Photo-catalysis and Polyoxo-anion Decatungstate in Organic Chemistry: A Manifold Concept for Green Chemistry

Ioannis      N. Lykakis; Eleni      Evgenidou; Michael      Orfanopoulos

Abstract

Over the last few decades decatungstate-mediated reactions have been explored extensively and have found widespread applications in catalysis. In particular, decatungstate has been successfully used as an efficient catalyst in many oxidative chemical transformations, via free radical pathways, and to a lesser extent under anaerobic conditions in synthetically useful chemical processes. In view of its unique photocatalytic properties, decatungstate (W10O32 4-) is rapidly emerging as a promising tool in organic chemistry. This review deals with the recent developments in the chemistry of decatungstate, including mostly synthetic and mechanistic aspects. Several representative examples that illustrate the diverse uses of decatungstate in organic synthesis via free radical carbon centered intermediates in organic and in aqueous media are presented. Thus, the decatungstate-mediated radical functionalization of several classes of organic compounds such as alkanes, alkenes, alcohols, aldehydes and sulfides, under both aerobic and anaerobic conditions, represents a reaction of fundamental and practical interest in academia and industry. Several new discoveries concerning the heterogenization of decatungstate for the development of sustainable methods with broad applications in catalysis, such as the photooxidation or photodegradation of various organic substrates, are also presented.

Keywords: Photocatalysis, Polyoxometalates, Decatungstate, Green chemistry, Oxidation, Photodegradation, aldehydes, photocatalytic oxidation, cyclohexanone, cyclohexanol.