TPPTS

Abstract: Sterically demanding, water-soluble alkylphosphines have been used in combination with various palladium salts in Suzuki, Sonogashira, and Heck couplings of aryl bromides under mild conditions in aqueous solvents. The tert-butyl-substituted ligands 2-(di-tert-butylphosphino)ethyltrimethylammonium chloride (t-Bu-Amphos) and 4-(di-tert-butylphosphino)-N,N-dimethylpiperidinium chloride (t-Bu-Pip-phos) in combination with palladium(II) salts were found to give catalysts that were significantly more active than catalysts derived from tri(3-sulfonatophenyl)phosphine trisodium (TPPTS). Suzuki couplings of unactivated aryl bromides occurred efficiently at room temperature in water/acetonitrile and water/toluene biphasic mixtures or in neat water. Notably, Suzuki couplings of hydrophilic aryl bromides gave high yields without using organic solvents for the reaction or purification. This methodology has been applied to a highly efficient synthesis of diflunisal. The catalyst derived from t-Bu-Amphos was recycled th...

Abstract: A homogenous catalytic system has been developed that efficiently and selectively decomposes formic acid into hydrogen and carbon dioxide. [Ru(H2O)6]2+, [Ru(H2O)6]3+ and RuCl3·xH2O are all excellent precatalysts in presence of TPPTS (TPPTS=meta-trisulfonated triphenylphosphine), the formic acid decomposition taking place in the aqueous phase, under mild conditions and over a large range of pressures. Optimisation of the reaction conditions is described together with a detailed mechanistic study leading to a tentative catalytic cycle. The performance of the catalytic system for continuous hydrogen generation is presented. Overall, the method proposed overcomes the limitations of other catalysts for the decomposition of formic acid making it a viable hydrogen-storage material.