SYNTHESIS AND CHARACTERIZATION OF NEW UNSYMMETRICAL DIGLYCOLAMIDES FOR ...

198 Pages·2016·2.39 MB·English

SYNTHESIS AND CHARACTERIZATION OF NEW UNSYMMETRICAL
DIGLYCOLAMIDES FOR TRIVALENT LANTHANIDE
METAL EXTRACTION

By
BENJAMIN GEORGE TOKHEIM

A dissertation submitted in partial fulfillment of
the requirements for the degree of

DOCTOR OF PHILOSOPHY

WASHINGTON STATE UNIVERSITY
Department of Chemistry

JULY 2016

© Copyright by BENJAMIN GEORGE TOKHEIM, 2016
All Rights Reserved
© Copyright by BENJAMIN GEORGE TOKHEIM, 2016
All Rights Reserved
To the Faculty of Washington State University:

The members of the Committee appointed to examine the dissertation of
BENJAMIN GEORGE TOKHEIM find it satisfactory and recommend that it be
accepted.

____________________________________
Kenneth L. Nash, Ph.D., Chair

____________________________________
Robert C. Ronald, Ph.D.

____________________________________
Scot E. Wherland, Ph.D.

____________________________________
Mark P. Jensen, Ph.D.

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ACKNOWLEDGEMENTS

I would like to thank my advisor, Ken Nash, for teaching me how to find patterns in the
seemingly inexplicable and how to persevere through repeated failures.
I would like to thank my mentor, Rob Ronald, for imparting a portion of his vast wisdom
to me and for showing me how to delight in everyday experiences.
I would like to thank my professor, Scot Wherland, for introducing me to the world of
inorganic chemistry and for sharing his passion for teaching with me.
I would like to thank my undergraduate assistant, Shane Kelly, for helping with the difficult
task of synthesizing and purifying many new compounds.
I would like to thank the Nash group post-doctoral associate, Joey Lapka, for sharing an
office and sharing his knowledge.
I would like to thank Yuji Sasaki of the Japan Atomic Energy Agency for his generous gift
of TODGA.
I would like to thank Gerhard Munske of the WSU Molecular Biology and Genomics Core
for helping to elucidate structures with his HRMS expertise.
I would like to thank Greg Helms and Bill Hiscox of the WSU Center for NMR
Spectroscopy for many hours of assistance and sage advice.
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I would like to thank my fellow graduate students for their assistance and support,
especially Guy Dutech, Ashleigh Kimberlin, Ian Hobbs, Jeff Berry, Bess O’Leary, Adam Burn,
Jeff Johnston, Jessica Drader, and Colt Heathman.
I would like to thank all my wonderful professors (Jim Togeas, Nancy Carpenter,
Jennifer Goodnough, Rob Rossi, George Shuffelton, Steve Kennedy, and Rick Penning) and
teachers (Vern Stevens, Deanna Jordahl, Maury Ferden, Butch Halterman, Teresa Goddard,
Darwin Tebeest, and Dan Hampton) from whom I have learned so much and owe my passion for
continued learning.
I would like to thank my father, Gene Tokheim, who always says that I am a success, even
after apparent failures.
I would like to thank my brother, Sam Tokheim, who provides excellent advice and comic
relief for every situation.
I would like to thank my brother, Luke Tokheim, who always shares some of his positive
outlook and creates fun wherever he goes.
Lastly, I would like to thank my mother, Lucy O’Laughlin, who always listens and sees
the beauty in everything.

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SYNTHESIS AND CHARACTERIZATION OF NEW UNSYMMETRICAL
DIGLYCOLAMIDES FOR TRIVALENT LANTHANIDE
METAL EXTRACTION

Abstract

by Benjamin George Tokheim, Ph.D.
Washington State University
July 2016

Chair: Kenneth L. Nash

Twelve new unsymmetrical diglycolamide (UDGA) ligands have been synthesized as
solvent extraction reagents for trivalent lanthanide ions from highly acidic nitrate media. The
asymmetry in the extractant design arises from attaching nonpolar alkyl chains (hexyl, octyl,
2-ethylhexyl, 3,7-dimethyloctyl) to one amide group and smaller, more compact, cyclic alkyl
groups (pyrrolidinyl, piperidinyl, morpholino) to the other amide moiety. This structural variant
of a well-known cation receptor reduces the interfacial footprint of the extractant and is designed
to increase the rate of phase transfer of the target cations. The partitioning of 152,154Eu(III) between
aqueous phases of varying nitric acid concentrations (0.01-3 M) and a 0.05 M UDGA in
5% v/v 1-octanol/n-dodecane organic phase was measured radiometrically and compared to the
symmetrical diglycolamide, N,N,N′,N′-tetraoctyldiglycolamide (TODGA). All twelve UDGA
ligands quantitatively extracted trivalent Eu(III) cations from 1 M nitric acid. Separate solvent
extraction slope analysis experiments were used to determine the stoichiometry and conditional
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extraction equilibrium constant (K' ) of the extracted Eu-UDGA complex in
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5% v/v 1-octanol/n-dodecane. The metal-ligand complex stoichiometry in the extracted species
was found to be approximately 1:3 for the UDGA ligands and TODGA while the conditional
extraction equilibrium constants (K' ) decreased with increasing ligand size and alkyl chain
ex
branching. Luminescence spectroscopy investigations established the relative stability and
stoichiometry of the complexes in acetonitrile. The overall trends in the conditional extraction
equilibrium constant (K' ) and the 1:3 conditional stability constant (β ) followed a similar
ex 103
pattern, indicating a correlation between complex stability and ligand structural features.

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TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ...................................................................................................... iii
ABSTRACT ................................................................................................................................ v
LIST OF TABLES ...................................................................................................................... x
LIST OF FIGURES ................................................................................................................. xii

CHAPTER ONE: INTRODUCTION
1. THE ATOMIC AGE ................................................................................................... 1
2. SOLVENT EXTRACTION COMPLEXANT DEVELOPMENT ........................... 13
3. REFERENCES ......................................................................................................... 33
CHAPTER TWO: SYNTHESIS AND CHARACTERIZATION OF NEW
UNSYMMETRICAL DIGLYCOLAMIDES

1. INTRODUCTION .................................................................................................... 40
2. MATERIALS ............................................................................................................ 46
3. METHODS ............................................................................................................... 47
4. SYNTHETIC DESIGN OBJECTIVES .................................................................... 49
5. SYNTHESIS AND PURIFICATION OF LIGANDS 1-9........................................ 51
Flash Chromatography: CombiFlash® Rf+ Lumen™...................................... 58
6. SYNTHESIS AND PURIFICATION OF LIGANDS 10-12.................................... 63
Flash Chromatography: MPLC #3 .................................................................... 71
7. CONCLUSIONS....................................................................................................... 73
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8. REFERENCES ......................................................................................................... 75
CHAPTER THREE: TRIVALENT LANTHANIDE METAL EXTRACTION
BEHAVIOR BY NEW UNSYMMETRICAL DIGLYCOLAMIDES

1. ABSTRACT .............................................................................................................. 77
2. INTRODUCTION .................................................................................................... 77
3. MATERIALS ............................................................................................................ 81
4. METHODS ............................................................................................................... 83
Radiotracer 152,154Eu Experiments ..................................................................... 84
ICP-MS Ln Experiments................................................................................... 86
5. EQUILIBRATION TIME ......................................................................................... 87
6. THIRD PHASE FORMATION ................................................................................ 90
7. LIGAND SOLUBILITY ........................................................................................... 92
8. NITRIC ACID EXTRACTION ................................................................................ 95
9. EU(III)-UDGA COORDINATION COMPLEXES ............................................... 100
10. NITRIC ACID DEPENDENCE EXTRACTIONS .............................................. 113
11. NITRATE DEPENDENCE EXTRACTION ........................................................ 124
12. LANTHANIDE SERIES EXTRACTIONS ......................................................... 125
13. CONCLUSIONS................................................................................................... 135
14. FURTHER WORK ............................................................................................... 136
15. REFERENCES ..................................................................................................... 137
CHAPTER FOUR: PROBING THE EUROPIUM-UNSYMMETRICAL
DIGLYCOLAMIDE COMPLEX USING LUMINESCENCE SPECTROSCOPY

1. INTRODUCTION .................................................................................................. 141
2. MATERIALS .......................................................................................................... 146
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3. METHODS ............................................................................................................. 147
4. LUMINESCENCE LIFETIMES FOR EU(III)-UDGA COMPLEXES ................. 148
5. LUMINESCENCE EMISSION SPECTROSCOPY FOR EU(III)-UDGA
COMPLEXES ............................................................................................................. 154

6. CONCLUSIONS..................................................................................................... 172
7. REFERENCES ....................................................................................................... 173
CHAPTER FIVE: CONCLUSIONS
1. PROJECT GOALS ................................................................................................. 175
2. ORGANIC SYNTHESIS ........................................................................................ 176
3. SOLVENT EXTRACTION STUDIES .................................................................. 176
4. LUMINESCENCE SPECTROSCOPY .................................................................. 178
5. FUTURE WORK .................................................................................................... 178

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