FLASH VACUUM PYROLYSIS (FVP) ON ZEOLITES - PYROLYSIS OF 5-BETA(HYDROXYETHYL)-5H-DIBENZO[A,D]CYCLOHEPTENE

FVP of the title alcohol (9) at 0.65 mbar in argon atmosphere at 350 d egrees C in the presence of seven different acidic zeolites afforded 7 H-benzo[c]fluorene (13) and 6,11b-dihydro-7H-benzo[c]fluorene (12) as main reaction products. The suggested carbocationic reaction mechanism is supported by: (a) the occurrence of two isomeric dibenzo(C9H10)hyd rocarbons, namely trahydro-1,6-methanodibenzo[a,e]cyclopropa[c]cyclo ( 6) and 9,10-dihydro-9,10-propenoanthracene (5), in the pyrolyses of 9 and (b) by the results of FVP of authentic samples of 6 (conducting ma inly to hydrocarbons 12 and 13), respectively 5 (affording to greatest extent the minor products observed in pyrolyses of 9). (C) 1997 Elsev ier Science B.V.