The reactions of oxygen atoms with some partially fluorinated olefins

Abstract

A detailed study was undertaken of the reaction of
ground state oxygen atoms with the fluoroethylenes and
with 14.32 trifluorobutene-1.
Phe O(3P)/ fluorocethylene study yielded the
following rate constants and Arrhenius parameters relative
to ethylene.

<table>

Reactivity differences between the cis and trans
isomers of 1,2 difluoroethylene have been attributed
to a combination of entropic and enthalpic factors.
. An attempt to relate reaction rates to various bond and
atomic properties of the fluoroethylenes indicated
that formation of a σ transition complex is probably
the rate determining process.

The reaction of ground state oxygen atoms with
1,1,2 trifluorobutene-1 yields 1 fiuoropropnee (cis and trans isomers) and carbonyl fluoride with quantum
yields near to unity. Minor products identified
included ethane, ethylene, propane, fluorocyclopropane
and propionyl fluoride. In sharp contrast to the
reactions of non-fluorinated olefins with oxygen
atoms, epoxide formation was not significant in this
system. The main primary process is thought to be
formation of carbonyl fluoride and ethylfluorocarbene.
CHZCHSCP:, fluorocyclopropane and 1 fluoropropene being
products of the isomerisation of this carbene.

Addition of oxygen to the system left the yield of
1 fluoropropene unchanged but greatly increased yields
of propionyl and carbonyl fluoride. This behaviour
has been attributed to the reaction of the biradical,
CHZCH5CF-CP50°, with molecular oxygen to yield
ultimately 1 fluoropropene, carbonyl fluoride and
propionyl fluoride.

The reaction schemes proposed satisfactorily
explain major and minor product formation both in the
presence and absence of molecular oxygen.

Date of Award	1972
Original language	English