Identification of diazonaphthoquinone esters of polyhydroxybenzophenone compounds

The seven possible 2,1-diazonaphthoquinone-5-sulfonates of 2,3,4- trihydroxybenzophenone have been isolated and characterized by IR, chromatographic and advanced NMR techniques. HPLC procedures for their analysis are given which show counterintuitive effects in the HPLC elution sequence due to the effect of intramolecular H-bonding on the polarity of some esters. A reaction scheme is proposed which qualitatively identifies preferred pathways to the trisester.