A weight growth route from 2-naphthylmethyl radical to tricyclic aromatics

A combined experimental and theoretical study was conducted to investigate the weight growth routes from 2-naphthylmethyl radical to tricyclic aromatics. Co-pyrolysis of 2-(chloromethyl)naphthalene with two C 3 H 4 isomers (allene and propyne) were experimentally studied using the flash pyrolysis microreactor employing synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Abundant propargyl radicals and naphthylmethyl radicals were detected in the two reaction systems. The similar signal intensities and photoionization efficiency spectrum curves of m/z = 180 (C 14 H 12 ) in both reaction systems are dominantly attributed to the products of the radical-radical reaction of 2-naphthylmethyl and propargyl. The possible candidates of m/z = 180 were assigned via the calculated adiabatic ionization energies . Further investigations on the kinetics of the radical-radical 2-naphthylmethyl + propargyl reaction indicate a severe competition among the adducts and tricyclic aromatics at the typical flame temperatures. At low pressures, the tricyclic C 14 H 11 radicals + H products possess overwhelming advantages, which may contribute to the formation of phenanthrene/anthracene or larger polycyclic aromatic hydrocarbons (PAHs) via the subsequent chain reactions. At atmospheric and higher pressures, most of the products are stabilized to the bicyclic adducts. The present work reveals a potential weight growth route from 2-naphthylmethyl radical to tricyclic aromatics, which should be considered in the model for the growth of PAHs.