Chemoselective oxidation of phenoxathiin-based thiacalix[4]arene and the stereoselective alkylation of products

Phenoxathiin-based thiacalix[4]arene was subjected to exhaustive oxidation. Depending on the reaction conditions, the macrocyclic systems bearing four sulfonyl groups or three sulfonyl and one sulfoxide group are available in high yields.

Voltammetry of Suspensions of Polyaniline-coated Graphene Composites

Flaky particles of polyaniline (PANI)-graphene (GN) with rectangular size of 1.0-1.5 mm are dispersed in aqueous solution so that their suspension is stable for one day without aggregation. The weight fraction of PANI in the particle is 75 %, which is independent of the loaded fraction of PANI in the synthesis. The PANI-GN film made of the suspension forms a self-standing, elastic, conductive film. The PANI-GN suspension exhibits both the reduction and the oxidation waves at potentials similar to those of PANI adsorbed on an electrode, whereas the PANI-GO suspension shows only the voltammetric reduction wave. The redox peak currents are controlled by diffusion of PANI-GN flakes. The PANI-GN film cast on the electrode shows voltammetric peaks for PANI, of which redox charge is larger than that of the electrochemically polymerized PANI film with the common weight of PANI. This fact can be explained in terms of the electrochemically exhaustive oxidation of PANI through the electric conduction of GN.

Photooxidation at Platinum Colloidal TiO2 Aqueous-Solution Interfaces. I. Ethylenediaminetetraacetic Acid and Related-Compounds

The photooxidation of ethylenediaminetetraacetic acid ( edta ) and related glycine derivatives, at Pt/TiO2/aqueous solution interfaces, has been monitored via the production of hydrogen and carbon dioxide. Yields are consistent with the exhaustive oxidation of methoxycarbonyl groups and the rate varied with the number and distribution of such groups. A photooxidation pathway is proposed which involves the oxidation of intermediate carbonium ions. Plausible molecular intermediates, such as formic acid and formaldehyde in the case of edta , have been shown in separate experiments to be photooxidized according to the proposed pathway. The maximum rate of oxidation for each donor depends on its oxidation potential and its tendency to adsorb on TiO2 surfaces. Desorption due to pH increase, as well as consumption of the donor, causes the rate to decline rapidly with illumination time. Acetic and malonic acids gave some hydrogen but underwent mainly (> c. 80%) photo-Kolbe decarboxylation to yield carbon dioxide and methane. By contrast the oxidation of oxomalonic, pyruvic and lactic acids proceeded mainly via a H2 producing pathway similar to that established for edta. The oxidation of pyruvic and lactic acids ceased at a yield of one mole of CO2 per mole of acid.