenation of levulinic acid
leads via 4-hydroxypentanoic acid to
γ-valerolactone(GVL), an important solvent
for paints, adhesives and insecticides.
Further, hydrogenation leads to 1,4-pentanediol (PDO), which can be dehydrated to
2-methyltetrahydrofuran (MTHF). The latter
is currently being discussed as a fuel or fuel
additive.
5 Esterification of levulinic acid is carried out,
e.g. with methanol, ethanol, n-butanol or
phenol. Typical catalysts are sulfuric acid,
polyphosphoric acid, ion exchange resins or
acidic molecular sieves. Levulinic acid esters
are used as flavors, plasticizers or solvents.
The use as oxygen-containing octane boosters
in fuels is also being discussed.
5 If levulinic acid is heated to its boiling point
(245 °C) in the presence of an acid and the
resulting water is removed by distillation,
angelica lactone is formed. Its reaction with
alcohols leads again to the levulinic acid
esters, its hydrogenation to γ-valerolactone.
5 Oxidation of levulinic acid, e.g. with oxygen
in the gas phase or with hydrogen peroxide
in the liquid phase, leads to succinic acid
(7 Sect. 6.3.1), which is also used in foods as a
flavor enhancer and acidifier. 1,4-butanediol,
THF and γ-butyrolactone are accessible via
succinic acid esters. The diacid is also discussed as monomer for biobased polyamides
and polyesters.
5 Levulinic acid and its esters can easily
undergo condensation reactions, e.g. with
aldehydes and ketones. The reaction of the
acid with formaldehyde leads to α-methylene-γ-valerolactone (MVL), a new acrylic
monomer based on renewable raw materials.
5 An important amine derivative of levulinic
acid is 5-aminolevulinic acid (ALA), an
intermediate product in porphyrin synthesis.