Chemistry Reference
In-Depth Information
therefore, that BF
3
-trioxane complexes don't form as suggested and do not result in initiations of
the polymerizations. Additions of small quantities of water, however, do result in initiations of the
polymerizations.
Another mechanism, is based on a concept that two molecules of BF
3
are involved in the initiation
process [
69
]. This also appears improbable since without water BF
3
fails to initiate the reaction. the
following mechanism, based on water as the cocatalyst was developed [
73
]:
H
2
O
O (C
4
H
9
)
2
H
BF
3
OH
+
BF
3
O (C
4
H
9
)
2
+
O
O
H
BF
3
OH
+
O
H
O
O
O
BF
3
OH
Chain growth in the reaction is accompanied by formations of tetraoxane and 1,3-dioxalane
because of backbiting [
71
,
74
].
Complex molybdenyl acetylacetones also act as catalysts for trioxane polymerization. The mech-
anism that is visualized involves formation of a coordinated intermediate [
75
]:
The termination mechanism and the catalyst requirement have not yet been fully explored.
Some transfer to water takes place during the reaction. As a result the polymer contains at least one
terminal hydroxyl group [
76
]. Besides water, methyl alcohol and low molecular weight ethers also act
as transfer agents [
77
].
