20 research outputs found

    Repercusió de l'alcoholisme crònic sobre l'organisme humà

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    L'avaluació i descripció dels principals efectes d'una malaltia que sovint és ignorada o menyspread

    Acid Catalysis with Alkane/Water Microdroplets in Ionic Liquids

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    Ionic liquids are composed of an organic cation and a highly delocalized perfluorinated anion, which remain tight to each other and neutral across the extended liquid framework. Here we show that n-alkanes in millimolar amounts enable a sufficient ion charge separation to release the innate acidity of the ionic liquid and catalyze the industrially relevant alkylation of phenol, after generating homogeneous, self-stabilized, and surfactant-free microdroplets (1–5 μm). This extremely mild and simple protocol circumvents any external additive or potential ionic liquid degradation and can be extended to water, which spontaneously generates microdroplets (ca. 3 μm) and catalyzes Brönsted rather than Lewis acid reactions. These results open new avenues not only in the use of ionic liquids as acid catalysts/solvents but also in the preparation of surfactant-free, well-defined ionic liquid microemulsions.PNICTOCHEM 804110 (G.A.)PID2019-111742-GA-I00CIDEGENT/2018/00

    Few layer 2D pnictogens (P & Sb) catalyze the alkylation of soft nucleophiles with esters

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    Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well-structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid-catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid-sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents

    Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters

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    Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well–structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid–catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid–sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents

    [Intervencions]

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    Escola i infància a Catalunya a finals del segle XVIII. 'Escuela e infancia en Cataluña a finales del siglo XVIII'

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    Destacar los referentes históricos que puedan ayudar al análisis de un proceso social e institucional que está en el origen de la configuración de nuestras instancias educativas. Escuelas de primeras letras y escuelas de niñas de Catalunya a finales del siglo XVIII (escuelas, maestros, infancia). Archivo del fiscal de la 'Reial Audiència de Barcelona' (1785-1791). Interpretación histórica basada en los documentos hallados sobre el tema. La escuela era útil a los niños y a las niñas. Indica los aspectos socio-geográficos que influyeron en el proceso de escolarización. El catalán tenia una clara vigencia cultural. La práctica docente era motivo de preocupación en los proyectos de reforma. Explica los métodos y contenidos de enseñanza. Ser maestro era poco atractivo. Se inició la profesionalización del maestro. Explica la situación de la infancia (la sociedad estaba preocupada por el tema, incoporación temprana al trabajo o tareas domésticas, etc.).CataluñaES

    La organización de la enseñanza en China

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    Dar una visión sistematizada y lo más objetiva posible de la evolución de la enseñanza en China en relación a la formación y desarrollo del moderno Estado. Historia de China. La organización del Sistema Educativo chino. Bibliografía en francés, español, inglés e italiano. Lectura bibliográfica. Un capítulo exclusivo de conclusiones, páginas: 229-240.CataluñaES
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