Add time:09/24/2019         Source:sciencedirect.com

A novel method for synthesis of 7-hydroxy-4-methylcoumarin from resorcinol and ethyl acetoacetate via the Pechmann reaction with polyvinylpyrrolidone-supported phosphotungstic acid (PVP–HPW) catalyst is developed. The catalysts were characterized by FTIR, TGA, elemental analysis, UV–vis and a Hammet acidity function test. HPW protonated PVP to form polymeric cations. The polymeric cations interacted strongly with phosphotungstic anions, leading to an ionic liquid structure. The performance of the PVP–HPW were compared with other catalysts such as HPW, NMP–H2SO4 and PVP–H2SO4. For PVP–HPW dosage of 9% based on the weight of resorcinol, the yield of 7-hydroxy-4-methylcoumarin reached 96.73% after two hours reflux reaction at 110 °C, which exhibited much higher value than other catalysts. The PVP–HPW can be easily separated from the reaction mixture and retains the activity during recycling.

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