KINETIC AND PRIMARY PRODUCT STUDIES OF THE REACTION OF O (P-3) WITH STYRENE IN THE GAS-PHASE

The rates of the reaction of styrene with atomic oxygen have been meas ured in a discharge flow system with mass spectrometric detection. The measurements were carried out under oxygen atom excess in the tempera ture range 298 K < T < 873 K. The main reaction channel at room temper ature is O atom addition to the vinyl side chain, yielding as main pro duct (identified by mass spectrometric product analysis) styrene oxide . Towards higher temperatures O atom addition to the aromatic ring as a second reaction channel becomes more important. Using Hammett plots the following Arrhenius expressions for the addition to the aromatic r ing (k(ar)) and to the alkene double bond (k(db)) of the side chain ca n be derived: k(ar)(T) = (1.70 +/- 0.34) . 10(13) . exp(-2051 +/- 205/ T) cm3 mol-1 s-1 k(dp)(T) = (0.14 +/- 0.03) . 10(13) . exp(+198 +/- 20 /T) cm3 mol-1 s-1.First experiments with indene give similar results, showing a somewhat higher reactivity for this molecule compared to sty rene.