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Anion Basicity and Ionicity of Protic Ionic Liquids by Mohammad Hasani a Dissertation Presented in Partial Fulfillment Of

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Anion Basicity and Ionicity of Protic Ionic Liquids by Mohammad Hasani a Dissertation Presented in Partial Fulfillment Of Anion Basicity and Ionicity of Protic Ionic Liquids by Mohammad Hasani A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved June 2016 by the Graduate Supervisory Committee: Chair: C. Austen Angell Jeffery Yarger Ian Gould ARIZONA STATE UNIVERSITY August 2016 ABSTRACT The field of Ionic Liquid (IL) research has received considerable attention during the past decade. Unique physicochemical properties of these low melting salts have made them very promising for applications in many areas of science and technology such as electrolyte research, green chemistry and electrodeposition. One of the most important parameters dictating their physicochemical behavior is the basicity of their anion. Using four sets of Protic Ionic Liquids (PILs) and spectroscopic characterization of them, a qualitative order for anion basicity of ILs is obtained. Protic Ionic Liquids are made by proton transfer form a Brønsted acid to a base. The extent of this transfer is determined by the free energy change of the proton transfer process. For the cases with large enough free energy change during the process, the result is a fully ionic material whereas if the proton transfer is not complete, a mixture of ions, neutral molecules and aggregates is resulted. NMR and IR spectroscopies along with electrochemical and mechanical characterization of four sets of PILs are used to study the degree of ionicity. i DEDICATION To My Family ii ACKNOWLEDGMENTS First and foremost, I would like to express my deep respect and gratitude to my advisor Reagent’s Professor C. Austen Angell not only for giving me the opportunity to work in his laboratory but for his continues support all throughout the years. I would also like to thank my dissertation committee members Professor Jeffrey Yarger and President’s Professor Ian Gould for their help and support. I am glad I had the opportunity to meet them. My coworkers in the lab, Dr. Zuofeng Zhao and Iolanda Klein, are acknowledged here for welcoming me in the group and for what they taught me of experimental techniques. I learned from them and will remember the setting up of new equipment, lab inspections, sink clogs, leaks and all the ups and downs we went through during these years. I am grateful to thank Dr. Stephen Davidowski and Dr. Brian Cherry for helping me with the NMR experiments and for teaching me what they knew without reservation. Dr. Brian Cherry is credited for keeping the NMR laboratory a place on which function one can count. I thank Dr. Jennifer Green for her understanding and support. I also thank Waunita Parrill, Martha McDowell, David Nutt and Gregory Memberto for their help and support during the years. iii TABLE OF CONTENTS Page LIST OF TABLES ................................................................................................................... vi LIST OF FIGURES .............................................................................................................. viii CHAPTER 1 INTRODUCTION TO IONIC LIQUIDS .................................................................. 1 Classes of Ionic Liquids ............................................................................. 3 Protic Ionic Liquids and Ionicity ............................................................... 8 Proton Free Energy Level Diagram ......................................................... 11 Acidity of Protic Ionic Liquids ................................................................ 12 Anion Basicity of Ionic Liquids .............................................................. 14 Works Cited .............................................................................................. 16 2 ON THE USE OF A PROTIC IONIC LIQUID WITH A NOVEL CATION TO STUDY ANION BASICITY ............................................................... 20 Introduction .............................................................................................. 21 Experimental and Results ........................................................................ 25 Discussion ................................................................................................ 45 Conclusion ................................................................................................ 63 Works Cited .............................................................................................. 64 3 NMR CHARACTERIZATION OF IONICITY AND TRANSPORT PROPERTIES FOR A SERIES OF TERTIARY AMINE BASED PROTIC IONIC LIQUIDS .............................................................................................. 69 Introduction .............................................................................................. 70 iv CHAPTER Page Experimental ............................................................................................ 79 Results and Discussion ............................................................................ 83 Conclusion ................................................................................................ 94 Works Cited .............................................................................................. 95 REFERENCES....... .............................................................................................................. 98 APPENDIX A RESPECTIVE COORDINATES OF OPTIMIZED STRUCTURES ................ 107 B 1H-1H AND 1H-14N J-COUPLING OF DEMAALCL4 PROTON ...................... 142 v LIST OF TABLES Table Page 2-1- Water Content KF Measurement Data for the PIL Samples. .................................... 27 2-2- The Effect of Added Water on Chemical Shifts of Different Nuclei ........................ 28 2-3- Measured Resistance and Calculated Conductivity Data of DMI-H2SO4 at Different Temperatures..................................................................................................................... 31 2-4- Measured Resistance and Calculated Conductivity Data of DMI-HOMs at Different Temperatures..................................................................................................................... 31 2-5- Measured Resistance and Calculated Conductivity Data of DMI-HTFA at Different Temperatures..................................................................................................................... 32 2-6- Viscosity Data for DMI-H2SO4 at Different Temperatures ...................................... 34 2-7- Viscosity Data for DMI-HOMs at Different Temperatures ...................................... 35 2-8- Viscosity Data for DMI-HTFA at Different Temperatures ...................................... 35 2-9- Equivalent Conductivity fluidity Relationship for DMI-H2SO4 at Different Temperatures..................................................................................................................... 38 2-10- Equivalent Conductivity Fluidity Relationship for DMI-HOMs at Different Temperatures..................................................................................................................... 38 2-11- Equivalent Conductivity Fluidity Relationship for DMI-HTFA at Different Temperatures..................................................................................................................... 39 2-12- DMI-HAlBr4 Vibration Frequencies of Normal Modes ......................................... 40 2-13- DMI-HAlCl4 Vibration Frequencies of Normal Modes .......................................... 41 2-14- DMI-HBF4 Vibrational Frequencies of Normal Modes .......................................... 42 Table Page vi 2-15- Calculated Gas-Phase Enthalpies of Acids and their Conjugate Anions ................ 43 2-16- Calculated Gas-Phase Enthalpies and Free Energies of DMI Adducts ................... 44 2-17- Exchangeable Proton 1H, Carbonyl 13C and 15N Chemical Shifts of DMI in its 1:1 Mixtures with Different Acids. ......................................................................................... 46 2-18- Hammet Acidity Function Values ........................................................................... 53 2-19- 1H Chemical Shift of the Acidic Proton in PILs Made from DEMA ...................... 62 3-1- Summary of Proton Affinity Calculation Results at Various Levels of Theory and Literature Values. .............................................................................................................. 73 3-2- Results of Diffusion NMR Experiments and Conductivity Measurements. ............. 90 vii LIST OF FIGURES Figure Page 1-1- Phase Diagram of the System Ethylpyridinium Bromide + AlCl3 ............................. 5 1-2- Concept of Complex Cations in Solvate Ionic Liquids ............................................... 6 + 1-3- Crown Ether- and Glyme-Based [Li(ligand)1] Solvate Models ................................ 7 1-4- Walden Plot Showing the Classification of Ionic Liquids .......................................... 9 1-5- Gurney Free Energy Level Diagram for Acid/Base Pairs ......................................... 12 2-1. Protonation of DMI ................................................................................................... 23 2-2- Ionic Conductivity of DMI PILs as a Function of Temperature ............................... 32 2-3- Dynamic Viscosity of DMI PILs as a Function of Temperature .............................. 36 15 2-4- N Spectra of DMI PILs ........................................................................................... 47 13 15 2-5- C and N Spectra of DMI in Media with Varying Acid Strengths
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