Short-time pyrolysis and spectroscopy of unstable compounds: 9. Elucidation of thermal rearrangement mechanisms by Curie-point and flow pyrolysis

Aromatic hydroxy and carbonyl compounds undergo elimination of carbon monoxide upon pyrolysis. The methods of Curie-point and vacuum-flow pyrolysis have been used. A flow pyrolysis apparatus coupled with a cell for low-temperature ultraviolet and infrared measurements is described. 1,5- 1,6-, 1,7-, 2,6- and 2,7-naphthalenediol are pyrolyzed to give 4-, 5-, 6-, and 7-indenole. 2,3-Naphthalenediol eliminates the first CO to form 2-indanone, which can eliminate CO, forming benzocyclobutene. Fuchsone loses CO and the resulting biradical rearranges either to benzoc]phenanthrene or to 1-phenylacenaphthylene. Bisanthrone forms (phenanthreno-9′,10′:9,10-phenanthrene)-1,1′-methylene ketone and dibenzog, p]chrysene by the same mechanism.