Indian Journal of Chemistry

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

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VOLUME 47A

NUMBER 8

August 2008

CONTENTS

 

1171

 

Insight into the electron delocalization in phenylacetylenes and phenylvinylenes: An NBO analysis

 

 

 

 

 

G Krishna Chaitanya, Anup Thomas, C R Sinu,
Biju Francis, K P Subhashchandran,
K Ramakrishna & K Bhanuprakash*

 

 

 

NBO analysis has been carried out on positional isomers of bis(phenylethynyl) benzene, phenyl ethenylphenylethynyl benzene and bis(phenylethenyl) benzene molecules to elucidate the delocalization energies in phenylacetylenes and phenylvinylenes, which make up the cruciform molecules. Substitution of donor and acceptor groups reduces the difference in delocalization energies between these isomers.

 

1181

 

Synthesis, characterization and catalytic properties of microporous silicotitaniumphosphate by neutral templating route

 

 

 

 

 

 

 

 

 

 

 

 

Krishanu Sarkar, Mahasweta Nandi &
Asim Bhaumik*

 

 

 

A new series of microporous silicotitaniumphosphate and its organic-inorganic hybrid analogue have been synthesized under hydrothermal conditions with a neutral structure-directing agent, 4,4'-trimethylenedipiperidine, at almost neutral pH. Studies suggest the presence of Si-O-P and Ti-O-Si bonds, and tetrahedral coordination of Ti(IV) in the samples. These samples show good catalytic activity towards partial epoxidation of cyclohexene and styrene under liquid phase condition.

 

 

 

1187

 

Influence of substitution of Ru on the electrocatalytic properties of the perovskite-type LaSrNiO4 electrode towards methanol oxidation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R N Singh*, A Singh, Anindita, D Mishra,
S K Tiwari & M K Gunjan

 

 

 

Ru-substituted perovskite oxides with molecular formulae LaSrNi1-xRuxO4 (0.1 ≤ x ≤ 0.5) have been obtained by a
modified citric acid sol-gel route at 600°C. The study shows that 0.2–0.5 mol Ru substitution improves the apparent electrocatalytic activity of the oxide towards electrooxidation of methanol, the improvement being highest with 0.2 mol Ru substitution.

 

 

 

1194

 

Kinetics and mechanism of iridium(III) catalyzed oxidation of ethylene glycol by cerium(IV) in sulfuric acid media

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Wei-song Bai, Yong-qing Zhai*, Hong-mei Liu, Hong-ying Lü & Wen-yu Song

 

 

 

K1

 
 


H++ HOCH2CH2OH                         HOCH2CH2OH2+

K2

 
 


HOCH2CH2OH2+ + Ir(III)               Ir(III)·HOCH2CH2OH2+ (adduct)

adduct + Ce(SO4)2Ir(IV)·HOCH2CH2OH2+ + Ce(III)

                                                                                   + 2SO42-

Ir(IV)·HOCH2CH2OH2+     Ir(III) +

                                                        + 2H+

   +    Ce*(IV)       Ce(III)

                                                                     + HOCH2CHO + H+

 

1199

 

Oxidation of L-cystine by 12-tungstocobaltate(III) in aqueous perchlorate medium: A kinetic approach

 

 

 

 

 

 

 

 

 

 

Prasanna Kumar Satpathy, Gobind Chandra Dash & Prakash Mohanty*

 

 

 

Oxidation reaction of L-cystine with 12-tungstocobaltate(III) (CoIIIW12O40 or CoIIIW) has been studied spectrophoto-metrically over the range, 1.15 £ 103[H4L2+]T £ 3.5;
2.0 £ pH£ 5.0, 25°C £ t £ 40°C and I = 0.3 mol dm-3 (NaClO4). Both the conjugate bases of L-cystine participate in the electron transfer reaction. The rate of the reaction increases with the increase in pH and [L-cystine]T. The reaction shows first order dependence both on [CoIIIW5 –] and [L-cystine]T.

 

Notes

 

1204

 

First report of structurally characterized dimorph of an oxovanadium(V)-hydrazonato complex containing V2O34+ core

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bipul Mondal, Michael G B Drew & Tapas Ghosh*

 

 

 

The orthorhombic crystalline variety (with Pbca space group) of [V2O3(L)2], incorporating the doubly deprotonated tridentate benzoyl hydrazone of 2-hydroxy-5-methylacetophenone has been synthesized by the decomposition of [VIVO(L)(bipy)] complex in CH2Cl2.

 

 

 

1208

 

Synthesis and physicochemical characterization of some Schiff base complexes of chromium(III)

 

 

 

 

 

 

 

 

R K Dubey*, U K Dubey & C M Mishra

 

 

 

Some chromium(III) complexes of the type, [Cr(L)2(H2O )2]Cl  (where L = Schiff bases derived from the condensation of
2-aminopyridine, 2-aminophenol, o-toluidine, p-toluidine,
3-nitroaniline and anthranilic acid with salicylaldehyde/vanillin and substituted benzimidazole/benzoxazole or mercapto-benzimidazole) have been prepared by the reaction of chromium(III) chloride with the corresponding ligands followed by immediate addition of ethanolic solution of anhydrous sodium acetate in 1:2 molar ratio. Octahedral structure is proposed for the complexes.

 

 

1213

 

Kinetics and mechanism of oxidation of aliphatic alcohols by [bis(trifluoroacetoxy)iodo]benzene

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jayshree Banerji, Pradeep K Sharma* &
Kalyan K Banerji

 

 

 

Oxidation of some aliphatic alcohols by [bis(trifluoro-acetoxy)iodo]benzene in aqueous acetic acid solution leads to the formation of the corresponding carbonyl compounds.

 

 

 

1218

 

Oxidation of diols by cetyltrimethylammonium dichromate

 

 

 

 

 

 

 

 

 

 

Sabita Patel,  Dae Dong Sung* & B K Mishra*

 

 

 

 

 

1222

 

Kinetics and mechanism of Mn(II) catalyzed oxidation of acridine yellow by chloramine-T

 

 

 

 

 

Brijesh Pare*, Manisha Ayachit &
S B Jonnalagadda

 

 

 

Kinetics and mechanism of the uncatalyzed and Mn(II) catalyzed oxidation of acridine yellow dye by chloramine-T in acidic media has been studied using spectrophotometry. With excess concentrations of other reactants, the reaction rate follows pseudo first order kinetics with respect to acridine yellow. The uncatalyzed reaction has fractional order dependence on chloramine-T as well as on H+ concentration. The catalyzed reaction follows first order kinetics in catalyst [Mn(II)].

 

 

1226

 

Kinetics of oxidation of gabapentin (neurontin) by chloramine-T in perchloric acid medium

 

 

 

 

 

 

 

 

 

 

K Mohan* & M B Jagadeesh

 

 

 

TsNH2Cl+  TsNHCl + H+                                          fast

 

TsNHCl + GP                        X (Complex I)                                 fast

 

X  X′ (Complex II)               slow & rate limiting step

X′ + TsNHCl  Products                                      fast

 

 

 

1230

 

Micellar properties of benzyldimethyldodecyl-ammonium bromide in aquo-organic solvent media

 

 

 

 

 

 

 

 

 

 

Kallol K Ghosh* & Vidyacharan Baghel

 

 

 

Micellar properties of benzyldimethyldodecylammonium bromide have been studied by conductivity method in binary mixtures
(10% v/v) of acetonitrile, dimethyl sulfoxide, tetrahydrofuran,
1,4-dioxane, methanol and ethylene glycol at different temperatures ranging from 300 to 319 K. The thermodynamics of micellization have also been determined. The increase of critical micelle concentration with solvent mixtures has been discussed on the basis of water structure, solvent properties and hydrophobic interactions.

 

 

Authors for correspondence are indicated by (*)

 

 


Indian Journal of Chemistry

Vol 47A, August 2008, pp.1171-1180

 

Insight into the electron delocalization in phenylacetylenes and phenylvinylenes: An NBO analysis

G Krishna Chaitanya, Anup Thomas, C R Sinu, Biju Francis, K P Subhashchandran, K Ramakrishna & K Bhanuprakash*

Received 13 February 2008; revised 18 June 2008

NBO analysis has been carried out for model molecules to elucidate the delocalization energies in phenylacetylenes and phenylvinylenes (which make up cruciform molecules). The model molecules considered are 1,2- , 1,3- and 1,4- positional isomers of bis(phenylethynyl)benzene, phenylethenyl-phenylethynylbenzene and bis(phenylethenyl)benzene which represent the bent-, cross- and linear-conjugation path ways respectively. The geometry has been obtained at
B3LYP/6-311G(d,p) level and the NBO analysis carried out at the same level. It is observed that the substitution of donor and acceptor groups reduces the difference in delocalization energies between these isomers.

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1181-1186

 

Synthesis, characterization and catalytic properties of microporous silicotitaniumphosphate by neutral templating route

 

Krishanu Sarkar, Mahasweta Nandi & Asim Bhaumik*

Received 15 May 2008; revised 25 June 2008

A new series of microporous silicotitaniumphosphate and its organic-inorganic hybrid analogue have been synthesized under hydrothermal condition with the assistance of a neutral structure-directing agent, 4,4¢-trimethylenedipiperidine under almost neutral pH condition. PXRD, FE-SEM, TEM and N2 sorption studies have been used to characterize these materials. FTIR and UV-visible studies suggest the presence of Si-O-P and Ti-O-Si bonds, and tetrahedral coordination of Ti(IV) in the samples. The thermal stability of the materials has been analyzed by TGA/DTA. These samples show good catalytic activity towards the liquid phase partial epoxidation of cyclohexene and styrene using dilute H2O2 as oxidant.

IPC Code: Int. Cl.8 B01J21/00; B01J29/00; B01J37/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1187-1193

 

Influence of substitution of Ru on the electrocatalytic properties of the
perovskite-type LaSrNiO4 electrode towards methanol oxidation

R N Singh*, A Singh, Anindita, D Mishra, S K Tiwari & M K Gunjan

Received 31 January 2008; revised 6 June 2008

Ru-substituted perovskite oxides with molecular formulae LaSrNi1-xRuxO4 (0.1 ≤ x ≤ 0.5) have been obtained by a modified, citric acid sol-gel route at 600°C for their possible use as anodes in a direct methanol fuel cell (DMFC). These oxides have been as film on a nickel support and investigated for electrocatalysis of methanol oxidation in 1M KOH using XRD, SEM, cyclic voltammetry, chronoamperometry, impedance and Tafel polarization. The study shows that 0.2-0.5 mol Ru substitutions improve the apparent electrocatalytic activity of the oxide towards electrooxidation of methanol; the observed improvement being the greatest (~ 80% at E = 0.55 V versus Hg/HgO) with 0.2 mol Ru substitution. During a chronoamperometric study of 5 h at E = 0.5 V in 1M KOH + 1M CH3OH, the Ru-substituted electrodes did not indicate any poisoning by the methanol oxidation intermediates/products. The methanol electrooxidation reaction follows a Tafel slope of ~ 40 mV decade-1 and the order with respect to [OH-] is `~ 2 on each electrocatalyst, regardless of the Ru content.

IPC Code: Int. Cl.8 B01J23/46; B01J23/755; H01M486/00; H01M4/92

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1194-1198

 

Kinetics and mechanism of iridium(III) catalyzed oxidation of ethylene glycol by cerium(IV) in sulfuric acid media

 

Wei-song Bai, Yong-qing Zhai*, Hong-mei Liu, Hong-ying Lü & Wen-yu Song

Received 12 October 2007; revised 9 July 2008

 

The kinetics and mechanism of trace iridium(III) catalyzed oxidation of ethylene glycol by cerium(IV) in sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 298-313K. The reaction is first order with respect to Ce(IV) and Ir(III), and a positive fractional order with respect to EG. It is found that the pseudo-first order ([EG]>>[Ce(IV)]>>[Ir(III)]) rate constant, kobs, decreases with the increase of [HSO4-] and increases with the increase of [H+]. Under nitrogen atmosphere, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a reasonable mechanism has been proposed. Rate equations derived from this mechanism can explain all the experimental results. From the dependence of kobs on the concentration of HSO4-, the kinetically active species has been found to be Ce(SO4)2. The rate constants of the rate determining step and the activation parameters have been evaluated.

IPC Code: Int. Cl.8 C07B33/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1199-1203

 

Oxidation of L-cystine by 12-tungstocobaltate(III) in aqueous perchlorate medium: A kinetic approach

Prasanna Kumar Satpathy, Gobind Chandra Dash & Prakash Mohanty*

Received 4 December 2006; revised 2 July 2008

The oxidation reaction of L-cystine with 12-tungstocobaltate(III) (CoIIIW12O40 or CoIIIW) has been studied spectrophotometrically over the range 1.15 £ 103[H4L2+]T. £ 3.5; 2.0 £ pH £ 5.0; 25°C £ t £ 40°C and I = 0.3 mol dm-3 (NaClO4). Both the conjugate bases of L-cystine participate in the electron transfer reaction. The rate of the reaction has been found to increase with the increase in pH and [L-cystine]T. The reaction shows first order dependence both on [CoIIIW5 –] and [L-cystine]T. The DH¹ (kJ mol-1) and S¹ (J K-1 mol-1) for k1 and k2 paths are 16.9±2.0, 16.1±0.5 and –205±6, –204±1.5, respectively. Negative activation entropy is indicative of ordered transition state for the reaction. The product of the reaction has been found to be the cystinesulphoxide.

IPC Code: Int. Cl.8 C07B33/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1204-1207

 

First report of structurally characterized dimorph of an oxovanadium(V)-hydrazonato complex containing V2O34+ core

Bipul Mondal, Michael G B Drew & Tapas Ghosh*

Received 4 April 2008 ; revised 26 May 2008

The orthorhombic crystalline variety (with Pbca space group) of the title complex [V2O3(L)2], incorporating the doubly deprotonated tridentate benzoyl hydrazone of 2-hydroxy-5-methylacetophenone has been synthesized from the decomposition of [VIVO(L)(bipy)] complex in CH2Cl2 and structurally characterized in contrast to its recently reported monoclinic variety (with C2/c space group) obtained from the reaction of [VO(acac)2] with H2L in acetone.

IPC code: Int. Cl.8 C07F9/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1208-1212

 

Synthesis and physicochemical characterization of some Schiff base complexes of chromium(III)

R K Dubey*,  U K Dubey & C M Mishra

Received 20 December 2007; revised 22 July 2008

Some chromium(III) complexes of the type, [Cr(L)2(H2O )2]Cl (1-10) [where L = Schiff bases (sbH, derived from the condensation of 2-amino pyridine, 2-aminophenol, o-toluidine,  p-toluidine, 3-nitroaniline and anthranilic acid with salicylaldehyde/vanillin) and substituted benzimidazole/ benzoxazole or mercaptobenzimidazole] have been prepared by the reaction of chromium(III) chloride with corresponding ligands followed by immediate addition of ethanolic solution of anhydrous sodium acetate in 1:2 molar ratio. The resulting products have been characterized by elemental analysis, spectral (IR, UV-visible and FAB-mass) as well as magnetic susceptibility measurements. Octahedral structure is proposed for the complexes.

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1213-1217

 

Kinetics and mechanism of oxidation of aliphatic alcohols by [bis(trifluoroacetoxy)iodo]benzene

 

Jayshree Banerji, Pradeep K Sharma* & Kalyan K Banerji

Received 14 December 2007; revised 4 July 2008

The oxidation of some aliphatic alcohols by [bis(trifluoro-acetoxy)iodo]benzene (TFAIB) in aqueous acetic acid solution leads to the formation of the corresponding carbonyl compounds. The reaction is first order in TFAIB and a Michaelis-Menten kinetics is obtained with respect to the alcohols. The reaction shows a first order dependence on hydrogen ions. The oxidation of [1,1-2H2]ethanol and [2-2H]propan-2-ol exhibits the presence of a substantial primary kinetic isotope effect at 298 K (kH/kD = 3.64 and 3.89 respectively). The rate of disproportionation of the intermediate is susceptible to both polar and steric effects of the substituents. A suitable mechanism has also been proposed.

IPC Code: Int.Cl.8 C07B33/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1218-1221

 

Oxidation of diols by cetyltrimethylammonium dichromate

Sabita Patel,  Dae Dong Sung & B K Mishra*

Received 29 November 2007, revised 3 July 2008.

The oxidation kinetics of some diols have been investigated using cetyltrimethylammonium dichromate as the oxidant in dichloromethane  in the presence of acetic acid and a cationic surfactant. A tentative mechanism has been proposed on the basis of (i) observed rate constant dependencies on the reactants, (ii) high negative entropy change and (iii) the kobs dependencies on surfactant concentration.

IPC Code: Int. Cl.8 C07B33/00

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1222-1225

 

Kinetics and mechanism of Mn(II) catalyzed oxidation of acridine yellow by Chloramines-T

Brijesh Pare*, Manisha Ayachit & S B Jonnalagadda

Received 3 March 2008; revised 9 July 2008

The kinetics and mechanism of the uncatalyzed and Mn(II) catalyzed oxidation of acridine yellow(3,6-diamino-2,7-dimethyl acridine hydrochloride) dye by chloramine-T in acidic media has been studied using spectrophotometry. With excess concentrations of other reactants, the reaction rate follows pseudo first order kinetics with respect to acridine yellow. The uncatalyzed reaction has fractional order dependence on chloramine-T as well as on H+ concentration. The catalyzed reaction follows first order kinetics in catalyst [Mn(II)]. Variations of ionic strength has no influence on the reaction rate suggesting that neutral charged species are involved  in  the  rate  determining  step.  Increase  in  the  addition of p-toluenesulfonamide results in decrease in rate constant values. The basic stoichiometric equation is as follows: AY+ ArSO2NHCl + H2O = P+ + ArSO2NH2 +CH3CH2OH + CH3CN + 2HCl, where P+ = 7-aminoquinoline-2, 3-dicarboxylic acid. The lowest catalytic limit for Mn(II) has been found to be 1.0x10-8 mol dm-3. On the basis of various kinetic investigations and product analysis mechanisms have been proposed.

IPC Code: Int. Cl.8 C07B33/00; C09B15/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp. 1226-1229

 

Kinetics of oxidation of gabapentin (neurontin) by chloramine-T in perchloric acid medium

K Mohan* & M B Jagadeesh

Received 16 May 2007; revised 6 June 2008

A kinetic study of oxidation of gabapentin (neurontin) by chloramine-T has been carried out in HClO4 medium at 303 K. The reaction rate is first order dependence on [CAT]o, fractional order on [GP]o and an inverse fractional order on [H+]. Effects of added p-toluenesulfonamide and halide ions, and varying ionic strength of the medium have been investigated and the activation parameters evaluated. The reaction fails to initiate polymerization of acrylonitrile. The reaction stoichiometry and oxidation products have been identified and a suitable mechanism has been proposed.

IPC code: Int. Cl.8 C07B33/00

 

Indian Journal of Chemistry

Vol. 47A, August 2008, pp.1230-1233]

 

Micellar properties of benzyldimethyldodecylammonium bromide in aquo-organic solvent media

Kallol K Ghosh* & Vidyacharan Baghel

Received 24 March 2007; revised 10 July 2008

The micellar properties of benzyldimethyldodecyl-ammonium bromide has been studied by conductivity method in the binary mixtures (10% v/v) of acetonitrile, dimethyl sulfoxide, tetrahydrofuran,1,4-dioxane, methanol and ethylene glycol at different temperatures ranging from 300 to 319 K. The thermodynamics of micellization i.e, Gibbs free energy (ΔG°m), enthalpy (ΔH°m), and entropy (ΔS°m) have also been determined. The increase of critical micelle concentration with solvent mixtures has been discussed on the basis of water structure, solvent properties and hydrophobic interaction.