CHITOCAT · Development of Chitosan-based Immobilized Catalysts for H/D Exchange in Continuous Flow Systems

Deuterium (D)-labelled compounds are highly significant in drug discovery and medicinal chemistry. In recent times, they have also started finding applications further afield e.g., in organic electronics, dyes, and catalysts, due to their higher stability and enhanced properties compared with their non-labelled counterparts. As such, there is an urgent need to develop sustainable chemistry to support the synthesis of D-labelled compounds. A promising approach is to use Continuous Flow Chemistry (CFC). This is considerably under-represented for deuteration, despite its reputation for being more efficient, safe, and sustainable than conventional batch processes. Additionally, to the best of my knowledge, there are no reported CFC systems featuring recyclable catalysts or reusable catalyst supports for the synthesis of D-labelled compounds.This project therefore aims to demonstrate the concept of a sustainable, bio-based catalyst support system for H/D exchange in continuous flow chemistry (CFC) systems. Specifically, I wish to evaluate the possibility of using chitosan, a biopolymer derived from seafood waste, to immobilize Kerrs catalyst, the gold standard catalyst for H/D chemistry (due to its substrate versatility). Chitosan is biodegradable, easily functionalized, and highly porous, making it an ideal support for catalysts in CFCs. I propose that this immobilized system will enhance the stability and operating lifetime of the catalyst while facilitating the recovery of the catalyst metal and reuse of the biopolymer support material.Key project objectives include synthesis of the immobilized catalyst, evaluation of its performance in H/D reactions for simple and complex molecules within batch and CFC systems, recovery of iridium from the used catalyst, and controlled degradation of the chitosan from the support to be used elsewhere. We hope that the results from this study will inspire further research in developing CFC systems based on circular chemistry