Abstract
A new Keggin-type heteropoly acid, namely decamolybdodivanadogermanic acid (H6GeMo10V2O40•16H2O), with nanosized particles (5-8 nm), has been synthesized by a hydrothermal method and characterized by elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and potentiometric titration. H6GeMo10V2O40•16H2O revealed high catalytic activity for acetylation of various alcohols and phenols with acetic anhydride at room temperature (298 ± 2 K) and under solvent-free conditions. The catalyst can be easily recovered and used repeatedly for five cycles with a slight loss of activity. The catalytic activity of H6GeMo10V2O40•16H2O was higher than that of other Keggin-type heteropoly acids, such as H3PW12O40, H3PMo12O40 and H4SiW12O40.
Highlights
Acetylation is an efficient route for protecting the OH functional group of alcohols and phenols during oxidation, peptide coupling and glycosidation reactions.[1]
In continuation of our interest in exploring green heterogeneous catalysts for organic reactions,[33] we report on the hydrothermally-assisted preparation of a new, nanosized V-substituted heteropoly acids (HPAs) (H6GeMo10V2O4016H2O) and its application as an efficient and recyclable heterogeneous catalyst for the acetylation of alcohols and phenols with acetic anhydride under solvent-free conditions
Nanosized HPA catalyst was prepared by a hydrothermal-assisted method and characterized by various techniques including elemental analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), UV-Vis spectroscopy and potentiometric titration
Summary
Acetylation is an efficient route for protecting the OH functional group of alcohols and phenols during oxidation, peptide coupling and glycosidation reactions.[1]. The use of heterogeneous catalysts seems one of the most promising solutions to avoid the above-mentioned problems.[18] Heterogeneous catalysts offer several advantages over homogeneous systems with respect to easy recovery, recycling and minimization of undesired toxic wastes. In this framework, several heterogeneous systems, including transition metal oxides,[19] montmorillonites,[20]
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