Turning organocatalysts green

Organocatalysis (catalysis using organic molecules) fulfils two green chemistry guidelines1 by avoiding the use of rare metals, and by being catalytic. Insoluble polymer (resin) bead immobilisation (heterogenation) of the catalyst facilitates recovery and reuse. The remaining aspect of organocatalysis that needs ‘greened’ is to be able to successfully perform an organocatalysed reaction in a sustainable solvent. We will develop a new concept in solid-phase chemistry: a tuning module, which will enable immobilised catalysts to be used in sustainable solvents allowing the full greening of heterogeneous organocatalysis.

In a traditional solid-phase approach, maximum resin swelling2 in the solvent is considered optimal. The reagents, key components of the reaction, are usually disregarded; their solubility in the reaction solvent is often the sole consideration. The swollen resin may partition reagents, giving a low concentration within the resin, the loci of the reaction. In this proposal, we will develop a modified approach by adding a fourth tuneable resin-bound component, the tuning module.

The tuning module is designed to optimise resin compatibility with sustainable solvent. The solvent may give excellent results in homogeneous reactions using a chosen catalyst but be less than optimal with a resin-immobilised catalyst. Judicious design of the tuning module will enhance resin-swelling in the sustainable solvent that is optimal for the chemistry.

Objectives:

1. To demonstrate the concept of a tuning module is valid in green heterogeneous organocatalysis.
2. To use the early results from (1) to generate a modelling approach for further development of tuning modules.

As a minimum, our goal by the end of the project is to have a set of tuning modules for different solvent, catalyst and bead combinations.

The candidate must have a background in organic synthesis and be willing to learn and embrace green chemistry.

This project is expected to be of significant commercial interest, especially by the pharmaceuticals sector. Solvents are critical to the chemistry carried out in this sector and are increasingly being banned or heavily restricted as their toxicities become better appreciated. Benzene and carbon tetrachloride are two well-known examples of previously widely used solvents that cannot now be used by the pharmaceuticals sector. The next solvents to be banned will be the polar aprotic amides such as DMF and NMP which are known to be reprotoxic. These solvents are heavily relied upon by the pharmaceuticals sector (for example in solid-phase peptide synthesis), so any work showing that biodegradable and non-toxic cyclic carbonates can be used as replacements for traditional polar aprotic solvents will be of significant interest. The project may give the student opportunities to interact /collaborate with interested industry.

All research students follow our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills. All research students take the core training package which provides both a grounding in the skills required for their research, and transferable skills to enhance employability opportunities following graduation. Core training is progressive and takes place at appropriate points throughout a student’s higher degree programme, with the majority of training taking place in Year 1. In conjunction with the Core training, students, in consultation with their supervisor(s), select training related to the area of their research.

The project is multi-disciplinary and will provide excellent student training as it involves a wide range of techniques (synthetic and analytical) across organic and sustainable chemistry. The students will gain a thorough knowledge/understanding of Green chemical principals and will be able to apply these. The student will be provided with a number of other opportunities to network and present their work as a poster or oral presentation both within and external to the Department. The student will be encouraged to attend at least one major international conference during their PhD.

The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel. Chemistry at York was the first academic department in the UK to receive the Athena SWAN Gold award, first attained in 2007 and then renewed in October 2010 and in April 2015.