Organophosphorus chemistry,XII. Reaction of furil with alkyl phosphites and ylide-phosphoranes

Summary The reaction of furil (1) with trialkyl phosphites2 yielded caged phosphorane derivatives of types3a-c. Dry hydrogen chloride gas converted3a-c into the respectivea-hydroxyvinyl-phosphates8a-c which are equally produced by reacting furil with the appropriate dialkyl phosphite7. The reaction of furil with ylide-phosphoranes10 proceeded according to the Wittig reaction mechanism to give the respective ethylenes11a-c. The new compounds have been characterized by their spectroscopic data (IR, PMR,³¹P-NMR, MS) and elementary analyses.Dedicated to Prof. M. Sidky on the occasion of his 60th birthday     

Preparation of cellulose and cellulose derivative azo compounds

Wood pulp and cotton linter are the most common sources of cellulose forindustrial use. Methyl cellulose (MC) and cellulose sulfate (CS) were preparedusing bleached wood pulp and cotton linter. Coloured azo compounds were alsoprepared from coupling cellulose, wood pulp, MC and CS with aromatic diazoniumsalt. The presence of electron-releasing or withdrawing substituents affectedthe electrophilic substitution reaction. The produced azo compounds werecharacterized by FT-IR methodology, as well as mass spectrometry, in which thefunctional groups and the ion fragments of the products were analyzed.     

Polarographic behaviour and determination of paracetamol and salicylamide after treatment with nitrous acid

A polarographic procedure is described for the determination of paracetamol (acetaminophen) and salicylamide after treatment with nitrous acid. The different experimental parameters affecting the derivatization process and the polarographic analysis were studied. The derivatization products were found to be reduced at the dropping mercury electrode over the whole pH range in Britton-Robinson buffers. At pH 7.0, well defined diffusion-controlled cathodic waves were produced for both compounds. Plots of limiting current vs. concentration were linear over the ranges 0.05–0.75 and 0.25–1.5mM for paracetamol and salicylamide, respectively, in the d.c. mode, with minimum detectability of 2.5 × 10^–6 and 1.25 × 10^–5 M, respectively. The procedure was applied to the analysis of some pharmaceutical dosage forms and the results were in good agreement with those obtained by official and compendial methods.     

Synthesis of proteophosphoglycans of Leishmania major and Leishmania mexicana

A novel approach for the synthesis of various fragments of proteophosphoglycans from Leishmania major and Leishmania mexicana proteophosphoglycans has been developed. These compounds have been obtained by coupling alpha-mannosyl and alpha-N-acetyl-glucosamine phosphoramidite derivatives with the serine hydroxyl of various amino acids and peptides to give, after oxidation with tert-BuOOH, phosphotriesters exclusively as alpha-anomers in good yield. The resulting compounds could be deblocked using conventional methods. Glycophosphorylation of preassembled and properly protected peptides was found to be more efficient for the preparation of proteophosphoglycan fragments than a building block approach strategy using a phosphoglycosylserine derivative.     

Application of Alizarine Derivatives as Chromogenic Reagents for the Spectrophotometric Determination of Some Sulfa Drugs

A spectrophotometric procedure for the determination of six pharmaceutical sulfonamides containing a primary aromatic amino group using alizarine (I), alizarine blue (II), alizarine red (III), and quinalizarine (IV), that offers advantages of simplicity, rapidity, sensitivity, precision, and stability, has been developed. The proposed method is based on the formation of colored products with the chromogenic reagents (I-IV). A linear correlation was found between absorbance at λ_max and the concentration. For more accurate results, Ringbom optimum concentration ranges are evaluated. The molar absorptivities (ε), absorptivities (a), and Sandell sensitivities for all sulfonamides derivatives with the chromogenic reagents tested were calculated. The procedures developed are applied for bulk sulfa drugs and some of their dosage forms.     

Brightly phosphorescent trinuclear copper(I) complexes of pyrazolates: substituent effects on the supramolecular structure and photophysics

Synthetic details, solid-state structures, and photophysical properties of a group of trimeric copper(I) complexes containing pyrazolate ligands are described. The reaction of copper(I) oxide and the fluorinated pyrazoles [3-(CF(3))Pz]H, [3-(CF(3)),5-(Me)Pz]H, and [3-(CF(3)),5-(Ph)Pz]H leads to the corresponding trinuclear copper(I) pyrazolates, {[3-(CF(3))Pz]Cu}(3), {[3-(CF(3)),5-(Me)Pz]Cu}(3), and {[3-(CF(3)),5-(Ph)Pz]Cu}(3), respectively, in high yield. The {[3,5-(i-Pr)(2)Pz]Cu}(3) compound was obtained by a reaction between [Cu(CH(3)CN)(4)][BF(4)], [3,5-(i-Pr)(2)Pz]H, and NEt(3). These compounds as well as {[3,5-(Me)(2)Pz]Cu}(3) and {[3,5-(CF(3))(2)Pz]Cu}(3) adopt trimeric structures with nine-membered Cu(3)N(6) metallacycles. There are varying degrees and types of intertrimer Cu...Cu interactions. These contacts give rise to zigzag chains in the fluorinated complexes, {[3-(CF(3))Pz]Cu}(3), {[3-(CF(3)),5-(Me)Pz]Cu}(3), {[3-(CF(3)),5-(Ph)Pz]Cu}(3), and {[3,5-(CF(3))(2)Pz]Cu}(3), whereas the nonfluorinated complexes, {[3,5-(Me)(2)Pz]Cu}(3) and {[3,5-(i-Pr)(2)Pz]Cu}(3) form dimers of trimers. Out of all the compounds examined in this study, {[3-(CF(3)),5-(Ph)Pz]Cu}(3) has the longest (3.848 Angstroms) and {[3,5-(Me)(2)Pz]Cu}(3) has the shortest (2.946 Angstroms) next-neighbor intertrimer Cu...Cu distance. The Cu...Cu separations within the trimer units do not vary significantly (typically 3.20-3.26 Angstroms). All of these trinuclear copper(I) pyrazolates show bright luminescence upon exposure to UV radiation. The luminescence bands are hugely red-shifted from the corresponding lowest-energy excitations, rather broad, and unstructured even at low temperatures, suggesting metal-centered emissions owing to intertrimer Cu...Cu interactions that are strengthened in the phosphorescent state. The {[3-(CF(3)),5-(Ph)Pz]Cu}(3) compound exhibits an additional highly structured phosphorescence with a vibronic structure corresponding to the pyrazolyl (Pz) ring. The luminescence properties of solids and solutions of the trimeric compounds in this study show fascinating trends with dramatic sensitivities to temperature, solvent, concentration, and excitation wavelengths.     

Electrochemical characterization and stress corrosion cracking behavior of α-brass in molybdate-containing electrolytes

One of the major challenges in material design is the achievement of reasonable operational efficiency through understanding the factors affecting the material’s performance particularly strength and service lifetime characteristics. In this work, the electrochemical behavior of 72Cu–28Zn α-brass alloy in Na₂MoO₄-containing electrolytes was investigated using potentiodynamic polarization and electrochemical frequency modulation techniques complemented with scanning electron microscopy. Also, stress corrosion cracking behavior of the alloy under both open-circuit potential and anodic applied potentials, using the slow strain rate technique, was evaluated. The results drawn from the different techniques are comparable.     

Sensing and photocatalytic properties of nanosized Cu(I)CN organotin supramolecular coordination polymer based on pyrazine

Orange prismatic crystals of the supramolecular coordination polymer (SCP) _∞³[Cu(CN)₂(Me₃Sn)(Pyz)], SCP 1 , were synthesized using a self‐assembly method under ambient conditions. Nanosized 1 was obtained using the same molar ratio in water by ultrasonic irradiation. SCP 1 was characterized using single‐crystal X‐ray diffraction, elemental analysis, thermal analysis and Fourier transform infrared spectroscopy. SCP 1 and its nanosized 1 particles were also examined using powder X‐ay diffraction and scanning electron microscopy. The luminescence emission of SCP 1 was studied as well as its use as a sensor for the detection of common organic solvents and metal ions. Also, the catalytic activities of nanosized 1 towards various organic dyes were investigated under ambient conditions, UV irradiation and ultrasonic irradiation. Nanosized 1 as a heterogeneous nanoparticle catalyst exhibits high catalytic activity for the degradation of eosin‐Y and acid blue dyes. The mechanism of degradation investigated using various scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals.     

Two validated chromatographic determinations of an antifungal drug,its toxic impurities and degradation product: A comparative study

Tolnaftate, a thionoester anti‐fungal drug, was subjected to alkaline hydrolysis to produce methyl(m‐tolyl)carbamic acid and β ‐naphthol (tolnaftate impurity A). N‐Methyl‐m‐toluidine, tolnaftate impurity D, was synthesized and structurally elucidated along with tolnaftate alkaline degradation products using IR, H¹NMR and MS. Two stability‐indicating HPTLC and RP‐HPLC methods were developed and validated, for the first time, for determination of tolnaftate, its alkaline degradation products and toxic impurities in the presence of methyl paraben, as a preservative in Tinea Cure^® cream. The proposed HPTLC method depended on separation of the studied components on TLC silica gel F₂₅₄ plates using hexane–glacial acetic acid (8:2, v/v) as a developing system and scanning wavelength of 230 nm. The proposed RP‐HPLC method was based on separation of the five components on an Eclipse plus C₁₈ column. The mobile phase used was acetonitrile–water containing 1% ammonium formate (40:60, v/v), with a flow rate of 1 mL/min and detection wavelength of 230 nm. The proposed methods allowed the assay of tolnaftate toxic impurities, β ‐naphthol and N‐methyl‐m‐toluidine, down to 2%, allowing tracing of β ‐naphthol that could be absorbed by the skin causing systemic toxic effects, unlike tolnaftate, indicating the high significance of such determination. International Conference on Harmonization guidelines were followed for validation.     

Synthesis and Antibacterial Activity of Some New S-Triazole Derivatives

Abstract

Alkylation of 4-anilino-5-phenyl-4H-1,2,4-triazole-3-thiol (1) with some halo compounds yielded the corresponding sulfides 2a–f. Some sulfides 2e,f were cyclized to give triazolothiadiazines 3 and 4. Triazolothiadiazoles 5 and 6 were prepared through the reaction of compound 1 with carbon disulfide or ethyl orthoformate, respectively. Treatment of compound 1 with ethyl chloroformate or phenyl isothiocyanate yielded triazolo-thiadiazole and triazole 9 and 10, respectively. Reaction of compound 1 with Lawesson's reagent gave triazolothiadiazaphosphole derivative 11. Also, compound 1 underwent cyclocondensation reactions with some bidentate reagents to give triazolothiazines 4, 12, and 13. Triazolo-thiazepines and triaziepine 14–16 were synthesized via the reaction of compound 1 with β-ketoesters or ethyl cyanoacetate. Tricyclic systems 19 and 20 were prepared through the reaction of compound 4 with the appropriate reagent. Some synthesized compounds were tested for antibacterial activity.

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