Synthesis And Characterization Of Coumarins Fluorescent Whitening Agent And Application In Fur Whitening

This article discusses the mechanism of fluorescent whitening agen（tFWA）and summarizes some typical synthesis of coumarins FWA and the newestresearch in recent years.We use4-hydroxy salicylaldehyde、4-(diethylamino) salicylaldehyde、3-(diethylamino) phenol、3-amino phenol to synthesize7-hydroxy-3-carboxycoumarin、7-diethylamino-4-methyl coumarin、7-(diethylamino)-3-carboxylcoumarin and7-amino-4-methyl-3-acetic coumarin.At the same time we use zinc chloride as catalyst to improve the synthesismethod of7-diethylamino-4-methyl coumarin. It makes the reaction easily todeal with，and increases the yield of product. The purity is achieved to99%.Then we also find a simple way to purify the7-amino-4-methyl-3-ethyl acetatecoumarin without column chromatography. And the purity is more than95%.We characterize four kinds of coumarins with IR spectra，NMR，UVspectra，fluorescence spectra. And we make a comprehensive analysis of them.Characteristic infrared absorption peaks confirm that they have structure ofsix-membered ring lactone. And fluorescence spectra shows their strongfluorescence properties at400nm-420nm. The experiment indicates that theemission spectra is not affected by the excitation wavelength. So if the excitationwavelength changes，the biggest emission spectra will not change relatively. Webelieve that the structures of these four compounds are so similar that theiroptical properties are similar too.We use the four kinds of coumarins to whiten fur. And we choose two kindsof them which can whiten furs effectively. Furthermore，we also make somecolor fastness experiments after whitening furs. At the same time,we deal with some experimental analysis and get conclusions. We find that the compound2have the best whitening effect. The compound4is better than the compound1.Then the experiment indicates that the compound3has no whitening effect onthe furs. It has much better effect at lower concentration when we use the FWAto whiten furs. Furthermore，it also indicates that we can whiten furs moreeffectively at lower temperature.