European Journal of Chemistry

The reaction between monoazido derivatives of 1,3,5-triazine and CH-active carbonyl compounds were studied in order to obtain novel coupled heterocyclic systems with potential bioactivity. Reaction conditions were varied and optimized, a series 2,4-disubstituted derivatives of 6-(1H-1,2,3-triazol-1-yl)-1,3,5-triazines were obtained with good yield.

In recent times, hyperuricaemia has been widely diagnosed in individuals due to changes in lifestyle and as a result of disease conditions that lead to elevated levels of uric acid in the blood. Our present work is on determination of the levels of uric acid in healthy individuals and patients with type 2 diabetes mellitus. Prevalence of hyperuricaemia in relation to age, gender and disease condition was monitored. The results indicated that, levels of uric acid are much higher in subjects that have a combined case of hyperuricaemia and type 2 diabetes mellitus.

A novel fluorescent co-polymer with an organoboron quinolate and an E-BODIPY (BODIPY: 4,4-difluoro-4-bora-3a-4a-diaza-s-indacene) moiety was synthesized with the aim of producing a donor-acceptor polymeric system where the organoboron quinolate acts as the donor and the E-BODIPY moiety is the acceptor. The polymer has three prominent absorption bands: 264 nm (corresponding to the organoboron quinolate), 397 nm (corresponding to the organoboron quinolate and BODIPY) and 516 nm (corresponding to the E-BODIPY moiety). Excitation of the organoboron quinolate at 264 nm resulted in emission at 525 nm, giving a 261 nm Stokes shift. Energy transfer from the donor (organoboron quinolate) unit to the acceptor (BODIPY) explains the origin of this large Stokes shift.

The novel compound, 2-methoxy-4,6-bis(4-nitrophenoxy)-1,3,5-triazine has been synthesized starting from 2,4,6-trichloro-1,3,5-triazine and characterized by ¹H NMR, ¹³C NMR, IR, mass spectroscopy and elemental analysis. The single crystal of the title compound was obtained and subjected to X-ray diffraction analysis. The single crystal data illustrates that it belongs to the monoclinic system, space group C2/c with a = 13.818(3) Å, b = 7.8964(16) Å, c = 30.718(6) Å, β = 96.52(3) ^o, V = 3330.0(12) ų, Z = 8, D_c = 1.537 g/cm³, C₁₆H₁₁N₅O₇, Mr = 385.30, µ (MoKα) = 0.124 mm⁻¹, F(000) = 1584, the final R = 0.0489 and wR = 0.1821 for 2491 observed reflections with I>2σ(I).

Bis-pyrazoline darivatives (2a-e) built around the alkyl chains of varying length were synthesized in good yield by refluxing bis-chalcones (1a-e) with phenyl hydrazine in CH₃COOH and ethanol. The structures of these compounds were elucidated by IR, ¹H NMR, ¹³C NMR, Mass (ESI) spectrometries and their purities were confirmed by elemental analyses. The antibacterial activity of these compounds were evaluated by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria and then the minimum inhibitory concentration of compounds were determined. The compounds 1,4-bis[1-(2-oxyphenyl)-5-(furan-2-yl)-4,5-dihydro-1H-pyrazole] butane (2a) and 1,10-bis[1-(2-oxyphenyl)-5-(furan-2-yl)-4,5-dihydro-1H-pyrazole]decane (2e) are better antibacterial agent as compared to Tetracycline and Gentamicin.

A short, highly efficient synthesis of advanced intermediates to reserpine 1 has been developed starting from enamide 8. The enamide underwent photocyclization reaction using high pressure mercury lamp to afford the lactam 9 in excellent yield. Then lactam was reduced to the required amine 10, which upon acidic hydrolysis gave the nonconjugate ketone product 11, followed by reaction with sodium hydroxide resulted the desired conjugate ketone 12. Epoxidation, and then ring opening of the epoxide 13 with methanol yielded the desired product 14, which is key intermediate to the total synthesis of (±)-reserpine.

Structure and superficial properties of tectosilicates found in soils with potential to retain uranium are studied in this work. These tectosilicates are largely available as natural minerals in the soil and are composed mainly by anorthite (CaAl₂Si₂O₈), albite (NaAlSi₃O₈) and orthoclase (KAlSi₃O₈), in which albite has approximately 3 times the content of orthoclase and 2.5 times the content of anorthite. However, anorthite has a double cell structure, which could result in approximately the same sorption effect as albite. The acidity constants calculated with the surface complexation model suggested that the three components have similar amphoteric behavior in presence of high ionic strength ground salt solutions. The composite mineral has a specific surface area of 20.5 m²g^-1 with site density of 2.8 sites nm^-2. These characteristics make this mineral a good candidate for uranium capture.

We report the synthesis of bis(4-bromo-N-(diethylcarbamothioyl)benzamido)nickel(II) complex of an benzoylthiourea derivative formulated as C₂₄H₂₈Br₂NiN₄O₂S_2. The structure of compound has been determined by single-crystal X-ray diffraction analysis. It crystallizes in the monoclinic space group, P2₁/c with unit cell dimensions of a = 12.9099(17) Å, b = 15.264(2) Å, c = 14.0287(19) Å, β = 92.140(4)^o and V = 2762.5(6) ų.  In this compound, the nickel atom is coordinated by two sulphur and two oxygen atoms from two 4-bromo-N-(diethylcarbamothioyl)benzamide molecules forming an distorted square-planar geometry.

A novel, sensitive and convenient method for the determination of tizanidine hydrochloride (TZD) based on the fluorescence quenching of thioglycolic acid-capped CdS quantum dots (TGA-CdS QDs) is proposed. Luminescent CdS semiconductor quantum dots modified by thioglycolic acid were synthesized from cadmium nitrate and sodium sulfide in alkaline aqueous solution. The modified CdS QDs are water-soluble, stable and highly luminescent. When TZD was added into the CdS QDs colloidal solution, the surface of CdS QDs generates the electrostatic interaction in aqueous medium, which induces the quenching of fluorescence emission at 518 nm upon excitation at 340 nm. Under the optimal conditions, the Stern-Volmer calibration plot of F­_ο/F against concentration of TZD was linear in the range of 3.0-18.0 μg/mL with a correlation coefficient of 0.9953. The detection limit was 1.35 μg/mL. The relative standard deviation for five determinations of 9 μg/mL TZD was 2.29%. The proposed method was successfully applied to commercial tablets with satisfactory results. The results were found to be in good agreement with those obtained by the reference method. The possible fluorescence quenching mechanism for the reaction is also discussed.

Aniline derivatives were diazotized and coupled with 3-aminocrotononitrile to give the corresponding 2-arylhydrazono-3-ketiminobutyronitriles. Cyclization of these arylhydrazono derivatives with hydrazine monohydrate afforded 5-amino-4-arylazo-3-methyl-1H-pyrazoles which were subsequently diazotized and coupled with malononitrile to yield a series of pyrazolylhydrazonomalononitriles. These compounds were then reacted with hydrazine monohydrate to provide, heterocyclic dyes, which were further diazotized and coupled with 4-hexylbenzene-1,3-diol to produce novel heterocyclic tetraazo dyes which were characterized by elemental analysis and spectral methods. The antimicrobial activity and absorption characteristics of the dyes were also examined in detail.

An efficient synthesis of 7-amino-9-hydroxy-6-oxo-6H-benzo[c]chromene-8-carbonitrile derivatives (2,6) and 4-methyl-2-oxo-2H-chromene-3-carbonitrile (5) via Claisen condensation of 2-hydroxyacetophenones (1,3) with ethyl cyanoacetate in the presence of sodium metal is reported. Reaction of 5 with thiosemicarbazide gave 1-(3-cyano-4-methyl-2-oxoquinolin-1(2H)-yl)thiourea (7). Treatment of 5 with 6,8-dichloro-4-oxo-4H-chromene-3-carboxaldehyde gave 4-(2-(6,8-dichloro-4-oxo-4H-chromen-3-yl)-2-hydroxyethyl)-2-oxo-2H-chromene-3-carbonitrile (9). Further treatment of 5 with ethyl acetate followed by condensation with 6,8-dichloro-3-formylchromone gave 7-((6,8-dichloro-4-oxo-4H-chromen-3-yl)methyleneamino)-9-hydroxy-6H-benzo[c]chromen-6-one (12). Structures of the products were established on the basis of elemental analysis, IR, ¹H and ¹³C NMR, mass spectra and semi-empirical AM1-MO calculations. The antimicrobial activities of the synthesized products were also studied.

9,17-Diaza-2,6,11,15-tetrathia-1,7,10,16-(1,2)-tetrabenzenacyclooctadecaphan-8,17-diene, macrocycle was synthesized, thereafter formulation and designing strategies applied for the preparation of coordination entities of Co(II) and Ni(II). Coordination behaviour of N₂S₄ donor macrocycle towards metal ion(s) was assessed by physiochemical measurements and spectral investigations viz. elemental analysis, molar conductance, magnetic susceptibility measurements, infrared, UV-Vis, ¹H and ¹³ C NMR, mass spectroscopy, electron paramagnetic resonance (EPR), cyclic voltammetry and molecular modeling. Side-by-side comparison of the spectral findings exposed different geometrical aspects of macrocycle and coordination entities. Cyclic voltammogram showed fully oxidized and reduced species in one unified experiment. Macrocycle and coordination entities were screened for antimicrobial effectiveness (antifungal properties against Aspergillus-niger).

Compound, 2-cyano-3-(2^ˊ,4ˊ-dichlorophenyl)-2-prpoenoyl chloride, 3, was reacted with nitrogen, sulfur, and oxygen nucleophilic reagents to give new 2-propenoyl amide and ester derivatives. Some of these derivatives were cyclized under the reaction conditions and/or with POCl₃ or Ac₂O to give new derivatives of heterocyclic systems. Some of these compounds were tested as antibacterial and antifungal agents.

The electrical conductance of nicoitinium dichromate has been measured in water-N,N-dimethyl formamide mixtures of different compositions in the temperature range 283-313 K. The limiting molar conductance, L_o and the association constant of the ion-pair, K_A have been calculated using Shedlovsky equation. The effective ionic radii (r_i) of (C₆H₆O₂)⁺ and (C₆H₆O₂NCr₂O₇)^- ions have been determined from L_i^o values using Gill’s modification of the Stokes law. The influence of the mixed solvent composition on the solvation of ions has been discussed with the help of ‘R’-factor. Thermodynamic parameters are evaluated and reported. The results of the study have been interpreted in terms of ion-solvent interactions and solvent properties.

The effects of solvents of various polarity on the electronic absorption and fluorescence spectra of 7-hydroxy-4-trifluoromethyl coumarin; 6,7-dihydroxy-4-trifluoromethyl coumarin and 7-methoxy-4-trifluoromethyl coumarin have been investigated. The singlet-state excited dipole moments (μ_e) and ground state dipole moments (μ_g) are estimated from Bakshiev and Kawski-Chamma-Viallet equations by using the variation of Stokes’ shift with the solvent’s dielectric constant (ε) and refractive index (n). The observed singlet-state excited dipole moments are found to be larger than the ground-state ones. In addition, the geometry and other electronic properties are computed using ab-initio method with correlation functions at 6-31G basis set.

The formation of isolated and fused benzo[f]chromene derivatives was achieved via reacting ethyl 3-amino-1-phenyl-1H-benzo[f]chromene-2-carboxylate (1) with some selected reagents under basic conditions. The new compound, ethyl 3-(dimethylaminomethyleneamino)-1-phenyl-1H-benzo[f]chromene-2-carboxylate  (2) was prepared from compound 1 and N,N-dimethyl formamide in presence of phosphorus oxychloride under mild conditions in excellent yield using Vilsmeier reaction. Also, 10-amino-12-phenyl-9-sulfanyl-12H-benzo[f] chromeno[2,3-d]pyrimidine-11(10H)-one (12), 10-aryl-14-phenyl-14H-benzo[f]chromeno [2,3-d][1,3,4]thiadiazolo[3,2-a]pyrimidine-13-one (15), ethyl 3-(4-oxo-2-thioxothiazolidin-3-yl)-1-phenyl-1H-benzo[f]chromene-2-carboxylate (18), ethyl 3-(4-phenyl-2-thioxothiazol-3(2H)-yl)-1-phenyl-1H-benzo[f]chromene-2-carboxylate (20), ethyl 3-acetamido-1-phenyl-1H-benzo[f]chromene-2-carboxylate (21), and 10-amino-9-methyl-12-phenyl-12H-benzo[f] chromeno[2,3-d]pyrimidine-11(10H)-one (23) were prepared. The structures of these compounds were established by elemental analysis, IR, MS and NMR spectral analy­sis.

In the present work, the effect of solvents on absorption and fluorescence spectra and dipole moments (μ_g, μ_e) of 7-diethylamino coumarin (7DEAC) and 7-diethylamino-4-methyl coumarin (7DEA4MC) have been studied in different solvents of various polarity at room temperature. The solvents have been selected in a way to cover the full range of intermolecular interactions from non-polar hexane to strongly polar formamide. Using the methods of solvatochromism, the difference in the first excited singlet-state (μ_e) and ground state (μ_g) dipole moments was estimated from Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet and McRae equations. The Onsager’s cavity radius of the probes has been calculated by AM1 and PM3 quantum chemical calculations and also by a direct relation. The change in dipole moment value (Δμ) was also calculated by using the variation of Stoke’s shift with microscopic solvent polarity parameter (E_T^N). The calculated dipole moments represent new results, as well as some of the solvatochromic results that were not studied earlier in such large number of solvents. It is observed that the values of excited singlet-state dipole moments are higher than the ground state ones in both the molecules, which shows that excited states are more polar than the ground states.

Pyrimidine is the parent substance of a large group of heterocyclic compounds and plays a vital role in many biological processes. It is also evident from literature; pyrimidines possess potential anti oxidant activities and cytotoxic activities. Chemoprotection by pyrimidines may be a consequence of their antioxidant properties, mediated via inhibition or induction of metabolic enzymes, by an anti-invasive effect or a reduction in nitric oxide production.  Free radicals are formed constantly in human system either as accidental products during metabolism or deliberately during the process of phagocytosis; or due to environmental pollutants, ionizing radiations, ozone, heavy metal poisoning, etc. Therefore, it is worthwhile to synthesize some pyrimidine derivatives by conventional and microwave (Catalyst systems) assisted synthesis methods. The synthesized compounds were purified by recrystallization or by chromatography and are characterized by ¹H NMR, ¹³C NMR and IR analysis. The compounds were tested for their potential cytotoxic activity and antioxidant activities by standard methods. The microwave irradiation method (MWI) is proved to be advantageous with considerable increase in the reaction rate with better yields, after over all observation it is found  that pyrimidine derivatives possessing cytotoxic and anti-oxidant activities.

This paper describes the versatile nature of clay that was obtained from Suez Gulf, Suez city, Egypt, as a new low cost natural resource which is non toxic to ecosystem and highly effective adsorbent material. The properties of the natural clay and its significance in removing Th(IV) and Ce(IV) as a representative of tetravalent actinides and lanthanides, respectively, La(III) as a representative of trivalent lanthanides as well as homologues of americium and Sr(II) as one of the fission products, in aqueous solutions have been studied, in order to consider its application for nuclear waste treatment. Batch experiments have been carried out to determine the effect of various factors such as initial metal ion concentration, clay dose, pH, contact time, and temperature on the adsorption process. The results have dictated that, the adsorption efficiency of the natural clay was significantly high at pH = 4. Maximum metal ion uptake capacity of clay has been obtained from batch studies was 99.24, 98.21, 77.76 and 57.94% for Th(IV), Ce(IV), La(III) and Sr(II), respectively. The thermodynamic parameters (ΔH^o, ΔS^o and ΔG^o) have been calculated from the temperature dependent adsorption isotherms. Furthermore, separation factors (α) have been calculated in order to separate these elements from each other at pH = 4.

Synthesis of heterocyclic compounds like benzothiazines has attracted attention in recent years due to their biological and industrial value. This article reflects up-to-date and comprehensive coverage of biochemical aspects of benzothiazines, their sulfones and ribofuranosides. The nitrogen and sulfur containing heterocycles were prepared by condensation followed by oxidative cyclization of 2-aminobenzenethiol with β-diketones/β-ketoesters in dimethylsulfoxide. These compounds were then used as base to prepare ribofuranosides by treating them with sugar (β-D-ribofuranose-1-acetate-2,3,5-tribenzoate). On refluxing with hydrogen peroxide in glacial acetic acid, these substituted dimethyl 4H-1,4-benzothiazines yielded 4H-1,4-benzothiazine-1,1-dioxides. Antioxidant and antimicrobial activity of these compounds were carried out and structure evaluation was done by spectral and elemental analysis.

Carmosine is mainly used as a colorant in food industries. The oxidative decolorization of this dye is of greater significance and understanding of its kinetic and mechanistic aspects in redox reactions is important. Chloramine-T bears diverse chemical properties and has been exploited as oxidant for a variety of substrates. It is commercially available, inexpensive, non toxic, water tolerant and easy to handle. A systematic kinetic study of the oxidation of carmosine with acidic chloramine-T (CAT: TsNClNa here Ts = CH₃C₆H₄SO₂^-) has been carried out in order to explore the mechanistic aspects of this redox system. UV-Visible spectrophotometry is used to monitor the reaction. Optimum conditions for the oxidative decolorization of carmosine with CAT were established. The kinetic results revealed that the reaction rate exhibits a first-order dependence each on [CAT]_o and [carmosine]_o and less than unit order dependence on [H⁺]. The reaction rate was examined for the effects of (a) p-toluenesulfonamide, (b) halide ions, (c) ionic strength, (d) dielectric permittivity and (e) solvent isotope. The reaction was studied at different temperatures and the activation parameters have been deduced. Oxidation products were characterized. Test for free radicals was found to be negative. The derived rate law based on the proposed mechanism is in complete agreement with the observed kinetic data.

A simple and efficient method for the synthesis of α-amino phosphonates has been developed by using aromatic aldehydes, amines, and trimethyl/triethyl phosphite, under catalyst and solvent free conditions, with the formation of the product in good to excellent yields. This method involves milder reaction conditions, easy work-up, and cleaner reaction profiles, and may have wide spread application in organic synthesis.

Potassium hydrogen sulfate, KHSO₄, has been used in many organic preparations as a good solid catalyst. The KHSO₄ has received considerable attention since it is an inexpensive, eco-friendly, highly reactive, easy to handle and non-toxic catalyst for various organic transformations, affording the corresponding products in excellent yields with high selectivity. We wish to report some applications of this catalyst in organic reactions.