Solvent effects in the depolymerization of coal

The depolymerization reaction of coal in the presence of Friedel-Crafts catalysts in a variety of phenolic and non-phenolic solvents has been investigated. Only the phenolic solvents were found to be useful in this reaction. Some interesting substituent effects were discovered when the isomeric cresols and dihydroxybenzenes were employed as solvents. The influence of temperature and catalyst concentration on the degree of depolymerization has also been examined. With non-phenolic solvents, polymerization is the predominant reaction.     

Epitaxy of noble metals and (111) surface superstructures of silicon and germanium part I: Study at room temperature

We have studied the growth mode and orientation at room temperature of Ag and Au deposits on the (111) cleavage faces of Si and Ge. Two-dimensional epitaxial layers are formed. In addition, we have observed by LEED and RHEED new superstructure patterns which depend strongly on the initial structural state of the substrates.     

Nouvelle synthese de derives de l'indazole par oxydation electrochimique de N-phenyl hydrazones du phenyl glyoxolonitrile,substituees en para du N-phenyle

The electrochemical oxidation of three hydrazones of phenyl glyoxolonitrile has been studied in acetonitrile. The electrochemical mechanisms have been investigated by rotating disc electrode voltammetry, cyclic voltammetry and controlled potential electrolysis at platinium electrodes. We have observed two intermediate oxidized species and we have synthetised a phosphonium salt and two 1 H-indazoles.     

Tuning the Peri Effect for Enantioselectivity: Asymmetric Hydrogenation of Unfunctionalized Olefins with the BIPI Ligands

The modular nature of the BIPI ligands allows for systematic optimization of each ligand region. The development of ligands optimized for asymmetric hydrogenation of the challenging unfunctionalized olefin substrate class is described. The naphthyl peri position, C‐8, has been identified as a critical stereocontrol element in the design of these ligands. Highly enantioselective ligands suitable for hydrogenation of tri‐ and tetrasubstituted olefins are detailed.     

Numerical simulation of pollutant dispersion around a building complex

The dispersion of exhausted pollutants from a building roof stack situated in the wake of a neighbouring tower has been studied using computational fluid dynamics (CFD) with the realizable k–? turbulence model for closure. Two scales are considered in this work, full-scale (1:1) and wind tunnel scale (1:200).Of primary interest are the distributions of the plume and of the pollutant concentrations on the building roof as well as on the leeward wall of the tower. Two stack heights and pollutant exhaust velocities have been considered for the distribution of pollutant concentrations in the neighbourhood of the building from which the pollutant is emitted. Results are compared with measurements from field and wind tunnel experiments to estimate the accuracy of simulations.