REACTIONS OF POLYCYCLIC ALKYLAROMATICS .1. PATHWAYS, KINETICS, AND MECHANISMS FOR 1-DODECYLPYRENE PYROLYSIS

1-Dodecylpyrene (DDP) was pyrolyzed at concentrations between 0.0007 and 0.47 M in a benzene diluent, at temperatures from 375 to 450-degrees-C. Product yields and selectivities were functions of both the conversion and the initial concentration. For instance, DDP pyrolysis at low conversions (< 25%) and low initial concentrations (< 0.14 M) yielded primary products analogous to those observed for alkylbenzene pyrolysis, whereas experiments at higher conversions and concentrations yielded n-dodecane and pyrene as the major products through the cleavage of the strong aryl-alkyl C-C bond. Kinetics analysis showed that this concentration-dependent behavior could be modeled by using the rate law previously derived for alkylbenzene pyrolysis plus an additional term accounting for the apparently autocatalytic decomposition of the strong aryl-alkyl bond. Pyrolyses of DDP with a hydrogen-transfer reporter molecule, 1,6-dimethylnaphthalene, showed that a selective hydrogenolysis mechanism was likely responsible for cleavage of the aryl-alkyl C-C bond.