Kinetic studies of copper-catalyzed homocoupling reactions of arylboronic acids in aqueous micellar media

The kinetic studies for copper-catalyzed homocoupling phenylboronic acids (1a-d) have been successfully carried out in an aqueous micellar medium under environmentally benign conditions (water as a solvent, micelle to help solubilize hydrophobic adducts) this study cetyl trimethyl ammonium bromide (CTAB ) is used surfactant produce micelle. Using different copper salts and complexes catalysts mild at temperature range (40-65˚C, air) without the addition of any additives (base, oxidant, ligands). reactions were followed using UV-Vis spectrophotometer absorbances measured maximum wavelengths biphenyl production each five selected (1a-d). observed rate constants (kobs) calculated pseudo-first-order equation unsubstituted 1a was optimization processes. experimental results showed good excellent curve fit (R2=0.9967-0.9998) origin software purpose. Among all catalysts, constant cupric acetate (Cu(OAc)2)is much higher than others, (kobs=0.1605 min-1), while CuCl2.2H2O has minimum constant, kobs=0.0216min-1. two [Cu(4-mba)2(tmeda)], [Cu(3-mba)2(H2O)2(tmeda)] require condition (85˚C) which other when reactant value kobs (0.0176, 0.0343 min-1) respectively, p-tolylboronic acid (1b) (0.0173, 0.0147 respectively.