H5BW12O40 as a green and efficient homogeneous but recyclable catalyst in the synthesis of 4H‐Pyrans via multicomponent reaction

Keggin‐type heteropolyacid, H₅BW₁₂O₄₀ (BWA) with a higher negative charge and stronger Brønsted acidity comparing to Si and P derivatives was used as an efficient, green, and reusable catalyst in a three‐component reaction involving the cyclocondensation of various β‐dicarbonyl compounds, differently substituted aromatic aldehydes and malononitrile in EtOH/H₂O for the facile, clean, and high yielding synthesis of 4H‐pyrans. All reactions were completed in short times and the products were obtained in good to excellent yields. The reaction medium could be recycled and reused several times without any loss of efficiency.     

Efficient access to novel tetra- and pentacyclic dihydroquinolin-2-ones by catalyst-free domino Knöevenagel hetero-Diels–Alder reactions from <Emphasis Type="Italic">N</Emphasis>-(2-formylphenyl)-<Emphasis Type="Italic">N</Emphasis>-methylcinnamamides and cyclic 1,3-dicarbonyls in water

An efficient catalyst-free synthesis of novel annulated hybrid derivatives of two known scaffolds, dihydroquinolinone and pyranopyranone, pyranopyrimidinedione, pyranocoumarin or chromenone is described. N-(2-Formylphenyl)-N-methylcinnamamides underwent a one-pot domino Knöevenagel hetero-Diels–Alder reaction with dimedone, N,N-dimethylbarbituric acid, 1,3-indanedione, 4-hydroxycoumarins and 4-hydroxy-6-methyl-2H-pyran-2-one in water, affording the desired tetra and pentacyclic pyranoquinolinones in excellent yields.     

Efficient synthesis of novel functionalized pyrazolo-pyranoquinoline and tetrahydrodibenzo-[1,8]naphthyridinone derivatives

The facile and efficient synthesis of 1,4-dihydropyrazolo-pyrano-[2,3-b]quinoline derivatives from the reaction of 2-chloroquinoline-3-carbaldehydes and pyrazolones is described. Moreover, a one-pot method for the development of functionalized tetrahydrodibenzo[b,g][1,8]naphthyridinone derivatives is reported by using a three-component reaction of 2-chloroquinoline 3-carbaldehydes, pyrazolone, and enaminones catalyzed by l-proline in EtOH.     

Solubility of Ketoconazole in Binary and Ternary Solvents of Polyethylene Glycols 200, 400 or 600 with Ethanol and Water at 298.2 K. Data Report and Analysis

The solubilities of ketoconazole in binary and ternary mixtures of water, ethanol and polyethylene glycols 200, 400 or 600 (185 data points) were determined at 298.2 K. Williams–Amidon and Jouyban–Acree cosolvency models were used to model the data, with overall mean relative deviations (OMRDs) for the solubility data in binary and ternary solvents of 17.5 and 23.5%, respectively. For predicting the solubility data of ketoconazole the trained versions of the models were used and the OMRD values were 47.7 and 33.0%, respectively.     

CuI catalyzed-novel one-pot synthesis of aryl alkenyl thioethers through Ullmann-type coupling reactions using carbon disulfide as a sulfur surrogate in the presence of nitroalkanes and aryl iodides

A mild, general and efficient copper-catalyzed system for C-S bond formation is developed. With CuI as catalyst and l-Proline as ligand, the S-arylation of nitroalkane-CS₂ adducts with aryl iodides were performed under mild conditions to give the corresponding products in good to excellent yields.     

HKUST-1 metal-organic framework for dispersive solid phase extraction of 2-methyl-4-chlorophenoxyacetic acid (MCPA) prior to its determination by ion mobility spectrometry

The authors describe a method for the extraction of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from agricultural products. The metal organic framework (MOF) HKUST-1 (a copper(II) benzene-1,3,5-tricarboxylate) was used as a sorbent for efficient clean-up and preconcentration of MCPA. The effects of pH value, stirring time, amount of sorbent on extraction were optimized by central composite design. Ultrasonic waves were used for desorption procedure and its advantage was demonstrated for an increase in extraction recovery. Corona discharge ion mobility spectrometry (IMS) was then applied for fast and sensitive determination of MCPA. The method was validated in terms of sensitivity, recovery and reproducibility. Under the optimum conditions the calibration plot is linear between 0.035–0.200 μg. L^?1. The detection limit is 10 ng L^?1, with relative standard deviations of <5%. Real samples (water, soil and agricultural product) were spiked and then analyzed by this method, and the results revealed efficient solid phase extraction and recovery.

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Graphical abstract Schematic presentation of a procedure for extraction of an organochlorine pesticide (2-methyl-4-chlorophenoxyacetic acid) from agriculture products using the HKUST-1 metal-organic framework prior to determination by ion mobility spectrometry based on its ionization in drift cell.

     

Hydroarylation of cinnamic acid with phenols catalyzed by acidic ionic liquid [H-NMP]HSO<Subscript>4</Subscript>: computational assessment on substituent effect

Hydroarylation of cinnamic acid with different substituted phenols, in the presence of acidic ionic liquid, N-methyl-2-pyrrolidonum hydrosulfate ([H-NMP]HSO₄) gave the corresponding dihydrocoumarins in high yields and excellent selectivity. Among these substituted phenols, while methyl phenol afforded the corresponding dihydrocoumarin, nitrophenol under the same reaction conditions diverted the course of reaction, affording 3-(4-nitrophenyl)-3-phenylpropanoic acids. We investigated this behavior from the energetic and electronic points of view, using quantum chemistry computational methods. In this respect, the electronic energy change values for the conversion reaction of substituted phenyl cinnamate esters to dihydrocoumarin compounds have been obtained via density functional theory calculations. We demonstrated that the conversion reaction in the presence of CH₃ substituent is more favorable energetically than NO₂ substituent. Moreover, we have concentrated on topological analysis of electron density on some key bond and ring critical points and their associated bond paths to assess the conversion of substituted phenyl cinnamate esters to dihydrocoumarins. Our calculated results showed that para-methyl phenyl cinnamate has more of electronic tendency to undergo the intramolecular cyclization step and, consequently, generate the corresponding dihydrocoumarin.     

Strong Microheterogeneity in Novel Deep Eutectic Solvents

With the increasing application of template assisted syntheses in deep eutectic solvents and successful application of hydrophobic deep eutectic solvents in extraction processes, where microheterogeneity plays a major role, suggestions for novel deep eutectic solvents which exhibit strong microheterogeneity are desirable. Therefore, classical molecular dynamics simulations were carried out on deep eutectic solvent systems constructed of choline chloride and some of its derivatives mixed with ethylene glycol in a molar composition of 1 : 2 since this is the optimal parent composition. The derivatives consisted of a series of elongated alkyl side chains and elongated alcohol side chains. Of these series only choline chloride ethylene glycol has been investigated experimentally, the other systems are suggested and theoretically investigated as possible target for synthesis. Our domain analysis supported by the clear distinction of polar and nonpolar parts from the electrostatic potentials reveals that strong microheterogeneity within these novel hypothetical deep eutectic solvents exists. Rather stretched than crumbled side chains maximize possible interaction sites for both polar and nonpolar parts which make the suggested compounds valuable objectives for experiments in order to exploit the microheterogeneity in deep eutectic solvents.     

Characterization of intermolecular interactions in crystalline aspirin: A computational NQR study

A computational study at the level of density functional theory was carried out to characterize the ¹⁷O and ²H nuclear quadrupole resonance (NQR) spectroscopy parameters in crystalline aspirin. To include O? H···O and C? H···O hydrogen bonding effects in the calculations, the most probable interacting molecules with the target molecule in the crystalline phase were considered through a pentamer cluster. The NQR calculations were performed with BLYP, B3LYP, and M06 functionals employing 6‐311++G** and Jensen's polarization‐consistent pcJ‐1 basis sets. Linear correlations are observed between the calculated ¹⁷O and ²H NQR parameters and the hydrogen bond strengths, suggesting the possibility of estimating hydrogen bonding information from calculated NQR data. Different contributions of various nuclei to hydrogen bonding interactions and observed trends of calculated NQR parameters are well justified by atoms in molecules analyses at the BCPs of these interactions. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Oxidation state and symmetry of magnesia-supported Pd13O(x) nanocatalysts influence activation barriers of CO oxidation

Combining temperature-programmed reaction measurements, isotopic labeling experiments, and first-principles spin density functional theory, the dependence of the reaction temperature of catalyzed carbon monoxide oxidation on the oxidation state of Pd(13) clusters deposited on MgO surfaces grown on Mo(100) is explored. It is shown that molecular oxygen dissociates easily on the supported Pd(13) cluster, leading to facile partial oxidation to form Pd(13)O(4) clusters with C(4v) symmetry. Increasing the oxidation temperature to 370 K results in nonsymmetric Pd(13)O(6) clusters. The higher symmetry, partially oxidized cluster is characterized by a relatively high activation energy for catalyzed combustion of the first CO molecule via a reaction of an adsorbed CO molecule with one of the oxygen atoms of the Pd(13)O(4) cluster. Subsequent reactions on the resulting lower-symmetry Pd(13)O(x) (x < 4) clusters entail lower activation energies. The nonsymmetric Pd(13)O(6) clusters show lower temperature-catalyzed CO combustion, already starting at cryogenic temperature.