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Selective reduction of halo-nitro aromatic compounds using [Rh]/DHTANa as catalyst in an aqueous bi-phase system
Full text linkThe 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 demonstrate
Synthesis of fine chemicals, such as pharmaceuticals, agrochemicals, fragrances by using catalytic reactions under homogeneous, heterogeneous and biphasic reaction conditions
No full textThe aim of this thesis work was the synthesis, characterization and application of new catalysts to be used in reactions as hydrogenation, Heck reaction, Friedel-Crafts acylations, etc., in homogeneous or heterogeneous and/or in biphase systems. These reactions were applied first on model substrates and then for the synthesis of target pharmaceuticals and for fine chemicals intermediate. In particular it was studied the hydrogenation of carbon-carbon double bonds catalyzed by: 1) new heterogeneous catalysts with a low content of precious metal (Pd 0.28%, Rh 0.18%) on alumina: these catalysts were very easily prepared in a new greener solvent and showed a very high activity and selectivity; 2) Rhodium and Palladium catalysts, with suitable ligands (in particular polysaccharides and lactic acid derivatives), able to operate in both aqueous biphasic or homogeneous system. Heck reactions were carried out in homogeneous system by using palladium based catalysts in the presence or absence of suitable phosphino ligands; Friedel-Crafts acylations of heterocyclic compounds were studied by using different metal catalysts, in particular new iron and gallium polymeric fluorosulphonate, easily prepared by a convenient protocol. Most of these reactions were applied for the synthesis of the two target pharmaceuticals, the calcimimetic Cinacalcet and the antimigrane Eletriptan. Finally, some reactions for the synthesis of Cinacalcet were carried out under microwaves conditions in order to reduce the catalyst amount, the reaction time and to increase the chemical yield. Moreover, these reactions were carried out in more environmentally friendly solvents as Me-THF, CPME and -valerolactone. When possible the activity of these new catalysts was compared to that of commercially available catalyst and in some cases they showed better performances with respect to largely applied industrial catalysts, appearing so suitable for a possible commercial development
Some Valuable Pharmaceutical Intermediates by Pd Catalyzed Heck and Hydrogenation Processes
Full text linkHydroformylation of 4-vinylpyridine catalyzed by rhodium complexes in homogeneous or in aqueous biphasic system
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Aqueous-phase hydrogenation and hydroformylation reactions catalyzed by a new water-soluble [rhodium]-thioligand complex
No full textRh(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
Novel iron and gallium salts of Aquivion® PFSA: synthesis, characterization and some catalytic applications
No full textThe 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
Aqueous-phase hydrogenation and hydroformylation reactions catalyzed by water-soluble [Rh]-thioligand complexes
No full textHeterogeneous Home-made Catalysts with a Low Content of Precious Metals and their Application in the Synthesis of Fine Chemicals
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