Comparative study on the catalytic properties of amino-functionalized silica materials for the transesterification of dimethyl oxalate with phenol

Abstract

A series of hybrid mesoporous MCM-41 materials containing different amino groups (such as 3-aminopropyl (AP-), (2-aminoethylamino)propyl (AAP-), or [2-(2-aminoethylamino)ethylamino] propyl (AEP-) group) were prepared by a post-grafting method, and characterized by means of X-ray powder diffraction (XRD), N2 adsorption, Fourier transform-infrared spectroscopy (FT-IR) and temperature-programmed desorption of CO2 (CO2-TPD). The catalytic properties of these hybrid materials were investigated for the transesterification of dimethyl oxalate with phenol. All the samples were active for the transesterification. Among them, the sample AEP-MCM-41 exhibited the highest activity under test conditions. And only a slight decrease in activity could be observed after few runs, indicating the good recyclability of this catalyst. Notably, the activity of the used catalyst could be regenerated by simple treatment with diluted basic agents under mild conditions. Moreover, effects of the density and the basic strength of the amino groups on the catalytic properties were taken into consideration for understanding the reaction mechanism and the possible formation route of the by-product anisole. © 2010 Sociedade Brasileira de Química.