Abstract:

A convenient synthetic method for the preparation of 3-carboxy-6, 8-dichloro-7-hydroxy coumarin (DClC) and 3-carboxy-6-chloro-7-hydroxy coumarin (MClC) is provided, wherein DClC have not been reported in literature. The structures were confirmed by NMR, IR and MS spectra. At the same time, through varieties in polarity of solvent，pH and surfactants, fluorescent and ultraviolet properties of the two coumarins are studied herein. The result indicates that when pH=10 the fluorescent intensity increased obviously.

Key words: 3-Carboxy-6, 8-dichloro-7-hydroxy coumarin, 3-Carboxy-6-chloro-7-hydroxy coumarin, Synthesis, Fluorescence properties