Indium-catalyzed intramolecular hydrarylation of alkynes : aplications in organic synthesis

[Resumen] En este trabajo de fin de grado se ha estudiado la reacción de hidroarilación intramolecular de alquinilbencenos catalizada por indio(III). Inicialmente se prepararon los diferentes sustratos objeto de estudio seleccionando alquinos terminales (4-fenil-1-butino) e internos (1-bromo-4-fenil-1-butino) además de un compuesto cetoalquinilbenceno, el cual destaca por la incorporación de un grupo cetona en posición bencílica (1-fenilpent-4-in-1-ona). A continuación se estudió la reactividad de estos compuestos bajo catálisis de indio y también se comparó esta metodología con el proceso catalizado por oro. En este estudio se ha observado que esta reacción de hidroarilación intramolecular puede llevarse a cabo de manera eficiente con el bromoalquino mediante catálisis de indio(III) y oro(I), mientras que con el alquino terminal sólo se obtiene el producto ciclado de hidroarilación bajo catálisis de indio(III) en un rendimiento muy bajo. Finalmente, se observó que el compuesto carbonílico es muy poco reactivo y que se favorece la formación del anillo de furano empleando complejos de oro como catalizadores.[Abstract] In this undergraduate research project the indium-catalyzed intramolecular hydroarylation of alkynylbenzenes was studied. Initially, various substrates were prepared by selecting terminal (4-phenyl-1-butyne) and internal (1-bromine-4-phenyl-1-butyne) alkynes and a ketoalkenylbenzene, which it stands out for the incorporation of a ketone at the benzylic position (1-phenylpent-4-yn-1-one). Then the reactivity of these compounds was studied under indium(III) catalysis using different indium salts. Furthermore, the synthetic utility of this methodology was compared with the gold-catalyzed process. During this study we observed that the intramolecular hydroarylation can be carried out efficiently with the bromoalkyne under catalysis of indium(III) and gold(I), while the terminal alkyne only afforded the intramolecular hydroarylation product in very low yield. Finally, the reaction of the formation of furan is favored under gold catalysis.Traballo fin de grao (UDC.CIE). Química. Curso 2014/201

Multilayer perceptron as inverse model in a ground-based remote sensing temperature retrieval problem

In this paper, a combustion temperature retrieval approximation for high-resolution infrared ground-based measurements has been developed based on a multilayer perceptron (MLP) technique. The introduction of a selection subset of features is mandatory due to the problems related to the high dimensionality data and the worse performance of MLPs with this high input dimensionality. Principal component analysis is used to reduce the input data dimensionality, selecting the physically important features in order to improve MLP performance. The use of a priori physical information over other methods in the chosen feature’s phase has been tested and has appeared jointly with the MLP technique as a good alternative for this problem.Publicad

Climate change projections for winter streamflow in Douro river

Ponencia presentada en: X Congreso de la Asociación Española de Climatología celebrado en Alicante entre el 5 y el 8 de octubre de 2016.[EN]Climate change projections for the winter streamflow of the Douro River have been obtained for the period 2071-2099, using the Principal Component Regression (PCR) method. The winter streamflow time series (January to March) from eight stations distributed over the basin, covering the period 1950-2011, were used as predictand variables, while the principal components (PCs) of the winter (December to February) anomalies of sea level pressure (SLP) were used as predictors of the streamflow for the development of a statistical downscaling model. The period 1950- 1995 was used for the calibration of the regression model, while 1996-2011 was used as validation period. The statistical downscaling model fitted from the observational SLP data was applied to the SLP outputs of three GCMs for the period 2071-2099, under the climate change scenarios RCP2.6, RCP4.5 and RCP8.5. The main result obtained is that all models and scenarios project a generalized decrease in the winter streamflow of the Douro River.[ES]Se han obtenido proyecciones de cambio climático para el caudal de invierno del Río Duero, para el periodo 2071-2099, usando el método de Regresión por Componentes Principales (PCR). Las series temporales de caudal (de enero a marzo) de ocho estaciones distribuidas a lo largo de la cuenca, cubriendo el periodo 1950-2011, han sido utilizadas como variables predictando, mientras que las componentes principales (PCs) de las anomalías de la presión a nivel del mar (SLP) en invierno (diciembre a febrero) fueron usadas como predictores del caudal para el desarrollo de un modelo de downscaling estadístico.This work has been financed by the projects P11-RNM-7941 (Junta de Andalucía- Spain) and CGL2013-48539-R (MINECO-Spain, FEDER)

Seasonal streamflow forecast in the Iberian Peninsula based on lagged teleconnection indices

Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014.[EN]This work assesses the potential of teleconnection indices as predictors of seasonal streamflow in the Iberian Peninsula (IP). The database comprises 382 streamflow time series from gauging stations, covering the period from October 1975 to September 2008. Four forecasting scenarios were developed, considering the information provided by teleconnection indices from one year to the previous season to the seasonal streamflow to be predicted.[ES]En este trabajo se ha evaluado la capacidad predictiva de los índices de teleconexión de estaciones previas sobre el caudal estacional de los ríos en la Península Ibérica. La base de datos de caudal la conforman 382 estaciones de aforo cubriendo el periodo desde octubre de 1975 hasta septiembre de 2008. Adicionalmente, se consideraron cuatro escenarios de predicción, en función de la información climática disponible con cuatro, tres, dos o una estaciones de adelanto.The Spanish Ministry of Science and Innovation, with additional support from the European Community Funds (FEDER), project CGL2010-21188/CLI and the Regional Government of Andalusia, project P11-RNM-7941, which had financed this study

Spatio-temporal analysis of maximum and minimum temperatures over Levant region (1987-2017)

Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018.[ES]El objetivo de este estudio es analizar los cambios espaciales y temporales en los promedios anuales y estacionales de las temperaturas máxima y mínima en la región del Levante durante 1987-2017. Estos promedios se calcularon a partir de datos diarios para cada estación y para toda la región de Levante. Las tendencias espaciales y temporales para tres variables se calcularon utilizando la prueba no paramétrica de Mann-Kendall. Además, la diferencia de medias anuales y estacionales entre los dos períodos 1987-2000 y 2001-2011 se evaluó mediante el uso de la prueba U no paramétrica de Mann-Whitney. Durante 1987-2017, la región de Levante fue testigo de un calentamiento significativo en las temperaturas máximas y mínimas anuales de 0.33 y 0.30ºC/década, respectivamente. Además, la primavera mostró una tendencia al calentamiento muy fuerte y significativa en comparación con otras estaciones en 0.53ºC/década para la temperatura máxima y en 0.51ºC/década para la temperatura mínima. La temperatura máxima y mínima anual, de primavera y verano han aumentado significativamente en esta región durante 2001-2017 en comparación con el período 1987-2000. Las tendencias decrecientes mostraron un patrón muy aislado y aleatorio en comparación con las tendencias de calentamiento amplias, intensivas y coherentes en los promedios anuales y estacionales de la temperatura máxima y mínima. Las tasas de calentamiento en Jordania fueron generalmente las más altas.[EN]This study aims to analyze the spatial and temporal variability of the annual and seasonal maximum (Tmax) and minimum (Tmin) temperatures, along with the diurnal temperature range (DTR) over the entire Levant region for the period 1987-2017. The temporal trends for these three variables were calculated at the annual and seasonal scales by using the non-parametric Mann-Kendall test. Furthermore, the difference of the means between the two periods (1987-2000 and 2001-2017) were assessed by using the non-parametric Mann-Whitney U test. During 1987-2017, the Levant region suffered a significant warming for the annual maximum and minimum temperatures around 0.33 and 0.30ºC\decade, respectively. In addition, spring showed very strong and significant warming trend (around 0.53ºC/decade for Tmax and 0.51ºC/decade for Tmin) compared with the other seasons. The annual, spring and summer means of Tmax and Tmin have significantly increased over the Levant region during 2001-2017 compared with the period 1987-2000. Spatially, the decreasing trends showed very isolated and random patterns compared with the broad, intensive and coherent warming trends at annual and seasonal time scales. The warming over Jordan was generally the highest.This work has been financed by the projects P11-RNM-7941 (Junta de Andalucía), CGL2013-48539-R (MINECO-Spain, FEDER) and CGL2017-89836-R (MINECO-Spain, FEDER)

Transferring Axial Molecular Chirality Through a Sequence of On-Surface Reactions

Fine management of chiral processes on solid surfaces has progressed over the years, yet still faces the need for the controlled and selective production of advanced chiral materials. Here, we report on the use of enantiomerically enriched molecular building blocks to demonstrate the transmission of their intrinsic chirality along a sequence of on-surface reactions. Triggered by thermal annealing, the on-surface reac-tions induced in this experiment involve firstly the coupling of the chiral reactants into chiral polymers and subsequently their transformation into planar prochiral graphene nanoribbons. Our study reveals that the axial chirality of the reactant is not only transferred to the polymers, but also to the planar chirality of the graphene nanoribbon end products. Such chirality transfer consequently allows, starting from ad-equate enantioenriched reactants, for the controlled production of chiral and prochiral organic nanoarchi-tectures with pre-defined handedness

Statistical downscaling of summer precipitation in Colombia

Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014.[ES]In this study an statistical downscaling (SD) model using principal component regression (PCR) for simulating summer precipitation in Colombia during the period 1950-2005, has been build, and the climate projections during the 2071-2100 period by applying the obtained SD model have been obtained. For these ends the PCs of the SLP reanalysis data from NCEP were used as predictor variables and the observed gridded summer precipitation as predictand variables. The period 1950-1993 was utilized for calibration and 1994-2010 for validation. The Bootstrap with replacement was applied to provide estimations of the statistical errors. All models perform reasonably well at the regional scales, and the spatial distribution of the correlation coefficients between predicted and observed gridded precipitation values show high values (between 0.5 and 0.93) along Andes range, north and north Pacific of Colombia.[EN]En este trabajo se ha construido un modelo de downscaling estadístico (DS) usando el método de regresión de componentes principales (PCR) para simular la precipitación de verano en Colombia durante el periodo 1950-2005, y se han obtenido sus proyecciones durante el periodo 2071-2100 aplicando el modelo obtenido. Para ello, se han usado las PCs de los datos de SLP de reanálisis del NCEP como variables predictoras y las series de precipitación observada en cada punto de rejilla como predictando. El periodo 1950-1993 ha sido utilizado para calibración y el 1994-2010 para validación. Para proporcionar estimaciones del error estadístico, se ha aplicado el método de Bootstrap con reemplazo. Todos los modelos representan razonablemente bien la precipitación a escala regional, y la distribución espacial de los coeficientes de correlación entre las series de valores predichos y observados en rejilla, muestra altos valores (entre 0.5 y 0.93) a lo largo de la cadena de los Andes, norte y Pacífico norte de Colombia.The Spanish Ministry of Science and Innovation, with additional support from the European Community Funds (FEDER), project CGL2010-21188/CLI and the Regional Government of Andalusia, project P11-RNM-7941, which had financed this study

Influence of tropical Pacific SST on seasonal precipitation in Colombia. Prediction using El Niño and El Niño Modoki

Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014.[EN]In this paper the forecast skill provided by the tropical Pacific SST associated with El Niño and El Niño Modoki over seasonal precipitation (Pt) in Colombia has been evaluated through a lagged Singular Value Decomposition analysis. This analysis has been made based on the results in a companion paper where the impact of El Niño and El Niño Modoki over the seasonal precipitation in Colombia was analyzed and quantified.[ES]En este estudio se evalúa la capacidad de predicción que posee la SST del Pacífico tropical asociada con los fenómenos El Niño y El Niño Modoki sobre la precipitación (Pt) estacional en Colombia, a través del Análisis de Descomposición del Valor Singular. Este análisis está soportado en los resultados obtenidos en un artículo complementario donde ha sido analizado y cuantificado el impacto de El Niño y El Niño Modoki sobre la precipitación estacional en Colombia.This work has been financed by the projects CGL2010- 21188/CLI (MICINN-Spain, FEDER) and P11-RNM-7941 (Junta de Andalucía-Spain)

High-resolution boreal winter precipitation projections over tropical America from CMIP5 models

Climate change projections for boreal winter precipitation in Tropical America has been addressed by statistical downscaling (SD) using the principal component regression with sea-level pressure (SLP) as the predictor variable. The SD model developed from the reanalysis of SLP and gridded precipitation GPCC data, has been applied to SLP outputs from 20 CGMS of CMIP5, both from the present climate (1971-2000) and for the future (2071-2100) under the RCP2.6, RCP4.5, and RCP8.5 scenarios. The SD model shows a suitable performance over large regions, presenting a strong bias only in small areas characterized by very dry climate conditions or poor data coverage. The difference in percentage between the projected SD precipitation and the simulated SD precipitation for present climate, ranges from moderate to intense changes in rainfall (positive or negative, depending on the region and the SD GCM model considered), as the radiative forcing increases from the RCP2.6 to RCP8.5. The disparity in the GCMs outputs seems to be the major source of uncertainty in the projected changes, while the scenario considered appears less decisive. Mexico and eastern Brazil are the areas showing the most coherent decreases between SD GCMs, while northwestern and southeastern South America show consistently significant increases. This coherence is corroborated by the results of the ensemble mean which projects positive changes from 10ºN towards the south, with exceptions such as eastern Brazil, northern Chile and some smaller areas, such as the center of Colombia, while projected negative changes are the majority found in the northernmost part.Departamento Física Aplicada, Facultad de Ciencias, Universidad de Granad