New Catalytic Concepts for Electron-Transfer Promoted Reactions
Restricted (Penn State Only)
- Author:
- Piane, Jacob
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- November 03, 2022
- Committee Members:
- Elizabeth Elacqua, Co-Chair & Dissertation Advisor
Eric Nacsa, Co-Chair & Dissertation Advisor
Christian Pester, Outside Unit & Field Member
Raymond Schaak, Major Field Member
Philip Bevilacqua, Program Head/Chair
Jonathan Kuo, Major Field Member - Keywords:
- Catalysis
Electrochemistry
Electrocatalysis
Phenothiazine
Photoredox
Pyrylium
Dehydration
Single-Chain Polymer Nanoparticles
Electron Transfer
Acyl Substitution
Amidation
Oxidation
Dimerization
Esterification - Abstract:
- This thesis describes the development of new catalytic concepts for electron-transfer promoted reactions. Chapter 1 describes the [2 + 2] dimerization of electron-rich styrenes through dual-photoredox and electron-relay catalysis. The newly developed catalysts hold pyrylium photocatalysts and pyrene electron-relay catalysts in close proximity to one another. This was achieved by functionalizing a polymer with pyrylium and styrylpyrene and subsequently cross-linking intramolecularly to form single-chain polymer nanoparticles. The confined nature of the polymer-bound catalysts enabled a 5-fold increase in the rate of the dimerization reaction with a 25-fold reduction in loading of the electron-relay catalyst. Chapter 2 describes the expansion of the scope of reactions that can be catalyzed by our newly developed single-chain polymer nanoparticle catalysts. First, we demonstrated the ability of these catalysts to catalyze an oxidation of benzylic alcohols to the corresponding aldehyde. The single-chain polymer nanoparticles also catalyzed the oxidative amidation of benzaldehydes with amines. Chapter 3 introduces phenothiazines as dehydrative electrocatalysts for acyl substitutions of carboxylic acids. Specifically, amides were prepared catalytically using phenothiazine electrocatalysts. 3,7,11-trimethoxy-9,9-dimethyl-9H-quinolino[3,2,1-kl]phenothiazine has been identified as the optimal catalyst to carry out this transformation at a constant current of 5 mA. Chapter 4 describes our attempt to circumvent decomposition of starting materials in the catalytic amidation by pre-formation of an anhydride. Using the same optimal catalyst identified in Chapter 3, anhydrides were synthesized at a constant potential of 4.2 V. Subsequent addition of amines facilitated amide bond formation. Some mechanistic studies were shown to probe the redox states of the electrocatalyst. Chapter 5 describes the phenothiazine-electrocatalyzed dehydrative esterification of carboxylic acids. The optimal catalyst for the esterification was identified as 3,7-dimethoxy-10-(4-methoxyphenyl)-10H-phenothiazine. Using this catalyst at a constant current of 10 mA resulted in high yields of a variety of esters. Chapter 6 describes the synthesis of phenothiazine electrocatalysts. In addition to the preparation of catalysts, this chapter details the mechanistic rationale behind each new catalyst.