Aqueous High-Temperature Chemistry of Carbo- and Heterocycles. 23.Reactions of Pyridine Analogs and Benzopyrroles in Supercritical Water at 460 .degree.C

Eleven nitrogen-containing heterocycles were chosen as fossil fuel model compounds: pyridine, quinoline, 2-methylquinoline (quinaldine), isoquinoline, acridine, phenanthridine, 1,2,3,4-tetrahy-droquinoline, indole, 2-methylindole, 2,3-dimethylindole, and carbazole. They were heated at 460 °C for 7 min and for 1 h in four different sets of conditions: (i) cyclohexane, (ii) water, (iii) aqueous 15 % formic acid, and (iv) aqueous 15 % sodium formate. Aquathermolyses under conditions (ii)-(iv) could thus be compared with purelythermal reactions under condition (i). Pyridine is almost unreactive at 460 °C under both thermolysis and aquathermolysis conditions, although in 15 % aqueous formic acid at 460 °C for 7 min, small quantities of N-alkylpiperidines were observed; however, on extending the reaction time to 1 h, small amounts of C-alkylated pyridines were formed