Vol. 8 & Issue 4 ; Section A : Chemical Sciences

Date : Aug. to Oct.2018

 

Electrochemical Oxidation of Ascorbic Acid Mediated by Ru (III) Schiff-base Complex/Multi-Walled Carbon Nanotube/Nafion Modified Carbon Electrode

Mirha Pazalja

[DOI: 10.24214/jcbps.A.8.4.60110.]

  • Abstract

    Carbon electrodes modified with Ru(III) Schiff base complex, multi-walled carbon nanotubes and Nafion® were used to develop a low potential sensor for ascorbic acid. Voltammetry measurements showed oxidation of ascorbic acid at the modified glassy carbon electrode at the potential of +0.23 V, and the bare electrode displays no redox peaks in the investigated potential range from 0.00 to +0.35 V. Flow injection amperometric measurements were performed at the operating potential of +0.20 V vs. Ag/AgCl in Britton-Robinson buffer (pH=5.00) with a flow rate of 0.40 mL min-1, and injection volume 100 μL. The modified electrodes shows a fast electric current response for ascorbic acid oxidation. Current response increased with increasing ascorbic acid concentration (dynamic range = 0.50-100 mg L-1) and displayed good linearity (R2 = 0.9946). The limit of detection was 0.25 mg L-1, while the limit of quantitation was 0.85 mg L-1. The repeatability was calculated as 2.10 % (n=5 measurement).

Photoinduced Deoxygenation of Epoxychalcones on TiO2

Somasundaram N and Ananthanarayanan L

[DOI: 10.24214/jcbps.A.8.4.61118.]

  • Abstract

    One of the most important transformations in organic synthesis is the deoxygenation of epoxides to olefins as it allows the use of oxirane ring as a protective group for double bonds. Though a number of reagents are available to accomplish this process by multi-step and one-step procedures with retention or inversion of the geometry of carbon-carbon double bonds, not much photochemical methods have been developed for the deoxygenation of epoxides with retention of geometrical (trans) configuration. Herein, a simple TiO2-mediated one-pot method of photodeoxygenation of epoxychalcones (a,b-epoxyketones) is established. In nitrogen purged acetonitrile solution on irradiated TiO2 gives the correspondinga,b-unsaturated ketones with retention of geometric configuration in excellent yields (³ 75%).

Kinetics and Mechanism of the Oxidation of some α-Hydroxy acids by Quinolinium Dichromate

Rajesh Kumar, Jyoti Solanki, Itishree Hedau, Priyanka Purohit and Vinita Sharma

[DOI: 10.24214/jcbps.A.8.4.61930.]

  • Abstract

    The oxidation of glycollic, lactic, malic and a few substituted mandelic acids by quinolinium dichromate (QDC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding oxoacids. The reaction is first order each in QDC. Michaelies-Menten type of kinetics is observed with respect to the hydroxy acids. Reaction is failed to induce the polymerisation of acrylonitrile. The oxidation of -deuteriomandelic acid shows the presence of a primary kinetic isotope effect (kH/kD = 5.71 at 298 K). The reaction does not exhibit the solvent isotope effect the reaction is catalysed by the hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b [H+]. Oxidation of p-methyl mandelic acid has been studied in 19 different organic solvents. The solvent effect has been analysed by using Kamlet’s and Swain’s multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed.

Kinetics and mechanism of the oxidation of lower oxyacids of phosphorus by pyridinium dichromate

Kanchan Kanwar, U. Songara, Ammilal Rao, A. Choudhary and Vinita Sharma

[DOI: 10.24214/jcbps.A.8.4.63141.]

  • Abstract

    Oxidation of lower oxyacids of phosphorus by pyridinium dichromate (PDC) in dimethylsuloxide (DMSO) leads to the formation of corresponding oxyacids with phosphorus in a higher oxidation state. The reaction exhibits 1:1 stoichiometry. The reaction is first order with respect to PDC. A Michaelis-Menten type of kinetics was observed with respect to the reductants. The reaction does not induce polymerization of acrylonitrile. Reactions are catalyzed by hydrogen ions. The ydrogen-ion dependence has the form: kobs = a + b[H+]. The oxidation of deuteriated phosphinic and phenylphosphinic acids exhibited a substantial primary kinetic isotope effect. The oxidation was studied in nineteen different organic solvents. The solvent effects were analysed in terms of Taft’s and Swain’s multiparametric equations. The effect of solvent indicates the solvent polarity plays a major role in the process. It has been shown that the penta-coordinated tautomer of the phosphorus oxyacid is the reactive reductant and it has been concluded that tricoordinated forms of phosphorus oxyacids does not participate in the oxidation process. A mechanism involving transfer of a hydride ion in the rate-determining step has been proposed.

Oxidation Studies of Aliphatic Secondary Alcohols by Pyridinium dichromate: A Kinetic and
Mechanistic Approach

Bhagyalaxmi, Rekha Sharma, Shobha Puniya, Om Prakash and Vinita Sharma

[DOI: 10.24214/jcbps.A.8.4.64253.]

  • Abstract

    Oxidation of several aliphatic secondary alcohols by pyridinium dichromate (PDC) in dimethylsulfoxide (DMSO) leads to the formation of corresponding ketones. The reaction is first order each in PDC. A Michaelis-Menten type of kinetics are observed with respect to the alcohols. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form: kobs = a + b[H+]. The oxidation of benzhydrol- α-d (PhCDOHPh) exhibited a substantial primary kinetic isotope effect (kH/kD = 5.75 at 298 K). The oxidation of 2-propanol has been studied in nineteen different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The reaction was subjected to both polar and steric effects of the substituents. A mechanism involving transfer of hydride ion from alcohol to the oxidant, via a chromate ester, has been proposed.

Synthesis and Characterization of Cu (II) and Co (II) complexes containing Schiff base ligands towards Potential Biological Application

Md. Saddam Hossain, A.S.M.E. Shaheed, Md. Nuruzzaman Khan, Md. Abdul Mannan,
M.M. Haque,  C. M. Zakaria, Ranjan K Mohapatra, Md. Kudrat-E-Zahan.

[DOI: 10.24214/jcbps.A.8.4.65468.]

  • Abstract

    Metal complexes of Cu(II) and Co(II) ions with two Schiff base ligands {2-((2-hydroxybenzylidene)amino)phenol}and {2,2'-((1,2-phenylenebis (azanylylidene)) bis (methanylylidene))diphenol} was derived from the condensation reaction of salicylaldehyde with 2-aminophenol and o-phenyldiamine respectively. The Structure and spectral properties of ligand and complexes were confirmed by UV-Visible, FT-IR and some physiochemical measurements. IR spectral studies show the N and O atom of the Schiff bases are binding sites of ligand with the metal ion. Molar conductance measurements give evidence in favor of non-electrolytic nature of the complexes. Magnetic susceptibility data coupled with electronic spectra suggested that the square planar structure of Cu(II) and octahedral structure of Co(II) complexes. The Schiff base ligands and their complexes were subjected to antimicrobial studies screened by using the Disc Diffusion method. All the synthesized compounds showed moderate to strong antibacterial activity. The complexes showed more antibacterial activity than their corresponding ligands.

Corrosion Inhibition of A106-B Steel in H₂SO₄ Solution by Clindamycin and Cefaclor Drugs as Environmentally Safe Inhibitors

M. I. Abbas, A. S. Fouda, M. T. Rashad,

[DOI: 10.24214/jcbps.A.8.4.66985]

  • Abstract

    The inhibiting effect of Clindamycin and Cefaclor compounds was studied on A106-B material in sulfuric acid solution. Some electrochemical techniques were utilized as (Potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and Electrochemical Frequency Modulation (EFM)). The two compounds were added in concentrations from 10 ppm to 900 ppm. The efficiency of the inhibition (IE) was increased with compound concentrations. PP tests indicated that these compounds are of mixed type. In addition, EIS data showed that transfer resistance increased but double layer capacitance decreased with addition of compounds concentration. EFM tests provided results in the same trend. The adsorption isotherms of the two compounds were found to obey Langmuir adsorption isotherm. The results obtained from all techniques were in good
    agreement. Surface morphology, Topography and X-ray analysis were utilized to characterize the specimens’ surfaces and verify the effect of the studied compounds

Synthesis, Characterization and Biological evaluation of Co (II) complex of 1-(2,4-dihydroxyphenyl) ethanone Semicarbazone

Ratnamala P. Sonawane

[DOI: 10.24214/jcbps.A.8.4.68795]

  • Abstract

    In this heterocyclic base adduct of cobalt (II) complex have been synthesized by the reaction of cobalt (II) chloride with 1-(2,4-dihydroxyphenyl) ethanone Semicarbazone. The synthesized 2,4-dihydroxy acetophenone, 1-(2,4-dihydroxyphenyl) ethanone Semicarbazone and its cobalt complex has been characterized by physical constant, TLC and IR spectral data. All the target compounds exhibit growth inhibitory activity against E.Coli,and S.Aureus bacteria studied by agar well diffusion method. It is observed that activity depends upon strain and structure. All the synthesized compounds have good to moderate antimicrobial activity.

Adsorption property and inhibition of Stainless Steel 304 corrosion in hydrochloric acid media by water-soluble amoxicillin drug

A.S. Fouda, S.M. Rashwan, A. Emam, M. Abdlfatah,

[DOI: 10.24214/jcbps.A.8.4.69614]

  • Abstract

    Corrosion inhibition of SS 304 in 2 mol L-1 HCl by amoxicillin drug in the concentration range of 50–300 ppm has been studied using weight loss (WL), potentiodynamic polarization (PP); electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. All experiments showed that the inhibition efficiency (IE %) increased with amoxicillin concentrations and decreased by raising the temperature. PP curves indicated that amoxicillin acted as a mixed-type inhibitor. The absorption of drug molecule on the SS 304 surface was confirmed by atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy and found to follow Langmuir adsorption isotherm. The results obtained from chemical and electrochemical techniques are in good covenant. All the experimental results concluded that amoxicillin acted as good corrosion inhibitor