6-Hydroxy-9- phenalenones

Since the proton tautomerism of naphthazarin [13] or 9-hydroxy-phenalenone [6] can be investigated precisely in an isolated system, it is intriguing to see how these tautomeric molecules behave as dielectrics in the solid state. Incidentally, if the tautomers keep the centrosymmetry during the tautomerization process, the dielectric response cannot be detected, because the changing directions of the dipole moments coupled with the tautomerization, even though they invert, cancel. 

The nitronates PhCHNOj and MejCNOj form the six-co-ordinate complexes Mn(nitronate)L2 (L = H20orpy L2 = tmen)- and o-hydroxy-l-phenalenone(L) forms the octahedral complex Mn(L — H)2,2H20. Co-ordination of Mn by penicillin and cephalosporin antibiotics has been studied by n.m.r. line-broadening. ... 

All the natural phenalenones, as derivatives of 2-hydroxy-IH-phenal-enone, have distinctive ultraviolet and visible absorption spectra. The... 

In the mass spectra of 9-arylphenalenones the occurrence of the (M-1)" ion is a useful diagnostic feature. When the structure of the phenalenone is fixed the ion gives the base peak and presumably has a structure of type (53). However when tautomerism is possible, as in 6-hydroxy-9-arylphenalenones, this peak is of lower intensity. 

It has been demonstrated that photolysis of 6-hydroxy-9-phenyl-phenalenones is an efficient method for synthesis of IH-naphtho-[2,l,8-w a]xanthen-l-one and its derivatives (62, 69). They have also been prepared by acid catalyzed cyclization of 6-hydroxy-9-(2-methoxy-phenyl) phenalenones 70, 71). For example cyclization and decarboxylation convert 7-carboxy-2,5-dimethoxy-6-hydroxy-9-(2-methoxy-... 

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