Spectrophotometric determination of 6,7-dihydroxycoumarin and its methoxy derivatives

Abstract

A spectrophotometric method for the determination of the single components in a mixture of 6,7-dihydroxycoumarin and its methoxy derivatives is described. The method is based on the determination of 6,7-dihydroxycoumarin after complexation with molybdophosphoric acid in buffered solution and of 6-hydroxy-7-methoxy-, 7-hydroxy-6-methoxy- and 6,7-dimethoxycoumarin by treatment with sodium methylate solution followed by difference absorbance measurements. This procedure has also been applied successfully to the study of the methylation reaction of 6,7-dihydroxycoumarin.