title: Mechanistic studies of magnetically recyclable Pd - Fe3O4 heterodimeric nanocrystal-catalyzed organic reactions.
abstract: Recently, we have reported several catalytic applications of new Pd - Fe3 O4 heterodimeric nanocrystals as magnetically separable catalysts. Successful applications of the nanocrystals towards various useful organic reactions such as Suzuki, Heck, and Sonogashira coupling reactions, direct C - H arylation, and Wacker oxidation have been recorded. However, detailed mechanistic courses of the reactions have not been delineated, and it was not clear whether these processes proceeded through a homogeneous or heterogeneous mechanism. Here, we report detailed mechanistic investigations of the reactions employing the Pd - Fe3 O4 nanoparticle catalysts. Suzuki coupling and Wacker oxidation reactions were chosen as two representative heterogeneous reactions employing the Pd - Fe3 O4 catalysts, and general kinetic studies, hot filtration tests, and three-phase tests were carried out for the two reactions. The studies showed that the reactions most probably proceed via a solution-phase mechanism.
authors.affiliation: Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747 (Korea), Fax: (+82) 2-872-7505.
authors.forename: Sangmoon
authors.initials: S
authors.lastname: Byun
authors.forename: Jooyoung
authors.initials: J
authors.lastname: Chung
authors.forename: Jungmin
authors.initials: J
authors.lastname: Kwon
authors.forename: B
authors.initials: B
authors.lastname: Moon Kim
keywords: Pd-Fe3O4 nanocrystals; heterogeneous catalysis; homogeneous catalysis; nanoparticles; reaction mechanisms