<p> Cyclic voltammetric oxidation of 1,2,3,4,5-pentaphenylcyclopentadiene has been studied in non-polar chloroalkane solvents (CH2Cl2 and CH2ClCH2Cl). The oxidation is reversible if tetra-n-butylammonium hexafluorophosphate (TBA^+PF6^-) is used as supporting electrolyte, but irreversible when tetra-n-butylammonium perchlorate (TBA^+ClO4^-) or tetra-n-butylammonium trifluoromethane sulfonate (TBA^+OTf^-) are used, and partially reversible when tetra-n-butylammonium tetrafluoroborate (TBA^+BF4^-) is used. Oxidation of 1,2,3,4,5-pentaphenyl-1-methylcyclopentadiene, which has no relatively acidic protons, was reversible with all four supporting electrolytes.</p> <p> The criteria for reversibility were observation of cathodic wave on scan reversal, equal anodic and cathodic peak currents, minor dependence of peak potentials on scan rate, v, and linearity of anodic peak current, ipa with the square root of scan rate, v^1/2 , corresponding to Randles-Sevcik equation for reversible processes.</p> <p> It is proposed that perchlorate (ClO4^-) and triflate (OTf^-) anions are sufficiently basic to accept a proton from 1,2,3,4,5-pentaphenylcyclopentadiene cation-radical intermediate, while tetrafluoroborate (BF4^-) and particularly hexafluorophosphate (PF6^-) are less basic, and therefore less reactive.</p> <p> Controlled potential electrolysis of 1,2,3,4,5-pentaphenylcyclopentadiene with tetra-n-butylammonium perchlorate as supporting electrolyte affords the cation, which is consistent with an ECE mechanism in which the chemical step is proton loss.</p> / Thesis / Master of Science (MSc)

<p> It is known that alkoxyoxadiazolines undergo thermal decomposition to form carbenes via an ylide intermediate. This project involved the preparation and subsequent thermolysis of spirooxadiazolines of type 4.</p> <p> Spiro oxadiazoline (4) was prepared by oxidation of (3) with lead tetraacetate in dichloromethane. The first order rate constant for the thermolysis of 4b in benzene at 111°C is determined. The primary thermolysis products were found to be acetone, nitrogen and the cyclic dioxacarbene (5). Formation of (5) was confirmed by various trapping experiments. (See Diagram in Thesis)</p> / Thesis / Master of Science (MSc)

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Macrocyclic polyether sulfides have been prepared by reacting an oligoethylene glycol dichloride with a dithiol or sodium sulfide in ethanol. The following new compounds were prepared: 1-thia-(9-crown-3), 1,4-dithia-(9-crown-3), 1,4-dithia-(12-crown-4), 1,4,7-trithia-(12-crown-4), 1-thia-(18-crown-6), I,4-dithia-(18-crown-6), 1,7-dithia-(18-crown-6), 1,4,7-trithia-(18-crown-6), 1,7-dithia-(21-crown-7), 1,4,7-trithia-(21-crown-7). Four other previously reported macrocyclic polyether sulfides were also prepared. The symmetry of the nmr spectra of these compounds give added evidence for the proposed ring structures. The following subjects were presented and discussed: studies of cyclization by-products, dependence of cyclization yield on the size of the rings, high dilution principle and its application, medium-sized rings, effect of hetero-atoms on cyclization and melting point correlations. Also included in the dissertation is a detailed review of the syntheses of macrocyclic sulfides.

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Yes / We present a formalism to represent cyclic models and study di erent semantic frameworks that support testing. These models combine sequences of observable actions and the passing of (discrete) time and can be used to specify a number of classes of reactive systems, an example being robotic systems. We use implementation relations in order to formally define a notion of correctness of a system under test (SUT) with respect to a specification. As usual, the aim is to devise an extension of the classical ioco implementation relation but available timed variants of ioco are not suitable for cyclic models. This paper thus defines new implementation relations that encapsulate the discrete nature of time and take into account not only the actions that models can perform but also the ones that they can refuse. In addition to defining these relations, we study a number of their properties and provide alternative characterisations, showing that the relations are appropriate conservative extensions of trace containment. Finally, we give test derivation algorithms and prove that they are sound and also are complete in the limit. / Engineering and Physical Sciences Research Council Grant numbers: EP/R025134/2. Ministerio de Economía y Competitividad Grant numbers: RTI2018-093608-B-C31. Comunidad de Madrid Grant numbers: S2018/TCS-4314