Kinetics of Pyrolysis of a Coal Model Compound, 2-Picoline, the Nitrogen Heteroaromatic Analogue of Toluene. 1. Product Distributions

Article abstract of DOI:10.1021/j100204a044

The pyrolysis of 2-picoline in dilute mixtures with argon has been investigated using the single-pulse shock tube and was found to decompose over the temperature range 1300-1550 K, at an average residence time of 800 μs and uniform pressure of 14-16 atm.The major products observed were acetylene, methane, hydrogen, HCN, and cyanoacetylene.Over the studied range of mixture compositions (0.06-0.20 molpercent of 2-picoline) the overall rate of disappearance of 2-picoline obeyed first-order kinetics.Arrhenius parameters for disappearance of picoline were found to be A_dis=10^17.4+/-1.1 s^-1 and E_a,dis=98+/-7 kcal mol^-1.From the distribution of observed products it is concluded that the principal initiation reactions were analogous to those known to occur in toluene, the hydrocarbon analogue of 2-picoline, and were found to be C-C bond fission to yield o-pyridyl and methyl radicals and C-H fission to yield H atoms and 2-picolyl, the N-containing analogue of benzyl.Major products were observed from decomposition of both the o-pyridyl and the 2-picolyl radicals.Cyanoacetylene arises principally from the secondary reactions of o-pyridyl.A product with m/z 91 was observed at the lowest temperatures at which 2-picoline decomposition could be detected.It has been identified as 1-cyanocyclopentadiene and arises from loss of H from the 2-picolyl radical.Other products arising from secondary decomposition of 2-picolyl at higher temperatures include HCN and cyclopentadienyl radicals.