Further experiments on pyrolysis of 2,2‐dimethylpropane behind shock waves

Abstract

AbstractPyrolysis of a dilute mixture of neopentane (2,2‐dimethylpropane) has been studied behind incident shock waves at an average pressure of 0.35 atm; the reaction was followed by absorption spectroscopy for H atoms. In the temperature range 1230–1455 K, the rate constant for dissociation of neopentane to t‐butyl and methyl radicals is 1.1 E 13 exp(−62 kcal/RT) s−1. These data and some of the literature results, between 1000 and 1450 K, can be fitted by an RRKM model of the hindered Gorin type, with five active internal rotors in the complex. To match our data with other literature data down to 800 K, a vibrational model was more satisfactory, but this did not fit very low pressure pyrolysis data in the 1000–1100 K range. Apparently, the VLPP data are too high because of heterogeneous processes or chain reactions.