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Synthesis of superbase and correlation between gas phase acidity and pKa study of ionic liquid
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Chu, Pingcheng. Synthesis of superbase and correlation between gas phase acidity and pKa study of ionic liquid. Retrieved from https://doi.org/doi:10.7282/T3445JHZ

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TitleSynthesis of superbase and correlation between gas phase acidity and pKa study of ionic liquid
NameChu, Pingcheng (author); Lee, Jeehiun Katherine (chair); Krogh-Jespersen, Karsten (internal member); Warmuth, Ralf (internal member); Rutgers University; Graduate School - New Brunswick
Date Created2013
Other Date2013-10 (degree)
SubjectChemistry and Chemical Biology, Ionic solutions, Protons
Extentxi, 82 p. : ill.
DescriptionSince chemical reactions involving proton transfer as a key mechanism step become prevalent, development of Brønsted bases has been the intense focus in terms of catalyzing proton transfer reactions. Lambert et al. found and confirmed one cyclopropenimine as a strong superbase by measuring its pKa in acetonitrile for the first time. Based on that, we calculated several cyclopropenimine’s proton affinity (PA) which are much higher than all the volatile reference superbases we’ve ever used. It means that if we could obtain those very basic superbases, they would be used as reference bases to bracket PAs of highly basic compounds. Herein, we tried to design and synthesize cyclopropenimine-based superbases and investigated their tunability of PA by modifying various electron withdrawing and donating groups. The corresponding calculation results are consistent with our proposal that cyclopropenimine superbase with EWG decrease PA while EDG increase PA. We also tried to measure PA of one cyclopropenimine superbase that we synthesized by Cooks kinetics method. The other project focuses on a special class of ionic liquid which is known as green solvent with several advantages over traditional organic solvent. This new type of ionic liquid is imidazolium-based ionic liquid with tunable aryl and alkyl substituents which was designed by Strassner et al.. They named this category of ionic liquid as tunable aryl-alkyl ionic liquids (TAAILs). The reason we are interested in them is looking into the correlation between TAAILs’ aqueous property and their theoretical acidity in gas phase and solution. If there was some correlation, we could predict imidazolium compounds’ pKa’s by their gas phase property. Based upon this conjecture, we measured different TAAILs’ acidity by LCQ bracketing method on mass spectrometry, calculated their free energy in solution phase as well as in gas phase and developed two methods to measure their pKa’s in solution. Their acidity results demonstrate that those TAAILs with electron-withdrawing groups on para-position of phenyl substituent have high acidity while other TAAILs with electron-donating para-substituent have low acidity. Besides, I successfully obtained the pKa value of one TAAILs as 25.4 in water via H/D exchange kinetics experiment on NMR.
NoteM.S.
NoteIncludes bibliographical references
NoteIncludes vita
Noteby Pingcheng Chu
Genretheses, ETD graduate
Persistent URLhttps://doi.org/doi:10.7282/T3445JHZ
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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