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Developing Green One-Step Organic Reactions in the High Speed Ball Mill Developing green, one-step organic reactions in the high speed ball mill A dissertation submitted to the Graduate School of the University of Cincinnati in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY (Ph.D.) in the Department of Chemistry of the College of Arts and Sciences 2014 Teresa L. Cook B.A., University of Cincinnati, 2008 Committee Chair: James Mack, Ph.D. Abstract In recent years, a great deal of effort has been put towards developing a more environmentally conscious America. Green chemistry has resulted from tragic environmental events in the past and the desire to prevent such incidents in the future. The United States Environmental Protection Agency describes green chemistry as the “design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Our lab uses a solvent-free method known as high speed ball milling (HSBM) as a way to conduct environmentally friendly organic reactions. HSBM works by placing reagents and a mixing ball inside a reaction vial and shaking it vigorously. The mechanical energy generated during the process of mixing and shaking is enough to overcome the activation barrier of the reaction. This dissertation will describe how the HSBM has successfully been used to conduct “click”, acid- base and aromatic substitution reactions. Each of these reactions has been carried out in a green, one-step method and will be discussed in more detail in their respective chapters. We believe this environmentally friendly, solvent-free technique is a viable alternative to solution-based organic reactions and can transform the way organic chemist approach their profession. ii iii Acknowledgements I would like to express my gratitude to my advisor, Dr. James Mack, for allowing me to join his research group to earn my PhD. Dr. Mack is an extremely intelligent man and I am grateful to have had such a knowledgeable advisor. I aspire to become at least half the chemist that he is. Being in Dr. Mack’s group allowed me to find my voice and stand up for what I believe in. The lessons I learned while being a graduate student in the Mack lab are countless. For that, I am eternally grateful. I sincerely thank my past and present committee members Dr. Brian Halsall, Dr. Anna Gudmundsdottir and Bruce Ault for their encouraging words and guidance along the way. I could not have made it this far without you all. Dr. Hairong Guan was not only my committee member, but has become a friend. Thank you for having standards and never compromising what you believe in. He is so passionate about chemistry and his enthusiasm for science is contagious. Hairong led by example and showed me what it means to be a great graduate student. Every day he pushed me to challenge myself and never settle for anything less than excellence. I am grateful that he was never afraid to give me constructive criticism and I really appreciate him for having tough conversations with me. I know Dr. Guan is someone that I can trust and depend on for anything I may need. Our lunches and discussions were a highlight in my day and I will truly miss them. These past few years were more enjoyable because of the people I met along the way. Thank you to the members of the Mack group and my fellow graduate students. I especially want to thank my brother, my boy, Kelley McKissic who was always in the trenches with me and challenged me to become a better chemist and person. We have shared so many experiences that iv I will never forget. Anytime we were together, laughter was in the air and I will surely miss that. Dr. Dan Waddell your kind, genuine spirit is appreciated. Thank you for being an incredible mentor. Dr. Bridgett Rakestraw, I have gained a true friend. Thank you for simply being you. Longrui “Rona” Chen, is truly a unique person that I never imagined having in my life. Longrui helped me to become a better mentor and leader. All of my accomplishments are not mine alone. I owe a great deal of debt to the amazing undergraduate students I had over the years. Especially, “Sweet” Allison Bergmann who has contributed so much work to this dissertation. I see a bright future for her and I know she will make an excellent chemist in the future. You all mean the world to me. Thank you to those who provided funding in support of my research, education, and salary during my time in graduate school; namely, the National Science Foundation, the American Chemical Society and the University of Cincinnati Department of Chemistry. Next, I want to express thanks and love to my family for being my support system on this long journey. I thank my mom for her unconditional love and faith. Thank you to my dad, brothers, aunts, uncles and cousins for their love, support and encouragement. Last, but not least, I would like to thank God, through him all things are possible. v TABLE OF CONTENTS ABSTRACT ......................................................................................................................................ii ACKNOWLEDGEMENTS ............................................................................................................iv TABLE OF CONTENTS ................................................................................................................vi LIST OF FIGURES .........................................................................................................................xi LIST OF SYMBOLS .......................................................................................................................xiv CHAPTER 1: History of green chemistry and Ball Milling ........................................................1 Early events that led to environmental awareness .............................................................................2 Solvent waste and green chemistry ....................................................................................................6 Mechanochemistry and the mechanics of high speed ball milling ....................................................9 Conclusion .........................................................................................................................................13 References ..........................................................................................................................................14 Chapter 2: .........................................................................................................................................15 Introduction ........................................................................................................................................16 Results and discussion .......................................................................................................................18 One-pot synthesis of triazoles ............................................................................................................20 Synthesis of alkyl azides ....................................................................................................................22 Investigating the shock sensitive nature of alkyl azides ....................................................................26 Concentration of copper metal in reaction product ............................................................................26 Investigation of the mechanism of “click” reaction in the high speed ball mill ................................27 Conclusion .........................................................................................................................................27 Experimental ......................................................................................................................................28 vi Typical reaction procedure for the CuAAC between alkyl azide and an acetylene derivative .........29 Typical reaction procedure for the multi-component CuAAC reaction ............................................29 References ..........................................................................................................................................30 Chapter 3: .........................................................................................................................................31 Introduction ........................................................................................................................................32 Results and discussion .......................................................................................................................35 Investigating amides ..........................................................................................................................42 Reacting cesium carbonate with ketones ...........................................................................................43 Reactions with cesium hydroxide ......................................................................................................47 Conclusion .........................................................................................................................................49 Future directions ................................................................................................................................50 Experimental ......................................................................................................................................50 Typical procedure for reaction with metal carbonates:1-bromo-4-(phenoxymethyl)benzene (12) ...51 di-(p-bromobenzyl)-ether
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