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Rotational Spectra and Structures of Diethanolamine And ROTATIONAL SPECTRA AND STRUCTURES OF DIETHANOLAMINE AND 2-AMINOPHENOL A thesis submitted To Kent State University in partial fulfillment of the requirements for the Degree of Master of Science By Gretchen Renee Laubacher August 2011 Gretchen Renee Laubacher B.S., University of Dayton, 2009 M.S., Kent State University, 2011 Approved by Michael Tubergen , Advisor Michael Tubergen , Chair, Department of Chemistry John R.D. Stalvey , Dean, College of Arts and Sciences ii Table of Contents Page List of Figures v List of Tables vii Acknowledgments ix Chapter 1. Introduction………………………………………………………… 1 2. Theory of Rotational Spectroscopy………………………………… 2 2.1 Mechanics of Rotating Bodies 2 2.2 Angular Momentum 5 2.3 Classes of Rigid Rotors 7 2.3.1 Symmetric Top Molecules 10 2.3.2 Asymmetric Top Molecules 11 2.4 Centrifugal Distortion 17 2.5 Nuclear Hyperfine Structure 19 2.6 Electronic Structure Calculations 21 2.6.1 Molecular Orbital Ab initio Models 21 2.6.2 Electron Correlation Methods 26 2.7 Structural Information 27 2.7.1 Comparison with High Level Theoretical Models 27 2.7.2 Kraitchman Isotopic Substitution 28 3. Experimental………………………………………………………… 31 3.1 History of Microwave Spectroscopy 31 3.2 Instrument 32 3.2.1 Background Information 32 3.2.2 Fabry-Perot Resonant Cavity 33 3.2.3 Supersonic Jet Expansion 34 3.2.4 Pulsed Radiation and Fourier Transformation 38 3.3 Experimental Initiation 38 3.4 Spectrometer Used for Current Research 39 3.4.1 Microwave Circuit 39 3.4.2 Sensitivity of Instrument and Basic Components of 42 Instrument 3.5 Synthetic Methods 44 3.6 Computational Methods 47 4. Diethanolamine……………………………………………………… 48 4.1 Background Information 48 4.2 Theoretical Modeling 50 4.2.1 Previous Theoretical Modeling 50 4.2.2 Current Theoretical Modeling for this Research 51 iii 4.3 Spectra and Hamiltonian Fitting 63 4.3.1 Spectrum A of Diethanolamine 63 4.3.2 Spectrum B of Diethanolamine 65 4.3.3 Discussion of Structure 68 4.4 Diethanolamine Isotopic Study 72 4.4.1 Structural Modeling of Deuterated Isotopomers 73 4.4.2 Spectra and Hamiltonian Fitting 74 4.4.2.1 Deuterated-Diethanolamine Spectrum A 74 4.4.2.2 Deuterated-Diethanolamine Spectrum B 77 4.4.2.3 Deuterated-Diethanolamine Spectrum C 80 4.4.2.4 Deuterated-Diethanolamine Spectrum D 82 4.4.3 Discussion 85 5. 2-aminophenol………………………………………………………. 92 5.1 Background Information 92 5.2 Theoretical Modeling 93 5.3 Spectrum and Hamiltonian Fitting 98 5.4 Discussion of Structure 101 6. Conclusion………………………………………………………… 103 References 105 iv LIST OF FIGURES Figure Page 1. Illustration of a spherical top molecule, carbon tetrachloride 8 2. Illustration of a prolate symmetric top molecule, chloromethane 8 3. Illustration of an oblate symmetric top molecule, benzene 9 4. Illustration of an asymmetric top molecule, water 9 5. Correlation diagram for asymmetric rotor state energies between the 16 oblate and prolate limits 6. Schematic illustrating randomness to directed flow seen in a supersonic 36 jet expansion 7. Schematic of instrument used in this research 41 8. Representative sample of 606-505 transition for diethanolamine 43 9. Picture of instrument used in this research 45 10. Deuteration sites for diethanolamine 46 11. Structure of diethanolamine 48 12. Structure of N-nitrosodiethanolamine 49 13. Structure of diethanolamine at B3LYP/6-311++G(d,p) level 50 14. Molecular structure and definitions of torsional angles for 55 Diethanolamine 15. Conformer ec1 of diethanolamine from MP2/6-311++G(d,p) level 61 16. Conformer ec2 of diethanolamine from MP2/6-311++G(d,p) level 62 17. Conformer ec3 of diethanolamine from MP2/6-311++G(d,p) level 62 18. Conformer ec4 of diethanolamine from MP2/6-311++G(d,p) level 63 19. Rotational transition of the 616-515 transition of Spectrum A for 67 Diethanolamine 20. Rotational transition of the 606-505 transition of Spectrum A for 67 Diethanolamine 21. Rotational transition of the 616-515 transition of Spectrum B for 70 Diethanolamine 22. Rotational transition of the 615-514 transition of Spectrum B for 71 Diethanolamine 23. Rotational transition of the 717-616 transition of d-DEA Spectrum A for 76 Diethanolamine 24. Rotational transition of the 716-615 transition of d-DEA Spectrum A for 76 Diethanolamine 25. Rotational transition of the 707-606 transition of d-DEA Spectrum B for 77 Diethanolamine 26. Rotational transition of the 817-716 transition of d-DEA Spectrum B for 77 Diethanolamine v 27. Rotational transition of the 615-514 transition of d-DEA Spectrum C for 81 Diethanolamine 28. Rotational transition of the 818-717 transition of d-DEA Spectrum C for 81 Diethanolamine 29. Rotational transition of the 616-515 transition of d-DEA Spectrum D 84 for diethanolamine 30. Rotational transition of the 717-616 transition of d-DEA Spectrum D 84 for diethanolamine 31. Deuteration sites on Conformer ec1 of diethanolamine 87 32. Deuteration sites on Conformer ec2 of diethanolamine 90 33. Structure of 2-aminophenol 92 34. Lowest energy cis-conformer of 2-aminophenol determined by 94 Soliman et al. 35. The trans conformer determined from Soliman et al. 94 36. The gauche conformer determined from Soliman et al. 95 37. Cis Conformer determined from RHF/6-311++G(d,p) level 97 38. Trans Conformer determined from RHF/6-311++G(d,p) level 97 39. 515-404 rotational transition of 2-aminophenol 100 40. 505-414 rotational transition of 2-aminophenol 100 vi LIST OF TABLES Table Page 1. Four classes of nonlinear rigid rotors 7 2. Asymmetric rotor energy levels of J=1 and 2 15 3. Configuration and relative energies of diethanolamine conformers 52-54 at RHF/6-31G(d) level 4. Configuration and relative energies of diethanolamine conformers 56-58 at RHF/6-311++G(d,p) level 5. Configuration and relative energies for four lowest energy 60 conformers at MP2/6-311++G(d,p) level 6. Relative dipole moments and rotational constants for conformers at 60 MP2/6-311++G(d,p) level 7. Experimental rotational constants determined for Spectrum A of 64 Diethanolamine 8. Rotational transitions of Spectrum A of diethanolamine 66 9. Experimental rotational constants for Spectrum B of 68 Diethanolamine 10. Rotational transitions for Spectrum B of diethanolamine 69 11. %ΔIrms values for conformers compared with Spectrum A 71 12. %ΔIrms values for conformers compared with Spectrum B 72 13. Possible deuteration sites for Conformers ec1 and ec2 73 14. Rotational transition frequencies and relative quantum numbers 75 for d-DEA Spectrum A 15. Experimental rotational constants for d-DEA Spectrum A 77 16. Experimental rotational constants for d-DEA Spectrum B 77 17. Rotational transition frequencies and relative quantum numbers 78 for d-DEA Spectrum B 18. Rotational transition frequencies and relative quantum numbers 80 for d-DEA Spectrum C 19. Experimental rotational constants for d-DEA Spectrum C 82 20. Rotational transition frequencies and relative quantum numbers 83 for d-DEA Spectrum D 21. Experimental rotational constants for d-DEA Spectrum D 85 22. %ΔIrms and rotational constants for possible deuterated 86 -diethanolamine molecules with d-DEA Spectrum A 23. Possible deuterated-diethanolamine molecules with deuterated 87 label and relative deuteration site on Conformer ec1 24. %ΔIrms and rotational constants of possible deuterated 88 diethanolamine molecules with d-DEA Spectrum B 25. %ΔIrms and rotational constants of possible deuterated- 89 diethanolamine molecules with d-DEA Spectrum C vii 26. Possible deuterated diethanolamine molecules with deuterated 90 label and relative deuteration site on Conformer ec2 27. %ΔIrms and rotational constants of possible deuterated 91 diethanolamine molecules with d-DEA Spectrum D 28. Relative energies for the cis, trans and gauche conformers at 95 various levels of theory 29. Principal dipole moments and relative energy for the Cis and 98 Trans Conformers determined from RHF/6-311++G(d,p) level of theory 30. Quantum numbers and relative frequencies for 2-aminophenol 99 Spectrum 31. Rotational constants of experimental spectrum with their relative 99 uncertainties 32. Results of %ΔIrms for Cis and Trans Conformers with compared 102 with Experimental Spectrum viii ACKNOWLEDGMENTS My sincere appreciation goes to God, whose inspiration and divine direction made it possible for me to accomplish this task. My inestimable appreciation goes to my family members for their moral advice and financial support throughout my studies. Without them, I would have been forever stressed. Thank you: mom, dad and siblings for putting up with me in my less than cheerful moments. My profound gratitude goes to my advisor, Dr. Michael Tubergen, for making this thesis possible through his wealth of academic experience in microwave spectroscopy. I joined the Tubergen laboratory with no prior knowledge of microwave spectroscopy, but was never made to feel inferior. Everything I know is owed to Dr. Tubergen. Thank you. My appreciation also goes to Andy Conrad, Heather Seedhouse, Katelin Byerly, and Ashley Fox. Without Andy’s help and guidance throughout my studies here at Kent State, I would have been lost. His patience and helpful advice was greatly appreciated. Heather Seedhouse was a joy to work with, and through her I made a great friend both in the lab and out of the lab. Together Katelin Byerly and I accomplished the 2- aminophenol project. ix 1. Introduction When I entered graduate school in the fall of 2009, I knew I wanted to do research on environmental molecules. I began interviewing the possible research advisors in order to decide which professor I would work with. Upon talking to Dr. Tubergen, I discovered that his research dealt with gas-phase molecules. Many environmental molecules are gases, as many are volatile organic compounds.
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