Phenylpropiolyl peroxide and its p-methyl -, p-methoxy-,
p-chloro -, and p-bromo-substituted analogues have been synthesised
in good yield and high purity by a method involving the reaction of
the corresponding carboxylic acid with 98% hydrogen peroxide and
The parent compound has been decomposed in a variety of
solvents and the mechanism of induced decomposition in these
The decomposition of the peroxides in chloroform at 65.0° in
the presence of equimolar (0.05M) quantities of 3,4- dichloroetyrene
to inhibit the induced decomposition enabled estimation of the
first-order rate constants.
Application of the Arrhenius' equation to the data from
decompositions carried out in chloroform at different temperatures
enabled estimation of the energy of activation for the decomposition
of the parent compound and the p- methyl - and p- methoxy- analogues.
The p-methoxy compound had a greatly enhanced rate of decomposition
and lower activation energy - suggesting a different mechanism and
the possibility of a non-homolytic decomposition.
The synthesis of systems designed to differentiate between
bridged and classical free radical intermediates by identification
of the reaction products has been investigated.
The production of radicals of this nature from aldehydes and
azo compounds was unsuccessful due to the difficulty experienced
in synthesis of the starting materials.
The synthesis of 4-t-butyl-2-bromocyclohexylformyl peroxide
has been achieved from the corresponding acid with 98% hydrogen
peroxide and dicyclohexylcarbodiimide.
4-t-butyl-l-cyanocyclohexene was found to undergo stereo-specific addition of hydrogen bromide to give exclusively the
trans addition product, namely, trans-4-t-butyl-cis-2-bromo -l-cyanocyclohexane,
under both free radical and ionic conditions.
The significance of this in relation to bridged radicals is
The decomposition of the bromo peroxide did not give the
expected products when investigated under similar conditions to
those employed for the parent compound, 4-t-butylcyclohexylformyl
peroxide. This limited the amount of information that could be