New approaches to aromatic substitution reactions with carbon electrophiles

The thesis gives an account of work directed towards developing new reagent systems and methodology, with particular reference to the Friedel–Crafts and Vilsmeier–Haack reactions of aromatic and heteroaromatlc compounds. Ways of improving regioselectivity and developing a stereoselective Friedel–Crafts reaction have been investigated for a range of hetero-atom stabilised carbocations. This work is divided into two main areas: (1) the synthesis and use of pyrophosphoryl chloride in the Vilsmeier–Haack reaction, the results of this has shed new light on the mechanism of this classical reaction; (2) the control of the Friedel–Crafts reactions of bi-functional derivatives of glyoxylic acid and the use of chiral relays to induce diastereoselectivity. [Continues.

Interaction Mechanism Insights on the Solvation of Fullerene B(80)with Choline-based Ionic Liquids

Beyond carbon allotropes, other nanostructures such as fullerene B80 are attracting a growing interest due to their potential applications. The use of new materials based on fullerene B80 is still in a premature stage; however many of these applications would require the use of B80 in solution. This paper reports an unprecedented density functional theory (DFT) analysis on the interaction mechanism between B80 and two choline-based ionic liquids as a first insight for the fullerene B80 solvation by ionic liquids. The analysis of properties such as binding energies, charge distributions or intermolecular interactions shed light on the main features, which should govern interaction between ionic liquids and fullerene B80. In addition, the optimization of systems composed by six ionic pairs around a fullerene B80 has supplied some information about the first solvation shell at the molecular level. As a summary, this paper provides the first insights in the rational design of ionic liquids with suitable properties for the solvation of B80.Gregorio García acknowledges the funding by Junta de Castilla y León (Spain), cofunded by European Social Fund, for a postdoctoral contract. This work was funded by Ministerio de Economía y Competitividad (Spain, project CTQ2013-40476-R) and Junta de Castilla y León (Spain, project BU324U14). We also acknowledge The Foundation of Supercomputing Center of Castile and León (FCSCL, Spain), Computing and Advanced Technologies Foundation of Extremadura (CénitS, LUSITANIA Supercomputer, Spain) and Consortium of Scientific and Academic Services of Cataluña (CSUC, Spain) for providing supercomputing facilities. This work was also made possible by NPRP grant # 6-330-2-140 from the Qatar National Research Fund (a member of Qatar Foundation). We also thank Dr. J. T. Muya and A. Ceulemans (University of Richmond) for providing us the optimized structures of pristine B80. The statements made herein are solely the responsibility of the authors

Graz vom Schloßberg.

Blick vom Schloßberg gegen Süden mit drei Brücke

Separation of aromatic hydrocarbons from alkanes using the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl) sulfonyl} amide

The liquid-liquid equilibrium for the ternary system formed by hexane, benzene and the ionic liquid 1-ethyl-3-methylimidazolium bis

An investigation of corporate governance mechanisms and value creation in the United Kingdom

Corporate governance refers to the set of mechanisms that affect the decision-making process taken by managers of quoted firms where the ownership and control are separate. The impact of corporate governance on corporate performance has been the main theme of research in accounting and finance at least since Jensen and Meckling (1976) published their work. Typically, empirical studies investigate whether different corporate governance mechanisms have an impact on directors' behaviour or corporate performance. However, corporate governance studies are complicated by the endogenous relationship that exists between control forces such as capital markets-the-regulatory system, factor markets, and internal governance mechanisms operating on a company and its decisions. This implies that the findings of empirical studies are questionable if these studies do not deal with endogeneity problems. A considerable number of empirical studies suggest that certain corporate governance mechanisms improve corporate performance, but those studies are affected by endogeneity issues. Roberts and Whited (2011) state that "endogeneity leads to biased and inconsistent parameter estimates that make reliable inference virtually impossible". The main purpose of this study, therefore, is to respond to these endogeneity concerns by using a well-developed generalised method of moments regression model (GMM) developed by Wintoki et al. (2012). The study examines the relationship between the board of directors' structure and corporate performance. Specifically, it investigates whether the presence of non-executive directors, duality, board size, director ownership, and the presence of board sub-committees have an impact on corporate performance. In addition, it also develops a governance index to find out whether the level of compliance with corporate governance regulations has an impact on corporate performance measured by ROA and Tobin's Q. To investigate these issues, the study adopts a comprehensive strategy which consists of three regression models, namely ordinary least square (OLS), fixed-effects model (FE), and generalised method of moments (GMM). Data for the analysis are extracted from annual reports, BoardEx database and Datastream databases for the period 1999 - 2009. The final sample includes a total of 634 UK firms listed on the London Stock Exchange. The results indicate that the level of compliance with corporate governance regulations and board structure are both partly determined by past corporate performance. After controlling for this, the results show that there is no relationship between current board of directors' structure and corporate performance. Further, the level of compliance with the recommendations of corporate governance has no impact on profitability measured by ROA. The results further reveal that the level of compliance with the Combined Code on Corporate Governance also has no impact on Tobin's Q as a proxy of corporate performance. These findings are inconsistent with many prior empirical studies and policy recommendations on corporate governance, which suggests that corporate governance mechanisms develop corporate performance. In addition, the findings indicate that the results of the earlier corporate governance studies that do not take into account the dynamic nature of corporate governance may be affected by bias.EThOS - Electronic Theses Online ServiceGBUnited Kingdo