A new class of easily accessible hemilabile benzimidazolyl phosphine ligands has been developed. The ligand skeleton is prepared from commercially available and inexpensive o-phenylenediamine and 2-bromobenzoic acid. With catalyst loading down to 0.5 mol% palladium, excellent catalytic activity towards the Suzuki-Miyaura coupling of aryl mesylates is still observed. This represents the lowest catalyst loading achieved so far for this reaction in general. X-Ray crystallography shows that new ligand L2 is coordinated with Pd in a κ(2)-P,N fashion.
The use of microorganisms in biosorption is one of the most promising ways to remove trace amounts of heavy metal ions. Nevertheless, the enhancement of the successful removal of heavy metal ions by using different combinations of biosorbents is not generally guaranteed which leaves room to explore the application of the technique. In this study, the performance of free and immobilized forms of a yeast strain, Candida krusei (C. krusei), and calcium alginate (CaAlg) are evaluated for their ability to remove copper(II). Infrared spectroscopy, studies on the effects of pH and temperature, and kinetics and isotherm modelling are carried out to evaluate the biosorption. The infrared spectroscopy shows that the primary biosorption sites on the biosorbents are carboxylate groups. In addition, a higher pH and higher temperatures promote biosorption while a decline in biosorption ability is observed for C. krusei at 50 °C. The kinetics study shows that C. krusei, CaAlg and immobilized C. krusei (MCaAlg) conform with good correlation to pseudo-second order kinetics. MCaAlg and CaAlg fit well to the Langmuir isotherm while C. krusei fits well to the Temkin isotherm. From the experimental data, encapsulating C. krusei showed improved biosoprtion and address clogging in practical applications.
A new class of easily accessible hemilabile benzimidazolyl phosphine ligands showing excellent catalytic activity in the Suzuki—Miyaura coupling of aryl mesylates at catalyst loadings as low as 0.5 mol% is presented.
P,N-Type Benzimidazolyl Phosphine Ligands for the Palladium-Catalyzed Suzuki Coupling of Potassium Aryltrifluoroborates and Aryl Chlorides. -A P,N-type benzimidazolyl phosphine proves to be an efficient ligand for the Pd-catalyzed Suzuki coupling of aryltrifluoroborates and aryl chlorides. -(WONG, S. M.; SO*, C. M.; CHUNG, K. H.; LUK, C. H.; LAU, C. P.; KWONG*, F. Y.; Tetrahedron Lett. 53 (2012) 29, 3754-3757, http://dx.
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