KINETICS and SOLVENT EFFECTS in the SYNTHESIS of IONIC LIQUIDS by Jay Schleicher Submitted to the School of Engineering And
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KINETICS AND SOLVENT EFFECTS IN THE SYNTHESIS OF IONIC LIQUIDS BY Jay Schleicher Submitted to the School of Engineering and the Faculty of the Graduate School of the University of Kansas. In partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering ______________________________ Chairperson: Professor Aaron Scurto Committee members* _____________________________* Professor Bala Subramaniam _____________________________* Professor Susan Stagg-Williams Date defended:___________________ The Thesis Committee for Jay Schleicher certifies that this is the approved version of the following thesis: KINETICS AND SOLVENT EFFECTS IN THE SYNTHESIS OF IONIC LIQUIDS Committee: __________________________________ Chairperson* Professor Aaron Scurto __________________________________ Professor Bala Subramaniam __________________________________ Professor Susan Stagg-Williams Date approved:______________________ i Dedicated To: My Supportive and Encouraging Wife: Misty Schleicher and My Parents: William and Barbara Schleicher ii Acknowledgements: I would like to pay special respects to my advisor, Professor Aaron Scurto, for his guidance and assistance during my time at the University of Kansas, and for assigning me a project which utilizes both, my chemistry background as well as my chemical engineering degree. Also, I would like to acknowledge the entire Chemical Engineering faculty and staff for all there assistance, and in particular Cyndi Hurst, Professor Colin “Chip” Howat, Professor Julie Howat, Professor Carl Locke, Professor Trung Van Nguyen, and Professor Marylee Southard for their extended interest in my success. I would like to thank Wei Ren, Azita Ahosseini, and Sylvia Nwosu for their assistance and camaraderie in the laboratory. I wish them great success in their future endeavors. On a personal note, I would like to thank my wife, Misty Schleicher, for her moral support and the number of sacrifices she has endured throughout my degree, and for understanding the long hours I spent absent from home while working in the laboratory. I would not be where I am today if she was not by my side. I would also like to thank my parents, William and Barbara Schleicher, for the values they have instilled upon me, and for molding me into the individual I have become today. Under their guidance I have gained a strong work ethnic, learned that persistence pays off, and that family always comes first. They have truly been an inspiration to me. I would also like to acknowledge all my friends and extended family for supporting and believing in my success. It is a great feeling to know I have so many people behind me who care and believe that I can succeed at everything I do. Thank you, Jay Schleicher iii Abstract: Ionic liquids (ILs) are being recognized as environmentally friendly (“green”) solvents. However, their synthesis is often conducted in the very solvents that they will reportedly replace. This research has investigated the kinetics and solvent effects involved in synthesizing ILs in organic solvents and using compressed carbon dioxide. The kinetics for producing ILs have been found to be highly dependent on solvent polarities, and varied by over an order of magnitude. These dramatic effects were correlated to various polarity parameters to predict the kinetic rates. A detailed study of solvent toxicity and environmental impact was conducted to explore greener synthesis methods. Compressed CO2 was investigated as a potential benign alternative as the phase behavior and kinetics can be tuned for combined reaction and separation. Through understanding the kinetics, human/environmental impact, and phase equilibrium, ILs may be produced in a manner which may achieve their environmentally-benign potential. iv Table of Contents: Acknowledgements......................................................................................................iii Abstract.........................................................................................................................iv Table of Contents...........................................................................................................v Table of Figures...........................................................................................................vii Table of Tables.............................................................................................................ix Table of Symbols...........................................................................................................x 1. Introduction............................................................................................................1 1.1. IL Background......................................................................................................1 1.2. Problems with Ionic Liquid Production and Use .................................................2 1.2.1. IL Synthesis /Analysis.......................................................................................3 1.2.2. IL Reaction Engineering and Process Intensification........................................4 1.3. Research Objectives..............................................................................................5 References......................................................................................................................7 2. Experimental Methods........................................................................................11 2.1. Kinetic Measurements........................................................................................11 2.1.1. Ambient Pressure.............................................................................................12 2.1.1.1. Mixture Densities..........................................................................................12 2.1.2. High Pressure...................................................................................................14 2.1.3 NMR Analysis..................................................................................................16 2.2. Determining Kamlet Taft Parameters.................................................................22 2.2.1. Solvatochromic Probes....................................................................................22 2.2.2. UV-.Vis............................................................................................................25 2.3 Vapor-Liquid Equilibrium: Carbon Dioxide Studies..........................................26 2.4. Materials.............................................................................................................28 References....................................................................................................................30 3. Solvent Effects on Kinetics of Ionic Liquid Synthesis......................................32 3.1 Introduction to Kinetic Theory and Analysis.......................................................32 3.1.1. Eyring Equation...............................................................................................33 3.1.2. Hughes and Ingold Rules.................................................................................35 3.1.3. Literature overview..........................................................................................36 3.2. Experimental Results/Modeling..........................................................................37 3.3. Kinetic Parameters..............................................................................................44 3.4. Steric, Electronic, and Concentration Effects on Kinetic Rate...........................46 3.4.1. Leaving Group Contribution............................................................................47 3.4.2. Chain Length Contribution..............................................................................48 3.4.3. Steric Effects....................................................................................................49 3.4.4. Concentration Effects on Kinetic Constant......................................................50 3.5. Summary of Results............................................................................................51 References....................................................................................................................53 4. Diffusion of Reactants and IL in Organic Compounds....................................56 4.1. Theory of NMR Diffusion..................................................................................56 4.2. NMR Diffusion Procedure..................................................................................59 4.3. Diffusion Results................................................................................................63 v 4.4. Diffusion Controlled Kinetic Analysis...............................................................67 4.4.1. Analyzing Diffusion Controlled Kinetics; DMSO..........................................67 4.5. Summary of Results............................................................................................68 References....................................................................................................................70 5. Reaction Engineering and Environmental Impact Analysis............................72 5.1. Rowan Solvent Selection Table..........................................................................73 5.2. GlaxoSmithKline’s(GSK) Pharmaceutical Solvent Selection Table..................75 5.3. Environmental Factor Analysis...........................................................................79