A ‘one pot’ synthesis of 2‐aryl‐4H‐1‐benzopyran‐4‐ones under coupled microwave phase transfer catalysis (PTC) and ultrasonic irradiation PTC

A ‘one pot’ synthesis of 2‐aryl‐4H‐1‐benzopyran‐4‐ones (3a‐3f) is being reported. A mixture of o‐hydroxyacetophenone, aroyl chloride, powdered n‐tetrabutylammonium hydrogensulphate (n‐TBAHSO₄) and potassium hydroxide (KOH) were either irradiated by microwaves or sonicated in an ultrasonic cleaning bath to afford flavones directly. On the contrary, conventional liquid‐liquid Phase Transfer Catalysis (PTC) using benzene as organic phase and aqueous KOH as the second phase afforded first β‐diketones in accordance with Baker‐Venkataraman synthesis which upon cyclization by p‐toluenesulphonic acid (p‐TSA) gave desired flavones in the next step. PTC coupled with microwaves or ultrasound show enhanced yields, the clean reaction conditions require less time, and have easier workup protocol. All synthesized compounds were characterized by their Proton Magnetic Resonance (PMR), IR, FAB Mass and elemental analyses.     

Aroylethenesulfonylacetic acid methyl ester: a synthon for novel sulfone linked bis heterocycles

Novel sulfone linked bis heterocycles containing two different heterocyclic rings viz., pyrazoline in combination with thiadiazole, oxadiazole and triazole were synthesized and studied their antimicrobial activity.     

Adsorption of molecular hydrogen on inorganometallic complexes B<Subscript>2</Subscript>H<Subscript>4</Subscript>M (M=Li,Be, Sc,Ti, V)

Molecular interaction between hydrogen molecules and B₂H₄M (M=Li, Be, Sc, Ti, V) complexes has been studied using the DFT method (M06 functional) and 6-311++G** basis set. The hydrogen uptake capacity of the complexes considered is higher than the target set by the US Department of Energy (5.5 wt% by 2020). The metal atom bound strongly to the B₂H₄ substrate. Adsorption of molecular hydrogen on Be-, Ti-, and V-decorated complexes is thermodynamically possible for all the pressures and temperatures considered whereas it is unfavorable for Li-decorated complexes for all the pressure and temperatures. For the Sc-doped complexes, adsorption of molecular hydrogen is favorable below 330 K and entire pressure range considered. All the H₂ adsorbed complexes are kinetically stable. For all the complexes, the interaction between the inorganometallic complexes and the H₂ molecules adsorbed is attractive whereas that between adsorbed H₂ molecules is repulsive. We have also performed molecular dynamics simulations to confirm the same number of H₂ molecule adsorption from the simulations and DFT calculations.     

Incorporating engineering intuition for parameter estimation in thermal sciences

This paper proposes a new method of incorporating priors based on engineering intuition for solving inverse problems. The thesis of this paper is that if an asymptote can be found to a problem in applied sciences or engineering, estimation of parameters can be first done for this asymptotic variant, which in principle should be simpler, since one or more parameters of the original problem may vanish for the asymptotic variant. Even so, by solving the inverse problem associated with the asymptotic variant, estimates of key parameters of the full problem can be obtained. This information can then be quantitatively incorporated as priors in the estimation of parameters for the full version of the problem which we call as prior generation through asymptotic variant. The goal is to see if this methodology will significantly reduce the uncertainties in the resulting estimates. To demonstrate this methodology, the classic problem of unsteady heat transfer from a one dimensional fin is chosen. The inverse problem is posed as the simultaneous estimation of the temperature dependent transfer coefficient (h _θ ) and the thermal diffusivity (α) of the fin material, given experimentally measured temperature–time histories at various locations along the fin. The asymptotic variant θ _(x,t) is the steady state problem where the influence of thermal diffusivity vanishes. Using surrogate temperature data generated from assumed values of h _θ , first the asymptotic variant of the problem is solved using the Markov Chain Monte Carlo method in a Bayesian framework to generate an estimate of h _θ . The estimate of h _θ is then used as an informative prior for solving the inverse problem of determining h _θ and α from θ _(x,t), and the effect of prior is quantitatively assessed by performing estimation with and without the prior. Finally, for purposes of validation, in-house experiments have been done where θ _(x,t) is generated using liquid crystal thermography and these data are used to estimate h _θ and α. A comparison of experimentally measured temperatures with those that are simulated by using estimated values of (h _θ , α) to solve the governing equation to the problem is also done.     

Structural response to the magnetic pre-ordering in LiFeSi2O6

The European Physical Journal B - It has experimentally been found by Lampo et al. [Biophys. J. 112, 532 (2017)] that, for two different types of cell, the distribution of the diffusivities of...     

A multicomponent synthesis of cyclopropanes

A multicomponent synthesis of cyclopropanes is described. The title compounds were obtained in high yields from commercially available materials.     

Polyethylene glycol(PEG-400): An efficient and recyclable reaction medium for the synthesis of novel 1,5-benzodiazepines and their antimicrobial activity

A new series of imidazole-containing 1,5-benzodiazepines have been synthesized by the condensation of chalcones with ophenylenediamine using piperidine in polyethylene glycol(PEG-400) as an efficient and green reaction solvent.The advantages of this protocol are environmental friendliness,easy work-up,high yields,mild reaction condition and avoidance of expensive catalyst. Furthermore,newly synthesized compounds were evaluated for their antimicrobial activity.     

A Facile Synthesis of Pyrazolo[3,4-b]pyridines

Pyrazolo[3,4-b]pyridines (4) and (5) have been obtained by the condensation of 3-(alkyl/aryl)-5-amino-1-phenyl-1H-pyrazole-4-carboxaldehydes (3) with active methylene compounds viz: diethyl malonate and malononitrile.     

Neat Formic Acid: an Excellent N-Formylating Agent for Carbazoles, 3-Alkylindoles,Diphenylamine and Moderately Weak Nucleophilic Anilines

Neat formic acid alone efficiently N-formylates carbazoles, 3-alkylindoles, diphenylamine and even moderately weak nucleophilic anilines to furnish the corresponding N-formyl derivatives in 72--87% yields.     

A stability-indicating ultra-performance liquid chromatographic method for estimation of related substances and degradants in paliperidone active pharmaceutical ingredient and its pharmaceutical dosage forms

A simple, linear gradient, rapid, precise and stability-indicating analytical method was developed for the estimation of related substances and degradants of paliperidone API and tablets. The chromatographic separations were achieved using an Acquity ultra-performance liquid chromatograph (BEH 100 mm, 2.1 mm, 1.7 μm C-18 column) employing 0.01 M potassium dihydrogen phosphate buffer (pH 2.0) as mobile phase A and acetonitrile-water (9:1) as mobile phase B. A linear gradient (mobile phase A, mobile phase B in the ratio of 84:16) with a 0.45 mL/min flow rate was chosen. All six impurities were eluted within five minutes of run time. The column temperature was maintained at 25 °C and a detector wavelength of 238 nm was employed. Paliperidone was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The stressed samples were analyzed by the proposed method. Considerable degradation of the analyte was observed when it was subjected to oxidative conditions and impurity F was found to be the major degradant. Peak homogeneity data of paliperidone obtained by photodiode array (PDA) detection demonstrated the specificity of the method in the presence of degradants. The method was validated with respect to linearity, precision, accuracy, ruggedness, robustness, limit of detection and limit of quantification.