Facile Synthesis of 2-(1,3-Benzoxazol/benzothiazol-2-yl)- 3H-benzo[f]chromen-3-one as Blue Fluorescent Brighteners
A novel synthetic method was developed to prepare new fluorescent 2-(1,3-benzoxazol/benzothiazol-2-yl)-3H-benzo [ƒ]chromen-3-one derivatives 3a-p by the Knoevenagel condensation between 2-hydroxy-1-naphthaldehyde and benzothiazole-2-yl-aceatates or N-methyl benzoxazole-2-yl-acetates using choline chloride/urea ionic liquid as a green catalyst. The results of fluorescence studies revealed that all the compounds show moderate to low emission intensities and are expressed in the form of quantum yields.
Keywords: Benzooxazolyl-3H-benzo[ƒ]chromen-3-one, benzothiazolyl-3H-benzo[ƒ]chromen-3-one, choline chloride/urea, fluorescent brighteners
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