Developing sustainable catalytic methods for selective oxidation reactions

• Main Author: Cao, Qun
• Published: Queen's University Belfast 2016
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705655

This project has investigated industrially applicable oxidation catalysis to produce nitriles and carbonyl compounds using molecular oxygen/H2O2 as oxidants. This project can be split into three subprojects: (1) A novel Cu/TEMPO-catalyzed aerobic oxidation method has been developed for the synthesis of nitriles from alcohols or aldehydes using aqueous ammonia as N source. This method showed wide substrate scope (aliphatic and aromatic aldehydes and aliphatic alcohols) with the use of standard glassware (10 mol% Cu(OTf)2). When reactions were carried out using reactors,cheaper catalyst (CuCI2) and lower catalyst loading (1 mol%) could be applied. (2) Ligated Pd(II) complexes have been studied for the catalytic oxidation of terminal olefins to their corresponding methyl ketones. The method uses aqueous hydrogen peroxide as the terminal oxidant; a sustainable and readily accessible oxidant. The choice of ligand, counterion and solvent all have a significant effect on catalytic performance and we were able to develop systems which perform well for these challenging oxidations. (3) A homogeneous Pd(II) catalyst utilizing a simple and inexpensive amine ligand (TMEDA) allows 2-alkynoates to be prepared in high yields via an oxidative carbonylation of terminal alkynes and alcohols. The catalyst system overcomes many of the limitations of previous palladium carbonylation catalysts. It has an increased substrate scope, avoids large excesses of substrate and uses a desirable solvent. The catalyst employs oxygen as the terminal oxidant and this can be operated under safer gas mixtures.