Indian Journal of Chemistry

Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical

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VOLUME 48A

NUMBER 3

March 2009

CONTENTS

 

315

 

Multi-channel reactions of intramolecular proton transfer on serinamide in the ground and excited states: A theoretical study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Xinming Zhou, An-guo Zhang, Zheng-yu Zhou*, Zhao-kun Jia & Rui-yan Hou

 

 

 

 

Multi-channel reactions of intramolecular proton transfer on serinamide have been determined by studying five pairs of mirror-image conformers of serinamide in excited state and eight pairs in ground state by DFT calculations at B3LYP/6-311++G** level. Four different channels for intramolecular proton transfer are confirmed for the excited and ground states. For the excited state intramolecular proton transfer, process CH2 (H10 from CH to O2) is considered to be the most favorable channel with the lowest energy barrier (Ea = 86.267 kJ/mol). Process CH1 (H9 from N3 to O2) is calculated to be both thermodynamically and kinetically favored for the ground state intramolecular proton transfer. Activation energies of these channels show that the intramolecular proton transfer reaction processes in excited state are much easier than those in the ground state.

 

 

327

 

Template synthesis and characterization of mesoporous CeO2 and Ru-loaded mesoporous CeO2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Laitao Luo*, Jianxin Wang & Xu Zhao

 

 

 

 

A series of mesoporous ceria have been synthesized using Brij 35 and some co-surfactants as template agents and characterized by XRD, FT-IR and N2 adsorption-desorption analyses. The mesoporous material prepared with CTAB and Brij 35 shows the best catalytic performance in comparison to material prepared using Brij 35 alone or along with other co-surfactants like PEG2000. The Ru/m-CeO2 catalyst shows the highest activity for the conversion of methanol.

 

 

 

333

 

Di- and tri-organogermanium carboxylates: Synthesis, spectroscopy and structures of [Me3Ge(O2CC9H6N)] and [Et2Ge(O2CC5H4N)2]

 

 

 

 

 

 

 

 

 

 

Alpa Y Shah, Amey Wadawale, V S Sagoria ,
Vimal K Jain*, Renu Sharma, Meena Nagar & Rakesh Bohra

 

 

 

 

Di- and tri-organogermanium carboxylates, [R2Ge(O2CAr)2] and [R3Ge(O2CAr)] (R = Me, Et or Bu; Ar = C5H4N, C9H6N), have been synthesized by the reactions of the corresponding dialkyldichloro germane and trialkylchloro/bromo germane with an appropriate sodium salt of N-heterocyclic carboxylic acid in 1:2 and 1:1 molar ratio in anhydrous benzene. The former has a distorted tetrahedral configuration around germanium with monodentate carboxylate group, while the latter has distorted trigonal bipyramidal geometry.

 

 

 

 

 

339

 

Oxidation of mephenesin and guaifenesin with chloramine-B in hydrochloric acid medium: Design of kinetic model

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Puttaswamy* & Anu Sukhdev

 

 

 

 

Kinetics of oxidation of mephenesin and guaifenesin by sodium N-chlorobenzenesulfonamide has been investigated in HCl medium at 303 K. The oxidation behaviour is similar for both the substrates. The rate shows a first order dependence on both [CAB]0 and [HCl], and is fractional in [substrate]0. The orders individually in [H+] and [Cl-] are fractional. The proposed mechanism assumes simultaneous catalysis by H+ and Cl- ions. The reaction is found to be moderately faster in guaifenesin in comparison with mephenesin, which may be attributed to the involvement of methoxy and methyl groups of the substrate.

 

 

 

 

346

 

Kinetics and mechanism of (salen)MnIIIcatalysed hydrogen peroxide oxidation of diphenyl sulphides

 

 

 

 

 

 

 

 

 

 

 

 

 

A Chellamani* & N M I Alhaji

 

 

 

 

The oxidation of diphenyl sulphides with H2O2 in the presence of (salen)MnIII complex is first-order in complex, zero-order in H2O2 and fractional-order in sulphide. A Michaelis-Menten type mechanism involving MnIII-hydroperoxide complex as reactive species has been proposed.

 

 

Notes

 

352

 

Surface functionalities of nitric acid treated carbon A density functional theory based vibrational analysis

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R Mahalakshmy, P Indraneel & B Viswanathan*

 

 

 

 

The appropriate combination of surface functionalities and their relative contribution to the total surface functionalities of oxidized carbon by nitric acid are evaluated by density functional theory calculations. Though the computed and experimental spectra do not exactly match in all respects, the methodology adopted has a definite role in understanding the complex surface functionalities of treated carbon.

 

 

 

357

 

Oxidation of thiosulphate by hexacyanoferrate(III) in aqueous perchloric acid medium  A kinetic and mechanistic study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R K Patil, S A Chimatadar & S T Nandibewoor*

 

 

 

 

Kinetics of oxidation of thiosulphate by hexacyanoferrate(III) in an aqueous perchloric acid medium has been studied spectrophotometrically by stopped flow method at 25 C. The reaction is first order with respect to hexacyanoferrate(III) and thiosulphate concentrations. Increase in perchloric acid concentration increases the rate of reaction (order = 0.40). The active species of oxidant is indicated to be HFe(CN)63-.

 

 


Fe(CN)63- + H+    HFe(CN)62-

 


HFe(CN)62- + S2O32-     S2O3- + HFe(CN)63-

 


2S2O3- + H+     S4O62-

 

 

362

 

Oxidative regeneration of carbonyl compounds from oximes by morpholinium chlorochromate: A kinetic and mechanistic study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Anurag Choudhary, S Agarwal & Vinita Sharma*

 

 

 

 

Oxidative deoximination of several aldo- and keto-oximes by morpholinium chlorochromate in dimethyl sulphoxide exhibits a first order dependence on both, oxime and MCC. The oxidation of ketoximes is slower than that of aldoximes.

 

 

 

367

 

Sonophotocatalytic behavior of cerium doped salts of Cu(II), Co(II) and Mn(II) in the degradation of phenol

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pankaj* & Mayank Verma

 

 

 

 

Crystals of CuSO4.5H20, CoCl2.6H2O, and MnCl2.4H2O doped with CeCl3 have been synthesized under sonicated and unsonicated conditions. Enhanced sonophotocatalytic effect of these crystals on the degradation of phenol under sonic conditions is attributed to the increased number of unpaired electrons following free radical mechanism.

 

20b, x370

 

 

Authors for correspondence are indicated by (*)

 

 

 


Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 315-326

 

 

Multi-channel reactions of intramolecular proton transfer on serinamide in the ground and excited states: A theoretical study

Xinming Zhoua, b, An-guo Zhangb, Zheng-yu Zhoua, b, *, Zhao-kun Jiab & Rui-yan Houb

aCollege of Chemistry & Chemical Engineering, China University of Petroleum, Shangdong, DongYing, 257061,
Peoples Republic of China

Email: zhengyu@mail.qfnu.edu.cn

bDepartment of Chemistry, Qufu Normal University, Shandong, Qufu 273165,
Peoples Republic of China and State Key Laboratory of Crystal Materials, Shandong University, Shandong, Jinan 250100,
Peoples Republic of China

Received 23 June 2008; revised and accepted 16 February 2009

Multi-channel reactions of intramolecular proton transfer on serinamide in the ground state and excited state have been determined by studying five pairs of mirror-image conformers of serinamide in excited state and eight pairs in ground state. Density function theory calculations have been made at B3LYP/6-311++G** level. Four different channels for intramolecular proton transfer are confirmed by theoretical calculations for the excited and ground states. For the excited state intramolecular proton transfer, process CH2 (H10 from CH to O2) is considered to be the most favorable channel with the lowest energy barrier (Ea = 86.267 kJ/mol). At the same time, process CH1 (H9 from N3 to O2) is calculated to be both thermodynamically and kinetically favored for the ground state intramolecular proton transfer. Comparing the activation energies of these channels, it may be inferred that the activation energy needed by the excited state intramolecular proton transfer process is much lower than that required by ground state intramolecular proton transfer process. Therefore, intramolecular proton transfer reaction processes in excited state are much easier than those in ground state.

Keywords: Theoretical chemistry, Density functional calculations, Intramolecular proton transfer, Multichannel reactions, Activation energies, Serinamide

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 327-332

 

 

Template synthesis and characterization of mesoporous CeO2 and
Ru-loaded mesoporous CeO2

Laitao Luo*, Jianxin Wang & Xu Zhao

Institute of Applied Chemistry, Nanchang University, NanChang 330031, PR China

Email: luolaitao@163.com

Received 21 August 2008; revised and accepted 13 February 2009

A series of mesoporous ceria (m-CeO2) have been synthesized using Brij 35 and some co-surfactants as template agents. The samples have been characterized by XRD, FT-IR and N2 adsorption-desorption analyses. The mesoporous material prepared with CTAB and Brij 35 shows the best catalytic performance in comparison to material prepared using Brij 35 alone or along with other co-surfactants like PEG2000. The Ru/m-CeO2 catalyst shows the highest activity for the conversion of methanol. The results also indicate that the synthesis temperature, ageing temperature and calcination temperature affect the surface area, pore volume, thermal resistance and the pore diameter of the prepared materials. Also, temperature plays an important role in the preparation of mesoporous ceria.

Keywords: Mesoporous materials, Template synthesis, Catalysts, Surface properties, Textural properties, Ceria, Ruthenium

IPC Code: Int. Cl.8 C01F17/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 333-338

 

 

Di- and tri-organogermanium carboxylates: Synthesis, spectroscopy and structures
of [Me3Ge(O2CC9H6N)] and [Et2Ge(O2CC5H4N)2]

 

Alpa Y Shaha, Amey Wadawalea, V S Sagoriaa, Vimal K Jaina, *, Renu Sharmab,
Meena Nagarb & Rakesh Bohrab

aChemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India

Email: jainvk@barc.gov.in

bDepartment of Chemistry, University of Rajasthan, Jaipur 302 004, India

Received 12 December 2008; accepted 3 February 2009

Di- and tri-organogermanium carboxylates, [R2Ge(O2CAr)2] and [R3Ge(O2CAr)] (R = Me, Et or Bu; Ar = C5H4N, C9H6N), have been synthesized by the reactions of the corresponding dialkyldichloro germane and trialkylchloro/bromo germane with an appropriate sodium salt of N-heterocyclic carboxylic acid, (C5H4N.COOH, C9H6N.COOH), in 1:2 and 1:1 molar ratio in anhydrous benzene. These compounds have been characterized by elemental analysis, IR and NMR (1H and 13C{1H}) spectroscopy. Molecular structures of [Me3Ge(O2CC9H6N)] and [Et2Ge(O2CC5H4N)2] have been determined unambiguously by X-ray diffraction study. The former has a distorted tetrahedral configuration around germanium with monodentate carboxylate group, while the latter has distorted trigonal bipyramidal geometry.

Keywords: Coordination chemistry, X-ray diffraction, Germanium, Carboxylates

IPC Code: Int. Cl.8 C07F7/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 339-345

 

 

Oxidation of mephenesin and guaifenesin with chloramine-B in
hydrochloric acid medium: Design of kinetic model

Puttaswamy* & Anu Sukhdev

Department of Post-Graduate Studies in Chemistry, Central College, Bangalore University, Bangalore 560 001, India

Email: pswamy_chem@yahoo.com

Received 1 September 2008; revised and accepted 13 February 2009

Kinetics of oxidation of mephenesin and guaifenesin by sodium N-chlorobenzenesulfonamide (CAB) have been investigated in HCl medium at 303 K. The oxidation behaviour is similar for both the substrates. The rate shows a first order dependence on both [CAB]0 and [HCl], and is fractional in [substrate]0. The orders individually in [H+] and [Cl-] are fractional. The variation of ionic strength and addition of the reduction product, benzenesulfonamide, has no significant effect on the reaction rate. The solvent isotope effect has been studied using D2O, and the oxidation products have been identified. Composite activation parameters for the reaction have been determined from Arrhenius plots. Michaelis-Menten type of kinetics is observed and activation parameters for the rate limiting steps have also been computed. The proposed mechanism assumes the simultaneous catalysis by H+ and Cl- ions. The reaction is found to be moderately faster in guaifenesin in comparison with mephenesin, which may be attributed to the involvement of methoxy and methyl groups of the substrate. The observed results have been explained by a plausible mechanism and the related rate law has been proposed.

Keywords: Kinetics, Reaction mechanisms, Oxidations, Propane diols, Mephenesin, Guaifenesin

IPC Code: Int. Cl.8 CO7B33/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp.346-351

 

 

Kinetics and mechanism of (salen)MnIIIcatalysed hydrogen peroxide
oxidation of diphenyl sulphides

A Chellamani* & N M I Alhaji

Department of Chemistry, Manonmaniam Sundaranar University, Tirunelveli 627 012, India

Email: achellamani@yahoo.co.in

Received 6 October 2008; revised and accepted 10 February 2009

The kinetics of (salen)MnIII complexes-catalysed oxidation of a few diphenyl sulphides by hydrogen peroxide have been investigated at 25oC in acetonitrile (80%) water (20%) spectrophotometrically. The reaction follows first-order kinetics in (salen)MnIII complex and zero-order kinetics in hydrogen peroxide. The order of the reaction with respect to sulphide is fractional. The effects of nitrogenous bases, free radical inhibitor and changes in solvent composition have also been studied. A suitable mechanism involving a manganese(III)-hydroperoxide complex as reactive species has been proposed.

Keywords: Kinetics, Reaction mechanisms, Oxidations, Manganese, Salen, Diphenyl sulphides

IPC Code: Int. Cl.8 C07B33/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp.352-356

 

 

Surface functionalities of nitric acid treated carbon A density functional theory based vibrational analysis

R Mahalakshmy, P Indraneel & B Viswanathan*

National Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India

Email: bvnathan@iitm.ac.in

Received 6 October 2008; accepted 9 February 2009

The appropriate combination of surface functionalities and their relative contribution to the total surface functionalities of oxidized carbon by nitric acid are evaluated by density functional theory calculations. Though the computed and experimental spectra do not exactly match in all respects, the methodology adopted has a definite role in understanding the complex surface functionalities of treated carbon.

Keywords: Theoretical chemistry, Density functional theory, Vibrational spectroscopy, Surface chemistry, Carbon, Functional groups

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp.357-361

 

 

Oxidation of thiosulphate by hexacyanoferrate(III) in aqueous
perchloric acid medium  A kinetic and mechanistic study

 

R K Patil, S A Chimatadar & S T Nandibewoor*

PG Department of Studies in Chemistry, Karnatak University, Dharwad 580 003, India

Email: stnandibewoor@yahoo.com

Received 25 April 2008; revised and accepted 19 January 2009

The kinetics of oxidation of thiosulphate by hexacyano-ferrate(III) in an aqueous perchloric acid medium has been studied spectrophotometrically by stopped flow method at 25C. The stoichiometry is 1:1, i. e., one mole of thiosulphate consumes one mole of hexacyanoferrate(III). The reaction products are identified as Fe(CN)62- and S4O62-. The reaction is first order with respect to hexacyanoferrate(III) and thiosulphate concentrations. Increase in perchloric acid concentration increases the rate of reaction (order=0.40). Added products do not have any significant effect on the rate of reaction. The effect of ionic strength and dielectric constants on the reaction rate has also been studied. The active species of oxidant is indicated to be HFe(CN)63-. A suitable mechanism is proposed and the reaction constants of the different steps involved have been evaluated. Activation parameters have also been calculated with respect to the slow step of the mechanism.

Keywords: Kinetics, Reaction mechanisms, Oxidations, Thiosulphate, Hexacyanoferrate

 

IPC Code: Int. Cl.8 C07B33/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 362-366

 

 

Oxidative regeneration of carbonyl compounds from oximes by
morpholinium chlorochromate: A kinetic and mechanistic study

 

Anurag Choudharya, S Agarwalb & Vinita Sharmaa, *

aDepartment of Chemistry, JNV University, Jodhpur 342 005, India

bGovt JDB Girls College, Kota 324002, Rajasthan, India

Received 13 August 2008; revised and accepted 12 February 2009

The oxidative deoximination of several aldo- and keto-oximes by morpholinium chlorochromate in dimethyl sulphoxide, exhibits a first order dependence on both the oxime and MCC. The oxidation of ketoximes is slower than that of aldoximes. The rate of oxidation of aldoximes correlate well in terms of Pavelich-Taft dual substituent-parameter equation. The low positive value of polar reaction constant indicates a nucleophilic attack by a chromate oxygen on the carbon. The reaction is subject to steric hindrance by the alkyl groups. The reaction of acetaldoxime has been studied in nineteen different organic solvents. The solvent effect has been analysed by multiparametric equations. A mechanism involving the formation of a cyclic intermediate in the rate-determining step has been proposed.

Keywords: Kinetics, Reaction mechanisms, Deoximation, Oxidative regeneration, Oximes, Ketooximes, Aldooximes

IPC Code: Int. Cl.8 C07B33/00

 

 

Indian Journal of Chemistry

Vol. 48A, March 2009, pp. 367-371

 

 

Sonophotocatalytic behavior of cerium doped salts of Cu(II), Co(II) and Mn(II) in the degradation of phenol

Pankaj* & Mayank Verma

Department of Chemistry, Faculty of Science, Dayalbagh Educational Institute, Agra, 282 005, India

Email: pankaj2@sancharnet.in

Received 11 December 2008; revised and accepted 30 January 2009

Crystals of CuSO4.5H2O, CoCl2.6H2O, and MnCl2.4H2O doped with CeCl3 under sonicated and unsonicated conditions have been synthesized. The crystals synthesized under sonicated conditions are different than those synthesized under unsonicated conditions with respect to shape, size, and color. The crystal composition has been estimated by atomic absorption spectrophotometry with graphite furnace and UV-visible spectrophotometer. Higher percentage of Cu(II), Mn(II) and Ce(III) in the crystals synthesized under sonication as compared to the unsonicated crystals may be attributed to the change in the composition of the lattice pattern due to the mechanical impact of ultrasound, whereas such an effect has not been found in the Co(II) salts. Enhanced sonophotocatalytic effect of these crystals on the degradation of phenol under sonic conditions is attributed to the increased number of unpaired electron following free radical mechanism.

Keywords: Sonocrystallization, Sonophotocatalysis, Degradation, Phenol degradation, Doped salts, Cerium, Copper, Cobalt, Manganese