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Arlegui Chamizo Aitor - One of the best experts on this subject based on the ideXlab platform.
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Organocatálisis y transferencia de quiralidad mediante porfirinas autoensamblantes solubles en agua
'Edicions de la Universitat de Barcelona', 2019Co-Authors: Arlegui Chamizo AitorAbstract:[spa] La quiralidad es una propiedad fundamental de la naturaleza. La vida en la Tierra se basa en la quiralidad. Casi todos los compuestos quirales presentes en los organismos vivos se encuentran solo en una de sus formas enantioméricas; el origen de este fenómeno, conocido como Homoquiralidad Biológica, sigue siendo uno de los misterios aún no resueltos por la Ciencia. La emergencia directa de la quiralidad de las biomoléculas esenciales mediante Síntesis Asimétrica Absoluta en el curso de la evolución química prebiótica parece improbable, debido a las importantes restricciones de autocatálisis enantioselectiva e inhibición mutua que presentan los sistemas involucrados (F.C. Frank, 1953). La reacción de Soai es hasta el momento el único ejemplo de reacción conocida que conduce a productos enantioenriquecidos a partir de reactivos aquirales en ausencia de ningún tipo de inducción quiral externa. Por el contrario, la emergencia de quiralidad neta mediante Ruptura Espontánea de Simetría Especular es mucho más común a una escala jerárquica superior, por ejemplo, en procesos de autoensamblaje a partir de unidades aquirales, como sucede en el caso de ciertas porfirinas capaces de formar agregados supramoleculares quirales. En la presente Tesis Doctoral se ha estudiado la posibilidad de transferir la quiralidad que presentan los J-agregados de las porfirinas tetraarilsulfonadas TPPS4 y TPPS3, generada mediante Ruptura Espontánea de Simetría Especular, a reacciones organocatalizadas por aminas secundarias cíclicas vía ion iminio en agua o en medio acuoso, mediante un proceso que hemos denominado Catálisis Asimétrica Absoluta (Absolute Asymmetric Catalysis). Se ha comprobado la posibilidad de transferencia de quiralidad en la reacción de Diels-Alder. Además, se han sintetizado una serie de porfirinas arilsulfonadas meso-sustituidas con una amina secundaria cíclica en su estructura, con el fin de ser utilizadas como organocatalizadores en reacciones aldólicas y de Michael en agua o medio acuoso.[eng] Chirality is a fundamental property of nature. Life on Earth is based on chirality. Almost all chiral compounds present in living organisms are found only in one of their enantiomeric forms; the origin of this phenomenon, known as Biological Homoquirality, remains one of the mysteries not yet solved by Science. The direct emergence of chirality of essential biomolecules by Absolute Asymmetric Synthesis in the course of prebiotic chemical evolution seems unlikely, due to the important restrictions of enantioselective autocatalysis and mutual inhibition presented by the systems involved (F.C. Frank, 1953). Soai's Reaction is so far the only known Reaction Example that leads to enantioenriched products from achiral reagents in the absence of any type of external chiral induction. On the contrary, the emergence of net chirality by Spontaneous Mirror Symmetry Breaking is much more common at a higher hierarchical scale, for Example, in self-assembly processes from aquiral units, as in the case of certain porphyrins capable of forming supramolecular chiral aggregates. In the present PhD thesis the possibility of transferring the macromolecular chirality of the J-aggregates of the tetraphenylsuphonated porphyrins TPPS4 and TPPS3, generated by Spontaneous Mirror Symmetry Breaking, to organocatalyzed Reactions by cyclic secondary amines via iminium ion in water or aqueous medium has been studied, through a process that we have called Absolute Asymmetric Catalysis. It is proved de possibility of transferring the chirality in the Diels-Alder Reaction. In addition, a series of meso-substituted arylsulphonated porphyrins have been synthesized with a cyclic secondary amine in their structure, in order to be used as organocatalysts in aldolic and Michael's Reactions in water or aqueous medium
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Organocatálisis y transferencia de quiralidad mediante porfirinas autoensamblantes solubles en agua
'Edicions de la Universitat de Barcelona', 2019Co-Authors: Arlegui Chamizo AitorAbstract:La quiralidad es una propiedad fundamental de la naturaleza. La vida en la Tierra se basa en la quiralidad. Casi todos los compuestos quirales presentes en los organismos vivos se encuentran solo en una de sus formas enantioméricas; el origen de este fenómeno, conocido como Homoquiralidad Biológica, sigue siendo uno de los misterios aún no resueltos por la Ciencia. La emergencia directa de la quiralidad de las biomoléculas esenciales mediante Síntesis Asimétrica Absoluta en el curso de la evolución química prebiótica parece improbable, debido a las importantes restricciones de autocatálisis enantioselectiva e inhibición mutua que presentan los sistemas involucrados (F.C. Frank, 1953). La reacción de Soai es hasta el momento el único ejemplo de reacción conocida que conduce a productos enantioenriquecidos a partir de reactivos aquirales en ausencia de ningún tipo de inducción quiral externa. Por el contrario, la emergencia de quiralidad neta mediante Ruptura Espontánea de Simetría Especular es mucho más común a una escala jerárquica superior, por ejemplo, en procesos de autoensamblaje a partir de unidades aquirales, como sucede en el caso de ciertas porfirinas capaces de formar agregados supramoleculares quirales. En la presente Tesis Doctoral se ha estudiado la posibilidad de transferir la quiralidad que presentan los J-agregados de las porfirinas tetraarilsulfonadas TPPS4 y TPPS3, generada mediante Ruptura Espontánea de Simetría Especular, a reacciones organocatalizadas por aminas secundarias cíclicas vía ion iminio en agua o en medio acuoso, mediante un proceso que hemos denominado Catálisis Asimétrica Absoluta (Absolute Asymmetric Catalysis). Se ha comprobado la posibilidad de transferencia de quiralidad en la reacción de Diels-Alder. Además, se han sintetizado una serie de porfirinas arilsulfonadas meso-sustituidas con una amina secundaria cíclica en su estructura, con el fin de ser utilizadas como organocatalizadores en reacciones aldólicas y de Michael en agua o medio acuoso.Chirality is a fundamental property of nature. Life on Earth is based on chirality. Almost all chiral compounds present in living organisms are found only in one of their enantiomeric forms; the origin of this phenomenon, known as Biological Homoquirality, remains one of the mysteries not yet solved by Science. The direct emergence of chirality of essential biomolecules by Absolute Asymmetric Synthesis in the course of prebiotic chemical evolution seems unlikely, due to the important restrictions of enantioselective autocatalysis and mutual inhibition presented by the systems involved (F.C. Frank, 1953). Soai's Reaction is so far the only known Reaction Example that leads to enantioenriched products from achiral reagents in the absence of any type of external chiral induction. On the contrary, the emergence of net chirality by Spontaneous Mirror Symmetry Breaking is much more common at a higher hierarchical scale, for Example, in self-assembly processes from aquiral units, as in the case of certain porphyrins capable of forming supramolecular chiral aggregates. In the present PhD thesis the possibility of transferring the macromolecular chirality of the J-aggregates of the tetraphenylsuphonated porphyrins TPPS4 and TPPS3, generated by Spontaneous Mirror Symmetry Breaking, to organocatalyzed Reactions by cyclic secondary amines via iminium ion in water or aqueous medium has been studied, through a process that we have called Absolute Asymmetric Catalysis. It is proved de possibility of transferring the chirality in the Diels-Alder Reaction. In addition, a series of meso-substituted arylsulphonated porphyrins have been synthesized with a cyclic secondary amine in their structure, in order to be used as organocatalysts in aldolic and Michael's Reactions in water or aqueous medium
Javier Fdez Sanz - One of the best experts on this subject based on the ideXlab platform.
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designing a new generation of catalysts water gas shift Reaction Example
Catalysis Today, 2015Co-Authors: Jesus Graciani, Javier Fdez SanzAbstract:Abstract In the present work, we briefly review the main conclusions harvested until now in our previous works regarding the WGS Reaction together with new results, Examples and key ideas for designing WGS catalysts. Most of the ideas and general statements included in the present work may be also very useful for designing catalysts for other Reactions that require the presence and combination of metals and oxides. Particularly relevant is the description of the nature, properties and future implications of the nano-mixed-oxide phase “naturally” generated at the interface of some systems which modifies and activates the whole catalytic process. Co-supporting metal and reducible-oxide nanoparticles on another oxide-support in systems with a strong oxide–oxide interaction opens the door to a new family of highly active catalysts suitable for Reactions such as water gas shift, CO oxidation or methanol synthesis, among others.
Jesus Graciani - One of the best experts on this subject based on the ideXlab platform.
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designing a new generation of catalysts water gas shift Reaction Example
Catalysis Today, 2015Co-Authors: Jesus Graciani, Javier Fdez SanzAbstract:Abstract In the present work, we briefly review the main conclusions harvested until now in our previous works regarding the WGS Reaction together with new results, Examples and key ideas for designing WGS catalysts. Most of the ideas and general statements included in the present work may be also very useful for designing catalysts for other Reactions that require the presence and combination of metals and oxides. Particularly relevant is the description of the nature, properties and future implications of the nano-mixed-oxide phase “naturally” generated at the interface of some systems which modifies and activates the whole catalytic process. Co-supporting metal and reducible-oxide nanoparticles on another oxide-support in systems with a strong oxide–oxide interaction opens the door to a new family of highly active catalysts suitable for Reactions such as water gas shift, CO oxidation or methanol synthesis, among others.
Volker Hessel - One of the best experts on this subject based on the ideXlab platform.
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novel process windows concept proposition and evaluation methodology and intensified superheated processing
Chemical Engineering Science, 2011Co-Authors: Volker Hessel, B Cortese, M H J M De CroonAbstract:The concept of novel process windows has recently been proposed by Hessel (2009) and his major processing variant, the pressurised superheated processing, is the topic of several recent reviews in the field. Different from process intensification and micro-process technology enhancing mass and heat transfer to reveal intrinsic kinetics, novel process windows aim at speeding up kinetics, i.e. dramatically reducing Reaction time. This idea is taken up more and more in micro-process technology, but origins as well from the encased processing practised since longer in microwave organic chemistry. Novel process windows as highly intensified processing approach tends to fully exploit the kinetics (reactivity) while maintaining selectivity at an acceptable level through use of harsh conditions, rather than to domesticate chemistry that is common practice in the process chemistry of the past. Reaction rates can be accelerated by orders of magnitude and Reaction times shrink from hours to minutes and seconds. The accompanied large increase in productivity is a further cornerstone in making micro-process technology a competitive concept as opposed to the economics of scale, practised since decades in production chemistry aiming at increasing the vessel size more and more. Different to the content provided in recent reviews, this compilation focuses on the process chemistry potential of superheated processing (while still providing a short summary on the other processing options), a methodology how to find novel processing conditions and how to evaluate these. Two Reactions, the Swern–Moffatt oxidation and the Claisen rearrangement, are discussed in detail, since these are ideal candidates for high-temperature investigations due to their eminent synthetic importance and well-known kinetics. As a practical Reaction Example with industrial guidance of a running European Project, the epoxidation of vegetable oils, the new methodology is exemplified beyond the level of the organic chemists’ descriptions given so far.
M H J M De Croon - One of the best experts on this subject based on the ideXlab platform.
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novel process windows concept proposition and evaluation methodology and intensified superheated processing
Chemical Engineering Science, 2011Co-Authors: Volker Hessel, B Cortese, M H J M De CroonAbstract:The concept of novel process windows has recently been proposed by Hessel (2009) and his major processing variant, the pressurised superheated processing, is the topic of several recent reviews in the field. Different from process intensification and micro-process technology enhancing mass and heat transfer to reveal intrinsic kinetics, novel process windows aim at speeding up kinetics, i.e. dramatically reducing Reaction time. This idea is taken up more and more in micro-process technology, but origins as well from the encased processing practised since longer in microwave organic chemistry. Novel process windows as highly intensified processing approach tends to fully exploit the kinetics (reactivity) while maintaining selectivity at an acceptable level through use of harsh conditions, rather than to domesticate chemistry that is common practice in the process chemistry of the past. Reaction rates can be accelerated by orders of magnitude and Reaction times shrink from hours to minutes and seconds. The accompanied large increase in productivity is a further cornerstone in making micro-process technology a competitive concept as opposed to the economics of scale, practised since decades in production chemistry aiming at increasing the vessel size more and more. Different to the content provided in recent reviews, this compilation focuses on the process chemistry potential of superheated processing (while still providing a short summary on the other processing options), a methodology how to find novel processing conditions and how to evaluate these. Two Reactions, the Swern–Moffatt oxidation and the Claisen rearrangement, are discussed in detail, since these are ideal candidates for high-temperature investigations due to their eminent synthetic importance and well-known kinetics. As a practical Reaction Example with industrial guidance of a running European Project, the epoxidation of vegetable oils, the new methodology is exemplified beyond the level of the organic chemists’ descriptions given so far.
