Oxalic Acid: An Efficient and Cost-Effective Organic Catalyst for the Friedländer Quinoline Synthesis under Solvent-Free Conditions

Summary. Oxalic acid is used as an efficient catalyst in the condensation of 2-aminoaryl ketones with carbonyl compounds leading to the formation of quinolines in excellent yields under solvent-free conditions. This methodology offers significant improvements for the synthesis of quinolines with regard to the yield of products, simplicity in operation, inexpensive reagents, and green aspects by avoiding toxic catalysts and solvents.     

Sodium Borohydride – Ammonium Carbonate: An Effective Reducing System for Aldehydes and Ketones

Reduction of aldehydes and ketones to the corresponding alcohols was achieved in a simple procedure using the system sodium borohydride and ammonium carbonate. This system needs lower excesses of reducing agent and leads to significantly shortened reaction times.     

Direct determination of U(VI) in TBP-kerosene extracts using first derivative ultraviolet spectroscopy

Summary The extractive first order derivative spectrophotometry is a selective method for the separation and determination of U(VI) using tri-n-butyl phosphate (TBP), which combines the roles of solvent and complexing agent. The complex is formed by extracting U(VI) from an aqueous 6M sodium nitrate solution at initial pH 3.0 into a 25% solution of TBP in kerosene. This extraction also separates U(VI) from many diverse ions that interfere. After extraction, the determination of uranium shows good accuracy and precision with relative standard deviation of 1.5% (n = 5) at 20 ppm using zero-order spectrum at l_max = 250 nm. Calibration curve was also found to obey Beer's law in the range of 10-100 ppm with 3.33 ppm detection limit. However, these accuracy and precision have been improved to give relative standard deviation of 0.7% (n = 5) at 20 ppm with a lower detection limit of 2.24 ppm using the first-derivative spectrum at l = 263 nm comparing to the normal one.     

Liquid chromatography and chemometric-assisted spectrophotometric methods for the analysis of two multicomponent mixtures containing cough suppressant drugs

Three methods were applied for the analysis of 2 multicomponent mixtures containing dextromethorphan hydrobromide, phenylephrine hydrochloride, chlorpheniramine maleate, methylparaben, and propylparaben, together with either sodium benzoate (Mix 1) or ephedrine hydrochloride and benzoic acid (Mix 2). In the first method, liquid chromatography was used for their simultaneous determination using an ODS column with a mobile phase consisting of acetonitrile-phosphate buffer, pH 2.7 (40 + 60, v/v), containing 5mM heptanesulfonic acid sodium salt and ultraviolet (UV) detection at 214 nm. Also, 2 chemometric methods, principal component regression, and partial least squares were used. For both chemometric calibrations, a concentration set of the mixture consisting of each compound in each mixture was prepared in distilled water. The absorbance data in the UV spectra were measured for the 76 or 71 wavelength points in the spectral region 210-240 or 210-224 nm considering the intervals of deltagamma = 0.4 or 0.2 nm for Mix 1 and Mix 2, respectively. The 2 chemometric methods did not require any separation step. These methods were successfully applied for the analysis of the 2 multicomponent combinations in synthetic mixtures and in commercial syrups, and the results were compared with each other.     

Mixed ligand complexes with 2-piperidine-carboxylic acid as primary ligand and ethylene diamine, 2,2′-bipyridyl, 1,10-phenanthroline and 2(2′-pyridyl)quinoxaline as secondary ligands: preparation,characterization and biological activity

Synthesis procedures are described for the new stable mixed ligand complexes, [Pd(Hpa)(pa)]Cl, [Pd(pa)(H₂O)₂]Cl, [Pd(pa)(en)]Cl, [Pd(pa)(bpy)]Cl, [Pd(pa)(phen)Cl], [Pd(pa)(pyq)Cl], cis-[MoO₂(pa)₂], [Ag(pa)(bpy)], [Ag(pa)(pyq)], trans-[UO₂(pa)(pyq)](BPh₄) and [ReO(PPh₃)(pa)₂]Cl (Hpa = 2-piperidine-carboxylic acid, en = ethylene diamine, bpy = 2,2′-bipyridyl, phen = 1,10-phenanthroline, pyq = 2(2′-pyridyl)quinoxaline). Their elemental analyses, conductance, thermal measurements, Raman, IR, electronic, ¹H-n.m.r. and mass spectra have been measured and discussed. 2-Piperidine-carboxylic acid and its palladium complexes have been tested as growth inhibitors against Ehrlich ascites tumour cells (EAC) in Swiss albino mice.     

Characterization of interfering effects in the determination of molybdenum by atomic absorption spectrometry

The effect of anions on molybdenum absorbance depends on the pH; low pH causes the formation of iso- or heteropoly anions which change the atomization process in the flame. Organic ligands also depress the release of molybdenum atoms but cyanide radicals in the flame scavenge, e.g., OH radicals from such ligands and prevent their depressive effect. Certain cations (La, Ce, Mg, Ca, Sr and Ba) appear to form spinels; boric acid minimizes this effect.     

Photocatalytic effect of nano-TiO<Subscript>2</Subscript> loaded cement on dye decolorization and <Emphasis Type="Italic">Escherichia coli</Emphasis> inactivation under UV irradiation

In the present study, titanium dioxide (TiO₂) nano-particles were synthesized by sol–gel technique and then used to provide nano-TiO₂ loaded cement samples at 1, 5, and 10 wt% for investigation of Malachite green pigment decomposition and Escherichia coli inactivation under UV irradiation. Surveys conducted on the synthesized TiO₂ nano-particles showed a 100 % anatase phase with a mean particle size of 66.5 nm, surface area of 64.352 m² g^?1, and a porosity volume of 0.1278 cm³ g^?1. Cement samples containing this catalyst exhibited stronger photocatalytic properties as compared to the same amount of pure catalyst. Considering both photocatalytic performance and cost of catalyst, 5 wt% titanium dioxide was suggested to be added to cement. By addition of 1 wt% polycarboxylic copolymer as super-plasticizer to the cement paste, the photocatalytic sample activities were reinforced so that a similar performance could be obtained at 1 wt% catalyst as compared to 5 wt% catalyst without super-plasticizer.     

Some Characterizations of Integral Operators Associated with Certain Classes of <Emphasis Type="Italic">p</Emphasis>-Valent Functions Defined by the Srivastava–Saigo–Owa Fractional Differintegral Operator

The purpose of this paper is to introduce new integral operators associated with Srivastava–Saigo–Owa fractional differintegral operator. We investigate some properties for the integral operators \({\mathcal {F}}_{p,\eta ,\mu }^{\lambda ,\delta }(z)\) and \({\mathcal {G}}_{p,\eta ,\mu }^{\lambda ,\delta }(z)\) to be in the classes \({\mathcal {R}}_{k}^{\zeta }\left( p,\rho \right) \) and \({\mathcal {V}}_{k}^{\zeta }\left( p,\rho \right) \).     

Development and Validation of LC Method for Simultaneous Determination of Two Binary Mixtures Containing Indapamide

A new sensitive, simple, rapid, and precise RP LC method with hydrochlorothiazide as internal standard has been developed for resolving two binary mixtures, perindopril with indapamide and captopril with indapamide, in pharmaceutical formulations. The drugs were separated at room temperature on a 250 mm × 4.6 mm, 5-μm particle, cyanopropyl column with 10 mm KH₂PO₄, pH 6.0-methanol 55:45 (v/v) as mobile phase at a flow rate of 1 mL min^?1. Detection was at 210 nm. Factors affecting the separation process were studied and optimized. The linearity, accuracy, and precision of the method were good, and the method was successfully applied to the determination of the two binary combinations in synthetic mixtures and commercial pharmaceutical products.