Simple halogen-free síntesis of aryl cinnamates using Mo-Keggin heteropoly acids as catalyst

V. PALERMO; D.M. RUIZ; J.C. AUTINO; P.G. VÁZQUEZ; G.P. ROMANELLI

PURE AND APPLIED CHEMISTRY

INT UNION PURE APPLIED CHEMISTRY

Año: 2012 vol. 84 p. 529 - 540

0033-4545

A convenient chlorine-free procedure for the direct esterification of cinnamic acidswith phenols is described. The method does not require stoichiometric activation of the carboxylgroup with thionyl chloride or condensing reagents. The methodology is very simple,environmentally friendly, and high-yielding for both electron-releasing and -withdrawingsubstituted phenols. The Keggin heteropoly acids H3PMo12O40 and H4SiMo12O40 wereemployed as catalyst in simple bulk form. The effects of temperature, reaction time, andamount of the catalyst used on the ester yield were checked. Suitable conditions for the reactioninclude a 1:1 molar ratio of reactants and a 1 mmol % of catalyst to reactant ratio.Seventeen aryl cinnamates were obtained, yields ranged from 80 to 91 % for most of theesters. The catalyst was shown to be reusable for at least four times without any appreciableloss of its activity.