Water as A Green Reaction Medium: Dial-A-Surfactant

The use of water in place of traditional organic solvents in chemical processes is a key objective of modern green chemistry. While some successes have been achieved, e.g. enzymatic transformations, water-based processes often suffer from low concentration/ productivity. This can result in high volume of contaminated water, negating the green benefits of such processes.

An elegant solution for this is micellar catalysis, aqueous processes wherein a surfactant is employed to generate micelles containing organic reactants. No organic solvent is required and the micelles absorb the organic reactants, giving rise to rate acceleration through concentration effect and potential charge stabilisation of transition states at the aqueous-organic interface. Its applications in organic reactions have been previously studied by many research groups and recently extended to catalytic reactions by Lipshutz and co-workers, giving >5 times reduction of E-factors. Improved green metrics, productivity and economics of synthetic routes using micellar catalysis was demonstrated by researchers at Novartis.

In spite of these successes, application of micellar catalysis in industrial processes is non-trivial. The reactions often happen at the organic-aqueous interface, which means size and population of micelles are critical. Each type of reaction also benefits from a specific type of surfactants, i.e. cationic, anionic and neutral. Given the wide range of commercially available surfactants, the lack of a rational approach, e.g. surfactant/co-solvent selection for solubilising capability and reaction performance, screening strategy, critical parameter operational space, is a major obstacle in more wide-spread adoption of micellar catalysis in synthetic processes.

In this project, the student will develop a new class of tunable polymeric surfactants which can streamline much wider application of micellar catalysis. Advanced polymerisation techniques will be employed to deliver ‘smart polymers’ which contain:
• A reaction enhancing segment which accelerates organic reactions.
• A hydrophilic segment which controls micellar size and shape.
• A ‘smart’ segment which provides tunable properties aiming at facile recovery and workup.

This new class of surfactants will be demonstrated in case studies, including API-relevant synthetic steps, in collaboration with industrial partners. The project will build on the uniquely established capability at the iPRD in multiphase reactors, analytical tools and process design.

The project is best suited to a student with strong background and interest in synthetic/polymer chemistry and nanoreactor/process design. No prior knowledge of continuous processes and modern polymerisation techniques is required, as training will be provided for these important transferable skills.

The student will also benefit from interdisciplinary training and seminar programmes in process chemistry as a member of the Institute of Process Research & Development, Leeds (http://www.iprd.leeds.ac.uk/).