Paula M. Uberman

Electrochemical synthesis of palladium nanoparticles in PVP solutions and their catalytic activity in Suzuki and Heck reactions in aqueous medium

Fil: Uberman, Paula Marina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones en Fisico-quimica de Cordoba. Universidad Nacional de Cordoba. Facultad de Ciencias Quimicas. Instituto de Investigaciones en Fisico-quimica de Cordoba; Argentina

Synthesis of biphenyl-based arsine ligands by Suzuki–Miyaura coupling and their application to Pd-catalyzed arsination

A versatile and efficient approach for the synthesis of new biphenyl-based arsine ligands, by a Pd-catalyzed arsination to introduce the -AsPh(2) moiety, and then a Suzuki-Miyaura cross-coupling for biaryl construction is reported. By Pd-catalyzed arsination with n-Bu(3)SnAsPh(2) (1), (2-bromophenyl)diphenylarsine (2, 83%) was obtained. The Suzuki-Miyaura reaction between the bromoarsine 2 and aryl boronic acids bearing different substituents provided biarylarsine ligands (80-99%). The efficiency of catalysts derived from the new biarylarsine ligands was evaluated in the Pd-catalyzed arsination with perfluoroalkyl iodides (R(f)I). Outstanding activities of catalysts derived from Pd/methoxybiarylarsine ligands were found in this coupling reaction affording perfluoroalkyl arsines in very good yields (57-100%).

PVP-Pd nanoparticles as efficient catalyst for nitroarene reduction under mild conditions in aqueous media

The catalytic activity of PVP-Pd nanoparticles synthesized by electrochemical methods was explored in nitroaromatic hydrogenation reaction. In this transformation, the colloidal nanocatalyst proved to have outstanding catalytic activity under sustainable reaction conditions. This mild process efficiently reduced the nitroaromatic group at room temperature, without high pressure of molecular hydrogen and in aqueous medium. Furthermore, several functional groups were tolerated, given the corresponding substituted arylamines in excellent yields and with high TOF. In addition, one-pot reactions and tandem process were explored, in which nitroaromatic hydrogenation reaction was included in the synthesis of modified amines. This methodology was effectively incorporated in tandem reactions and one-pot procedures, achieving N-arylamines functionalized in good isolated yields. Finally, comparison of sustainable chemistry metrics analysis demonstrated that this methodology is a reliable approach to perform the nitro compound hydrogenation process.

Synthesis, Characterization, and Nanocatalysis Application of Core–Shell Superparamagnetic Nanoparticles of Fe3O4@Pd

There is a wide number of different synthetic methods to obtain magnetite (Fe3O4) superparamagnetic nanoparticles (SPNPs). However, only a few are able to produce very small and well defined SPNPs with narrow size distribution. We report a modification of the metal-complex decomposition in organic media method in which we replace iron(iii) acetylacetonate (Fe(Acac)3) with an iron–urea complex (Fe-Urea) as metal source for the synthesis. With this modification we were able to obtain small particle sizes with a good control in size distribution. The Fe-Urea complex is easy to prepare with excellent yields. Core–shell nanoparticles are then prepared using palladium(ii) acetylacetonate as a Pd source, to obtain a Pd0 shell stabilised by oleylamine. The core–shell superparamagnetic nanoparticles of Fe3O4@Pd-OA are extensively characterized by FT-IR, powder X-ray diffraction, transmission electron microscopy, UV-vis, thermogravimetric analysis/differential scanning calorimetry, and magnetic susceptibility measurements, and tested in a palladium-catalyzed cross-coupling Suzuki–Miyaura reaction with promising results.

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

Aqueous Mizoroki–Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h−1). The advantages like operational simplicity, high robustness, efficiency and turnover frequency, the utilization of aqueous media and simple product work-up make this protocol a great option for stilbene syntheses by Mizoroki–Heck reaction.