Morita Invariance for Infinitesimal Deformations

Algebras and Representation Theory - Let A and B be two Morita equivalent finite dimensional associative algebras over a field ��. It is well known that Hochschild cohomology is...     

Pd-catalyzed regioselective hydroarylation of α-(2-aminoaryl)-α,β-ynones with organoboron derivatives as a tool for the synthesis of quinolines: experimental evidence and quantum-chemical calculations

The Pd-catalyzed hydroarylation of β-(2-aminoaryl)-α,β-ynones with organoboron derivatives, leading to 2,4-diarylquinolines in good to excellent yields through sequential cycloamination, has been investigated. The reaction is catalyzed by both Pd(II) and Pd(0) precatalysts, and can be carried out even under neutral conditions. The regiochemical outcome is inverted with respect to the Pd-catalyzed hydroarylation of β-(2-aminoaryl)-α,β-ynones with aryl iodides. This aspect has been rationalized using quantum-chemical calculations, which show significant differences between the energy barriers of the regioisomeric transition states for the migratory insertion (hydropalladation) step, and are consistent with the charge density of the π complex that undergoes such insertion.     

Constraints on the dynamical and chemical theories of the ?Ozone Hole?

Summary We report calculation results which could impose some constraints for the proposed chemical and dynamical theories on the ozone hole. One set of calculations is about the consistency between the observed optical thickness of polar stratospheric clouds (PSC) and the surface required for the heterogeneous reactions by the chemical theories. Assuming a reaction rate for ClNO₃+H₂O we find the sticking coefficient to be larger than 0.1 for consistency with observed PSC extinctions. The other set of calculations is about the perturbation to the residual circulation due to the presence of additional heating produced by PSCs. The perturbed residual circulation is of the opposite sign (i.e. downward) with respect to that necessary for the dynamical generation of an ozone hole.     

A safe and mild synthesis of organic carbonates from alkyl halides and tetrabutylammonium alkyl carbonates

A safe and mild procedure for the synthesis of mixed organic carbonates is described. Reaction of commercially available tetrabutylammonium methoxide and ethoxide with carbon dioxide yields the corresponding methyl and ethyl tetrabutylammonium carbonates (TBAMC and TBAEC). The reactions of these new compounds with several different alkyl halides give methyl and ethyl carbonates in high yields. The use of classic toxic and harmful chemicals such as phosgene and carbon monoxide is avoided.