Massenspektrometrische Untersuchung der Kinetik von H-Atom-Reaktionen mit ungesättigten Kohlenwasserstoffen in der Gasphase

Abstract

The reaction of hydrogen atoms with benzene was investigated in the gas phase at low pressure (< 1 Torr) using a stationary gas flow method with a mass spectrometer as detector for the reaction components. The loss of hydrogen atoms through wall recombination, favoured by adsorbed organic reaction components, and the pressure drop along the reaction tube was taken into account for the determination of the rate constants. For the initial reaction the rate constant is 

k(H + C₆H₆) = (1.55 ± 0.14) ・ 10⁷ (M^-1 s^-1). 

It is found that the main reaction does not proceed to cyclohexane for low pressures but dominantly yields methane and C₂-products, probably by ring opening of the vibrationally excited cyclohexadienyl radical.