Indium Trichloride (InCl3) Catalyzed Synthesis of Fused 7‐Azaindole Derivatives Using Domino Knoevenagel‐Michael Reaction

An efficient and high yielding methodology developed for the synthesis of fused 7‐azaindole derivatives via one pot multicomponent assembly process of cyclic 1,3‐dicarbonyls with substituted aldehydes and 5‐amino‐1‐tert‐butyl‐1H‐pyrrole‐3‐carbonitrile. The transformation occurs via domino Knoevenagel‐ Michael reaction followed by intramolecular cyclization in the presence of catalytic amount of InCl₃ (10 mol %). Mild reaction conditions, easy isolation of products, and good to excellent yields in a shorter period of time are the silent features of present methodology. Structures of all the newly prepared compounds have been corroborated by various spectroscopic methods.     

A catalyst-and solvent-free multicomponent synthesis of 7-azagramine analogues via a Mannich type reaction

A catalyst-and solvent-free protocol for the synthesis of 7-azagramine analogues is described via a three-component Mannich type reaction between 7-azaindole, aromatic aldehydes and heterocyclic amines in acceptable to excellent yields. Structures of the compounds were confirmed satisfactorily by ¹H NMR, IR, mass, TOCSY, HSQC and HMBC spectral analyses.     

Synthesis and antimicrobial activity of novel spirocompounds with pyrazolone and pyrazolthione moiety

The paper focuses on the utility of 2‐pyrazoline‐5‐ones and 2‐pyrazoline‐5‐thiones as active Michael donors for the synthesis of novel spirocyclohexanone derivatives. The sulphur containing compounds when screened for antimicrobial activity showed promising inhibition of S. Typhi, S Aures and E Coli bacteria.     

Charge state distribution studies of pure and oxygen mixed krypton ECR plasma – signature of isotope anomaly and gas mixing effect

We report the charge state distributions of the pure, 25% and 50% oxygen mixed krypton plasma to shed more light on the understanding of the gas mixing and the isotope anomaly [A. G. Drentje, Rev. Sci. Instrum. 63 (1992) 2875 and Y Kawai, D Meyer, A Nadzeyka, U Wolters and K Wiesemann, Plasma Sources Sci. Technol. 10 (2001) 451] in the electron cyclotron resonance (ECR) plasmas. The krypton plasma was produced using a 10 GHz all‐permanent‐magnet ECR ion source. The intensities of the highly abundant four isotopes, viz. ⁸²Kr (~11.58%), ⁸³Kr (~11.49%), ⁸⁴Kr (~57%) and ⁸⁶Kr (17.3%) up to ~ +14 charge state have been measured by extracting the ions from the plasma and analysing them in the mass and the energy using a large acceptance analyzer‐cum‐switching dipole magnet. The influence of the oxygen gas mixing on the isotopic krypton ion intensities is clearly evidenced beyond +9 charge state. With and without oxygen mixing, the charge state distribution of the krypton ECR plasma shows the isotope anomaly with unusual trends. The anomaly in the intensities of the isotopes having quite closer natural abundance, viz. ⁸²Kr, ⁸⁶Kr and ⁸³Kr, ⁸⁶Kr is prominent, whereas the intensity ratio of ⁸⁶Kr to ⁸⁴Kr shows a weak signature of it. The isotope anomaly tends to disappear with increasing oxygen mixing in the plasma. The observed trends in the intensities of the krypton isotopes do not follow the prediction of linear Landau wave damping in the plasma. Copyright © 2016 John Wiley & Sons, Ltd.     

Mechanical unfolding of ensemble biomolecular structures by shear force

Mechanical unfolding of biomolecular structures has been exclusively performed at the single-molecule level by single-molecule force spectroscopy (SMFS) techniques. Here we transformed sophisticated mechanical investigations on individual molecules into a simple platform suitable for molecular ensembles. By using shear flow inside a homogenizer tip, DNA secondary structures such as i-motifs are unfolded by shear force up to 50 pN at a 77 796 s⁻¹ shear rate. We found that the larger the molecules, the higher the exerted shear forces. This shear force approach revealed affinity between ligands and i-motif structures. It also demonstrated a mechano-click reaction in which a Cu(i) catalyzed azide–alkyne cycloaddition was modulated by shear force. We anticipate that this ensemble force spectroscopy method can investigate intra- and inter-molecular interactions with the throughput, accuracy, and robustness unparalleled to those of SMFS methods.

Shear force in a homogenizer mechanically unfolds an ensemble set of biomolecular structures.     

Ion-isotopic exchange reaction kinetics using Duolite ARA-9366B and Indion-AGR resins

Radiotracer isotopic technique as an effective analytical tool was used to study the kinetics of ion-isotopic exchange reactions in the nuclear- and nonnuclear-grade anion exchange resins Duolite ARA-9366B and Indion-AGR. On the basis of kinetic data, specific reaction rate (per minute), amount of ion exchanged (millimoles), initial rate of iodide ion exchange (millimoles per minute), and log K _d values were calculated for the two resins. It was observed that under identical experimental conditions of 35.0 °C, 1.000 g of ion exchange resins, and 0.002 mol/L of labeled iodide ion solution, the values calculated were 0.200 min^?1, 0.278 mmol, 0.056 mmol/min, and 9.6, respectively, for Duolite ARA-9366B resin, which were higher than 0.102 min^?1, 0.216 mmol, 0.022 mmol/min, and 5.7, respectively, for Indion-AGR resins. An identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that under identical experimental conditions, Duolite ARA-9366B resins show superior performance than Indion-AGR resins. The results of the present experimental work have demonstrated that the radioanalytical technique used here can be successfully applied for the characterization of different ion exchange resins so as to evaluate their performance under various process parameters.     

Novel synthesis of 1,2,4‐triazolophanes and 1,3,4‐oxadiazolophanes: A dieckmann condensation approach

The Dieckmann condensation has been used for the first time for the syntheses of novel 1,2,4‐triazolophanes and 1,3,4‐oxadiazolophanes. The bis‐1,3,4‐oxadiazol‐2‐thiols 1a and 1b were reacted with ethyl bromoacetate to give the diesters 2a and 2b . Diesters 2a and 2b were treated under dry conditions with sodium methoxide in methanol to afford desired symmetrical 1,3,4‐oxadiazolophanes 3a and 3b . Similarly, diesters of macrocycle precursors containing 1,2,4‐triazole moiety, that is, 6a , 6b , 10 , 13a , 13b , and 13c were synthesized from 5a , 5b , 9 , 12a , 12b , and 12c , respectively. Dieckmann condensation of these diesters afforded symmetrical ketones 7a , 7b , 11 , 14a , 14b , and 14c . Extrusion of CO₂ was observed after in situ hydrolysis of the conventional Dieckmann product during neutralization by dilute mineral acids to afford highly symmetrical ketone in good yields. Further, the ketones 14a , 14b , and 14c were converted into their respective thiones by the reaction with Lawesson's reagent. All the products were synthesized with good yields, and structures were confirmed by various spectroscopic tools and elemental analyses. J. Heterocyclic Chem.,, (2012).     

Prediction of amount of entrained droplets in vertical annular two-phase flow

Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air–water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam–water annular flow conditions. In each experiment, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using the liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant [Sawant, P.H., Ishii, M., Mori, M., 2008. Droplet entrainment correlation in vertical upward co-current annular two-phase flow. Nucl. Eng. Des. 238 (6), 1342–1352] for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible.Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air–water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air–water, helium–water and air–genklene experimental data measured by Willetts [Willetts, I.P., 1987. Non-aqueous annular two-phase flow. D.Phil. Thesis, University of Oxford]. However, comparison of the correlations with the steam–water data available in literature showed significant discrepancies. It is proposed that these discrepancies might have been caused due to the inadequacy of the liquid film extraction method used to measure the entrainment fraction or due to the change in mechanism of entrainment under high liquid flow conditions.     

2-Nitrobenzaldehyde Thiocarbohydrazone Assisted Precise Extraction Spectrophotometric Method for the Determination of Ruthenium(III) in Alloy and Catalysts

A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)?2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1?6 g/mL of ruthenium(III), the optimum concentration range was 2?5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 10⁴ L/mol/cm and 0.0075 μg/cm², respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.     

Chromatographic determination of itopride hydrochloride in the presence of its degradation products

Two sensitive and reproducible methods are described for the quantitative determination of itopride hydrochloride (IH) in the presence of its degradation products. The first method is based on HPLC separation on a reversed phase Kromasil column [C18 (5-microm, 25 cm x 4.6 mm, ID)] at ambient temperature using a mobile phase consisting of methanol and water (70:30, v/v) adjusted to pH 4.0 with orthophosphoric acid with UV detection at 258 nm. The flow rate was 1.0 mL per min with an average operating pressure of 180 kg/cm2. The second method is based on HPTLC separation on silica gel 60 F254 using toluene:methanol:chloroform:10% ammonia (5.0:3.0:6.0:0.1, v/v/v/v) as mobile phase at 270 nm. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of IH determination in dosage form by means of HPLC and HPTLC methods. The drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, UV, and photodegradation. The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. In addition the pH-rate profile of degradation of IH in constant ionic strength buffer solutions in the pH range 2-11 was studied.