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267
Polymerization of phenyl propane monomers
The phenolic hydroxyl has a special property by being susceptible to
dehydrogenation, leading to a free radical (phenoxy radical). In plants, this
reaction is catalysed by enzymes. The radical is stabilized by resonance:
The phenoxy radicals are very reactive and can form linkages with other
monomers at different positions. The most important linkages are:
HC
CH
CH
2
OH
OH
OCH
3
HC
CH
CH
2
OH
O
OCH
3
-(e
-
+ H
+
)
HC
C
CH
2
OH
O
OCH
3
HC
C
CH
2
OH
O
OCH
3
HC
C
CH
2
OH
O
OCH
3
HC
C
CH
2
OH
O
OCH
3
C
C
C
OH
C C CH
2
OH
O
β
-O-4
C
C
C
OH
C C C
O
α
-O-4
C
C
C
OH
C
C
C
O
β
-5
C
C
C
OH
C
C
C
OH
5
-5