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Chapter 11 · The “Wood-Stuff” - Lignin
11
11.2.1 Monolignols
In principle, lignin is composed of three different building blocks which are linked together in
different ways to form a macromolecule. These
three building blocks are of the phenylpropanoid
class, i.e. phenols substituted with a C3 side
chain. All three alcohols are shown in . Fig. 11.3.
It is evident that this is a very complex structure which is not comparable with other chemical
structures known to us. On closer look, however,
one can recognize that certain structures are
repeated. These are based on the one hand on the
structure of the interconnected building blocks
(the so-called monolignols) and on the other hand
on the interconnection pattern of the monomers.
Let us first look at the monomeric building blocks.
O
H3CO
HC
CH
HOC
CH2OH
HC
CH2OH
O
OCH3
CHOH
HC
H2C
O
CH
CH
O
CH2OH
H3CO
CO
CH
O
CH2OH
H3CO
CHOH
CHOH
CH2O
O
HC
CHOH
CH2OH
OH
OCH3
OCH3
OH
OCH3
HC
HC
H2C
O
O
CH2
CH
CH
H3CO
O
CH
CH2OH
HC
O
OH
OCH3
O
CH
HOC
CH2OH
H3CO
CO
CH
CH2
HC
CH2OH
HC
O
H3CO
OH
H3CO
CHOH
CH
CH2OH
O
H3CO
HC
O
C
CH2OH
H3CO
CH2
CH2
CH2OH
(Carbohydrate)
O
H3CO
CH
HC
CH2OH
OCH3
OH
O
HC
CHO
CH2OH
CH
O
CH2OH
H3CO
HC
CH
CH2OH
HO
H3CO
O
CH2
HC
CHOH
OH
OCH3
O
OCH3
HC
HC
CH2OH
O
OCH3
CH2
CH2
CHO
O
OCH3
CHOH
HC
CH2OH
O
CH
HO
CH
CH2OH
O
H3CO
CH2
CH
CH2OH
OH
H3CO
CH2
CH2
CH2OH
Coniferyl alcohol
Sinapyl alcohol
H3CO
p-Coumaryl
alcohol
. Fig. 11.2 Example of a section of a lignin molecule from spruce wood
. Fig. 11.3 Structural
formulae of the three
phenylpropanoids
(monolignols) from which
lignin are composed
CH
CH
CH 2 OH
OH
CH
CH
CH 2 OH
OCH 3
OH
CH
CH
CH 2 OH
OCH 3
OH
H 3 CO
1
2
3
4
5
6
1
2
3
4
5
6
1
2
3
4
5
6
p-Coumaryl
alcohol
Coniferyl
alcohol
Sinapyl
alcohol