Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

Abstract

Reactive species like high-valent metal-oxo complexes and carbon and oxygen centered radicals are important intermediates in enzymatic systems, atmospheric chemistry, and industrial processes. Understanding the pathways by which these intermediates form, their relative reactivity, and their fate after reactions is of the utmost importance. Herein are described the mechanistic detail for the generation of several reactive intermediates, synthesis of precursors, characterization of precursors, and methods to direct the chemistry to more desirable outcomes yielding 'greener' sources of commodity chemicals and fuels. High-valent Chromium from Hydroperoxido-Chromium(III) The decomposition of pentaaquahydroperoxido chromium(III) ion (hereafter CraqOOH 2+) in acidic aqueous solutions is kinetically complex and generates mixtures of products (Craq 3+ , HCrO4-, H2O2, and O2). The yield of high-valent chromium products the presence and absence of ABTS 2as the scavenger, the yields of H2O2 increased with increasing [H + ]. These results are discussed in terms of a dual-pathway mechanism for the decay of CraqOOH 2+. The H +-catalyzed path leads to the dissociation of H2O2 from Cr(III), while in the H +-independent reaction, CraqOOH 2+ is transformed to Cr(V). Both scavengers rapidly remove Cr(V) and simplify both the kinetics and products.