Catalytic Synthesis of Nitriles in Continuous Flow

The objective of this thesis is to report the development of a new, alternative process for the flexible production of nitrile compounds in continuous flow. Nitriles are an important class of compounds that find applications as solvents, chemical intermediates and pharmaceutical compounds. The process reported here involves the oxidative dehydrogenation of amine compounds to their corresponding nitrile using air as the oxidant, water as the solvent where possible and solid RuO2/Al2O3 catalysts.Chapter 1 beings by outlining the aims of this thesis and then gives a short, basic introduction to concepts and techniques that are important to the contents of this thesis.

Furthermore, relevant literature is reviewed to support the choice of using RuO2/Al2O3 catalysts and the oxidative dehydrogenation of amines for the desired new process for the production of nitriles.Chapter 2 describes a new, alternative path to acetonitrile from ethanol via the oxidative dehydrogenation of ethylamine.

The catalytic activity and product ratios of the batch and continuous flow reactions are compared and the effect of reaction conditions on the reaction is investigated. The effects of ammonia in the reaction and of catalyst calcination are also explored. High conversions (up to 100 %) and selectivities (80-90 %) are reported using optimized reaction conditions.Chapter 3 includes details of in situ infrared spectroscopy experiments, observing the surface of the RuO2/Al2O3 catalyst during calcination in air, oxidative dehydrogenation of ethylamine and post-reaction purging.Chapter 4 outlines the application of RuO2/Al2O3 catalysts to the oxidative dehydrogenation of benzylamine in air, utilizing a new reaction setup.

Again, batch and continuous flow reactions are compared and the effects of reaction conditions, ammonia presence and catalyst calcination are reported. Moderate benzonitrile yields (up to 62 %) and high conversions (up to 100 %) are reported.Chapter 5 describes the detailed characterization of RuO2/Al2O3 catalysts and optimization of the catalyst ruthenium loading.

Application of optimized RuO2/Al2O3 catalysts to the oxidative dehydrogenation of benzylamine is described and increased benzonitrile yields are reported (up to 82 %).Chapter 6 reports the application of oxidative dehydrogenation of amines using air and RuO2/Al2O3 catalysts to a range of substituted aromatic amines and longer chain aliphatic amines.

Substituent groups of aromatic amines are found to effect both the rate of amine conversion and nitrile production. Novel attempts are made to apply the Hammett relationship to the oxidative dehydrogenation of amines using air and RuO2/Al2O3 catalysts in continuous flow. The effect of the presence of water in the reaction is also investigated.Chapter 7 includes an overview of how the contents of this thesis attempt to cover the aims stated in Chapter 1 and suggests future improvements to be made to the nitrile production process.