oa South African Journal of Chemistry - Synthesis of new benzocoumaryl oxadiazolyls as strong blue-green fluorescent brighteners : research article



The benzocoumarin-3-ethylcarboxylate on treatment with hydrazine hydrate at room temperature afforded benzocoumarin-3-carbohydrazide . The compound served as key intermediate in the synthesis of the title compounds. Thus, benzocoumarin-1,3,4-oxadiazolyls were obtained in two ways, one by direct cyclization of benzocoumarin-3-carbohydrazide with substituted benzoic acids in POCl and the other by cyclization of Schiff bases of compounds in the presence of bromine/acetic acid. The structures of the novel benzocoumaryl oxadiazolyls were confirmed by spectral analysis. The benzocoumarin-1,3,4-oxadiazolyls exhibited strong blue and green fluorescent properties. The Stoke's shifts range from 43 to 165 nm. The absorption and fluorescence maxima of the benzocoumaryl oxadiazolyls showed good bathochromic shifts.


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