Rfc. Brown et al., CYCLOPENT[A]INDENE (BENZOPENTALENE) AND PENTALENE - PYROLYTIC FORMATION FROM 3-PHENYL-PHTHALIC AND 3-VINYL-PHTHALIC ANHYDRIDES, Australian Journal of Chemistry, 48(2), 1995, pp. 185-198
Pyrolysis of 3-phenylphthalic anhydride at 900 degrees/0.02 mm gives c
yclopent[a]indene, characterized by H-1 n.m.r. at -70 degrees and by f
ormation of a cyclopentadiene adduct and of a dimer at room temperatur
e. Pyrolysis of 3,4-, 3.5- and 3,6-diphenylphthalic anhydrides also gi
ves much cyclopent[alpha]indene by loss of the additional phenyl group
. 3,4-Diphenylphthalic anhydride forms triphenylene as the major produ
ct. The pyrolysate from 5-vinylphthalic anhydride contains the known d
imer of pentalene, and phenylacetylene. Pyrolyses of 3-(1-naphthyl)pht
halic anhydride and of 4-phenylphenanthrene-2,3-dicarboxylic anhydride
are described.