Electrochemical oxidation of phenolic and other organic compounds at boron doped diamond electrodes for wastewater treatment: effect of mass transfer

The paper presents the results of an experimental study on oxidation at boron doped diamond electrodes (BDD) of some phenolic compounds: phenol (PH), para-hydroxibenzoic acid (PHB), cathecole (CT), hydroquinone (HQ) are considered, singularly contained in aqueous solutions or in the presence of glucose (G), which was selected to represent the class of biodegradable compounds. Oxidation of benzoquinone (BQ) and maleic acid (MA), generally detected as intermediates products from phenol degradation, is also investigated. Great attention is paid to verify the feasibility of a selective process in which the oxidation is specifically addressed to the phenolic fraction up to non toxic intermediate products which are more biodegradable than the original phenols.     

Force-field calculations of the packing energy of monolayers of C3 and C4 hydrocarbon molecules adsorbed on single crystal metal surfaces

Force-field calculations are applied to investigate the packing energy of overlayers of C₃ and C₄ hydrocarbons adsorbed on Pt(111) and Rh(111), in which Van der Waals adsorbate-adsorbate interactions play a significant role. The packing energies are used to compare various adsorbate structures for which Low Energy Electron Diffraction patterns have been obtained and corresponding detailed structures have been proposed. In particular, the conformation of methylacetylene (HCCCH₃) in a (2 × 2) arrangement, and of propylidyne (CCH₂CH₃) and butylidyne (CCH₂CH₂CH₃) in (2 × 2), c(4 × 2) and ($\text{2}\text{3}\text{× 2}\text{3}\text{)R30°}$ arrangements are considered.     

Adsorbate-adsorbate interactions and the ordering of organic monolayers on metal surfaces

To study the ordering of molecules adsorbed on single-crystal substrates, a molecular cross-section (MCS) is defined, which measures the surface area occupied by each molecule. With this MCS, a two-dimensional packing coefficient C_2D is then defined for ordered arrays of adsorbed molecules. Values and trends for MCS and C_2D are discussed for known surface structures, especially for benzene adsorbed on metal surfaces. The packing is found to be generally less dense at surfaces than one would expect from comparison with packing in three-dimensional organic crystals. The Van der Waals packing energy and the repulsive dipole-dipole energy are also computed to study this issue. The lack of close-packing is attributed to the need to respect structural coincidence with the substrate and/or co-adsorption of small molecules like CO. These concepts are then applied to the prediction of the long-range order that a monolayer of adsorbed molecules may adopt: thereby possible adsorption structures can be defined, restricting the number of possibilities in a further structural determination.     

A full dynamical leed analysis of the NI(111) P(2 × 2)-C2H2 structure

The p(2 × 2) structure formed upon adsorption of acetylene on the Ni(111) surface, for 0.5 L exposure at 250 K, is studied by a full dynamical LEED analysis based on the comparison of only five I7ndash;V profiles at normal incidence. Among the several models tested, the most probable one is that with the adsorbed molecule parallel to the surface plane in a μ-bridging bonding site. The NiC distance is equal to 2.1 Å.     

3-(4-iodomethyl-2-oxo-1-azetidinyl)propynoic acidt-butyl ester: a new β-lactam derivative,synthesis of an ynamide by reaction of 4-iodomethylazetidin-2-one with the t-butyl ester of propiolic acid in the presence of copper(i)

The reaction of 4-iodomethylazetidin-2-one (2) with the t-butyl ester of propiolic acid (4) in the presence both of equimolar amounts of copper(I) and oxygen results unexpectedly in the fomation of the β-lactam ynamide 5. Its structure was suggested by spectroscopic data and confirmed by single-crystal X-ray analysis.     

Electrostatic Defromation Properties in the Crystal Structure of Tricyclo[4.4.1.01,6]undeca-2,4,7,9-tetraene-11,11-dicarbonitrile

The deformation density and potential have been determined in molecular crystals of tricyclo[4.4.1.0^1,6]ndeca-2,4,7,9-tetraene-11,11-dicarbonitrile at 150 K from X-ray diffraction measurements. A significant degformation density peak is found near the mid-poind of the the transannular bond. The four short bonds in the annuelene ring acquire slightly more residual density compared to the other bonds, confirming the bisnorcaradienic character of the molecule. Similar trends are noted in the deformation electrostatic potential maps.