Catalytic activity of Keggin heteropolycompounds in the Pechmann reaction

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• 作者：R. Torviso ; D. Mansilla ; A. Belizá ; n ; E. Alesso ; G. Moltrasio ; P. Vá ; zquez ; L. Pizzio ; M. Blanco ; C. Cá ; ceres
• 关键词：Catalysts ; Keggin heteropolycompounds ; Pechmann reaction
• 刊名：Applied Catalysis A: General
• 出版年：2008
• 出版时间：15 April 2008
• 年：2008
• 卷：339
• 期：1
• 页码：53-60
• 全文大小：492 K

文摘

Different heteropolycompounds were used as catalysts in the synthesis of coumarins from phenols and ethyl acetoacetate. The H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ Keggin heteropolyacids were supported on different types of silica. On the other hand, the aluminium salts of these heteropolyacids and that of the H₄SiW₁₂O₄₀ acid were prepared. The specific surface area (S_BET), and the mean pore diameter of the obtained catalysts were estimated from the adsorption isotherms of nitrogen at 77 K. Their Fourier transform infrared spectra were recorded and their acidity was determined by potentiometric titration with a solution of n-butylamine in acetonitrile. The catalytic activity using several phenols such as resorcinol, 3,5-dimethoxyphenol, sciencedirect.com/scidirimg/entities/204e.gif"" alt=""greek small letter alpha"" title=""greek small letter alpha"" border=""0"">-naphtol and β-naphtol were determined. High yield of product was obtained in the case of 4-methyl-7-hydroxycoumarin (80–95 % ), 4-methyl-5,7-dimethoxycoumarin (60–92 % ) and 4-methyl-7,8-benzocoumarin (90 % ). However, the 4-methyl-5,6-benzocoumarin yield was low. The use of microwave radiation as power source increases the reaction yield and mainly decreases the reaction time.