Environmentally friendly oxidation
Researchers design robust catalyst for olefin oxidation with hydrogen peroxide
In organic chemistry, many reactions require metal catalysts to selectively obtain one of the possible reaction products. But in the case of oxidation with hydrogen peroxide, the co-production of water poses serious difficulties to chemists, since it destroys the catalyst. Now, ITQB chemists from the Homogeneous Catalysis Lab in collaboration with researchers from the University of Alcalá in Spain have designed a new class of robust titanium catalysts for the selective oxidation of olefins with aqueous hydrogen peroxide. This work is published in Inorganic Chemistry, an American Chemical Society journal.
Many processes in organic synthesis start with the oxidation of olefins (molecules with a carbon-carbon double bond), a reaction that leads to value-added products, such as epoxides, alcohols, and ketones, which in turn are important building blocks for many useful compounds. Among the oxidants used in the catalytic oxidations of olefins, hydrogen peroxide is an attractive choice, because it is cheap and produces only water as by-product. However, since most transition metal catalysts are very sensitive to water, the preparation of water stable catalyst for efficient, selective, and environmentally benign oxidation processes is a challenging task for synthetic chemists. The novel titanium complexes now designed show excellent reactivity and selectivity toward both cyclic and lineal olefins and are also remarkably stable, as shown in successive oxidation reactions carried out by recharging the reaction mixture with new charges of oxidant and substrate.
The work was supported by CRUP (Portugal) and Ministerio de Educación y Ciencia (Spain) through the “Acção Integrada Luso-Espanhola Nº-E-79/12”.
Cyclopentadienyl-Silsesquioxane Titanium Complexes: Highly Active Catalysts for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide
María Ventura, Marta E. G. Mosquera, Tomas Cuenca, Beatriz Royo and Gerardo Jimenez