Approaches for Transition Metal-Free Photocatalytic Oxidation Reactions

by Waldemar Schilling
Doctoral thesis
Date of Examination:2021-03-22
Date of issue:2021-04-30
Advisor:Prof. Dr. Shoubhik Das
Referee:Prof. Dr. Shoubhik Das
Referee:Prof. Dr. Manuel Alcarazo
Persistent Address: http://dx.doi.org/10.53846/goediss-8580

 

 

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Description:Dissertation of Waldemar Schilling with the title: Approaches for Transition Metal-Free Photocatalytic Oxidation Reactions

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Abstract

English

The recent resurface of photocatalysis was accompanied by the technological and mechanistic improvements, which enabled new possibilities for chemical reactions to fulfill the target of green chemistry. The utilization of organic compounds, as photocatalysts, brings the befit to achieve well known reactions in greener and safer ways, with the addition of less toxic and complex technical aspects. The primary objective of this thesis was the investigation of organic molecules for photocatalytic oxidation of several substrate groups and the optimization of the oxidation to achieve high yield, minimized use of additives and low catalyst loadings. The focus was on greener, safer and milder reaction conditions, ideally under low energy LED-light, or utilizing direct solar radiation. Three different oxidation reactions were investigated including full mechanistic investigations to propose reasonable mechanisms. First reaction was the oxidation of activated and unactivated primary and secondary alcohols. Second reaction type was the oxygenation of indoles and pyrroles and third was the singlet oxygen-initiated 1,2-acyl shift reaction of secondary enamino ketones. All protocols show advances, broad substrate scopes and were utilized for the synthesis of bioactive compounds. The obtained results were utilized to develop new photochemical reaction concepts in batch and flow, which were characterized in comparison with the original concept. Additionally, reaction concepts for the synthesis of graphitic carbon nitrides were investigated, build and utilized to synthesis of a variety of different structural motives to obtain photochemical active heterogenous semiconducting materials, as active photocatalyst and support materials.
Keywords: Photochemistry; Photocatalysis; Green Chemistry; Synthesis of Carbon Nitrides; Transition Metal-Free; Mechanistic Investigations; Characterization of Photochemical Setups; Oxidation Reactions; Additive-Free; Activation of Oxygen; Reactive Oxygen Species
 
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