A new rapid and versatile approach using Ionic Liquid/DMSO as a chemical reagent for the synthesis of fused heterocyclic compounds in a highly efficient way is described. This method offers the advantages of proceeding in neutral conditions, giving high to excellent isolated yields (83-92%) for Niementowski synthesis with easy workup procedure. The inherent Bronsted acidity of ionic liquid and ...

Rotation about the C-N bond in amides can be catalyzed by Bronsted and Lewis acids, as well as nucleophiles and bases. Catalysis of amide isomerization occurs in biological systems via "rotamase" enzymes; however, the mechanisms by which these proteins operate are not completely understood. We outline investigations that provide experimental support for mechanisms believed to be feasible for th...

The bell-shaped pH rate profile for the reaction of tetrahydrofolic acid with formaldehyde to form 5, lo-methylene tetrahydrofolic acid has been shown to result from a change in rate-determining step with changing acidity. In alkaline solution, the rate-determining step is the acid-catalyzed dehydration of hydroxymethyl tetrahydrofolic acid and its conjugate base. This step is subject to genera...

Protic ionic liquids (PILs) are currently being shown to be as interesting and valuable to chemical manipulations as the well-known aprotic ionic liquids (APIL). PILs have the additional advantage that the proton activity (PA) can be adjusted by the choice of Bronsted base and Bronsted acid used in their formation. In the absence of solvent, the PA plays the role of pH in ordinary solutions. Pr...

The adsorption of pyridine on a complete monolayer molybdenum oxide-Al203 catalyst was studied. Both Lewis and Bronsted acid sites are present on a catalyst with a Mo valence of -4.1. The orientation of adsorbed pyridine was studied by means of its interaction with surface OD groups, which leads to the formation of only 2-deuteriopyridine. The fraction of molybdenum ions active for hydrogenatio...

In this study, three raw Brazilian clays from Joao Pessoa, Paraiba State (Aco AP, AVL and Verde Lodo) were characterized before after purification acid activation. Several instrumental techniques used, the classified as dioctahedral smectites with different compositions, where sample had highest content of montmorillonite. addition, analyses showed modification in clay mineral mainly due to rem...

Methyl benzoate (MB) compounds are prepared by reacting various benzoic acids with methanol using an acidic catalyst. In this study, the solid of zirconium metal solids fixed substances were studied. We determined that catalysts Ti had best activity. The catalytic synthesis a series MB titanium was direct condensation acid and metallic Lewis without other auxiliary Bronsted is reported for firs...

a water soluble, bronsted acid, 5-sulfosalicylic acid as an efficient organocatalyst was used for the synthesis of physiologically active 2-substituted benzimidazole derivatives from o-phenylenediamine and aromatic aldehydes in ethanol at reflux condition. cost-effectiveness, use of non-hazardous solvents, metal free and commercially available catalyst, single-step, environmentally friendly gre...

according to the bronsted definition, any compound which has a hydrogen atom is an acid, since itmay be lost as a proton. a thermodynamical cycle is proposed to calculate absolute pka values forbronsted acids in aqueous solution. the equilibrium of dissociation of a bronsted acid depends onthe interaction of the acid and its conjugate base with solvent molecules. there fore the pka valuedepends...

2,5 hexadione is produced from cellulose using ZrW in the presence of hydrogen while lactic acid is the main product in helium atmosphere. FTIR and kinetics studies strengthened the proposed mechanism which involves as important elementary steps hydroxyls abstractions and hydride transfers promoted by the Lewis acid sites of ZrW. Moreover the important increase of cellulose conversion in the pr...