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Sirtori, Italy

Paganelli S.,University of Venice | Piccolo O.,SCSOP | Pontini P.,University of Venice | Tassini R.,University of Venice | Rathod V.D.,University of Venice
Catalysis Today | Year: 2014

Rh(DHTANa) is a new water-soluble catalyst easily obtained by mixing in water the catalytic precursor [Rh(COD)Cl]2 and the dihydrothioctic acid sodium salt (DHTANa). This catalyst showed to be very active in the hydrogenation of unsaturated substrates as 2-cyclohexen-1-one, the biomass-derived furfural and acetophenone. In this last case the catalytic system obtained by using as water-soluble ligand (R)-(DHTANa) afforded (R)-1-phenylethanol with very modest enantioselectivity. Rh(DHTANa) was active also in the aqueous biphase hydroformylation of styrene producing exclusively the two corresponding aldehydes with 80-86% selectivity toward the branched aldehyde 2-phenylpropanal. This new catalytic system was easily recycled in both hydrogenation and hydroformylation processes and no leaching phenomenon was observed. © 2014 Elsevier B.V. All rights reserved.

Rathod V.D.,University of Venice | Paganelli S.,University of Venice | Piccolo O.,SCSOP
Catalysis Communications | Year: 2016

The use of water as co-solvent for biphasic reactions and of easily recyclable water-soluble catalysts are highly desirable for the realization of greener processes. The selective reduction of halo nitroarenes to the corresponding haloanilines is a very important industrial transformation for the production of agrochemicals, pigments, bactericides and pharmaceuticals and is not easy to obtain. The application of a water soluble catalyst, prepared by rhodium species and a cheap thioligand, in the hydrogenation of some halonitroarenes is here described. Excellent conversions, good recyclability of the catalytic species embedded in the aqueous phase and very high selectivity are demonstrated. © 2016 Elsevier B.V. All rights reserved.

Baldi F.,University of Venice | Marchetto D.,University of Venice | Paganelli S.,University of Venice | Piccolo O.,SCSOP
New Biotechnology | Year: 2011

Iron and palladium binding an exopolysaccharide (EPS) were obtained and purified from cultures of bacterial cells of Klebsiella oxytoca BAS-10. The strain BAS-10 was able to grow under anaerobic conditions with Fe(III)-citrate as energy and carbon source, producing Fe(III)-EPS that was extracted and used as catalyst in the oxidation reaction of phenol with H 2O 2. The same bacterial strain was cultivated anaerobically with Na-citrate and Pd 2(NO) 3 was added during the exponential growth to afford a Pd-EPS, named Bio-Pd (A), that, after isolation and purification, was used as catalyst in the reductive dehalogenation of chlorobenzene as model reaction. For comparison other two palladium binding polysaccharides were prepared: (a) a second type Pd-EPS, named Bio-Pd (B), was obtained by an exchange reaction with Pd acetate starting from an iron-free EPS produced by strain BAS-10 growing on Na-citrate medium; (b) a third type of palladium, named Bio-Pd (C), bound to a different polysaccharide, was recovered after the same exchange reaction applied on glycolipid emulsan obtained from an aerobic culture of Acinetobacter venetianus RAG 1. The superiority of Bio-Pd (A), as catalyst, vs Bio-Pd (B) and (C) was demonstrated. This approach to use microorganisms to prepare metal bound polysaccharides is novel and permits to prepare metal species, sequestrated in aqueous phase that can be useful either as catalysts for synthetic applications or to support the microbial biotransformation of pollutants. © 2011 Elsevier B.V.

Paganelli S.,University of Venice | Piccolo O.,SCSOP | Baldi F.,University of Venice | Tassini R.,University of Venice | And 2 more authors.
Applied Catalysis A: General | Year: 2013

A palladium species bound to an exopolysaccharide (Pd-EPS) was obtained from alive bacterial cells of Klebsiella oxytoca BAS-10 grown in static mode in the presence of Pd(NO3)2. Pd-EPS, after isolation and purification, was used as catalyst in the aqueous biphasic hydrogenation either of unfunctionalyzed olefins, as styrene, 1-octene and 1,3-diisopropenylbenzene, or of some α,β-unsaturated aldehydes. The catalytic system was very active under mild reaction conditions and its activity was maintained in some recycle experiments. Even more efficient was the "activated Pd-EPS", obtained by a pre-treatment of Pd-EPS with 1 MPa of H2 at 30 °C for 21 h; while Pd-EPS originally contains only Pd(II), as demonstrated by XPS measurements, the activated catalyst shows the presence of both Pd(II) and Pd(0) in the ratio 1.9/1. The two catalytic systems show different structures at TEM observations evidencing the transformation of electron ultradense nanoaggregates (Pd-EPS) into jagged microaggregates ("activated Pd-EPS"). © 2012 Elsevier B.V.

Arcon I.,University of Nova Gorica | Arcon I.,Jozef Stefan Institute | Piccolo O.,SCSOP | Paganelli S.,University of Venice | Baldi F.,University of Venice
BioMetals | Year: 2012

A strain of Klebsiella oxytoca, isolated from acid pyrite-mine drainage, characteristically produces a ferric hydrogel, consisting of branched heptasaccharide repeating units exopolysaccharide (EPS), with metal content of 36 wt%. The high content of iron in the EPS matrix cannot be explained by a simple ferric ion bond to the sugar skeleton. The bio-generated Fe-EPS is investigated by X-ray absorption spectroscopy. Fe K-edge XANES analysis shows that iron is mostly in trivalent form, with a nonnegligible amount of Fe 2+ in the structure. The Fe EXAFS results indicate that iron in the sample is in a mineralized form, prevalently in the form of nanosized particles of iron oxides/hydroxides, most probably a mixture of different nano-crystalline forms. TEM shows that these nanoparticles are located in the interior of the EPS matrix, as in ferritin. The strain produces Fe-EPS to modulate Fe-ions uptake from the cytoplasm to avoid iron toxicity under anaerobic conditions. This microbial material is potentially applicable as iron regulator. © Springer Science+Business Media, LLC. 2012.

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