Mo- and W-containing layered double hydroxides: Mild and selective oxidation of alkenes with H2O2

Abstract

Molybdenum- and tungsten-containing (M₇O₂₄^6-, M = Mo or W) layered double hydroxides (LDHs) with Mg²⁺ and Al³⁺ cations in the brucite-like layer have been prepared by direct anion exchange, starting from the corresponding terephthalate precursor. The solids have been characterized by various instrumental techniques such as elemental chemical analysis, powder X-ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The M₇O₂₄^6- intercalated LDHs have been explored as catalysts for the selective oxidation of a series of alkenes at room temperature using safer, inexpensive and environmentally benign hydrogen peroxide as oxidant. Reaction conditions have been optimized considering different reaction parameters to achieve maximum conversion in the catalytic oxidation reaction. Recycling of the catalyst has shown that it can be reused up to three more cycles without significant loss of performance.