The development of continuous flow systems for manganese catalysed oxidation reactions

Abstract

This thesis examines the use of flow chemistry in the development of scalable and industrially attractive Mn(II)/2-picolinic acid/peracetic acid oxidation processes. The use of a continuous process eliminates the risk typically encountered when manipulating peracetic acid, allowing for a sustainable and scalable process. Chapter 2 focuses on alkene epoxidation with a Mn(OAc)2/2-picolinic acid/peracetic acid system. Epoxidation of alkenes is a valuable transformation in the synthesis of fine chemicals. Described herein is the design and development of a continuous flow process for carrying out the epoxidation of alkenes with a homogeneous manganese catalyst at metal loadings as low as 0.05 mol%. In this process, peracetic acid is generated in situ and telescoped directly into the epoxidation reaction, thus reducing the risks associated with its handling and storage, which often limit its use at scale. This flow process lessens the safety hazards associated with both the exothermicity of this epoxidation reaction and the use of the highly reactive peracetic acid. Controlling the speciation ligand: manganese ratio was key to the success of the reaction. This continuous flow process offers an inexpensive, sustainable, and scalable route to epoxides. Chapter 3 focuses on the oxidation of primary and secondary alcohol substrates with a Mn (OAc)2/2 picolinic acid/peracetic acid system. Efficient oxidation of benzylic alcohol substrates could be achieved using Mn(II) loadings as low as 0.05 mol% and excellent efficiency in peracetic acid. The applicability of this oxidation system was further improved through the development of a continuous process with peracetic acid generated in situ and telescoped directly into alcohol oxidation reaction.

Date of Award	Dec 2023
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Peter Knipe (Supervisor), Paul Dingwall (Supervisor) & Mark Muldoon (Supervisor)