A novel
water-dispersible magnetically recyclable Pd heterogeneous
catalyst, denoted as Pd-γ-Fe2O3-2-ATP-TEG-MME,
was initially synthesized and then characterized by diverse methods
such as FT-IR, TEM, TGA, XPS, VSM, ICP, and elemental analysis. The
new catalyst was utilized as a water-dispersible/magnetically separable
Pd heterogeneous catalyst for C–C cross-coupling reactions
including cyanation of aryl halides, fluoride-free Hiyama and Suzuki
reactions in neat water. By using this approach numerous arylcyanides
and biaryls were synthesized in good to high yields via the reaction
of aryl iodides, bromides, and chlorides (far more extensively available
and cheaper than aryl iodides and bromides) with K4[Fe(CN)6]·3H2O, triethoxyphenylsilane, or phenyl boronic
acid, respectively. The presence of triethylene glycol tags with hydrophilic
character on the Pd-complex supported on magnetic nanoparticles provides
dispersion of the catalyst particles in water, which leads to both
higher catalytic performance and also facile catalyst recovery and
reuse by successive extraction and final magnetic separation. Using
water as a green solvent, high turnover number (TON), facile catalyst
recovery and reuse, simple workup, and not requiring any additive
make this method an ecofriendly protocol for the C–C cross-coupling
reactions.