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A simple and cost effective hydrothermal method has been employed to synthesis morphology controlled pure and Cr doped (4 and 8 at. %) CuO nanostructures. Crystalline purity and structure of the nanostructures were validated by X-ray diffraction and Retvield analyses. Field emission scanning electron microscopy revealed the evolution of rod-like, sheet-like and boat-like morphologies for pure, 4 and 8 at. % Cr doped CuO nanostructures respectively. The optical band gap estimated using the K-M function plot from diffused reflectance spectroscopy showed a shift in band gap from 1.68 to 1.90 eV with respect to Cr concentration. The synthesized CuO nanostructures were investigated for the efficient room temperature gas sensing of ammonia, ethanol and methanol vapours under different concentrations (100-600 ppm). The 8 at. % Cr doped CuO nano-boats showed enhanced gas sensitivity than other CuO nanostructures owing to their typical morphology, larger surface area and related properties. more...

Substitution reactions of some parasubstituted anilines with 2-chloro-5-nitropyridine and 2-bromo-5-nitropyridine were carried out conductometrically in dimethylsulfoxide/acetonitrile mixtures. The correlation of second order rate constants with Hammett's substituent constants yields a fairly linear straight line with a negative slope. The correlation of rate data with Kamlet–Taft's solvatochromic parameters is excellent (100R2= 97%) in both the substrates. The solvation model proposed is well supported by the solvatochromism exhibited by aniline in the solvent mixture under investigation. The molar extinction coefficient (emax ) of aniline varies appreciably up to ∼25% with the change in composition of the mixture. The multivariate correlation analysis of emax (with α, β, π*) suggests that the solvation around NH2 moiety of aniline through hydrogen bond donor (HBD) property is found to be dominant in the solvation process and consequently in altering the rate. The observation is that the dominance of HBD property in solvation is further confirmed by the cyclic voltammetric oxidation of aniline in the solvent mixture. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 409–417, 2011 more...

Imidazolium fluorochromate (IFC) oxidation of 11 meta- and para-substituted benzylamines, in varying mole fractions of benzene/2-methylpropan-2-ol binary mixtures, is first order in IFC and acid and zero order in substrate The Hammett correlation yielded a U-shaped curve, indicating a change in the relative importance of bond formation and bond fission in the transition state The rate data failed to correlate with macroscopic solvent parameters such as epsilon(r) and E(T)(N) The correlation of k(obs) With Kamlet-Taft solvatochromic parameters Suggests that. H-bonding between the reacting species and the solvent plays a major role in governing the reactivity (C) 2010 Wiley Periodicals. Inc Int J Chem Kinet 42 159-167, 2010 more...

Electrochemical oxidation of 15 para- and meta-substituted anilines in different mole fractions of water in 2-methylpropan-2-ol has been investigated in the presence of 0.1 M sulfuric acid as a supporting electrolyte. The oxidation potential data of anilines correlate well with the Brown–Okamoto's substituent constants affording a negative reaction constant. The effect of para- and meta-substituents on the oxidation potential confirms to Swain's F and R, affording negative reaction constants. The oxidation potential values also correlate satisfactorily with macroscopic solvent parameter such as relative permittivity, er. The results of Kamlet–Taft multiple correlation analysis show that specific solute–solvent interactions play a dominant role in governing the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 289–297, 2007 more...

Substitution reactions of 13 para- and meta-substituted anilines with benzenesulfonyl chloride in varying mole fractions of benzene in propan-2-ol have been investigated conductometrically. The second-order rate constants correlate well with pKa values of anilines and with the Hammett's equation. The negative Hammett reaction constant indicates the formation of an electron-deficient transition state. The rate data correlate satisfactorily with macroscopic solvent parameters such as relative permittivity, er, and polarity, ETN. Correlation of rate data with Kamlet–Taft solvatochromic parameters (α, β, π*) suggests that both the specific and nonspecific solute–solvent interactions influence the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 657–663, 2007 more...

The kinetics of oxidation of 11 para- and meta-substituted benzylamines by imidazolium fluorochromate (IFC) in different organic solvent media has been investigated in the presence of p-toluenesulfonic acid (TsOH). The reaction was run under pseudo-first-order conditions. The rate of the reaction was found to be first order in IFC and found to increase with increase in [TsOH]. Solution IR studies in combination with kinetic measurements were used to get a better insight into the mechanism of the oxidation process. The product analysis was carried out using GC–MS. Various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of the isokinetic relationship. The specific rate of oxidizing species benzylamines reaction (k2) correlates with Hammett's substituent constants affording positive reaction constants. The rate data failed to correlate with macroscopic solvent parameters, such as er and ENT, while showing satisfactory correlation with Kamlet–Taft's solvatochromic parameters (α, β, and π*) which suggests that the specific solute–solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute–solvent complexation. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 362–369, 2007 more...

The imidazolium fluorochromate (IFC) oxidation of meta- and para-substituted anilines, in seven organic solvents, in the presence of p-toluenesulfonic acid (TsOH) is first order in IFC and TsOH and is zero order with respect to substrate. The IFC oxidation of 15 meta- and para-substituted anilines at 299–322 K complies with the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies within the experimental range. The specific rate of oxidizing species-anilines reaction (k2) correlates with substituent constants affording negative reaction constants. The rate data failed to correlate with macroscopic solvent parameters such as er and ENT. A correlation of rate data with Kamlet–Taft solvatochromic parameters (α, β, π*) suggests that the specific solute–solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute–solvent complexation. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 166–175, 2006 more...

The kinetics of oxidation of 15 para- and meta-substituted anilines by nicotinium dichromate (NDC) in different organic solvent media in the presence of p-toluenesulfonic acid (TsOH) has been investigated. The rate of the reaction is zero order with respect to substrate, first order in NDC, and is found to increase with increase in {TsOH}. The various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of the isokinetic relationship. The specific rate of oxidizing species-anilines reaction (k 2 ) correlates with Hammett's substituent constants affording negative reaction constants. The effect of para-and meta-substituents on the oxidation rates confirms to Swain et al.'s substituent constants F and R, both with negative reaction constants. The rate data failed to correlate with macroscopic solvent parameters such as e r and E N T while showing satisfactory correlation with Kamlet-Taft's solvatochromic parameters (α, β, and π*). more...