Towards green synthesis of organic carbonates: Utilization of CO2 as a chemical feedstock

La present Tesi doctoral es basa en l'ús de diòxid de carboni tant com a matèria prima per a la síntesi de carbonats cíclics i policarbonats d'alt valor afegit, com a dissolvent alternatiu. S'ha estudiat el potencial de diferents sistemes catalítics metàl·lics, destacant l'alta activitat i selectivitat; l'ús de condicions suaus i catalitzadors favorables per el medi ambient i, també, l'aclariment del mecanisme de reacció centrant-se en el paper de cada component catalític. S'ha descrit l'alt potencial catalític dels complexes amb baixa toxicitat i gran abundància terrestre com per exemple, els complexos d' Al(III) i Fe(III) amb lligands tetradentats N2O2; i els complexes de Zn(II) i Fe(III) amb lligands tridentats NN'O. A més, en el transcurs d'aquesta Tesi es va aconseguir l'obtenció de carbonat de metil oleat, derivat d'olis naturals, mitjançant els complexes d'Al(III), Zn(II) i Fe(III). D'altra banda, es van trobar que els complexes de Fe(III) són actius tant per l'epoxidació d'olefines i la síntesi de carbonats orgànics. Així mateix, es va realitzar un estudi preliminar sobre la carboxilació oxidativa de l'estirè per a l'obtenció de carbonat d'estirè utilitzant scCO2 tant com a reactiu i solvent amb un complex de Fe(III) amb lligand tridentat NN'O.La presente Tesis doctoral se centra en el uso de dióxido de carbono tanto como materia prima para la síntesis de carbonatos cíclicos y policarbonatos de alto valor añadido, como disolvente alternativo. Se ha estudiado el potencial catalítico de diferentes sistemas catalíticos metálicos, destacando la alta actividad y selectividad; el uso de condiciones suaves y catalizadores favorables para medio ambiente y, también, el esclarecimiento del mecanismo de reacción centrandose en el papel de cada componente catalítico. Se ha descrito el alto potencial catalítico de los complejos con baja toxicidad y gran abundancia terrestre como por ejemplo, los complejos de Al(III) y Fe(III) con ligandos tetradentados N2O2; y los complejos de Zn(II) y Fe(III) con ligandos tridentados NN'O. Además, en el transcurso de esta Tesis se logró la obtención de carbonato de metil oleato, derivado de aceites naturales, mediante los complejos de Al(III), Zn(II) y Fe(III). Por otra parte, se encontraron que los complejos de Fe(III) son activos tanto para la epoxidación de olefinas y la síntesis de carbonatos orgánicos. Asimismo, se realizó un estudio preliminar sobre la carboxilación oxidativa del estireno para la obtención de carbonato de estireno utilizando scCO2 tanto como reactivo y solvente con un complejo de Fe(III) con ligando tridentado NN'O.This doctoral Thesis was focused on the use of carbon dioxide as both C1 building block for the synthesis of useful cyclic carbonates and polycarbonates and its uses as a plausible alternative solvent. We studied the catalytic potential of different metal-catalyzed systems, highlighting the high catalytic activity and selectivity; the use of mild conditions and environmentally friendly metal catalysts and also the elucidation of the possible reaction mechanism giving a plausible catalytic role of each component. It was described the high potential of a low-toxic and earth-abundant Al(III) and Fe(III) complexes bearing tetradentate N2O2-donor ligand whereas the high activity of Zn(II) and Fe(III) complexes bearing tridentate NN'O-donor ligands. An important and greener goal of this Thesis was the obtention of methyl oleate carbonate, derived from natural oils, with those metal earth abundant Al(III), Zn(II) and Fe(III) complexes. Moreover, iron complexes were found to be active both for olefin epoxidation and organic carbonate synthesis. A preliminary study of direct oxidative carboxylation of styrene towards styrene carbonate using scCO2 as both reactive and solvent with Fe(III) complex bearing NN'O-donor ligand was undertaken

Complete mitochondrial DNA profile in stroke : A geographical matched case-control study in Spanish population

Altres ajuts: acords transformatius de la UABIntroduction: Stroke, the second leading cause of death worldwide, is a complex disease influenced by many risk factors among which we can find reactive oxygen species (ROS). Since mitochondria are the main producers of cellular ROS, nowadays studies are trying to elucidate the role of these organelles and its DNA (mtDNA) variation in stroke risk. The aim of the present study was to perform a comprehensive evaluation of the association between mtDNA mutations and mtDNA content and stroke risk. Material and methods: Homoplasmic and heteroplasmic mutations of the mtDNA were analysed in a case-controls study using 110 S cases and their corresponding control individuals. Mitochondrial DNA copy number (mtDNA-CN) was analysed in 73 of those case-control pairs. Results: Our results suggest that haplogroup V, specifically variants m.72C > T, m.4580G > A, m.15904C > T and m.16298 T > C have a protective role in relation to stroke risk. On the contrary, variants m.73A > G, m.11719G > A and m.14766C > T appear to be genetic risk factors for stroke. In this study, we found no statistically significant association between stroke risk and mitochondrial DNA copy number. Conclusions: These results demonstrate the possible role of mtDNA genetics on the pathogenesis of stroke, probably through alterations in mitochondrial ROS production

Halogenated meso-phenyl Mn(III) porphyrins as highly efficient catalysts for the synthesis of polycarbonates and cyclic carbonates using carbon dioxide and epoxides

12 meses embargo author can archive pre-print (ie pre-refereeing) author can archive post-print (ie final draft post-refereeing)Introduction of halogen electron withdrawing atoms (chloro and fluoro) in the ortho position of the aryl groups of meso-tetraphenylporphyrin manganese(III) complexes increased their activity as catalysts in the reaction of carbon dioxide with epoxides, when compared with the meso-tetraphenylporphyrin manganese(III) counterpart, even in the absence of co-catalysts. In the polymerization reaction of carbon dioxide and cyclohexene oxide, almost ten-fold increase of the TOF was observed when 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinatomanganese(III) acetate or 5,10,15,20-tetra(2,6 difluorophenyl)porphyrinatomanganese(III) acetate complexes were used as catalysts. Under similar conditions, when terminal epoxides were used as substrates, the selective cycloaddition of CO2 with styrene oxide, epichlorohydrin, propylene oxide, and 1,2-epoxytetradecane yielded exclusively the corresponding cyclic carbonates (conversion 54-98 %)

Highly active and selective Zn(II)-NN'O Schiff base catalysts for the cycloaddition of CO2 to epoxides

Mononuclear Zn(II) complexes with tridentate NN'O-donor base Schiff ligand N-(2- pyridyl)methyl-2-hydroxy-3,5-di-tert-butylbenzaldimine (1H) combined with a cocatalyst are active for the cycloaddition of CO2 and epoxides. They provide cyclic carbonates selectively even with the more hindered substrates such as cyclohexene oxide and methyl epoxyoleate. The best conditions were achieved running the reaction in expanded neat substrate in CO2 as reaction media. The activity obtained for the cycloaddition of CO2 to styrene oxide reached an initial TOF of 3733 h-1. The solid state structures of [Zn(1)2] and [Zn(1)(OAc)2]n were determined by X ray diffraction methods. Relative stability of the species in solution was analysed by DFT calculations

Chromium complexes with tridentate NN'O Schiff base ligands as catalysts for the coupling of CO2 and epoxides

10.1016/j.molcata.2013.11.026New Cr(III) hexacoordinated complexes with tridentate NN'O-donor Schiff base ligands, M(NN'O)2Cl, have been prepared. They form active catalytic systems for the coupling of epoxides and carbon dioxide in the presence of co-catalysts. Best results were obtained with the complex with N-(2-pyridylmethyl)-3,5-di-tert-butyl-salicylaldimine (1) ligand and a co-catalyst. Cyclohexene oxide reacts with carbon dioxide in the presence of these catalysts to form mixtures of polycarbonate (PC) (productivity up to ca. 900 g PC/g Cr) and cyclic carbonate depending on the co-catalyst and conditions employed. Cyclopentene, styrene and propylene oxides form selectively the cyclic carbonates at the conditions studied (epoxide conversion up to 97%). Although some of the co-catalysts are also active for the cycloaddition, the presence of both complex and co-catalyst has proved to be beneficial