A CoCl 2 ?6H 2 O/cationic 2,2'-bipyridyl system was proven to be an efficient and reusable catalyst for the coupling of aryl halides with thiols in water under aerobic conditions, leading to the formation of thioethers. Aryl iodides and bromides could couple with various thiols giving the corresponding thioethers using only a 3 mol% catalyst loading in the presence of 1 equiv KOH and 1.5 equiv Zn at 100 uC. For aryl chlorides, reaction at 140 uC and prolongation of the reaction time was performed. After reaction, the residual aqueous solution could be reused several times without any additional treatment and regeneration, making this cobalt-catalyzed S-arylation reaction greener.

Efficient and selective aqueous-phase hydrogenation of phenol by a novel Pd catalyst supported on dually and selectively functionalized mesoporous MMT-1 silica nanoparticles has been developed. The catalyst features small (~1.1 nm) Pd nanoparticles surrounded by unevenly distributed nitrogen-or heteroatom-free organic groups in the helical mesopores and the presence of non-hydrogen-bonded isolated silanol groups on mesopore surface. The catalyst exhibited superior conversion of phenol and high selectivity of cyclohexanone at room temperature under atmospheric pressure of hydrogen and remained highly active after ten catalytic runs. The catalyst was active for the aqueous-phase hydrogenation of a variety of mono-and dihydroxylated aromatic compounds. The green protocol with the designed catalyst would be practical for the hydrogenation of phenol and other derivatives.

A water-soluble and air-stable Pd(NH3)2Cl2/cationic 2,2’-bipyridyl system was found to be a highly-efficient and reusable catalyst for the coupling of aryl iodides and alkenes in neat water using Bu3N as a base. The reaction was conducted at 140 °C in a sealed tube in air with a catalyst loading as low as 0.0001 mol % for the coupling of activated aryl iodides with butyl and ethyl acrylates, providing the corresponding products in good to excellent yields with very high turnover numbers. In the case of styrene, Mizoroki-Heck coupling products were obtained in good to high yields by using a greater catalyst loading (1 mol %) and TBAB as a phase-transfer agent. After extraction, the residual aqueous solution could be reused several times with only a slight decrease in its activity, making the Mizoroki-Heck reaction “greener”.

Functionalized SBA-15-supported Pd catalysts were prepared as efficient and recyclable catalysts for ligand-free Hiyama cross-coupling under relatively mild reaction conditions.

A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.

A reusable CuSO 4 · 5H 2 O/cationic 2,2 -bipyridyl system catalyzed the homocoupling reaction of terminal alkynes in water using I 2 as the additive in the presence or absence of tetrabutylammonium bromide, giving the 1,3-diynes in good to high yields. After reaction, the residual aqueous solution could be reused several times.

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A reusable Pd(NH 3 ) 2 Cl 2 /cationic 2,2 -bipyridyl system for the catalysis of the conjugate addition of arylboronic acids to α,β-unsaturated enones in water under air was developed. Addition of arylboronic acids to both cyclic and acyclic enones progressed smoothly, providing the products in good to high yields, the best result being obtained when HBF 4 was used to adjust the pH value to 1.0. After the reaction, the residual aqueous solution could be reused several times, making the reaction greener and reducing wastage of precious metals.