This paper presents synthesis of Pd–NHC-γ-Fe2O3-n-butyl-SO3H and its activity as bifunctional heterogeneous nanocatalyst containing Pd–NHC and acidic functional groups.

A novel base-metal multifunctional nanomagnetic catalyst is prepared by the immobilization of tungstate anions onto γ-Fe2O3 supported with imidazolium moieties. The (γ-Fe2O3-Im-Py)2WO4 was fully characterized using FT-IR, XPS, TEM, FESEM, ICP, TGA, VSM and XRD and used as a multifunctional heterogeneous catalyst for the synthesis of 2-amino-3-cyano-4H-chromenes via a multicomponent tandem oxidation process starting from alcohols under solvent-free conditions. During this process, tungstate catalyzes the oxidation of a wide range of alcohols in the presence of TBHP as a clean source. The in-situ formed aldehydes are condensed with malononitrile and β-dicarbonyl compounds/naphthols/4-hydroxycumarin through promotion by pyridine and imidazolium moieties of the catalyst. By this method, a variety of 2-amino-3-cyano-4H-chromenes are generated in good to high yields from alcohols as inexpensive and easily available starting materials. The catalyst is recovered easily by the aid of an external magnetic field and reused in five successive runs with insignificant decreasing activity.

Pd-N-heterocyclic carbene complex immobilized on magnetic nanoparticles is synthesized and characterized by different techniques such as FT-IR, XPS, TEM, EDX, FESEM, VSM, TGA and ICP. The synthesized catalyst was used as a new water dispersible heterogeneous catalyst in the fluoride-free Hiyama, Suzuki and cyanation reactions in pure water. By this method, different types of biaryls and aryl nitriles were synthesized in good to high yields by the reaction of a variety of aryl iodides, bromides and chlorides with triethoxyphenylsilane, phenylboronic acid and K 4 [Fe(CN) 6 ]•3H 2 O, respectively. The presence of sulfonates as hydrophilic groups on the surface of the catalyst offers a highly water dispersible, active and yet magnetically recoverable Pd catalyst. The possibility to perform the reaction in water as a green medium, easy catalyst recovery and reuse by successive extraction and final magnetic separation, and the absence of any additives or co-solvents make this method as an eco-friendly and economical protocol for the synthesis of biaryl derivatives and aryl nitriles.

No abstract