Aqueous biphasic treatment of some nitrocompounds with hydrogen in the presence of a biogenerated Pd-polysaccharide

A strain of Klebsiella oxytoca BAS-10, known to produce a specific exopolysaccharide (EPS), when grown aerobically in static mode in the presence of Pd(NO3)(2), generated the species Pd-EPS that was used as catalyst precursor in the aqueous biphasic treatment of some nitrocompounds with hydrogen. Nitrobenzene was hydrogenated to aniline with almost quantitative yields and the catalyst, embedded in the aqueous phase, was used with success and with near the same efficiency in three recycling experiments. In the case of 1-iodo-4-nitrobenzene only nitrobenzene was obtained while the unsaturated nitro compound beta-methyl-beta-nitrostyrene afforded both the corresponding oxime and the saturated nitro derivative

Hydrodechlorination of Aroclor 1260 in aqueous two-phase mixture catalyzed by biogenerated bimetallic catalysts

The PCBs are known recalcitrant and toxic pollutants and significant values of contamination could be found in water. PCBs can be hydrodechlorinated using Pd-based catalysts and hydrogen, but the research to identify more efficient heterogeneous catalysts, able to work in an aqueous phase, less sensible to deactivation and easily removable at the end of the treatment, remains a considerable interesting goal. A strain of Klebsiella oxytoca, DSM 29614, known to produce a specific exopolysaccaride (EPS), was grown in different media with sodium citrate or with sodium citrate plus ferric citrate, as sole energy and carbon sources under anaerobic conditions. The cultures were amended with 50 mg of palladium as Pd(NO3)2 to generate Pd-EPS (Pd content 13%) or FePd-EPS (Pd content 8.4%; Fe 7.4%) species which were secreted from the cells, isolated by treatment with a cold ethanol solution (70%) and dried under vacuum as powders. The catalytic ability of these mono- and bi-metallic species was tested in the hydrodechlorination reaction of the Aroclor 1260 PCBs mixture under aqueous biphasic conditions. Here we demonstrate that the degree of PCBs hydrodechlorination is dependent by the nature of catalyst and of base used to neutralize HCl produced, the bimetallic species being more active and an organic base resulting more effective. Working with a substrate/catalyst 8/1 molar ratio, at 3 MPa H2 and 60°C in 20 h a significant removal of highly chl orinated PCBs was obtained under the best conditions. The result seems promising for remediation of groundwater contaminated with PCBs

A new biogenerated Rh-based catalyst for aqueous biphasic hydroformylation

A new bio-generated rhodium based system embedded in a peculiar polysaccharide matrix (Rh-EPS), was obtained and purified from cultures of bacterial cells of Klebsiella oxytoca DSM 29614. The product was analyzed with different techniques to obtain information on its structure-property correlation. In order to determine its catalytic activity and selectivity in the aqueous biphasic hydroformylation some olefins were chosen as model substrates, obtaining fine-good results.A new bio-generated rhodium based system embedded in a peculiar polysaccharide matrix (Rh-EPS), was obtained and purified from cultures of bacterial cells of Klebsiella oxytoca DSM 29614. The product was analyzed with different techniques to obtain information on its structure-property correlation. In order to determine its catalytic activity and selectivity in the aqueous biphasic hydroformylation some olefins were chosen as model substrates, obtaining fine-good results

Studio di sistemi catalitici innovativi per la sintesi di prodotti della chimica fine

The aim of this work of thesis was the synthesis, characterization and use of new catalytic species in different types of reactions, on both model substrates and in the preparation of some fine chemicals. These new catalytic species were then designed, prepared and characterized in collaboration with some Italian and foreign research laboratories. The new catalytic species obtained during this work of thesis are: a) heterogeneous catalysts (Pd-, Pt- and Rh-based) supported on alumina, characterized by very low contents of precious metal (from 0.18 up to 0.28%), easy preparation and high activity and selectivity; b) Pd and Rh nanostructured bio-generated catalysts, eventually in the co-presence of ferric oxide, embedded in a polysaccharidic matrix and active in aqueous or in organic solvent-water biphasic system. These new catalytic species were obtained, in collaboration with the microbiology laboratory of the DSMN of Ca' Foscari, by using a strain of Klebsiella oxytoca BAS-10 which is capable to produce a particular exopolysaccharide (EPS) able to bind metal nanoparticles if an appropriate metal salt is added during the stationary growth phase of the microorganism; c) Lewis acids heterogeneous catalysts obtained by a simple and innovative method by using a perfluorosulphonate ionomer (Aquivion®) d) a water-soluble and recyclable Rh based catalyst obtained by employing a cheap bis-thiol ligand; e) a biocatalyst able to selectively reduce carboxylic acids to the corresponding aldehydes. This biocatalyst was prepared by fermentation of an engineered microorganism and subsequently purified. This work was carried out during a three month stage in a biotechnological company in Scotland The main and most significant studied reactions in this project were: hydrogenation of carbon-carbon double bonds, reduction of some functional groups, hydrodehalogenation, carbonylation, hydroformylation, Friedel-Crafts alkylations and acylations and other acid-catalyzed reactions. The reactions were carried out both on model substrates and on molecules of industrial interest. The studied catalytic processes were employed to obtain some industrial products such as aldehydic and ketonic fragrances (HelionalTM and LioralTM, 5-isopropylthiophene-2-carbaldehyde, 2-propionyl-5-ethylthiophene, 3-phenylpropanal) , flavours (5-ethylthiophene-2-carbaldehyde), drugs and intermediates for drugs (Nabumetone®, m-chloroaniline), intermediates for agrochemicals (beta-keto-aryl esters) and intermediates for bulk chemicals such as cyclohexanone. The performances of these new catalytic species were compared to those of commercial catalysts and, very interestingly, in some cases, these new homemade catalysts showed higher activity and selectivity. Basing on the results obtained we can assert that the strategies developed during this research work appear suitable for a possible commercial development

Novel iron and gallium salts of Aquivion (R) PFSA: Synthesis, characterization and some catalytic applications

The objective of this study was to prepare, characterize and test the catalytic properties of iron and gallium salts of Aquivion (R) PFSA (hereinafter Aquivion-H). The samples were characterized by the determination of metal loading in fresh and used materials, ATR-FTIR, and thermogravimetric analysis (TG-DSC). The salts were screened in Friedel-Crafts acylation of some heterocyclic compounds and compared with some homogeneous and heterogeneous Lewis acids as well as with pure Aquivion-H. These new salts revealed efficient catalytic activity and recyclability. (C) 2015 Elsevier B.V. All rights reserved