University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2012 Synthesis and Catalytic Applications of 1,2,4- Triazoles in Oxidative Processes Ashesh Shirish Belapure [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation Belapure, Ashesh Shirish, "Synthesis and Catalytic Applications of 1,2,4- Triazoles in Oxidative Processes. " PhD diss., University of Tennessee, 2012. https://trace.tennessee.edu/utk_graddiss/1480 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Ashesh Shirish Belapure entitled "Synthesis and Catalytic Applications of 1,2,4- Triazoles in Oxidative Processes." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Chemistry. Shane Foister, Major Professor We have read this dissertation and recommend its acceptance: Shawn R. Campagna, Craig E. Barnes, Thomas A. Zawodzinski Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Ashesh S. Belapure entitled “Catalytic applications of 1,2,4-triazoles in oxidative processes”. I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry. Shane Foister, Major Professor We have read this dissertation and recommend its acceptance: Shawn R. Campagna Craig E. Barnes Thomas A. Zawodzinski Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official student records.) Synthesis and Catalytic Applications of 1,2,4- Triazoles in Oxidative Processes A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Ashesh Shirish Belapure August 2012 Dedication For my parents ii Acknowledgements The road to getiing a PhD is filled with many obstacles and cannot be completed without the guidance, help and constant encouragement of many. I would like to thank my parents who inculcated the values of education, honesty and perseverance in me. My mother and father have always been my strongest supporters. They are my role models and I can only hope to be as good as them one day. I would also like to express my deepest gratitude to my gradmother who has been a teacher her whole life. She has helped countless students achieve their goals and I count myself fortunate to be one of them. My road to PhD actually began when I joined Garware College for pursuing M.Sc. It was the teachers that I met there who encouraged me to continue my academic journey and not be satisfied until I achieved the highest education possible. I must thank Dr. Arun Natu, Dr. Suhas Gadre, Dr. Hari Damle and Dr. Paradkar for showing me how exciting the world of organic chemistry was. Of course, the actual graduate school would have been impossible to complete if not for the guidance of my advisor Dr. Shane Foister. His enthusiasm, knowledge and constant push has helped me continue to drive myself towards the eventual goal. Dr. Ramez ElgammaI, the post doc researcher in our group has been a great help to me throughout this journey. I would like to thank him for his constant support. I would also like thank my committee, Dr. Shawn Campagna, Dr. Craig Barnes and Dr. Thomas Zawodzinski. I am priviledged to have such distinguished committee members, who iii despite their busy schedules have always extended their help to me. The support staff at the Department of chemistry at UT has been instrumental in making my life much easier and I would like to offer my sincerest thanks to them. I wish to thank all former and current members of the Foister Groups. Thank you, Dr. Jeremiah Harden, Dr. Ashleigh Prince, Dave Schneider, Rachel Glazener, Belinda Lady, Chinmay Dabke for your constant support and helpful discussions. I would like to extend special thanks to Belinda Lady and Chinmay Dabke who have helped me beyond what was expected of them. I wish you all the best in your future plans. My sincerest thanks to Dr. Gabriel Goenaga and Dr. Alex Papandrew for their help on the ORR project. A lot was achieved in a short time because of them. Last but not the least, none of this would have been possible without the constant and loving support of my dear wife, Sneha. Thank you for always thinking about me and being there for me. You are the best companion one could hope for. Abstract Pollution due to use of fossil fuels is a growing problem in today’s world. In recent years, chemical research has been focused on catalysis as the possible means of providing economical alternatives to conventional energy sources. Enhanced capabilities in the area of chemical catalysis could play a significant role that can extend from more efficient production of low or non-carbon fuels (e.g., water-splitting, electrolysis, methane oxidation), to more efficient fuel and electrolytic cells. This dissertation describes the homogeneous as well as heterogeneous synthesis of 1,2,4-triazole complexes with transiton metals. The application of these complexes for catalysis of hydrocarbon oxidation, ORR (oxygen reduction reaction) and aziridination are described. Extensive studies into effects of ligand topology and electronics are described. Metal complexes involving 1,2,4-triazole ligands showed remarkable selectivity and activity for hydrocarbon oxidation. These observations led to further exploration of the applications of these catalysts for ORR in fuel cells. Research efforts led to the identification of carbon black immobilized 1,2,4-triazole based catalysts as a potential alternatives for current platinum based catalysts. Finally, the utility of triazole catalysts was extended to the aziridination reaction. Reaction parameter optimization studies led to the discovery of a relatively mild Ni(II)-1,2,4-triazole based catalytic system. A broad substrate scope is observed for this system making it a potent synthetic tool for organic chemists. Table of Contents 1. Catalytic applications of 1,2,4-triazoles in oxidative processes .................................... 1 1.1. Introduction ................................................................................................................................. 1 1.2. Inspirations from nature .............................................................................................................. 2 1.3. Choice of 1,2,4-triazoles as ligands for oxidative catalytic processes ......................................... 5 1.4. Ligand accelerated copper catalyzed hydrocarbon oxidation reactions ..................................... 9 1.5. Oxygen reduction reaction (ORR) .............................................................................................. 14 1.6. Aziridination .............................................................................................................................. 20 2. Homogeneous 1,2,4-triazole synthesis ..........................................................................25 2.1. Introduction ............................................................................................................................... 25 2.2. Synthesis of substituted 1,2,4-triazole derivatives ................................................................... 25 2.2.1. Synthesis of 4-substituted 1,2,4-triazoles ............................................................................. 27 2.2.2. Synthesis of 1-substituted triazoles ...................................................................................... 33 2.2.3. Synthesis of 3,5-disubstituted triazoles ................................................................................ 35 2.2.4. Synthesis of 3,4,5-trisubstituted-1,2,4-triazoles ................................................................... 40 2.2.5. Synthesis of fused-1,2,4-triazoles ......................................................................................... 41 2.2.6. Synthesis of 3-substituted triazoles by diazotiation ............................................................. 47 2.3. Conclusions ................................................................................................................................ 51 2.4. Experimental .............................................................................................................................. 51 3. Solid Phase Synthesis .....................................................................................................75 3.1. Introduction ............................................................................................................................... 75 3.1.1. General synthetic strategy .................................................................................................... 76 3.1.2. Polystyrene supported ligands .............................................................................................