Hydrogen-atom attack on 1-phenylpropene at high temperatures

Abstract

The reactions of hydrogen atom with 1-phenylpropene (IPP) have been studied in single-pulse shocktubeexperiments. Contribution from a large number of the possible reactive channels has been observed. The prime channels are the displacement of the methyl group resulting from addition to the olefinic structure and abstraction of a hydrogen from the methyl group followed by internal displacement of the hydrogen, forming indene. Displacement from the ring is less favored. The following rate expressions at temperatures of 990–1100 K and pressures of 1.4–2.0 atm have been determined. k ( H + 1 − p h e n y l p r o p e n e → s t y r e n e + m e t h y l ) = 10 13.6 ± 0.5 exp ⁡ ( − 1200 ± 1000 / T ) k ( H + 1 − p h e n y l p r o p e n e → p r o p e n e + p h e n y l ) = 10 14.0 ± 0.7 exp ⁡ ( − 5300 ± 1500 / T ) k ( H + 1 − p h e n y l p r o p e n e → p r o p e n y l + b e n z e n e ) = 10 14.2 ± 0.7 exp ⁡ ( − 6300 ± 1500 / T ) k ( H + 1 − p h e n y l p r o p e n e → 3 − p h e n y l a l l y l + H 2 + H 2 ) ⩽ 10 14.2 ± 0.5 exp ⁡ ( − 5600 ± 1000 / T ) , where the relative and absolute uncertainties in the rate constants are factors of 1.10 and 1.25, respectively. An attempt has been made to relate these rate expressions to basic thermal processes, and similarities to those for the appropriate smaller olefins have been noted. Displacement rate constants are made smaller by the reversibility of the hydrogen addition reaction, and together with possible isomerizations, they represent an additional complicating feature