Flow-vacuum pyrolysis of cis-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-5,10-diol and cis-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-5,10-dione

The flow-vacuum pyrolyses of cis-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-5,10-diol (8) and cis-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-5,10-dione (9) were studied by GC/MS at 1.33 mbar and 600–950 °C for 8 and 800–1050 °C for 9. The main reaction products of 8 were: diketone 9, 2-phenylindene, cis-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-5-one, 9,10-anthraquinone, anthracene and phenanthrene. The pyrolysis products of 9 were: dibenzosuberenone, 9,10-anthraquinone, anthracene, phenanthrene, 4b,8b-dihydro-benzo[a]cyclobuta[1,2-a]indene-9-one and diphenylacetylene. A reaction mechanism including diradicalic intermediates is proposed for pyrolyses of 8 and 9 and a comparison between these pyrolyses is made.