Classical chemical sciences
Water/n-propanol/cetyltrimethylammonium bromide/allylbenzene micellar systems were formulated. The ratio (w/w) of n-propanol/ cetyltrimethylammonium bromide equals 2/1. The extent of the micellar region as function of temperature was determined. The micellar systems were characterized by the volumetric parameters, density, excess volume, ultrasonic velocity and isentropic compressibility. The micellar densities increase with the increase in the water volume fraction. Excess volumes increase with the water volume fraction and temperature. Ultrasonic velocities increase with water volume fraction up to 0.8 then decrease. Ultrasonic velocities increase with temperature for water volume fractions below 0.8 and increase for water volume fractions above 0.8. Isentropic compressibilities decrease with the water volume fraction up to 0.8 then increase. Isentropic compressibilities increase with temperature for water volume fractions below 0.8 and decrease for water volume fractions above 0.8. Structural transitions from water-in-oil to bicontineous to oil-in-water occur along the micellar phase. The particle hydrodynamic diameter of the oil-in-water micellar systems decrease with temperature. In the diluted region nanoemulsions systems were observed.
Keywords: phase behavior, ultrasonic velocity, density, isentropic compressibility, hydrodynamic diameter; cetyltrimethylammonium bromide, allylbenzene, n-propanol, water
New series of N-[3-(2-amino-5-nitrothiazolyl)-propyl]-4-(substitutedphenyl)-3-chloro-2-oxo-1-azetidine-carboxamide, compounds 4a-4j have been synthesized and characterized by chemical and spectral analyses such as IR, 1H NMR, 13C NMR and FAB-Mass. All the synthesized compounds 4a-4j were screened for their antibacterial and antifungal activities against some selected bacteria and fungi with their MIC values and antitubercular activity screened against M. tuberculosis. Anti-inflammatory activity was in vivo screened against albino rats. Some compounds of the series showed good activities.
Keywords: Synthesis, 2-amino-5-nitrothiazole, azetidinone, antimicrobial, antitubercular, antiinflammatory.
The 1,2-dicyano-1,2-bis(2-ethoxy-2-oxo-1-ethylthio)ethylene has been prepared from sodium cis-1,2-dicyano-1,2-ethylenedithiolate (NaMNT) and ethyl chloroacetate by treatment with sodium iodide in dry acetone. 2,3,7,8,12,13,17,18-octakis[(2-propyloxy-2-oxo-1- ethyl)thio]-21H,23H-porphyrazine was obtained from 1,2-dicyano-1,2-bis(2-ethoxy-2-oxo-1-ethylthio)ethylene in magnesium propoxide (PrOMg) and dry propanol. All compounds have been fully characterized by spectroscopic data.
Keywords: octakis[(2-propyloxy-2-oxo-1-ethyl)thio]-21H,23H-porphyrazine, 1,2-dicyano-1,2-thioethylene, sodium cis-1,2-dicyano-1,2-ethylenedithiolate, magnesium propoxide; 1,2-dicyano-1,2-bis(2-ethoxy-2-oxo-1-ethylthio)ethylene
Utility of (E)-4-(acetylamino)phenyl-4-oxo-2-butenoic acid with new sulfur reagents e.g. 2-amino-5-aryl-thiadiazoles 2 to afford the corresponding adducts (3, 4, 5, 6). Reaction of the latter compounds with different electrophilic and nucleophilic reagents affords some important heterocycle such as various furanones, thiadiazoles, pyridazinones, imidazolo[2,3-b]1,3,4-thiadiazoles, thiadiazolopyrimidines, bezoxazinones, fused quinoxalinylquinazolinones
Keywords: (E)-4-aryl-4-oxo-2-butenoic acid , furanones, thiadiazoles, pyridazinones, imidazolo[2,3-b]1,3,4-thiadiazoles, thiadiazolopyrimidines, bezoxazinones, fused quinoxalinylquinazolinones
The diamine 1,4-phenylenedi(oxy-4,4-aniline) was prepared via the nucleophilic substitution reaction and polymerized with different dianhydrides either by a one step solution polymerization reaction or a two steps procedure. These polymers had inherent viscosities ranging from 0.64-0.83 dL g-1. Few of the polymers were soluble in most of the organic solvents such as DMSO, DMF, DMAc, NMP and m-cresol even at room temperature and some were soluble on heating. The degradation temperature of the resultant polymers falls in the ranges from 300-450 oC in nitrogen (with only 10% weight loss). The specific heat capacity at 200 oC ranges -4.0322-2.4059 J g1 K1. The maximum degradation temperature ranges from 550-600 oC. Tg values of the polyimides were found from 207 to 228 oC. The activation energy and enthalpy of the polyimides were found in the range of 36.6-94.5 and 34.8-92.5 kJ mole-1 and the moisture absorption from 0.24- 0.75%
Keywords: Polyimides, ether diamines, 1,4-phenylenedi(oxy-4,4-aniline), solubility, thermal stability
A series containing eight 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazoline derivatives have been synthesized by microwave assisted, solid acidic green catalyst SiO2-H3PO4 catalyzed cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrochloride under solvent free conditions. The yields of the pyrazolines were more than 85%. The purities of these pyrazolines were checked by their physical constant, micro analysis, Infrared, Nuclear magnetic resonance and Mass spectroscopic data published earlier in literature. From the spectral frequencies, infrared (cm-1) of C=N, C-S, C-Br, 1H and 13C NMR chemical shifts (δ, ppm) of pyrazoline ring proton, carbon and C=N carbons were assigned and correlated with Hammett substituent constants, F and R parameters. From the results of statistical analysis the effects of substituent on the spectral frequencies have been discussed.
Keywords: 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines; Green synthesis; IR and NMR spectra; Hammett correlations
Density, viscosity and speed of sound of binary liquid mixtures of butyl propionate with tetrahydrofuran, 1,4-dioxane, anisole and butyl vinyl ether were measured at ( 303.15,308.15 and 313.15 ) K and over the entire composition range. From the experimental data values of excess volume VE, viscosity deviations Δη, deviation in speeds of sound Δu, isentropic compressibility Ks and deviation in isentropic compressibility ΔKS, have been determined. The speeds of sound data have been analysed on the basis of Jouyban–Acree and Vandeal– Vangeel models.
Keywords: density, viscosity, speed of sound, binary mixture, n-butyl propionate
The reaction of 3-cyano-2-diazo-4,5,6,7-tetrahydrobenzo[b]thiophene (1) with active methylene reagents 2a-e gave the respective hydrazono derivatives 3a-e. The reactivity of the latter derivatives towards different chemical reagents was studied. The antimicrobial activity of the newly obtained products was studied and evaluated in terms of minimal inhibitory concentration (MIC) in μg mL-1. The results showed that compounds 3b, 7a and 15a are the most active compounds towards E. coli ECT 101; compounds 5f, 13b, 17a and 23 are active towards B. Cereus CECT 148; while 10, 19a and 19b towards B. subtilis CECT 498 and 3c, 5c and 13b towards C. albicans CECT 1394.
Keywords: Tetrahydrobenzo[b]thiophene, pyridazines, pyrazoles, antimicrobial activity
A new series of 2,3-disubstituted quinazolin-4(3H)-one derivatives was synthesized via nucleophilic attack at C(2)of the corresponding key starting material 2-(4-bromophenyl)-4H-3,1-benzoxazin-4-one (Scheme 5). The reaction proceeded via amidinium salt formation (Scheme 3) rather than via an N-acyl anthranilamide. The structure of the prepared compounds were elucidated by physical and spectral data like FTIR, 1H-NMR, and mass spectroscopy.
Keywords: Benzoxazin-4-one, 2,3-disubstituted quinazolin-4-one, glycine
Experimental solubilities are reported for 3,4-dimethoxybenzoic acid dissolved in 16 alcohol, 5 alkyl alkanoate, 5 alkoxyalcohol and 6 ether solvents. The measured solubility data were correlated with the Abraham solvation parameter model. Mathematical expressions based on the Abraham model predicted the observed molar solubilities to within 0.083 log units.
Keywords: 3,4-dimethoxybenzoic acid solubility, alcohol solvents, alkyl acetate solvents, alkoxyalcohol solvents, solute descriptors.
Several novel pyridine, pyrido[2,3-d]pyrimidine and pyrido[2,3-d] 3,1-oxazine derivatives were prepared using the readily obtainable starting material 2-amino-6-aryl-4-(3,4,5-trimethoxyphenyl) pyridine-3-carbonitrile 1a,b via the reaction with one carbon donors such as phenylisothiocyanate, carbon disulphide and formic acid. The IR, 1H-NMR and mass spectra for the new synthesized compounds were discussed.
Keywords: pyrido[2,3-d]pyrimidines, pyrido[2,3-d]-3,1-oxazines, one carbon donors
A facile and green one pot four component synthesis of polyhydroquinoline derivatives from aldehydes, dimedone, ethyl acetoacetate and ammonium acetate in the presence of a spinel (ZnFe0.2Al1.8O4) composite catalyst has been reported under microwave irradiation. The method offers excellent yield of products in short reaction time.
Keywords: polyhydroquinolines, Hantzsch’s condensation, ZnFe0.2Al1.8 O4 nanocomposite catalyst, microwave irradiation.
Benzimidazole derivatives have been synthesized using a catalytic amount of Fe(ClO4)3/SiO2 at room temperature with excellent yields under solvent-free conditions. The solid phase conditions and use of a heterogeneous, and inexpensive catalyst are attractive features of this method.
Keywords: benzimidazole, Fe(ClO4)3/SiO2, heterogeneous, synthesis, catalyst
A new regio- and diastereoselective 1,3-dipolar cycloaddition reaction of 7,9-bis[(E)-arylidene]-1,4-dioxa-spiro[4,5]decane-8-ones, sarcosine/1,3-thiazolane-4-carboxylic acid and acenapthequinone has been developed for the synthesis of trispiropyrrolidine/thiapyrrolizidine derivatives using 2,2,2-trifluoroethanol as a green solvent. The solvent (TFE) can be readily separated from reaction products and recovered in excellent purity for direct reuse. A regio- and stereochemical outcome of the cycloaddition reaction was ascertained by X-ray crystallographic study.
Keywords: Spiroheterocycles; cycloaddition; azomethine ylides; 2,2,2-trifluoroethanol; trispiropyrrolidine and thiapyrrolizidine derivatives
Materials and environmental chemistry
The corrosion inhibition of inhibitor tris(hydroxymethyl)amino methane (THAM) and 1-hydroxyethylidenediphosphonic acid (HEDP) in combination with a bivalent cation like Zn2+ in controlling corrosion of carbon steel immersed in aqueous solution containing 60 ppm Clwas investigated using weight loss method and electrochemical impedance spectroscopy .The combined corrosion inhibition efficiency offered by 50 ppm of THAM, 250 ppm of HEDP, 50 ppm of Zn2+ has 86%. The synergistic effect of the inhibiting compound was calculated. The corrosion inhibition was observed due to the formation of more stable and compact protective film on the metal surface. Fluorescence spectral analysis was used in detecting the presence of iron-inhibitor complex and the coordination sites of the metal inhibitor with iron were determined by the FTIR spectra. The surface morphology of the protective film on the metal surface was characterized by using Scanning Electron Microscope (SEM)
Keywords: Corrosion inhibition, Carbon steel, Scanning Electron Microscope, Fluorescence spectra, Nano film
The corrosion inhibition effect of carbon steel in sea water by 2-carboxyethylphosphonic acid (2-CEPA) and Ni2+ has been investigated using weight loss method and cyclic voltammetry. The results show that 73% inhibition efficiency is achieved with binary system consisting of 250 ppm of 2-CEPA and 50 ppm of Ni2+. Surface evaluation technique like FTIR is used to determine the nature of the protective film formed on the metal surface. The protective film consists of Fe2+ – 2-CEPA complex, Ni2+ – 2-CEPA complex and Ni(OH)2. Cyclic voltammetry study reveals that the protective film is more compact and stable even in 3.5% NaCl environment.
Keywords: corrosion inhibition; carbon steel; sea water; cyclic voltammetry; FTIR
Old and young municipal landfill leachates samples were radiation processed with γ rays at a dose rate of 1 kGy h-1. The fate of the soluble organic matter (humic substance) present in the leachates was followed by the chemical oxygen demand (COD) measurements. The radiolysis of old landfill leachate is a not an effective process in comparison to ozonolysis but can be enhanced significantly by the addition of H2O2 to the old leachate prior to radiolysis and by bringing the pH of the leachate to zero. Some radiolyzed sample were further ozonized to reduce to the minimum possible the COD level. Young landfill leachate results instead more prone to radiolysis and less sensitive to ozonolysis than the old landfill leachate.
Keywords: landfill leachate, pollution, COD, radiolysis; ozonolysis
Solid state synthesis approach was used to prepare magnetic ferrofluid loaded with maghemite nanoparticles. This magnetic material was then used to study adsorptive removal of zinc ions in presence of applied magnetic field. Studies revealed that application of magnetic field results in remarkably increased adsorption efficiency of these ferrofluids.
Keywords: Magnetic field; Ferrofluid; Maghemite; Nanoparticle; Adsorption; Wastewater; Zinc removal
New membrane sensors for lead (II) ions are described based on the use of a newly synthesized pyridine carboximide derivatives as neutral ionophore in plasticized PVC membranes (sensor 1) and PbS nanoparticles (NPs) capped in polyvinyl alcohol (PVA) (sensor 2). The sensors exhibited significantly enhanced response towards lead (II) ions over the concentration range 1.0x10-7-1.0x10-3 mol L-1 at pH 3.0 - /6.5 with a lower detection limit of 7.0-10.0 ng mL-1. The sensors displayed near-Nernstian slope of 28.2-33.5 mV per decade for Pb(II) ions. The sensors showed long life span, good selectivity for Pb(II) over a wide variety of other metal ions, long term stability, high reproducibility, and fast response. Validation of the method by measuring the lower detection limit, range, accuracy, precision, repeatability and between-day-variability revealed good performance characteristics of the proposed sensors. Membrane incorporating the neutral ionophore in a flow detector was used in a two channels flow injection set up for continuous monitoring of Pb2+ at a frequency of ca. 48-50 samples h-1. Direct determination of lead in water samples as well as in biological fluids gives results in good agreement with data obtained using standard AAS method.
Keywords: Potentiometric sensors; PbS nanoparticles; FIA; Hazardous waste.
In this paper, a clay based drug delivery system comprising of [poly(D,L-lactide-co-glycolide)] (PLGA)/montmorillonite (MMT) nanocomposite has been explored for the oral sustained release of diclofenac sodium (DS) using double emulsion solvent evaporation technique. Encapsulation of diclofenac sodium in PLGA matrix and clay matrix was also undertaken to assess the role of clay and PLGA in drug encapsulation and its subsequent release from the respective formulations. A drug encapsulation efficiency of 98 % was obtained for the synthesized PLGA/MMT nanocomposite system. The drug was found to be intercalated in the PLGA/MMT nanocomposite as confirmed by the X-Ray diffraction studies. The thermal analysis shows the crystalline nature of the encapsulated drug in the nanocomposite. The particle size of the drug loaded PLGA/MMT nanocomposite was found to be in the range of 10-20 nm as analysed by high resolution transmission electron microscopic (HRTEM) technique. The in vitro drug release studies of the drug encapsulated PLGA/MMT nanocomposite under simulated gastric fluid (phosphate buffer saline, PBS 1.2) shows no drug release while a sustained release was seen under simulated intestinal condition (phosphate buffer saline, PBS 7.4) releasing 51% drug in 8 hours.
Keywords: diclofenac sodium, montmorillonite, PLGA nanocomposite, sustained release