No abstract

The structure of radicals of type (11) formed by the thermal decomposition of 2,2 '-dioxo-3,3'-diphenyl-2,2',3,3'tetrahydrobibenzo[b]furan-3-y1 (I) has been studied. The approximate values of the coupling constants were determined using methyl or deuterium substitution and the e.s.r. spectra of (11) and some of its derivatives were computer-simulated. Spin densities were calculated by the IN DO and McLachlan-Honeybourne methods. The calculated coupling constants were compared with those obtained by computer simulation.'THE benzo[b]furan ring is present in many naturally occurring oxygen-containing heterocycles. Information on free-radical reactions in this system is very limited and no e.s.r. study of the benzo[b]furanyl radical has been published so far.The present work is devoted to a study of stable free radicals of type ( 11), with 2,2'-dioxo-3,3'-diphenyl-2,2',3,3'-tetrahydrobibenzo[b]furan-3-y1 (DTDB) (I) as precursor. The structure of the latter suggests that the 3,3'-bond will be easily broken thermally due to steric hindrance. The radicals thus formed are expected to be stabilized by delocalization. Thus, e.g. a xylene solution of (I) becomes blue when heated to 70 "C. This colour disappears when the solution is cooled. The presence of

No abstract

No abstract

No abstract