Cover Picture: Measuring the Relative Reactivity of the Carbon–Hydrogen Bonds of Alkanes as Nucleophiles (Angew. Chem. Int. Ed. 42/2018)

Analysis of Rabbit Vascular Responses to DBI, an Ingol Derivative Isolated from Euphorbia canariensis

Abstract We have analysed the effects of 7,12-O-diacetyl-8-O-benzoil-2,3-diepiingol (DBI), an ingol derivative isolated from E. canariensis, on isometric tension developed by isolated rabbit basilar and carotid arteries. Concentration-response curves to DBI (10−8 - 3 × 10−5 m) were obtained cumulatively in both arteries at resting tension and active tone (KC1, 50 mm). At resting tension, DBI induced a concentration-dependent contraction, which was not inhibited in Ca2+-free medium. H7 (1-(5-isoquinoline sulphonyl)-2-methylpiperazine dichloride) (10−4 m) inhibited the DBI-induced contraction both in basilar and in carotid arteries. Calmidazolium (10−4 m) inhibited the maximum contraction of …

Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide

International audience; The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10−3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, prop…

Effects of the exercise in the cerebral blood flow and metabolism: A review

In recent years it has been shown that cerebral blood flow is affected by intense exercise, what may even lead to a reduction in the cognitive capacity. This statement is contrary to the traditional belief that cerebral blood flood remains constant and unaltered even when exercise is performed. During physical exercise of moderate intensity, cerebral blood flow increases in the cerebral areas responsible for movement. Moreover, recent studies have observed that cerebral blood flow decreases during high-intensity exercise as a consequence of a local hyperventilation and vasoconstriction of the areas with lower cerebral activity. Traditionally, the glucose has been considered as the main and …

Supercritical Carbon Dioxide: A Promoter of Carbon-Halogen Bond Heterolysis

as the leaving groupdeparts from the carbon atom prior to the entrance of thenucleophile. Polar protic solvents with high dielectric con-stants promote polar bond heterolysis by providing effectiveH-bonding and electron-pair donation interactions to theleaving group and the incipient carbocation, respectively.Then, the solvent captures the carbocation intermediate togive the corresponding S

Teaching-learning methods and their effect on professional development and the development of graduates’ competencies / Métodos de enseñanza-aprendizaje y su efecto en el desarrollo profesional y competencial de los egresados

This article analyses the effect of the teaching-learning methods used in Spanish universities on three measures of educational output: average mark, graduates’ assessment of their professional per...

A Quantitative Model for Alkane Nucleophilicity Based on C−H Bond Structural/Topological Descriptors

A first quantitative model for calculating the nucleophilicity of alkanes is described. A statistical treatment was applied to the analysis of the reactivity of 29 different alkane C−H bonds towards in situ generated metal carbene electrophiles. The correlation of the recently reported experimental reactivity with two different sets of descriptors comprising a total of 86 parameters was studied, resulting in the quantitative descriptor‐based alkane nucleophilicity (QDEAN) model. This model consists of an equation with only six structural/topological descriptors, and reproduces the relative reactivity of the alkane C−H bonds. This reactivity can be calculated from parameters emerging from th…

Titelbild: Measuring the Relative Reactivity of the Carbon–Hydrogen Bonds of Alkanes as Nucleophiles (Angew. Chem. 42/2018)

Innovation at the workplace: Do professional competencies matter?

Abstract This paper analyzes individuals' propensity to innovate in professional environments, by focusing on the specific competency profile of individuals who play a role in the incorporation of product, technological, and knowledge innovations at work. The analysis draws on economic and managerial literature on innovation, innovative behavior, and competencies to gain a better understanding of the relationships between the process of competency development and innovative behavior in working environments. Using data from REFLEX, a European survey on the transition from higher education to labor markets, the empirical component of this study estimates discrete response models to explain th…

Favoring alkane primary carbon-hydrogen bond functionalization in supercritical carbon dioxide as reaction medium

The selectivity of a catalytic alkane functionalization process can be modified just changing the reaction medium from neat alkane to supercritical carbon dioxide (scCO2). A silica supported copper complex bearing an Nheterocyclic carbene ligand promotes the functionalization of carbon-hydrogen bonds of alkanes by transferring the CHCO2Et group from N2=CHCO2Et (ethyl diazoacetate, EDA). In neat hexane only 3% of the primary C-H bonds (ethyl heptanoate being the product) are functionalized in that manner, whereas the same reaction carried out in scCO2 provides a 30% yield in this linear ester. Such effect seems to be induced by an electronic density flux from the NHC ligand to the surroundin…

Functionalization of CnH2n+2Alkanes: Supercritical Carbon Dioxide Enhances the Reactivity towards Primary Carbon-Hydrogen Bonds

The functionalization of the primary sites of alkanes is one of the more challenging areas in catalysis. In this context, a novel effect has been discovered that is responsible for an enhancement in the reactivity of the primary C-H bonds of alkanes in a catalytic system. The copper complex Cu(NCMe) (=hydrotris{[3,5-bis(trifluoromethyl)-4-bromo]-pyrazol-1-yl}borate) catalyzes the functionalization of CnH2n+2 with ethyl diazoacetate upon inserting the CHCO2Et unit into C-H bonds. In addition, the selectivity of the reaction toward the primary sites significantly increased relative to that obtained in neat alkane upon using supercritical carbon dioxide as the reaction medium. This was attribu…

Business Cycle Affiliations in the Context of European Integration

We study affiliations for the countries of the European Economic and Monetary Union (EMU) with Germany and the USA, using various business cycle measures derived from quarterly real GDP. These measures are Hodrick-Prescott and Baxter-King filtered series and annual growth rates. By using rolling contemporaneous and maximum (over a short lead/lag interval) correlations, we document increasing correlations of EMU countries with Germany, with these typically being largest during the 1990s. We also document a strong leading role for the USA in relation to these countries in the period since 1993, thereby correcting the fallacy that the European business cycle was disjointed from the USA for mos…

ChemInform Abstract: Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

Above 31.1 °C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO2) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO2 is presented.

Discovering Copper for Methane C–H Bond Functionalization

The copper complex Tp(CF3)2,BrCu(NCMe) (1, Tp(CF3)2,Br = hydrotris((3,5-bis(trifluoromethyl)-4-bromo)-pyrazol-1-yl)borate) catalyzes the insertion of the CHCO2Et group (from ethyl diazoacetate N2CHCO2Et, EDA) into the C–H bonds of methane, in a homogeneous process that uses supercritical carbon dioxide (scCO2) as the reaction medium. Other light alkanes such as ethane, propane, and butane have been also functionalized with this copper-based catalyst, in the first example of the derivatization of the series of C1–C4 alkanes with this metal and a soluble catalyst.

A System of Indicators for Evaluating Public Broadcasting Corporations

We describe an operational procedure to build an integrated information system (IIS) for monitoring and evaluating the performance of public broadcasting corporations (PBC). The procedure grounds in a conceptual framework derived from evaluation models, and consists of two stages. The first stage is the selection, through expert judgment, of simple indicators that illustrate the most relevant aspects of the corporations. The second stage is the definition of a system of indicators related to each level of the hierarchy of objectives planned by the corporations. The system of indicators has two levels. The first level is a basic indicator system that allows description and monitoring of the …

Silver-Catalyzed C-C Bond Formation between Methane and Ethyl Diazoacetate in Supercritical CO2

Even in the context of hydrocarbons’ general resistance to selective functionalization, methane’s volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH4) with ethyl diazoacetate (N2CHCO2Et) to yield ethyl propionate (CH3CH2CO2Et). The use of supercritical carbon dioxide (scCO2) as the solvent is key to the reaction’s success. Although the catalyst is only sparingly soluble in CH4/CO2 mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.

Measuring the Relative Reactivity of the Carbon-Hydrogen Bonds of Alkanes as Nucleophiles

We report quantitative measurements of the relative reactivities of a series of C-H bonds of gaseous or liquid CnH2n+2 alkanes (n = 1-8, 29 different C-H bonds) towards insitu generated electrophiles (copper, silver, and rhodium carbenes), with methane as the reference. This strategy surpasses the drawback of previous model reactions of alkanes with strong electrophiles suffering from C-C cleavage processes, which precluded direct comparison of the relative reactivities of alkane C-H bonds.

Higher education and the development of competencies for innovation in the workplace

PurposeThis paper aims to analyze the production function nexus between higher education practice and the development of innovation‐related competencies by university graduates in Spain. The research hypothesis is the presence of statistically significant relationships between the development of innovational competencies and the modes of teaching and learning used in higher education practice.Design/methodology/approachThe relationships are modeled through a set of stochastic frontier and variance component equations with the development of each competency as the dependent variable. The main explanatory variables capture the prevalence of diverse teaching/learning modes and the behavior of …

Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

Above 31.1 degrees C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO(2)) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO(2) is presented.

CCDC 1037192: Experimental Crystal Structure Determination

Related Article: Riccardo Gava, Andrea Olmos, Bárbara Noverges, Teresa Varea, Eleuterio Álvarez, Tomás R. Belderrain, Ana Caballero, Gregorio Asensio, and Pedro J. Pérez|2015|ACS Catalysis|5|3726|doi:10.1021/acscatal.5b00718

CCDC 1037194: Experimental Crystal Structure Determination

Related Article: Riccardo Gava, Andrea Olmos, Bárbara Noverges, Teresa Varea, Eleuterio Álvarez, Tomás R. Belderrain, Ana Caballero, Gregorio Asensio, and Pedro J. Pérez|2015|ACS Catalysis|5|3726|doi:10.1021/acscatal.5b00718

CCDC 1037193: Experimental Crystal Structure Determination

Related Article: Riccardo Gava, Andrea Olmos, Bárbara Noverges, Teresa Varea, Eleuterio Álvarez, Tomás R. Belderrain, Ana Caballero, Gregorio Asensio, and Pedro J. Pérez|2015|ACS Catalysis|5|3726|doi:10.1021/acscatal.5b00718