Answers to the Quickies
365
tates and can be separated. The cyclodextrins can then be regenerated and reused.
10. For the structural formula of α-cyclodextrin
. Fig. 10.1. Permethylated means in this
context that all free hydroxyl groups carry a
methyl group. This is achieved by reacting
with methyl chloride under basic conditions
(7 Chaps. 7 and 8).
Answers to 7 Chap. 11
1. Lignin is essential for the stability of plants
by forming a composite structure with cellulose and hemicelluloses that contributes to
the lignification of plant tissue. Lignin is the
filling material of this composite structure
and fills the gaps between micro- and macrofibrils of cellulose.
2. Marine plants, such as algae, do not need
stabilizing lignin in their plant cells, as
buoyancy in the water provides the necessary stability. Trees, on the other hand, have
to counteract gravity through lignification in
order to grow taller.
3. Sinapyl alcohol carries two methoxy groups
in ortho position to the phenolic hydroxyl
group, whereas coniferyl alcohol carries
only one. Therefore, the carbon atom C5
of the coniferyl alcohol combines with the
β-carbon atom of the sinapyl alcohol.
4. The lignin of conifers is rich in coniferyl
alcohol (up to 90%), while the lignin of
grasses has an increased content of coumaryl alcohol.
5. The largest amounts of lignin are produced
as a by-product of pulp production using the
sulfate process. As this is mainly operated
with softwoods, the largest lignin resources
are softwoods such as pine or spruce.
6. By using low-boiling organic solvents, little
energy is required for their recovery. An
almost completely closed chemical cycle is
achieved, resulting in less polluted wastewater. By avoiding sulfur compounds to
decompose the wood, the environment
is less polluted. A higher quality lignin is
achieved, which can be sold to cover part of
the process costs.
7. Lignin has a calorific value of approximately
23 GJ t −1 , making it an excellent fuel for
maintaining the process temperatures of
the sulfate process. In addition, the lignin
present in the black liquor is heavily contaminated and would therefore have to be
thoroughly purified and separated, making
its use unprofitable.
8. Lignosulfonates are soluble in water over
a wide pH range and are physiologically and ecologically harmless. They are
surface-active and have dispersing and
emulsion-stabilizing properties. They are
present as polyanions and can therefore be
used as complexing agents and stabilizers in
electrolyte solutions.
9. Lignin is converted with hydrogen in a
hydrogenation process and the resulting
decomposition products are separated by
distillation. The main products are various
substituted phenols, which can be further
converted to duroplasts.
10. Vanillin (4-methoxy-3-hydroxybenzalde -
hyde) can be produced from the waste liquors of the sulfite process in a yield of about
3–5 g l −1 by oxidative degradation.
Answers to 7 Chap. 12
1. Diterpenes: C 20 ; sesquiterpenes: C 15 ; hemiterpenes C 5 ; tetraterpenes C 40 ; monoterpenes: C 10 .
2. Isoprene has a C=C double bond at which a
methyl group is located (= “head” h) and a
vinyl group (= “tail” t). The natural terpenes
are predominantly head-tail (ht)-linked. In
the triterpene squalene, the two C 15 units
are tt-linked.
3. Terpenes are often attractants to lure pollinating insects or repellents to defend against
enemies. The pleasant smell of the monoterpene nerol in lavender is supposed to attract
bees; the unpleasant terpentine-like smell
of the pinene is supposed to keep the bark
beetles away from the spruces and pines.
4. In steam distillation, hot steam is blown into
a vessel with flowers or leaves. The water
partial pressure lowers the boiling point of
the terpenes, which are collected relatively
gently in a cooled receiver. (A detailed
description can be found in 7 Chap. 18.)
5. Classically, terpenes are extracted with
ethanol, which can be gently removed by
365
tates and can be separated. The cyclodextrins can then be regenerated and reused.
10. For the structural formula of α-cyclodextrin
. Fig. 10.1. Permethylated means in this
context that all free hydroxyl groups carry a
methyl group. This is achieved by reacting
with methyl chloride under basic conditions
(7 Chaps. 7 and 8).
Answers to 7 Chap. 11
1. Lignin is essential for the stability of plants
by forming a composite structure with cellulose and hemicelluloses that contributes to
the lignification of plant tissue. Lignin is the
filling material of this composite structure
and fills the gaps between micro- and macrofibrils of cellulose.
2. Marine plants, such as algae, do not need
stabilizing lignin in their plant cells, as
buoyancy in the water provides the necessary stability. Trees, on the other hand, have
to counteract gravity through lignification in
order to grow taller.
3. Sinapyl alcohol carries two methoxy groups
in ortho position to the phenolic hydroxyl
group, whereas coniferyl alcohol carries
only one. Therefore, the carbon atom C5
of the coniferyl alcohol combines with the
β-carbon atom of the sinapyl alcohol.
4. The lignin of conifers is rich in coniferyl
alcohol (up to 90%), while the lignin of
grasses has an increased content of coumaryl alcohol.
5. The largest amounts of lignin are produced
as a by-product of pulp production using the
sulfate process. As this is mainly operated
with softwoods, the largest lignin resources
are softwoods such as pine or spruce.
6. By using low-boiling organic solvents, little
energy is required for their recovery. An
almost completely closed chemical cycle is
achieved, resulting in less polluted wastewater. By avoiding sulfur compounds to
decompose the wood, the environment
is less polluted. A higher quality lignin is
achieved, which can be sold to cover part of
the process costs.
7. Lignin has a calorific value of approximately
23 GJ t −1 , making it an excellent fuel for
maintaining the process temperatures of
the sulfate process. In addition, the lignin
present in the black liquor is heavily contaminated and would therefore have to be
thoroughly purified and separated, making
its use unprofitable.
8. Lignosulfonates are soluble in water over
a wide pH range and are physiologically and ecologically harmless. They are
surface-active and have dispersing and
emulsion-stabilizing properties. They are
present as polyanions and can therefore be
used as complexing agents and stabilizers in
electrolyte solutions.
9. Lignin is converted with hydrogen in a
hydrogenation process and the resulting
decomposition products are separated by
distillation. The main products are various
substituted phenols, which can be further
converted to duroplasts.
10. Vanillin (4-methoxy-3-hydroxybenzalde -
hyde) can be produced from the waste liquors of the sulfite process in a yield of about
3–5 g l −1 by oxidative degradation.
Answers to 7 Chap. 12
1. Diterpenes: C 20 ; sesquiterpenes: C 15 ; hemiterpenes C 5 ; tetraterpenes C 40 ; monoterpenes: C 10 .
2. Isoprene has a C=C double bond at which a
methyl group is located (= “head” h) and a
vinyl group (= “tail” t). The natural terpenes
are predominantly head-tail (ht)-linked. In
the triterpene squalene, the two C 15 units
are tt-linked.
3. Terpenes are often attractants to lure pollinating insects or repellents to defend against
enemies. The pleasant smell of the monoterpene nerol in lavender is supposed to attract
bees; the unpleasant terpentine-like smell
of the pinene is supposed to keep the bark
beetles away from the spruces and pines.
4. In steam distillation, hot steam is blown into
a vessel with flowers or leaves. The water
partial pressure lowers the boiling point of
the terpenes, which are collected relatively
gently in a cooled receiver. (A detailed
description can be found in 7 Chap. 18.)
5. Classically, terpenes are extracted with
ethanol, which can be gently removed by