Indian Journal of Chemistry

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

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VOLUME 48A

NUMBER 8

August 2009

CONTENTS

 

1055

 

Micellar effect on the reaction of chromium(VI) oxidation of some representative ahydroxy acids in the presence and absence of 2,2´-bipyridyl in aqueous acid media: A kinetic study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ruhidas Bayen, Monirul Islam & Asim K Das*

 

 

 

 

Kinetics of chromic acid oxidation of α-hydroxy acids in presence and absence of 2,2´-bipyridyl in aqueous acid media has been  studied at different temperatures with [α-hydroxy acid] >> [Cr(VI)]T and [bpy]T >>[Cr(VI)]T. Monomeric Cr(VI) is the kinetically active species in the absence of bpy while in the bpy-catalysed path, the Cr(VI)bpy complex is the active oxidant. Both the paths show first order dependence on [α-hydroxy acid]T and [Cr(VI)]T. The bpy-catalysed path is also first order in [bpy]T. In the presence of N-cetylpyridinium chloride and sodium dodecyl sulfate, the reaction orders remain unchanged, with the former retarding and the latter accelerating the rate for both paths.

 

 

 

1062

 

Catalytic non-thermal plasma reactor for total oxidation of volatile organic compounds

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ch Subrahmanyam

 

 

 

A dielectric barrier discharge reactor with inner electrode modified with oxides of Ti, Mn and Co has been designed and tested for the oxidation of diluted volatile organic compounds, viz., toluene, isopropanol and trichloroethylene. Among the catalysts studied, MnOx/SMF shows the best performance. The MnOx-modified electrodes and TiO2 effectively destroy trichloroethylene due to the synergy between plasma excitation of the trichloroethylene molecules and catalytic behavior. The catalytic process is further enhanced by photocatalysis since TiO2 absorbs UV light produced by the non-thermal plasma.

 

 

1069

 

Densities, speeds of sound and viscosities of
L-alanine in aqueous fructose, maltose and lactose solutions at different temperatures

 

 

 

 

 

 

 

 

 

 

 

Amalendu Pal* & Nalin Chauhan

 

 

 

 

Density, speed of sound and viscosity measurements have been made for L-alanine (0.02 - 0.20 mol kg-1) in aqueous fructose, maltose and lactose solutions, ranging from pure water to
25 mass % of saccharides at 288.15, 298.15 and 308.15 K. These measurements have been used to evaluate the apparent molar volume, limiting apparent molar volume, transfer volume, viscosity B-coefficients of Jones-Dole equation, transfer
B-coefficients, apparent molar adiabatic compressibility, limiting apparent molar adiabatic compressibility and its transfer values at infinite dilution.

 

 

1078

 

Palladium(II) complexes of hydrazones derived from 4-dodecyloxybenzoylhydrazine with some aliphatic and aromatic aldehydes and their mesogenic behaviour

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

M B H Howlader*, M T H Tarafder &
M A A A A Islam

 

 

 

 

Hydrazinato complexes, Pd[C12H25OC6H4C(O)=N-N=CHR]2, are formed by the reaction of C12H25OC6H4C(=O)NHNH2, with formaldehyde, acetaldehyde, butyraldehyde, crotonaldehyde, cinnamaldehyde, benzaldehyde, 4-chloro­benzaldehyde, 2-chlorobenzaldehyde and 2,4-dimethoxybenzaldehyde and subsequent addition of palladium(II) chloride. All the complexes are square planar. Pd[C12H25OC6H4C(O)=N-N=CHCH2CH2CH3]2 shows enantiotropic behaviour while the complexes, Pd[C12H25OC6H4C(O)=N-N=CHCH=CHC6H5]2 and Pd[C12H25OC6H4C(O)=N-N=CHC6H3(OCH3)2]2, show monotropic behaviour.

 

 

 

1085

 

Agar/sodium alginate-graft-polyacrylonitrile,
a stable hydrogel system

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mahesh U Chhatbar, Ramavatar Meena,
Kamalesh Prasad & A K Siddhanta*

 

 

 

 

Polyacrylonitrile grafted agar/sodium alginate has been synthesized in aqueous medium under reflux conditions in the presence of potassium persulphate as a free radical initiator. The swelling capacity of Agar/Na-Alg-graft-PAN is 8.5g/g at pH 1.2 and the swelled material is stable for over 24 h.

 

 

 

Notes

 

1091

 

Thermal decomposition of CF3CFClO radical–
A computational study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hari Ji Singh*, B K Mishra & N K Gour

 

 

 

 

Theoretical study on the decomposition pathways of haloalkoxy radical formed from 2-chloro-1,1,1,2-tetrafluoroethane is reported. Single point energy calculations have been performed using MP4, QCISD(T) and CCSD(T) levels of theory. Critical energy barriers for C-C bond scission and Cl elimination, the two prominent decomposition channels, are 8.4 and 1.5 kcal mol-1 respectively. Cl elimination is the dominant path involving a lower barrier height. Using transition state theory, rate constants for Cl elimination and C-C bond scission at 298 K and 1 atm pressure are 4.6×105 and 5.1×104 s-1 respectively.

 

 

 

1096

 

Density functional theory investigation of electrophilic addition reaction of chlorine to
3,4-benzobicyclo[3.2.1]octadiene

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rza Abbasoglu* & Abel Magerramov

 

 

 

 

Full geometric optimization of 3,4-benzobicyclo[3.2.1]octadiene has been carried out by DFT/B3LYP method using the
6-311G(d), 6-311G(d,p) and 6-311+G(d,p) basis sets. The double bond is endo-pyramidalized and its two faces are not equivalent. The stable configurations of the BBOD-Cl2 system correspond to BBOD…Cl2(exo) and BBOD…Cl2(endo) molecular complexes which are formed by the exo and endo orientation respectively of Cl2 molecule to the double bond of BBOD in axial position.
Exo-complex is relatively more stable than the endo-complex.

 

 

 

 

1102

 

Syntheses, crystal structures and antibacterial activities of two end-on azido-bridged copper(II) complexes with Schiff bases

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rui-Hua Hui*, Peng Zhou & Zhong-Lu You

 

 

 

 

Reactions of 4-bromo-2-[(2-diethylaminoethylimino)methyl] phenol and 1-[(2-ethylaminoethylimino)methyl]-naphthalen-2-ol with copper acetate and ammonium thiocyanate, respectively, afford two centrosymmetric azido-bridged dinuclear copper complexes, [Cu(L1)21,1-N3)2] and [Cu(L2)21,1-N3)2]. The
Cu atom in the complexes is
five-coordinate in a distorted square pyramidal geometry.

 

 

 

 

1107

 

Oxidative cleavage of gabapentin with
N-bromosuccinimide in acid medium: A kinetic and mechanistic study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

P M Ramdas Bhandarkar & K N Mohana*

 

 

 

Kinetics of oxidative degradation of gabapentin with
N-bromosuccinimide in HClO4 medium has been studied at
308 K. The stoichiometry of the reaction is found to be 1:1, and (CH2CO)2N+HBr is postulated to be the reactive oxidizing species. The oxidation reaction fails to induce polymerization of the added acrylonitrile.

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

 

   

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1055-1061

 

 

Micellar effect on the reaction of chromium(VI) oxidation of some representative ahydroxy acids in the presence and absence of
2,2´-bipyridyl in aqueous acid media: A kinetic study

Ruhidas Bayen, Monirul Islam & Asim K Das*

Department of Chemistry, Visva-Bharati University, Santiniketan 731 235, India

Email: ak_das3@yahoo.com

Received 14 May 2009; revised and accepted 11 July 2009

The kinetics and mechanism of chromic acid oxidation of a-hydroxy acids in the presence and absence of  2,2´-bipyridyl in aqueous acid media have been studied at different temperatures by quenching technique under the conditions of [a-hydroxy acid] >> [Cr(VI)]T and [bpy]T >>[Cr(VI)]T. Under the kinetic conditions, the monomeric species of Cr(VI) has been found to be kinetically active in the absence of bpy while in the bpy-catalysed path, Cr(VI)bpy complex is suggested as the active oxidant. In the bpy-catalysed path, Cr(VI)-bpy complex receives a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a 2e-transfer redox decomposition leading to Cr(IV)-bpy complex and keto acid. Then the
Cr(IV)-bpy complex participates in the oxidation of
 a-hydroxy acid in faster steps and ultimately is converted into the inert Cr(III)-bpy complex. In the uncatalysed path, Cr(VI)-substrate ester undergoes a redox decomposition through 2e-transfer at the rate determining step. The uncatalysed as well as the bpy-catalysed paths show first order dependence on both [a-hydroxy acid]T and [Cr(VI)]T. The bpy-catalysed path is first order in [bpy]T. In the presence of surfactants like N-cetylpyridinium chloride and sodium dodecyl sulfate, the reaction orders remain unchanged. The former has been found to retard both the uncatalysed and bpy-catalysed paths while the latter shows rate accelerating effect for both the paths. The observed micellar effects have been explained by considering hydrophobic and electrostatic interactions between the reactants and surfactants in terms of the proposed mechanism.

Keywords: Kinetics, Reaction mechanisms, Oxidations, Micellar effects, Hydroxy acids

IPC Code: Int. Cl.9 C07B33/00

 

 

Indian Journal of Chemistry

Vol.48A, August 2009, pp. 1062-1068

 

 

Catalytic non-thermal plasma reactor for total oxidation of
volatile organic compounds

Ch Subrahmanyam

Department of Chemistry, National Institute of Technology Trichy (NITT),

Trichy 620 015, India

Email: csubbu@nitt.edu, challa168@hotmail.com

Received 11 May 2009; revised and accepted 15 July 2009

A dielectric barrier discharge reactor with inner electrode modified with metal oxides of Ti, Mn and Co has been designed and tested for the oxidation of diluted volatile organic compounds (VOCs) of different nature like toluene, isopropanol and trichloroethylene. It has been observed that at a fixed concentration of VOC, total oxidation of isopropanol is achieved at lower specific input energy compared to toluene and trichloroethylene. Among the catalysts studied, MnOx/SMF shows the best performance, probably due to the formation of active oxygen species by in situ decomposition of ozone on the catalyst surface. The electrodes modified with MnOx and TiO2 catalyst effectively destroy trichloroethylene due to the synergy between plasma excitation of the trichloroethylene molecules and catalytic behaviour. The catalytic process is further enhanced by photocatalysis since TiO2 absorbs UV light produced by the non-thermal plasma.

Keywords: Catalysis, Photocatalysis, Oxidations, Photooxidation, Non-thermal plasma, Volatile organic compounds

IPC Code: Int. Cl9. B01D53/70; B01D53/86; B01J21/06; B01J23/24; H05H1/24

 

 

Indian Journal of Chemistry

Vol.48A, August 2009, pp. 1069-1077

 

 

Densities, speeds of sound and viscosities of L-alanine in aqueous fructose, maltose and lactose solutions at different temperatures

Amalendu Pal* & Nalin Chauhan

Department of Chemistry, Kurukshetra University, Kurukshetra 136 119, India
Email: palchem@sify.com

Received 8 April 2009; revised and accepted 17 July 2009

Density, speed of sound and viscosity measurements have been made for L-alanine (0.02 - 0.20 mol kg-1) in aqueous fructose, maltose and lactose solutions, ranging from pure water to 25 mass % of saccharides at 288.15, 298.15 and 308.15 K. These measurements have been used to evaluate some important parameters, viz., apparent molar volume, limiting apparent molar volume, transfer volume, viscosity B-coefficients of Jones-Dole equation, transfer B-coefficients, apparent molar adiabatic compressibility, limiting apparent molar adiabatic compressibility and its transfer values at infinite dilution. The activation free energy in different saccharide solutions have been calculated from B-coefficients and partial molar volume data. Hydration number and interaction coefficients have also been calculated from these data. These parameters have been discussed in terms of solute-solvent interactions.

Keywords: Solution chemistry, Density, Viscosity, Amino acids

 

 

\Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1078-1084

 

 

Palladium(II) complexes of hydrazones derived from
4-dodecyloxybenzoylhydrazine with some aliphatic and aromatic aldehydes and their mesogenic behaviour

 

M B H Howlader*, M T H Tarafder & M A A A A Islam

Department of Chemistry, Rajshahi University, Rajshahi, Bangladesh

Email: mbhhowlader@yahoo.com

Received 19 January 2009; revised and accepted 13 July 2009

Hydrazinato complexes, Pd[C12H25OC6H4C(O)=N-N=CHR]2, have been formed by the reaction of ligand precursor, C12H25OC6H4C(=O)NHNH2, with some aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, crotonaldehyde, cinnamaldehyde, benzaldehyde, 4-chlorobenzaldehyde, 2-chlorobenzaldehyde and 2, 4-dimethoxybenzaldehyde and subsequent addition of palladium(II) chloride. The complexes have also been formed by the direct reaction of the ligand, C12H25OC6H4C(=O)NH-N=CHR, with palladium(II) chloride. All the complexes are square planar in nature. Complex Pd[C12H25OC6H4C(O)=N-N=CHCH2CH2CH3]2 shows enantiotropic behaviour while the complexes Pd[C12H25OC6H4C(O)=N-N=CHCH=CHC6H5]2 and Pd[C12H25OC6H4C(O)=N-N=CHC6H3(OCH3)2]2 show monotropic behaviour.

Keywords: Coordination chemistry, Liquid crystals, Mesogenic behaviour, Schiff bases, Hydrazines, Aldehydes, Palladium

IPC Code: Int. Cl.9 C07C251/02; C07F15/00

 

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1085-1090

 

 

Agar/sodium alginate-graft-polyacrylonitrile, a stable hydrogel system

Mahesh U Chhatbar, Ramavatar Meena, Kamalesh Prasad & A K Siddhanta*

Marine Biotechnology & Ecology Discipline, Central Salt & Marine Chemicals Research Institute,

Council of Scientific & Industrial Research, GB Marg, Bhavnagar 364 002, Gujarat, India

Email: aks@csmcri.org

Received 16 April 2009; revised and accepted 13 July 2009

Polyacrylonitrile grafted agar/sodium alginate (Agar/Na-Alg-graft-PAN) has been synthesized in aqueous medium under reflux conditions in the presence of potassium persulphate as a free radical initiator. By varying the reaction parameters, e.g., concentrations of acrylonitrile monomer and K2S2O8, reaction time and temperature, the optimum grafting conditions have been identified as that having the highest grafting ratio (Gr 1.87), total conversion (Ct 1.05) and grafting efficiency (Ge 0.89). The blend and grafted products have been characterized by FTIR, X-ray diffraction, differential scanning calorimeter and scanning electron microscopy.  The swelling capacity of Agar/Na-Alg-graft-PAN is found to be 8.5g/g at pH 1.2 and the swelled material is stable for over 24 h. This copolymer hydrogel system may be exploited in various applications utilizing its swelling properties and stability.

Keywords: Polymers, Graft polymers, Copolymers, Biopolymers, Alginates, Polyacrylonitriles, Hydrogels

IPC Code: Int. Cl.9 C08B37/04; C08F251/00

 

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1091-1095

 

 

Density functional theory investigation of electrophilic addition reaction of chlorine to 3,4-benzobicyclo[3.2.1]-octadiene

Rza Abbasoglua,* & Abel Magerramovb

aDepartment of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey

bDepartment of Chemistry, Baku State University, Baku, Azerbaidjan

Email: rabbas@ktu.edu.tr

Received 9 March 2009; revised and accepted 22 July 2009

Full geometric optimization of 3,4-benzobicyclo[3.2.1]- octadiene (BBOD) has been carried out by DFT/B3LYP method using the 6-311G(d), 6-311G(d,p) and 6-311+G(d,p) basis sets. The double bond is endo-pyramidalized and its two faces are not equivalent. The BBOD-Cl2 system have been investigated by B3LYP/6-311+G(d,p) method and stable configurations determined. The stable configurations of the BBOD-Cl2 system correspond to BBOD…Cl2(exo) and BBOD…Cl2(endo) molecular complexes which are formed by the exo and endo orientation respectively of Cl2 molecule to the double bond of BBOD in axial position. Exo-complex is relatively more stable than the endo-complex. Exo-chloronium cation was found to be more stable than endo-chloronium cation by the DFT method. Exo-facial selectivity is expected in the addition reaction to BBOD of chlorine. The non-classical delocalized chlorocarbonium cation(IV) is the most stable ion among the cationic intermediates, and the ionic addition reaction occurs via this cation. The mechanism of the addition reaction is also discussed.

Keywords: Theoretical chemistry, Electrophilic additions, Density functional calculations, Addition reactions, Geometric optimization

 

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1096-1101

 

 

Thermal decomposition of CF3CFClO radical – A computational study

Hari Ji Singh*, B K Mishra & N K Gour

Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273 009, Uttar Pradesh, India

Email: hari_singh81@hotmail.com

Received 15 June 2009; revised and accepted 27 July 2009

A theoretical study on the decomposition pathways of haloalkoxy radical formed from 2-chloro-1,1,1,2-tetrafluoroethane has been reported. Structures of all the reactants, products and transition states involved in the decomposition pathways have been optimized and characterized at MP2(full)/6-31G(d,p) level of theory. Single point energy calculations have been performed using MP4, QCISD(T) and CCSD(T) levels of theory. Critical energy barriers have been calculated for C-C bond scission and Cl elimination, the two prominent decomposition channels considered in the present investigation, and found to be 8.4 and 1.5 kcal mol-1 respectively. Results show that Cl elimination is the dominant path involving a lower barrier height. Using transition state theory, rate constants for the decomposition pathways, viz., Cl-elimination and C-C bond scission, calculated at 298 K and 1 atm pressure are found to be 4.6×105 and 5.1×104 s-1, respectively. The existence of transition states on the corresponding potential energy surface has been ascertained by performing Intrinsic Reaction Coordinate calculations.

Keywords: Theoretical chemistry, Chlorofluorocarbons, Haloalkoxy radicals, Decompositions, Transition state theory

 

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1102-1106

 

 

Syntheses, crystal structures and antibacterial activities of two end-on azido-bridged copper(II) complexes with Schiff bases

 

Rui-Hua Huia,*, Peng Zhoub & Zhong-Lu Youb

aDepartment of Chemistry, Anshan Normal University, Anshan 114007, PR China

Email: ruihua_hui@126.com

bDepartment of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029, PR China

Received 28 May 2009; revised and accepted 13 July 2009

Reactions of 4-bromo-2-[(2-diethylaminoethylimino)methyl] phenol and 1-[(2-ethylaminoethylimino)methyl]-naphthalen-2-ol with copper acetate and ammonium thiocyanate, respectively, afford two centrosymmetric azido-bridged dinuclear copper complexes, [Cu(L1)21,1-N3)2] (1) and [Cu(L2)21,1-N3)2] (2). Each Cu atom in the complexes is five-coordinate in a distorted square-pyramidal geometry. The antibacterial activities of the Schiff base and the two complexes have been tested.

Keywords: Coordination chemistry, Schiff base, Copper, Dinuclear complexes, X-ray crystallography

IPC Code: Int. Cl.9 C07C251/02; C07F1/08

 

 

Indian Journal of Chemistry

Vol. 48A, August 2009, pp. 1107-1112

 

 

Oxidative cleavage of gabapentin with N-bromosuccinimide in acid medium: A kinetic and mechanistic study

P M Ramdas Bhandarkar & K N Mohana*

Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India

Email: knmsvp@yahoo.com

Received 13 April 2009; revised  and  accepted 2 July 2009

The kinetics of oxidative degradation of gabapentin with N-bromosuccinimide in HClO4­ medium has been studied at 308 K. The experimental rate law obtained is , where x and y are less than unity. The reaction was subjected to changes in concentration of succinimide, the reduction product of NBS, concentration of the added neutral salt, dielectric permittivity and ionic strength of the medium. Solvent isotope effect has been studied using D2O. The stoichiometry of the reaction has been found to be 1:1, and oxidation products have been identified and characterized by FTIR and 1H NMR spectral studies. Activation parameters for the overall reactions have been computed from Arrhenius plot. (CH2CO)2N+HBr has been postulated as the reactive oxidizing species. The oxidation reaction fails to induce polymerization of the added acrylonitrile. The proposed mechanism and the derived rate law are consistent with the observed kinetic data.

Keywords: Kinetics, Reaction mechanisms, Oxidations, Gabapentin

IPC Code: Int. Cl.9 C07B33/00