Acetic Acid Medium Research Articles

Meso-tetraphenylporphyriniron(iii) chloride catalyzed oxidation of aniline and its substituents by magnesium monoperoxyphthalate in aqueous acetic acid medium

Abstract The catalytic properties of the first generation catalyst meso-tetraphenylporphyriniron(III) chloride and magnesium monoperoxyphthalate (MMPP) as oxidant have been studied in the oxidation of aniline and its substituents in acetic acid medium. The thermodynamic parameters for the oxidation have been determined and discussed. It confirms the Exner relationship (only at the low range of temperatures) and also some of the activation parameters to the isokinetic relationships. The magnesium monoperoxyphthalate oxidation with 18 ortho- meta- and para-substituted anilines fulfills with isokinetic relationship but not to any of the linear free energy relationships. The reaction mechanism and the rate law were proposed.

Synthesis of Highly Functionalized Piperidines via One-Pot, Five-Component Reactions in the Presence of Acetic Acid Solvent

A simple and efficient method was developed for one-pot, five-component synthesis of highly functionalized piperidines from reactions of β-keto esters, aromatic aldehydes, and various amines catalyzed in acetic acid medium. The reaction proceeded smoothly to generate the corresponding product in good yield. We have found that the use of acetic acid as reaction medium has a remarkable beneficial effect on the reaction, allowing it to be performed without the need to incorporate a catalyst, which is the case in other similary reported methodologies. In all cases, the substituted piperidine precipitates out of solution.

Critical Role of Suspension Media in Electrophoretic Deposition: The Example of Low Loss Dielectric BaNd2Ti5O14 Thick Films

The importance of electrophoretic deposition (EPD) is well recognized for thick film technology, but unfortunately there is no universal suspension medium for the EPD of oxides. Thus, the selection of the medium, the stability of the suspensions, and the control of the particle potentials, critical for a good deposition, need to be established for each new material being processed by EPD. In this article, we investigate the key parameters, studying the electrochemistry of BaNd(2)Ti(5)O(14) (BNT) suspensions, and establish relationships between suspension media, EPD process conditions, microstructure of the deposits, and resulting electrical properties of the BNT films. Suspension stability of water, ethanol, acetic acid, and acetone-based media was analyzed in terms of zeta potential, particle size distribution, UV transmittance, and inductively coupled plasma spectrometry. The highest absolute zeta potential values determined for acetone with I(2) and acetic acid media are in good agreement with the high stability, small and narrow particle size distribution, and low UV light transmittance measured for these suspensions. Very high quality thick deposits were consequently achieved. However, it was demonstrated that aging of the acetic acid-based suspension have serious negative effects on the EPD process for BNT materials, including leaching of the metallic elements with a consequent modification of the material stoichiometry, change of the conductivity of the suspension, and degradation of the films microstructure. These facts severely restrict the use of acetic acid. Our results clearly indicate that, besides the stability of the suspension, the electrochemistry and aging behavior are key aspects for the EPD of functional oxides. Our systematic approach could be viewed as providing a set of guidelines for the development of EPD of other oxides.

Development of novel (1-H) benzimidazole bearing pyrimidine-trione based MAO-A inhibitors: Synthesis, docking studies and antidepressant activity

The synthesis of some novel (1-H) benzimidazole bearing pyrimidine-trione based MAO-A inhibitors were achieved by the reaction between 2E)-1-(1H-benzimidazol-2-yl)-3-phenylprop-2-en-1-ones(4a–f) and barbituric acid in the presence of a catalytic amount of acetic acid medium. All the final structures were assigned on the basis of IR, 1HNMR and mass spectra analyses. All the synthesized derivatives showed good antidepressant activity when compared to the standard clomipiramine at a dose level of 20mg/kg. The compound (5d) 5-{(2E)-1-(1H-benzimidazol-2-yl)-3-[4-(dimethylamino)phenyl] prop-2-en-1-ylidene} pyrimidine-2, 4, 6(1H,3H,5H)-trione significantly reduced the duration of immobility times at 50mg/kg−1 dose level when compared to the standard drug. Molecular docking studies revealed the need for an extra hydrophobic interaction in the titled scaffold for acquiring the promising experimental values. It has been concluded that the computational values obtained after the docking calculation are in good agreement with the experimental values.

Synthesis of new 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazole derivatives as potential antimicrobial agents

New (E)-1-aryl-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones 6 (pyrazolic chalcones) were synthesized from Claisen–Schmidt reaction of 3-aryl-1-phenylpyrazol-4-carboxaldehydes 4 with several acetophenone derivatives 5. Subsequently, the cyclocondensation reaction of chalcones 6 with phenylhydrazine in acetic acid medium afforded the new 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazoles 7. The synthesized compounds were characterized by spectral studies and evaluated for their in vitro antibacterial activity against three pathogenic bacterial strains, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, and in vitro antifungal activity against three pathogenic fungal strains Aspergillus flavus, Chrysosporium keratinophilum, and Candida albicans.

The Growth and Investigation of Interface of Sio2/Si by Anodic Oxidation Technique Using Acetic Acid Medium

The Growth and Investigation of Interface of Sio2/Si by Anodic Oxidation Technique Using Acetic Acid Medium

Cyclometallated Pt(II) and Pd(II) complexes of 2-Phenylbenzothiazole with acetate ligands

Aryl-substituted benzothiazoles are effective fluorophores used as activating additives in scintillators [1]. The cyclometallation of luminophores in the acetic acid medium leads to the formation of complexes with bridging acetate ligands, which makes it possible to modify considerably their optical properties [2, 3]. In the present work the complexes [M(C^N)(μ-OAc)]2 (I, II) [M = Pt(II), Pd(II); (C^N) is the deprotonated form of 2-phenylbenzothiazole, OAc is acetate ion] have been obtained and characterized by the NMR, IR, and electronic spectroscopy and by the voltammetry method. DOI: 10.1134/S1070363212090228

Electrochemical behaviour of Al–Zn–Ga and Al–In–Ga alloys in chloride media

The influence of Ga content on the electrochemical behaviour of Al–Zn–Ga and Al–In–Ga alloys in chloride acid and acetic acid media was studied. The presence of Ga in concentration greater than 2.5wt.% causes an open circuit potential (OCP) shifts of Al–Zn–Ga alloys in chloride solution towards more negative values (−1.38V(SCE)). The OCP for Al–In–Ga alloys in chloride solution varies between −1.62 and −1.73V(SCE). The anodic behaviour of these ternary alloys can be interpreted in terms of an amalgam mechanism.

Polyaniline–TiO2 hybrid‐coated cotton fabric for durable electrical conductivity

AbstractA polyaniline–TiO2 hybrid was coated on cotton fabric to make it electrically conductive. A One‐pot method of synthesis with acetic acid medium was used, in which TiCl4 was used as precursor. The oxidative polymerization of aniline adsorbed on TiO2 (anatase form) was performed in the presence of cotton fabric. Fabric crystallinity was least affected by the coatings, as confirmed by XRD analysis. FTIR studies revealed interactions between fiber and hybrid. The morphological study through SEM showed the uniform coating of hybrid over the fibers of the cotton fabric and AFM analysis revealed the rod‐like structure of the hybrid. The strength of the coated fabrics was assessed using abrasion tests. The electrical conductivity was determined using electrochemical impedance spectroscopy (EIS).The conductivity value varied with respect toTiO2 content and ranged in the order 10−4 to 102S/cm. The effect of atmospheric aging was assessed. A more durable conductivity was observed in hybrid‐coated fabric than pristine polyaniline‐coated fabric. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Simultaneous first order derivative spectrophotometric determination of vanadium and zirconium in alloy steels and minerals

A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of trace amounts of vanadium(V) and zirconium(IV) in acetic acid medium using a newly synthesised reagent diacetylmonoxime salicyloylhydrazone (DMSH), without any prior separation. The molar absorptivity and Sandell’s sensitivity of the coloured species are 1.30 x 104 and 1.82 x 104 Lmol−1cm−1 and 3.9 and 2.5ngcm−2 for V(V) and Zr(IV), respectively. Beer’s law is obeyed between 0.26–2.80 and 0.30–3.20μgmL−1 concentration of vanadium (V) and zirconium (IV) at 405 and 380nm respectively. The stoichiometry of the complex was found to be 1:1 (metal:ligand) for V(V) and 1:2 for Zr(IV) complexes. These metal ions interfere with the determination of each other in zero order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of V(V) and Zr(IV) at zero crossing wavelengths of 445nm and 405nm, respectively. The optimum conditions for maximum colour development and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of zirconium and vanadium in standard alloy steel samples, mineral and soil samples.

Kinetics of Oxidation of dl-Tartaric Acid by Potassium Permanganate in Aqueuos and Aqueous Micellar Media

The kinetics of oxidation of dl-tartaric acid (TA) by potassium permanganate in acetic acid medium in the presence and absence of TX-100 (non-ionic surfactant) was investigated. At early stages, the reaction was found to be first order with respect to both permanganate and TA. The presence of TX-100 was found to catalyse the reaction and this effect was interpreted successfully in terms of pseudo-phase model. Activation parameters of the reaction in the presence/absence of TX-100 were obtained. A suitable mechanism, which agreed with the experimental findings was suggested.

Non-aqueous and two-phase titrimetric assay of isoxsuprine hydrochloride in pharmaceuticals

Based on the nitrogenous base or quaternary ammonium moiety in isoxsuprine hydrochloride (ISX), two highly accurate and selective titrimetric methods are proposed f or the determination of ISX in spiked human urine, injection and tablets. Non-aqueous titration (Method A) involves removal of protonated amine using mercuric acetate for enhanced basic nitrogen prior to titration with perchloric acid in an acetic acid medium using crystal violet as indicator. Two-phase titration (Method B) is based on ion association complex formation between sodium lauryl sulphate (SLS) and protonated amine of ISX at pH 2.5 in aqueous phase, end point being detected by change in dimethyl yellow color in chloroform layer. The methods are applicable over the concentration range 2.0–20.0 mg and 1.0–10.0 mg for method A and method B, respectively. Calculations are based on 1: 1 molar ratio, i.e., JSX: HClO4 for method A and ISX: SLS for method B, owing to the presence of one nitrogen atom. Method A is applicable to the determination of ISX in tablets whereas method B is applicable to spiked human urine, injection and tablets. The methods are validated statistically by comparing the results with those of the reference method by applying the Student’s t-test and F-test. The accuracy was further ascertained by recovery studies via standard addition technique.

Catalytic features of the reaction of oxidative cross-coupling of styrene and hexene-1

The reaction of oxidative cross-coupling of styrene and hexene-1 in the medium of ice acetic acid was studied in the presence of various active phases based on palladium deposited on carbon-containing carrying agents, activated carbon, fullerenes, astralenes, and nanotubes.

Micelle Catalyzed Oxidation of 4-Methyl-2-Pentanone by NBP in the Presence of Acetic Acid

The effect of cationic micelles of cetyl trimethyl ammonium bromide (CTAB) and anionic micelles of sodium dodecyl sulphate (SDS) on the kinetics of oxidation of 4-methyl-2-pentanone by N-bromophthalimide (NBP) was studied iodometrically at 308 K. In addition to kinetic experiments, conductivity measurements have also been done to obtain critical micelle concentration and other thermodynamic properties. The kinetic observations indicate fractional order and first order dependence, with respect to [4-methyl-2-pentanone] and [NBP] respectively. Cationic surfactant (CTAB) strongly catalyzes the oxidation of 4-methyl-2-pentanone in aqueous acetic acid medium and typical kobs and [CTAB] profile was observed, that is, with the progressive increase in [CTAB], the reaction rate increased, at higher concentration constancy in kobs was observed, whereas anionic surfactant (SDS) was found to show no considerable effect on reaction rate. Mercuric acetate and phthalimide exhibited nil effect on the reaction rate. The presence of inorganic salts (KCl, KBr) exhibits a severe hike in the reaction rate. The various activation parameters in presence of CTAB and SDS have been also evaluated. A suitable mechanism consistent with the experimental findings has been proposed. The rate constants k(obs), cooperativity index (n), binding constants (Ks) with surfactants has been evaluated.

Extraction of copper(II) carboxylates with chloroform under substoichiometric conditions

The features are considered of binding carboxylic acids (HR) as dimeric solvated copper(II) complexes at the copper(II) extraction with chloroform under substoichiometric conditions, with excess of the metal ion in the aqueous phase. The fundamental difference in the optimization of the quantitative extraction of copper(II) in the form of any carboxylate with a maximum ratio of Cu:R and the total binding with carboxylic acids to form the copper complex of the minimum stoichiometry was noted. It was found that quantitative binding of HR occurred at the extraction of mixed-ligand acetate-carboxylate copper(II) complexes without control over the aqueous phase acidity when acetic acid medium or copper(II) acetate was used, but not copper chloride, nitrate, perchlorate, or sulfate. The possibility of determination by extraction-photometric method by the color of the Cu(II) complex was shown that was suitable only to those carboxylic acids, whose logarithm of the partition coefficient in the water-chloroform mixture was higher than three.

Determination of vanadium (V) employing a new combined single drop micro-extraction and diffuse reflectance Fourier transform infrared spectroscopy technique

The present work deals with a new micro-extraction mode for the selective separation and determination of vanadium in the form of a metaloxy anionic species viz. vanadate () using N 1-hydroxy-N 1,N 2-diphenylbenzamidine (HDPBA) reagent in to a single drop of dichloromethane and its subsequent and rapid diffuse reflectance Fourier transform infrared spectroscopic (DRS-FTIR) determination on potassium bromide matrix. The vibrational infrared peak at 500 cm−1 is selected for the quantitative analysis for the determination. The vanadate combines with the nitrogen and oxygen atoms of N 1-hydroxy-N 1,N 2-diphenylbenzamidine (HDPBA) and forms a selective 1 : 2, V(V) : HDPBA binary complex in acetic acid medium. The chemistry of pure vanadate and that of its HDPBA complex is discussed. The limit of detection (LOD) and the limit of quantification (LOQ) of the method are found to be 40 µg L−1 and 130 µg L−1 V(V), respectively. The precision of the method, in terms of standard deviation and relative standard deviation value, at a level of 10 µg V(V)/5 mL aqueous phase for n = 10 is found to be 0.26 µg V(V) and 2.6%, respectively. The relative standard deviation (n = 6) for the determination of vanadate () in some environmental and real human biological fluid samples is observed to be in the range 4.6–7.8%.

Effect of the Type of Solvent and Bi-Stoichiometric Excess on the Purity of Nanocrystalline Bismuth Ferrite Single Phase

ABSTRACTThe main challenge associated with the synthesis of pure bismuth ferrite (BFO) is the extremely high stability of parasitic or secondary phase Bi-oxides, which contaminates the single ferrite phase and affects the corresponding functional properties. Therefore, any attempt to determine the optimum synthesis conditions conducive to the inhibition of the formation of those impurity phases becomes indispensable. Accordingly, the present work addresses the systematic evaluation of the type of solvent and synthesis parameters to exclusively produce the BFO structure. Nanocrystalline BFO powders were synthesized after thermal treatment of the solid intermediates formed in ethylene glycol and acetic acid media. The experimental work also considered the effect of the excess of Bi species with respect to the BiFeO3stoichiometry and the annealing of the intermediates at different temperatures. The structure formation was confirmed by XRD analysis and magnetic properties were studied by VSM. X-ray diffraction analyses confirmed that powders exhibiting single phase BFO structure were produced after annealing the intermediate which was formed in acetic acid for one hour at 700°C. The average crystallite size and lattice parameter were calculated to be approximately 40 nm and 5.36 Å, respectively. It was also found that the synthesis under 7% of Bi-stoichiometric excess inhibited the formation of the parasitic phases after annealing the intermediate produced in ethylene glycol medium. The saturation magnetization of the powders annealed at 700°C were 0.15 emu/g and 0.17 emu/g when the BFO intermediates were formed in ethylene glycol and acetic acid media, respectively. The corresponding coercivity values were 6 Oe and 21 Oe.

Multicomponent approaches to 8-carboxylnaphthyl-functionalized pyrazolo[3,4-b]pyridine derivatives

A simple and novel protocol for the efficient synthesis of a series of 8-carboxylnaphthyl functionalized pyrazolo[3,4-b]pyridine derivatives was developed through a one-pot, three-component reaction involving acenaphthylene-1,2-dione and 1H-pyrazol-5-amine in acetic acid medium. The reaction represents the first facile conversion of acenaphthenequinone to naphthoic acid via C-C bond cleavage without need for multi-step transformation.

α‐Alumina Fiber with Platelet Morphology Through Wet Spinning

Highly loaded Al(OH)3 slurries were prepared in a 2 vol% aqueous acetic acid medium up to 33.3 wt% powder loading. The slurries were blended with 4 wt% chitosan in 2 vol% acetic acid and formed into ceramic fibers through wet spinning in sodium tripolyphosphate (STPP) bath. A gelation kinetics study of the chitosan‐blended slurry also showed instantaneous gelation behavior under oscillatory mode rheological measurement. The slurries with moderate viscosities up to 150 Pa·s were spinnable in STPP bath due to ionotropic gelation. Low viscous slurries were formed into a lump during spinning due to low powder loading and less chitosan present in the blend. The green fibers crystallized into α‐alumina during sintering at ~950°C with an average diameter varying between 70 and 120 μm. α‐alumina platelets were formed at 1350°C and changed to hexagonal platelets at 1550°C. The crystallite size of α‐alumina varied between 26 and 112 nm which was measured from XRD data using Scherrer formula. The grain size of sintered fibers was ~4.5 μm at 1350°C. The fibers were assembled into a cylindrical scaffold and sintered to produce a crushing strength of 0.9 MPa with density 0.9 g/cm3.

Synthesis of pyrazolo[3,4- b]pyridines under microwave irradiation in multi-component reactions and their antitumor and antimicrobial activities – Part 1

An efficient one-pot synthesis in multi-component system (MRCs) for the preparation of pyrazolo[3,4- b]pyridine derivatives from the reaction of 5-amino-1-phenyl-3-(pyridin-3-yl)-1 H-pyrazole with 4-anisaldehyde and p-substituted β-ketonitriles or with pyruvic acid and some aromatic aldehydes in acetic acid medium. The reactions were carried out by two different techniques, conventional heating and microwave irradiation. These compounds were screened for their antibacterial activity against Gram-positive bacteria ( Bacillus), Gram-negative bacteria ( Escherichia coli, Enterobacter cloaca and serratia) and antifungal activity against Fusarium Oxysporum and Penicillium expansum. Also, among the synthesized compounds 4a– f tested for antitumor activity against liver cell line. Compounds 6-(4-Fluorophenyl)-4-(4-methoxyphenyl)-1-phenyl-3-(pyridin-3-yl)-1H-pyrazolo[3,4- b]pyridine-5-carbonitrile ( 4e) and 4-(4-Methoxyphenyl)-1-phenyl-3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4- b] pyridine-5-carbonitrile ( 4a) showed the highest activity.