Indian Journal of Chemistry

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

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CODEN: ICACEC; ISSN: 0376-4710 (Print), 0975-0975 (Online)

 

 

 

 

VOLUME 54A

NUMBER 3

MARCH 2015

 

CONTENTS

 

 

309

 

Promotional effects of PPy-modified ZrO2 composite as support and microemulsion medium for selective hydrogenation of cinnamaldehyde over supported
Ru catalyst

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lei Zong, Zhengbin Tian, Yan Li* & Fusui Lu*

 

 

 

Adsorption ability of PPy/ZrO2 in microemulsion promotes selective hydrogenation of cinnamaldehyde and shows high conversion and good selectivity for cinnamyl alcohol. Also, the conversion and selectivity for cinnamyl alcohol in microemulsion medium are higher than in ethanol medium.

 

 

 

 

316

 

Surface embedded enhancement of fluorescence
of coumarinyl-azo-imidazolium stabilized gold nanoparticles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chiranjit Patra, Himanish Roy, Chandana Sen, Ambikesh Mahapatra & Chittaranjan Sinha*

 

 

 

Surface implantation of 1,3-dialkyl-2-(coumarinyl-6-azo)-imidazolium bromide (CAI-(CnH2n+1)2+Br-) stabilizes gold nanoparticles and reduces the size from 20.5 nm to 2-10 nm. The quantum yields of CAI-(CnH2n+1)2+Br- are increased by 10-25 times, which may be due to the reduction of PET (Coumarin*→Imidazolium) and vibrational relaxation of imidazolium coated GNP surface.

 

 

 

 

324

 

Solid phase extraction of Fe(III) utilizing alumina modified with phenolic compounds produced via microwave approach

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Salwa A Ahmed

 

 

 

Increase in adsorptive efficiency of alumina surface toward Fe(III) has been achieved by modification of its surface with
2-aminophenol and 1-naphthol by microwave technique.
The two new alumina adsorbents show a higher percentage extraction (≥98.2%) and uptake capacity (>1.0 mmol/g) of Fe(III) from aqueous media in comparison with native alumina.

 

 

 

 

333

 

Co(II) catalyzed oxidation of organic compounds by peroxomonosulphate

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C Lavanya, P Andal & M S Ramachandran*

 

 

 

The Co(II) ion catalyzed decomposition of peroxomonosulphate and the influence of organic substrates such as ethanol, t-butanol, α-hydroxy acids (AHA) and glycine is studied at pH ≤1.0 and 4.0−5.2. In strong acid medium, the reaction is inhibited by the organic compounds, suggesting a redox process through the formation of sulphate radical intermediate. However in buffered medium (pH 4.055.20), the substrates other than t-butanol, catalyze the reaction and get oxidized quantitatively. The catalytic effect of Co(II) is observed with concentrations of ppm or lower level.

 

 

 

 

 

345

 

Clouding and hydrodynamic behaviour of
Triton X-100 in aqueous media in the presence of linear and cyclic glycols, their oligomers and ethers

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Urja Patel, P Parekh* & P Bahadur

 

 

 

The effects of various linear glycol ethers and cyclic ethers on cloud point and hydrodynamic diameter of aqueous micellar solution of Triton X-100 has been studied spectrophotometrically. For short chain glycols (EG, DEG, PG, DPG) and their oligomers, and, monoalkyl ethers, increase in the cloud point with corresponding decrease in micelle size is observed, while the opposite trend is observed for the higher homologues. The thermodynamic parameters for the mixture are also calculated as a function of glycol concentrations.

 

 

 

 

Notes

 

351

 

Catalytic effect of CTAB reverse micelles on the oxidation of indigo carmine by periodate

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K V Nagalakshmi, P Shyamala* & P V Subba Rao

 

 

 

The kinetics of oxidation of indigo carmine by periodate has
been investigated in the presence of CTAB reverse micellar medium. The reaction obeys first order kinetics with
respect to each of the reactants and is markedly catalysed in the presence of CTAB reverse micelles as compared to in aqueous medium under identical conditions. The specific rate constant,
k3 {= k'/ [IO4][H2O]} is found to be constant for all values of
W > 4.4, implying that water is one of the reactants and is involved in the rate determining step.

 

 

 

356

 

Oxidation of diphenylamine on illuminated Fe2O3 surface

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C Karunakaran* & S Karuthapandian

 

 

 

On illuminated Fe2O3 surface, diphenylamine in ethanol is oxidized to N-phenyl-p-benzoquinonimine. The reaction follows Langmuir-Hinshelwood kinetics.

 

 

 

 

Authors for correspondence are indicated by (*)

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 309-315

 

 

Promotional effects of PPy-modified ZrO2 composite as support and microemulsion medium for selective hydrogenation of cinnamaldehyde over supported Ru catalyst

Lei Zong, Zhengbin Tian, Yan Li* & Fusui Lu*

College of Chemistry and Material Science, Shandong Agricultural University, 271018, PR China

Email: liyan2010@sdau.edu.cn (YL); lfs@sdau.edu.cn (FL)

Received 28 September 2014; revised and accepted 22 February 2015

Polypyrrole-modified ZrO2 (PPy/ZrO2) nanocomposites are prepared via the in situ polymerization method and used as catalyst support in selective hydrogenation of cinnamaldehyde. Ru based bimetallic catalysts supported on ZrO2 and PPy/ZrO2 are prepared by the impregnation method. Physicochemical properties of support and catalyst are examined by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption ability of PPy and the advantage of microemulsion medium have been employed in the cinnamaldehyde hydrogenation reactions. The results show that the catalysts supported on PPy/ZrO2 show a higher activity than that supported on ZrO2 under the same conditions. Besides, catalysts in microemulsion medium show a higher activity in terms of conversion and cinnamyl alcohol selectivity as compared with previously studied ethanol medium.

Keywords: Catalysts, Supported catalysts, Hydrogenation, Selective hydrogenation, Nanocomposites, Adsorption, Microemulsion medium, Zirconia, Polypyrrole-modified zirconia, Cinnamaldehyde

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 316-323

 

 

Surface embedded enhancement of fluorescence of coumarinyl-azo-imidazolium stabilized gold nanoparticles

Chiranjit Patra, Himanish Roy, Chandana Sen, Ambikesh Mahapatra & Chittaranjan Sinha*

Department of Chemistry, Jadavpur University, Kolkata 700 032, India

Email: c_r_sinha@yahoo.com

Received 20 October 2014; revised and accepted 23 February 2015

Coumarinyl-azo-imidazole (CAI-H) undergoes double alkylation to yield 1, 3-dialkyl-2-(coumarinyl-
6-azo)imidazolium bromide (CAI-(CnH2n+1)2
+Br-) of long chain alkyl groups CnH2n+1 (n = 6, 9, 12, 15, 18) attached to imidazolyl motif. These compounds are characterized by spectroscopic data (FT-IR, UV-vis and 1H NMR). The size of the gold nanoparticles stabilized with tetraoctylammonium bromide (avg size 20.5 nm) is reduced to 210 nm upon surface implantation of CAI-(CnH2n+1)2+; these have been characterized by FESEM/TEM. The spectroscopic investigation has established the stability of gold nanoparticles. The fluorescence emissivity of these nanoparticles is enhanced 1025 folds as compared to free CAI-(CnH2n+1)2+Br, which may be due to coupling of plasmonic band with emission of fluorescent dye molecules and the reduction of PET (Coumarin*→ Imidazolium) and vibrational relaxation of imidazolium coating on the gold nanoparticles surface.

Keywords: Nanoparticles, Gold nanoparticles, Fluorescence, Quantum yield, Coumarins,
1, 3-Dialkyl-2-(coumarinyl-6-azo)
imidazolium bromide

 

 

 

 

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 324-332

 

 

Solid phase extraction of Fe(III) utilizing alumina modified with phenolic compounds produced via microwave approach

Salwa A Ahmed

Chemistry Department, Faculty of Science, Minia University, Minia 61111, Egypt

Email: salwa_kasem2003@yahoo.com

Received 26 November 2014; revised and accepted 19 February 2015

This study describes the use of microwave approach to improve the adsorptive efficiency of alumina surface toward Fe(III). Due to the strong tendency of Fe(III) for reacting with phenolic compounds, the improvement process had been achieved via modification of alumina surface with 2-amino phenol and 1-naphthol by the microwave technique. The two new adsorbents are characterized by Fourier transform-infrared spectroscopy, scanning electron microscope and X-ray diffraction. The adsorption properties of the adsorbents for Fe(III) are studied, optimized and evaluated under various experimental conditions. The results show higher ferric ions extraction (≥98.2%) by the two new adsorbents as compared to native alumina. The experimental results are well fitted by Langmuir and Freundlich isotherms and pseudo-second order kinetics. High recovery values of Fe(III) spiked natural water samples are obtained (95.0%) by column and batch techniques.

Keywords: Solid phase extraction, Extraction, Iron, Alumina, Modified alumina, Phenols, Microwave technique, Chelates, Adsorption

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 333-344

 

 

Co(II) catalyzed oxidation of organic compounds by peroxomonosulphate

C Lavanya, P Andal & M S Ramachandran*

School of Chemistry, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
Email: ramachandran_mku@yahoo.co.in

Received 25 November 2014; revised and accepted 28 February 2015

The Co(II) ion catalyzed decomposition of peroxomonosulphate (PMS) and the influence of organic substrates such as ethanol, t-butanol, α-hydroxy acids (AHA) and glycine is studied at pH ≤1.0 and 4.0−5.2. In strong acid medium, the reaction is inhibited by the organic compounds and the present results, in accordance with the earlier reports, suggest a redox process through the formation of sulphate radical intermediate. Ethanol and AHAs are more effective quenchers than t-butanol. However in buffered medium (pH 4.055.20), the substrate other than t-butanol catalyze the reaction and get oxidized quantitatively. Ethanol is oxidized in the presence of AHA and glycine, suggesting a molecular mechanism involving a complex intermediate and subsequent oxygen atom transfer from . The catalytic effect of Co(II) is observed with concentrations of ppm or lower level.

Keywords: Kinetics, Reaction mechanisms, Oxidation, Decomposition, Peroxomonosulphate decomposition, Cobalt, Sulphate ion radicals

 

 

 

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 345-350

 

 

Clouding and hydrodynamic behaviour of Triton X-100 in aqueous media in the presence of linear and cyclic glycols, their oligomers and ethers

Urja Patel, P Parekh* & P Bahadur

aDepartment of Chemistry, Veer Narmad South Gujarat University, Surat 395 007, India

Email: paresh7884@gmail.com

Received 11 November 2014; revised and accepted 27 February 2015

The effects of various linear glycol ethers and cyclic ethers on cloud point and hydrodynamic diameter of aqueous micellar solution of a nonionic surfactant Triton X-100 (TX-100) has been studied spectrophotometrically. For short chain glycols (EG, DEG, PG, DPG) and their oligomers, and, monoalkyl ethers, increase in the cloud point with corresponding decrease in micelle size is observed, while the opposite trend is observed for their higher homologues. The effect of short chain glycols on CP/Dh is discussed in terms of their solubility in solution, micelles hydration and cosurfactant/ cosolvent of TX-100 micellar system. These effects are strongly dependent on additive concentration. For longer chain glycols or more hydrophobic glycols, the effects can be explained in terms of their partitioning in the micellar region and changes in size and shape of the micelles. A different approach for normalising the cloud points to their relative values has been made for a better insight on effect of these glycol ethers. The thermodynamic parameters for the mixture are also calculated as a function of glycol ether concentrations.

Keywords: Surfactants, Nonionic surfactants, Thermodynamics parameters, Cloud point, Dynamic light scattering,
Glycol ethers

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 351-355

 

 

Catalytic effect of CTAB reverse micelles on the oxidation of
indigo carmine by periodate

K V Nagalakshmia, P Shyamalab, * & P V Subba Raoc

aDepartment of Chemistry, G V P College of Engineering (Autonomous), Madhurawada, Visakhapatnam 530 048, India

bDepartment of Physical Chemistry, Andhra University,
Visakhapatnam 530 017, India
Email: shyamalapulipaka@rediffmail.com

cDepartment of Chemistry, GVPPG College (Autonomous), Visakhapatnam 530 017, India

Received 18 November 2014; revised and accepted 16 February 2015

The kinetics of oxidation of indigo carmine by periodate has been investigated in the presence of CTAB reverse micellar medium. The reaction obeys first order kinetics with respect to each of the reactants. The reaction is markedly catalysed in the presence of CTAB reverse micelles as compared to in aqueous medium under identical conditions. The significant increase in rate is attributed to the special properties of the water pool of reverse micelles which are controlled by a W parameter where W = ([H2O]/[CTAB]). The specific rate constant, k3 {= k'/ [IO4] [H2O]} is found to be constant for all values of W > 4.4, implying that water is one of the reactants and is involved in the rate determining step. Such studies regarding the role of water cannot be obtained in conventional aqueous medium. The effect of CTAB has been analyzed using the Berezin pseudo-phase model.

Keywords: Kinetics, Oxidation, Periodate oxidation, Reverse micelles, Surfactants, Dyes, Indigo dyes, Water pools, CTAB

 

Indian Journal of Chemistry

Vol. 54A, March 2015, pp. 356-360

 

 

Oxidation of diphenylamine on illuminated Fe2O3 surface

C Karunakaran* & S Karuthapandian

Department of Chemistry, Annamalai University, Annamalainagar 608 002, Tamilnadu, India

Email: karunakaranc@rediffmail.com

Received 4 August 2014; revised and accepted 17 February 2015

Diphenylamine (DPA) in ethanol is oxidized to N-phenyl-p-benzoquinonimine (PBQ) on the surface of Fe2O3, illuminated with UV light or natural sunlight in the presence of air. The dependence of rate of formation of PBQ on [DPA], catalyst loading, airflow rate, photon flux, etc., has been studied. The yield of PBQ is higher on illumination at 254 nm than at 365 nm. The catalyst is reusable and magnetically recoverable. The photocatalytic mechanism has been discussed and the product formation has been analyzed using a kinetic model.

Keywords: Photooxidation, Photocatalysis, Solar photocatalysis, Semiconductors, Langmuir-Hinshelwood kinetics