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Title: Ionic liquid effects on nucleophilic substitutions
Author: Fraser, Georgina
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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In this thesis we demonstrate a fundamental difference between nucleophilic substitution reaction mechanisms in ionic liquids versus conventional solvents. Reported herein are the effects of ionic liquid solvents on substitution reactions between a cationic electrophile and the chloride anion of various organic and inorganic salts. We have combined novel quantitative studies of the nucleophilic source [Cat]Cl with our studies of [C4C1im]Cl and compared their reactivities, k2. For the first time, Eyring activation parameters have been calculated for substitution reactions between charged species in ionic liquid solvents and reveal a hitherto unprecedented role of the cation in the transition state. The activation parameters (ΔH≠ and ΔS≠) suggest the reactivity of the chloride anion can be manipulated by varying the size and chemical nature of the cation, and also shed light on cation hydrogen bond donating effects. The superior ability of ionic liquid solvents to fully screen the charges of reactant ions is shown to break down as ions become larger, less charge dense and display a tendency to self-aggregate.
Supervisor: Welton, Tom Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available