Chemistry Reference
In-Depth Information
Also, intramolecular hydrogen abstraction is assumed to occur through a seven-membered ring
transition state. This can provide a route to chain scission:
OAc
H
O
+
H
O
O
O
O
O
O
O
In subsequent studies of photo-degradation of poly(vinyl acetate) and poly(vinyl propionate) in
vacuum, it was found that acids, aldehydes, and carbon dioxide were the principal products [
553
].
Two mechanisms, one involving hydrogen abstractions, were postulated. One of them takes place by
abstraction by acyl radicals formed through Norrish Type I cleavages and the other by intramolecular
hydrogen abstraction by excited carbonyl groups followed by fragmentation [
553
]:
∗
H
O
hν
+
O
OO
R H
R
R
O
hν
R
O
+
O
O
O
OH
R
R
O
O
*
A second, perhaps more viable mechanism, was pictured for the production of aldehydes involving
hydrogen abstraction as follows [
553
]:
*
hν
H
O
O
O
O
R
R
R
R
O
O
O
O
O
O
+
O
O
R
R
O
O
O
