Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
67684 | Journal of Molecular Catalysis A: Chemical | 2008 | 6 Pages |
Nano-crystalline sulfated-zirconia solid acid catalyst has been studied for microwave-assisted solvent free synthesis of hydroxy derivatives of 4-methyl coumarin by Pechmann reaction. The catalyst showed good activity for activated m-hydroxy phenol substrates, viz., phloroglucinol and pyrrogallol with ethyl acetoacetate for the synthesis of 5,7-dihydroxy 4-methyl coumarin and 7,8-dihydroxy 4-methyl coumarin, respectively, showing significant yields ranging from 78 to 85% within 5–20 min at 130 °C. However, the less activated phenol and m-methyl phenol was observed to be inactive for the synthesis of 4-methyl coumarin and 4,7-dimethyl coumarin, respectively, under the studied experimental conditions.
Graphical abstractNano-crystalline sulfated-zirconia catalysts showed good catalytic activity for microwave-assisted solvent free synthesis of hydroxy derivatives of 4-methyl coumarin by Pechmann reaction using activated m-hydroxy phenol substrates and ethyl acetoacetate. Less activated phenolic substrates were observed to be inactive under the experimental conditions studied.Figure optionsDownload full-size imageDownload as PowerPoint slide