Unprecedented Copper(II) Coordination Induced Nucleophilic Cleavage of Quinoxaline Heterocycle: Structural and Computational Studies

A straightforward catalyst-free synthetic approach has been developed for the synthesis of quinoxaline derivative, 4-phenyl-4-(pyridin-2-yl)-4,5-dihydropyrrolo[1,2-a]quinoxaline (L) by the reaction of 2-benzoyl pyridine and pyrrole-1-anillin in ethanol. The L in presence...

C-Terminally modified peptides via cleavage of the HMBA linker by O-, N- or S-nucleophiles

A direct and convenient method for the release of protected peptides with C-terminal modification from the HMBA linker by nucleophilic cleavage with amines, alcoholates or thiolates.

Thermal Treatment of Cerium Oxide and Its Properties: Adsorption Ability versus Degradation Efficiency

Cerium oxide belongs to the most important heterogeneous catalysts, but its applicability as so-called reactive sorbent for the degradation of toxic chemicals was only recently discovered. For these purposes, cerium oxide is prepared by precipitation of insoluble cerium salts (carbonates) with a subsequent thermal decomposition. Properties of cerium oxide prepared from the carbonate precursor are strongly affected by the temperature during the calcination. Main physicochemical properties of cerium oxide (specific surface area, crystallinity, and surface chemistry) were examined in dependence on the calcination temperature. As the adsorptive properties of CeO2are undoubtedly of great importance in the abovementioned applications, the adsorption ability was studied using an azo dye Acid Orange 7 (AO7) as a model compound. The highest sorption efficiency towards AO7 exhibited sorbents prepared at temperatures below 700°C, which was attributed mainly to the presence of hydroxyl groups on the oxide surface. A strong correlation was found between an adsorption efficiency of cerium oxides and their degradation efficiency for organophosphate pesticide parathion methyl. The >Ce–OH groups on the sorbent surface are responsible for the dye binding by the surface-complexation mechanism, and probably also for the nucleophilic cleavage of the P–O–aryl bond in the pesticide molecule.