Pechmann Condensation over Copper-Mesoporous Molecular Sieves Materials

The Pechmann reaction over a series of copper-containing mesoporous silicas with different Cu contents has been investigated. These materials (Cu-HMS-n, where n is the Si/Cu ratio in the precursor gel, n = 15, 25, and 50) have been prepared at room temperature using a route based on hydrogen bonding and self-assembly between neutral primary amine micelles (S°) and neutral inorganic precursors (I°). The obtained materials were analyzed by Chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption to determine the structural order and textural properties. The results show that the copper-containing HMS catalysts exhibit superior catalytic performance in the pechmann condensation reaction (liquid phase condensation of resorcinol and ethyl acetoacetate), the 7-hydroxy-4-methylcoumarin was the only product observed in this reaction. The reaction parameters were optimized to obtain high selectivity of the desired product at maximum resorcinol conversion at a temperature of 150°C. The enhanced catalytic performance of copper-HMS catalysts may be attributed to the homogeneous dispersion and uniformity of the active copper species and to the larger manganese surface areas attained on the HMS support with large pore diameters and surface areas.