Search results for "química"
showing 10 items of 1552 documents
E,Z-Stereodivergent synthesis of N-tosyl α,β-dehydroamino esters via a Mukaiyama-Michael addition
2016
The stereodivergent synthesis of N-tosyl α,β-dehydroamino esters via a Mukaiyama–Michael addition is reported. The reaction of silylketene acetals with N-tosylimines derived from β,γ-unsaturated α-keto esters in dichloromethane provided the corresponding (Z)-α,β-dehydroamino esters while the (E)-isomers were obtained when the reaction was carried out in the presence of 10 mol% copper(II) triflate.
Strong Influence of the Ancillary Ligand over the Photodynamic Anticancer Properties of Neutral Biscyclometalated IrIII Complexes Bearing 2-Benzoazol…
2018
In this paper, the synthesis, comprehensive characterization and biological and photocatalytic properties of two series of neutral IrIII biscyclometalated complexes of general formula [Ir(C^N)2(N^O)], where the N^O ligands are 2‐(benzimidazolyl)phenolate‐N,O (L1, series a) and 2‐(benzothiazolyl)phenolate‐N,O (L2, series b), and the C^N ligands are 2‐(phenyl)pyridinate or its derivatives, are described,. Complexes of types a and b exhibit dissimilar photophysical and biological properties. In vitro cytotoxicity tests conclusively prove that derivatives of series a are harmless in the dark against SW480 cancer cells (colon adenocarcinoma), but express enhanced cytotoxicity versus the same cel…
Halide-Mediated Modification of Magnetism and Electronic Structure of α-Co(II) Hydroxides: Synthesis, Characterization, and DFT+U Simulations.
2019
The present study introduces a comprehensive exploration in terms of physicochemical characterization and calculations based on density functional theory with Hubbard's correction (DFT+U) of the whole family of α-Co(II) hydroxyhalide (F, Cl, Br, I). These samples were synthesized at room temperature by employing a one-pot approach based on the epoxide route. A thorough characterization (powder X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis/mass spectroscopy, and magnetic and conductivity measurements) corroborated by simulation is presented that analyzes the structural, magnetic, and electronic aspects. Beyond the inherent tendency of intercalated anions to …
Enantioselective synthesis of chiral oxazolines from unactivated ketones and isocyanoacetate esters by synergistic silver/organocatalysis
2018
[EN] A multicatalytic approach that combines a bifunctional Brønsted base¿squaramide organocatalyst and Ag+ as Lewis acid has been applied in the reaction of unactivated ketones with tert-butyl isocyanoacetate to give chiral oxazolines bearing a quaternary stereocenter. The formal [3+2] cycloaddition provided high yields of the corresponding cis-oxazolines with good diastereoselectivity and excellent enantioselectivity, being applied to aryl¿alkyl and alkyl¿alkyl ketones.
Copper-Catalyzed Aerobic Oxidative Alkynylation of 3,4-Dihydroquinoxalin-2-ones
2019
Herein, we described a ligand-free copper-catalyzed aerobic oxidative functionalization of 3,4-dihydroquinoxalin-2(1H)-ones with terminal alkynes using visible-light and oxygen as terminal oxidant to give 3-ethynyl-3,4-dihydroquinoxalin-2(1H)-one, cyclic propargylic amines, in moderate to good yields. Moreover, we demonstrate the versatility of the 3-ethynyl-3,4-dihydroquinoxalin-2(1H)-ones obtained by preparing several 3,4-dihydroquinoxalin-2-one derivatives.
A thermally/chemically robust and easily regenerable anilato-based ultramicroporous 3D MOF for CO 2 uptake and separation
2021
The combination of the properly designed novel organic linker, 3,6-N-ditriazoyil-2,5-dihydroxy-1,4-benzoquinone (trz2An), with CoII ions results in a 3D ultramicroporous MOF with high CO2 uptake capacity and separation efficiency, with particular attention to CO2/N2 and CO2/CH4 gas mixtures. This material consists of 1D chains of octahedrally coordinated CoII ions linked through the anilato ligands in the equatorial positions and to the triazole substituents from two neighbouring chains in the two axial positions. This leads to a 3D microporous structure with voids with an affinity for CO2 molecules and channels that enable the selective entrance of CO2 but not of molecules with larger kine…
Catalytic enantioselective aza-Reformatsky reaction with seven-membered cyclic imines dibenzo[b,f][1,4]oxazepines
2017
A catalytic enantioselective aza-Reformatsky reaction is reported with cyclic dibenzo[b,f][1,4]oxazepines and ethyl iodoacetate leading to the synthesis of chiral ethyl 2-(10,11-dihydrodibenzo[b,f][1,4]oxazepin-11-yl)acetate derivatives with excellent yields and high enantioselectivities (up to 98% yield and 97 : 3 er) using a readily available diaryl prolinol L4 as the chiral ligand and Me2Zn as the zinc source under an air atmosphere. Furthermore, different transformations were carried out with the corresponding chiral β-amino esters, preserving in all cases the optical purity.
Biotrickling filtration of isopropanol under intermittent loading conditions
2013
This paper investigates the removal of isopropanol by gas phase biotrickling filtration. Two plastic packing materials, one structured and one random, have been evaluated in terms of oxygen mass transfer and isopropanol removal efficiency (RE). Oxygen mass transfer experiments were performed at gas velocities of 104 and 312 m h-1 and liquid velocities between 3 and 33 m h-1. Both materials showed similar mass transfer coefficients up to liquid velocities of 15 m h-1. At greater liquid velocities, the structured packing exhibited greater oxygen mass transfer coefficients. Biotrickling filtration experiments were carried out at inlet loads (IL) from 20 to 65 g C m-3 h -1 and empty bed residen…
Biotrickling filter modeling for styrene abatement. Part 1: Model development, calibration and validation on an industrial scale
2017
Abstract A three-phase dynamic mathematical model based on mass balances describing the main processes in biotrickling filtration: convection, mass transfer, diffusion, and biodegradation was calibrated and validated for the simulation of an industrial styrene-degrading biotrickling filter. The model considered the key features of the industrial operation of biotrickling filters: variable conditions of loading and intermittent irrigation. These features were included in the model switching from the mathematical description of periods with and without irrigation. Model equations were based on the mass balances describing the main processes in biotrickling filtration: convection, mass transfe…
Dynamic Mathematical Modelling of the Removal of Hydrophilic VOCs by Biotrickling Filters
2015
A mathematical model for the simulation of the removal of hydrophilic compounds using biotrickling filtration was developed. The model takes into account that biotrickling filters operate by using an intermittent spraying pattern. During spraying periods, a mobile liquid phase was considered, while during non-spraying periods, a stagnant liquid phase was considered. The model was calibrated and validated with data from laboratory- and industrial-scale biotrickling filters. The laboratory experiments exhibited peaks of pollutants in the outlet of the biotrickling filter during spraying periods, while during non-spraying periods, near complete removal of the pollutant was achieved. The gaseou…