Pyrolysis of Polycyclic Perhydroarenes. 1. 9-n-Dodecylperhydroanthracene

Abstract

9-n-Dodecylperhydroanthracene (DDPA), a prototypical long-chain, n-alkylnaphthene, was pyrolyzed neat and in benzene at temperatures between 400 and 450 C. The global reaction order for the disappearance kinetics was 1.05 {+-} 0.23, which was taken to be first order in subsequent analyses. The first-order Arrhenius parameters were [log{sub 10} A (s{sup {minus}1}), E (kcal/mol)] = [10.5 {+-} 1.9, 44.7 {+-} 6.1]. All of the reported uncertainties are 95% confidence intervals. The major primary reaction products were dodecahydroanthracene plus n-dodecane, perhydroanthracene plus 1-dodecene, and methyleneperhydroanthracene plus n-undecane. These six products accounted for about 35% of the reacted DDPA at moderately low conversions. The balance of the DDPA formed numerous primary products such as alkanes, alkenes, and substituted perhydroanthracenes, the individual yields of which were very low. Secondary reactions included ring opening, which led to the formation of substituted tetralins and naphthalenes, and dehydrogenation, which led to octahydroanthracene, tetrahydroanthracene, and anthracene. The primary product spectrum can be accounted for by viewing DDPA pyrolysis as proceeding through four parallel free-radical chain reactions. Three of these parallel chains lead to the three sets of major primary products, and the fourth chain leads to the minor products.