Synthesis and molecular structures of 1‐boracyclopent‐2‐enes

The reaction of 1‐silyl‐1‐borylalkenes with alkyn‐1‐yltin compounds affords borol‐2‐enes, organometallic‐substituted allenes, mixtures thereof or even more complex mixtures with buta‐1,3‐dienes, depending on the third substituent at the C?C bond (Bu or Ph), on the number of Si? Cl functions (two or three) and the nature of the alkyn‐1‐yltin compound. Six new borol‐2‐enes were isolated in pure state, and two of them were characterized by X‐ray structural analysis. The solution‐state structures of all major products were clearly established by multinuclear magnetic resonance methods (¹H, ¹¹B, ¹³C, ²⁹Si, ¹¹⁹Sn NMR). Copyright © 2009 John Wiley & Sons, Ltd.     

Microfabricated Solid-contact Potentiometric Sensor for Determination of Tedizolid Phosphate,Application to Content Uniformity Testing

Solid contact sensors were designed for determination of the antibiotic prodrug tedizolid phosphate. The sensors are based on; microfabricated copper as cost-effective electrode substrate and graphene layer as a transducer. The ion sensing PVC polymeric membrane was optimized by proper selection of the anion exchanger. The graphene layer was characterized by scanning electron microscopy, Raman spectroscopy, FT-IR, besides measuring electrochemical impedance for the fabricated sensors. The potential drift decreased down to 0.133 mV h⁻¹ compared to 6.67 mV h⁻¹ for graphene free sensor. The sensors have been used to determine tedizolid phosphate in its pharmaceutical formulation and content uniformity testing applications.     

Potentiometric titrimetry for the simultaneous quantification of ticarcillin and clavulanic acid in bulk and injectable dosage forms

Summary A direct potentiometric procedure for the simultaneous determination of ticarcillin and clavulanic acid in binary mixtures and injectable dosage formulations has been developed. Adoption of non-aqueous potentiometry, using 0.1 mol/l acetic HClO₄, enables the simultaneous quantification of the two named drugs in a single sample run. Recovery of each individual drug was found fairly satisfactory on the application to clavulanate-potentiated ticarcillin (100.86% for ticarcillin and 101.47% for clavulanic acid).     

State space approach to unsteady magnetohydrodynamics natural convection heat and mass transfer through a porous medium saturated with a viscoelastic fluid

A technique of the state space approach and the inversion of the Laplace transform method are applied to dimensionless equations of an unsteady one-dimensional boundary-layer flow due to heat and mass transfer through a porous medium saturated with a viscoelastic fluid bounded by an infinite vertical plate in the presence of a uniform magnetic field is described. Complete analytical solutions for the temperature, concentration, velocity, and induced magnetic and electric fields are presented. The inversion of the Laplace transforms is carried out by using a numerical approach. The proposed method is used to solve two problems: boundary-layer flow in a viscoelastic fluid near a vertical wall subjected to the initial conditions of a stepwise temperature and concentration and viscoelastic fluid flow between two vertical walls. The solutions are found to be dependent on the governing parameters including the Prandtl number, the Schmidt number, the Grashof number, reaction rate coefficient, viscoelastic parameter, and permeability of the porous medium. Effects of these major parameters on the transport behavior are investigated methodically, and typical results are illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity, temperature, concentration, and induced magnetic and electric field distributions, as well as the local skin-friction coefficient and the local Nusselt and Sherwood numbers.     

Chemical and biological study of the seeds of Eragrostis tef (Zucc.) Trotter

A chemical study of the red type of the seeds of Eragrostis tef (Zucc.) Trotter (Poaceae) led to the isolation of seven compounds from its ethanol extract, namely β-sitosterol (1), β-amyrin-3-O-(2'-acetyl(glucoside (2), β-sitosterol-3-O-β-D-glucoside (3), naringenin (4), naringenin-4'-methoxy-7-O-α-L-rhamnoside (5), eriodictyol-3',7-dimethoxy-4'-O-β-D-glucoside (6) and isorhamnetin-3-O-rhamnoglucoside (7), which are reported for the first time in the genus Eragrostis. This is the first report for the isolation of compounds (2) and (6) in nature. The isolated compounds were identified using different spectroscopic methods (EIMS, UV, 1H NMR, 13C NMR, HMQC and HMBC). A proximate analysis revealed the high nutritive value of the seeds: carbohydrates (57.27%), protein (20.9%), essential amino acids (8.15%) with major leucine and lysine (1.71 and 1.35%, respectively), vitamin B? (1.56?mg/100?g) and potassium and calcium (32.4 and 9.63%, respectively). The seeds yielded 22% w/w of fixed oil rich in unsaturated fatty acids (72.46%), among which oleic acid, was predominant (32.41%), followed by linolenic acid (23.83%). The ethanolic extract and fixed oil of the seeds exhibited anti-hyperlipedaemic and anti-hyperglycaemic activities. Oral administration of the fixed oil for 10 days resulted in a rise in serum calcium levels in rats.     

UV, 1H NMR Studies and a Semiempirical Mo Calculations of Some Substituted Phenylthiomethyl Benzoic Acid Derivatives

The effect of substituents on the spectral behavior of some arylthiomethyl benzoic acid derivatives, the corresponding sulfoxides and sulfones were studied. The chemical shifts of ortho hydrogen of benzyl moieties gave linear correlations with Hammett constants for acid sulfides and concave curves for sulfide esters. The effect of substituents on the conformation of sulfides were discussed.     

Spectral Characterization of Some Phenylazodihydroxy Naphthalene Derivatives

A series of azo dyes namely: 4-phenylazo-1,3-dihydroxynaphthalene 1, 4-phenylazo-1,5-dihydroxynaphthalene 2, 1-phenylazo-2,8-dihydroxynaphthalene 3, 1-phenylazo-2,3-dihydroxynaphthalene 4 and 1-phenylazo-2,7-dihydroxynaphthalene 5 have been prepared and their UV, IR, NMR and mass spectra are recorded. The spectra have been analysed to give a complete picture of the hydroxyazo-quinone hydrazone tautomerism present in these class of compounds. It is found that dyes 1, 2 and 4 exhibit quinone hydrazone tautomerism while dyes 3 and 5 exist as a mixture of hydroxyazo and quinone hydrazone tautomers. The change due to a second hydroxyl group in the naphthalene moiety is compared with azonaphthols. The fragmentation process in the mass spectra displays C-N and -N = N-cleavage and indicated that the two tautomers are present except in dye 2 which exhibits a quinone hydrazone form.     

Equilibrium and hydrolysis of α-amino acid esters in mixed-ligand complexes with diethylenetriaminepalladium(II)

Summary The mixed-ligand complexes of palladium(II) containing diethylenetriamine as a primary ligand and -amino acid esters as secondary ligands were studied using potentiometric and conductometric techniques. The equilibrium and/or stability constants of the binary and mixed-ligand complexes formed were determined. The kinetics of base hydrolysis of the above esters in the presence and absence of Pd^II-dien complexes were studied at 30°C. The rate and catalysis constants were determined.