Hydrocarbons are widely available from fossil fuel sources but have little utility in the synthesis of more complex molecular structures in either academic or industrial settings due to their limited chemical reactivity. As a result they are converted into higher value fine chemicals through an array of industrial processes that are undertaken on a huge scale worldwide. Amongst the many transformations that can be used, oxidative processes are highly desirable due to their ability to rapidly introduce significant reactivity and structural complexity in simple organic structures, but are underutilised, frequently due to their high environmental impact. In this project we sought to develop new catalytic methodology for the environmentally benign oxidation of hydrocarbon substrates using hydrogen peroxide as the oxidant. We were particularly interested in developing systems capable of generating epoxides from alkenes, substrates which are widely used in the bulk chemical, fine chemical, pharmaceutical and agrochemical industries, which therefore have significant importance in wider society.
The overall objectives of the project were to (i) investigate whether the addition of Lewis acid additives to a catalytic system that is known to be active in oxidative catalysis, which we have previously worked on, would result in an increase in reactivity; (ii) to develop a range of new ligand architectures to coordinate metals in which we included triazole moieties generated through ‘click’ reactions; the rationale for including the ‘click’ triazoles being that that they provided a similar structural motif to the commonly used pyridine ligand in other oxidative systems, allowed for modular syntheses to be developed and ultimately might provide a means of attaching the catalyst to solid supports; (iii) in the final objective we envisioned the use of solid supports to develop routes to heterogenised versions of the catalytic systems developed in (ii) so that they could be applied in flow reactors.
