Facile Montmorillonite K-10-Supported Synthesis of Xanthene Derivatives Under Microwave and Thermal Conditions

Microwave-assisted and thermal condensations of aromatic and aliphatic aldehydes with β-naphthol adsorbed onto montmorillonite K-10 were conducted in a one-pot procedure leading to the formation of a variety of xanthene derivatives. Under microwave irradiation, reactions completed within 4–6 min. The procedure is applicable to both aromatic and aliphatic aldehydes, and the catalyst was recycled and reused efficiently in later reactions.     

Tetra‐n‐butylammonium Hydroxide (TBAH)–Catalyzed Knoevenagel Condensation: A Facile Synthesis of α‐Cyanoacrylates, α‐Cyanoacrylonitriles,and α‐Cyanoacrylamides

Tetra‐n‐butylammonium hydroxide (TBAH) has been utilized as a novel and efficient catalyst for the Knoevenagel condensation of aldehydes with acidic methylene compounds such as methyl‐ and ethylcyanoacetate, malononitrile, and cyanoacetamide to afford substituted olefins.     

One-Pot,Three-Component Uncatalyzed Quantitative Synthesis of New Aminonaphthols (Betti Bases) in Water

One-pot, three-component reaction of 2-naphthol, aromatic aldehyde, and heteroaryl amine in water at room temperature leads to the formation of the corresponding aminonaphthols (Betti bases). Reaction details and study of enantiomeric resolution of 1-(p-methylphenyl (2-pyrazinylamino) methyl) naphthalene-2-ol with the aid of ¹H NMR spectroscopy using chiral europium shift reagent is presented.     

Combined effect of gamma irradiation and hot water dipping on the selected nutrients and shelf life of peach

Gamma irradiation in combination with hot water dipping treatment was tested for maintaining storage quality and extending the shelf life of peach fruit. The matured peaches fruits (local variety no, Tex-A-6-69) were first dipped in hot water having temperature of 0, 40 and 60 °C for 60 seconds and they were exposed to 0.5 and 1.0 kGy doses of gamma radiation and stored in paper cartons under ambient (temperature 25 ± 2 °C, RH 70 %) conditions for their physico-chemical evaluations on weekly basis. The combine effect of hot water dipping treatment and irradiation for peach was study for the first time in Pakistan. The parameters studied included % weight loss, % ash content, % moisture content, total soluble solids (TSS), titratable acidity and ascorbic acid. The sensory indices studied were size, shape, color and overall acceptability. The sensory evaluation values at 0 days for the controlled peach sample were recorded for comparison. Statistical analysis was performed to find determinates of irradiation alone and in combination with hot water dipping techniques on peaches. Studies revealed that irradiation treatment in combination with hot water treatments significantly (LSD at 5 %) maintained the storage quality of peach fruit under ambient conditions. Data obtained for weight loss, moisture, shape and overall acceptability showed significant results while non-significant values were recorded for ash, TSS and size. Overall, consumers rated the acceptability of treated peaches higher than untreated peaches. This particular type of research also helps in improving one’s country export quality of fruits.     

Synthesis,crystal structure,and properties of hybrid-3D copper tetraphosphonate: [Cu3((HO3PCH2)2N–CH2C6H4CH2–N(CH2PO3H)2)(H2O)4] n

The new copper(II) tetraphosphonate, [Cu₃(HO₃PCH₂)₂N–CH₂C₆H₄CH₂–N(CH₂PO₃H)₂)(H₂O)₄] _n (1) was hydrothermally synthesized from the reaction of Cu(NO₃)₂ and (H₂O₃PCH₂)₂N–CH₂C₆H₄CH₂–N(CH₂PO₃H₂)₂, (H₈L). Compound 1 was structurally characterized by means of X-ray single crystal diffraction. The structure of 1 showed a 3D structure constructed from two types of Cu(II) and chelating and bridging modes of (HO₃PCH₂)₂N–CH₂C₆H₄CH₂–N(CH₂PO₃H)₂, and features a (4⁴.6¹⁰.8) topological network. The 3D compound is further stabilized by hydrogen bonds. UV–Vis diffuse reflectance and infrared spectroscopy as well as elemental analysis of compound 1 are also presented.     

Electromembrane extraction of zwitterionic compounds as acid or base: Comparison of extraction behavior at acidic and basic pHs

This study has performed on electromembrane extraction (EME) of some zwitterionic compounds based on their acidic and basic properties. High performance liquid chromatography (HPLC) equipped with UV detection was used for determination of model compounds. Cetirizine (CTZ) and mesalazine (MS) were chosen as model compounds, and each of them was extracted from acidic (as a cation) and basic (as an anion) sample solutions, separately. 1-Octanol and 2-nitrophenyl octylether (NPOE) were used as the common supported liquid membrane (SLM) solvents. EME parameters, such as extraction time, extraction voltage and pH of donor and acceptor solutions were studied in details for cationic and anionic forms of each model compound and obtained results for two ionic forms (cationic and anionic) of each compound were compared together. Results showed that zwitterionic compounds could be extracted in both cationic and anionic forms. Moreover, it was found that the extraction of anionic form of each model compound could be done in low voltages when 1-octanol was used as the SLM solvent. Results showed that charge type was not highly effective on the extraction efficiency of model compounds whereas the position of charge within the molecule was the key parameter. In optimized conditions, enrichment factors (EF) of 27–60 that corresponded to recoveries ranging from 39 to 86% were achieved.     

A characterization of maximal and minimal Fermat curves

In this article we provide a characterization of maximal and minimal Fermat curves using the classification of supersingular Fermat curves.     

On explicit,purely analytic solutions of off-centered stagnation flow towards a rotating disc by means of HAM

In this article, the off-centered stagnation flow towards a rotating disc is studied analytically. The governing non-linear equations and their associated boundary conditions are transformed into coupled non-linear ordinary differential equations. The series solution of the problem is obtained by utilizing the HAM. The convergence of the obtained series solutions is carefully checked. Graphical results are presented to investigate the influence of the rotation ratio on the flow field. An important point to note is that the non-alignment complicates the flow field and surface shear, but does not affect the torque. It is noted that the behavior of the HAM solution for velocity components is in good agreement with the numerical solution given in reference [C.Y. Wang, Off-centered stagnation flow towards a rotating disc, Int. J. Eng. Sci. 46 (2008) 391–396].