Preyssler catalyst: An efficient catalyst for esterification of cinnamic acids with phenols and imidoalcohols

In the present work a series of eco-friendly Preyssler solid acids and their salts H(14)[NaP(5)W(29)MoO(110)] (M), H(14)[NaP(5)W(30)O(110)] (PWMo). K(12.5)Na(1.5)[NaP(5)W(30)O(110)]center dot 15H(2)O (PWK), K(12.5)Na(1.5)[NaP(5)W(29-)MoO(110)]center dot 15H(2)O (PWMoK) and 10% silica-supported H(14)[NaP(5)W(29)MoO(110)] (PWSiO(2)), and H(14)[NaP(5)W(30)O(110)] (PWMoSiO(2)) have been used as catalysts for the direct esterification of cinnamic acids with phenols or 2-(N-phthalimidoethanol). Effects of the reaction conditions were studied, including temperature, reaction time, and type and amount of catalyst. These solids were characterized by several techniques, such as diffuse reflectance spectroscopy, Fourier transformed infrared spectroscopy, optical and scanning electron microcopies, and X-ray diffraction, among others. The most adequate catalyst for performing the title reaction was H(14)[NaP(5)W(30)O(110)] (PWMo). The catalyst was applied for the synthesis of various substituted cinnamates, giving very good yields. (c) 2009 Elsevier B.V. All rights reserved.