Indian Journal of Chemistry

 

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

Total visitors: 1,318     since 25-07-06

 

VOLUME 45A

NUMBER 7

July 2006

CONTENTS

Papers

 

1601

 

On distribution of π-electrons in rhombus-shaped benzenoid hydrocarbons

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ivan Gutman*, Nedžad Turković & Boris Furtula

 

 

 

The distribution of π-electrons into rings of rhombus-shaped benzenoid hydrocarbons is reported here. In this class of benzenoid systems, the unique Clar formula represents only a minute fraction of the total number of Kekulč structures, and therefore, a breakdown of the Clar model could be expected.

 

 

 

 

1605

 

NMR and thermal studies of
N-acryloylcarbazole / methacrylonitrile copolymers

 

 

 

 

 

 

A S Brar* & Pravin Kumar Singh

 

 

 

Copolymers with different compositions of
N-acryloylcarbazole and methacrylonitrile are reported. The comonomer reactivity ratios, determined by both Kelen-Tudos and nonlinear error-in-variables methods are rA= 1.27 ± 0.13, rM= 0.69 ± 0.06, and
rA= 1.30, rM= 0.69, respectively. The methylene carbon signals of both units have been found to be sequence sensitive.

 

 

 

1611

 

Homogeneous catalysis of aquachloro-ruthenium(III) complex and evaluation of individual kinetic and thermodynamic parameters of bromate-mandelic acid reaction

 

 

 

 

 

 

 

 

 

Ch Sanjeeva Reddy* & T Vijaya Kumar

 

 

 

Aquachlororuthenium(III) complex catalysed bromate-mandelic acid reaction involves complex formation between mandelic acid and ruthenium(III), which in turn forms a ternary complex with two moles of bromate.  The slow decomposition of the ternary complex to form products constitutes the rate-determining step.

 

 

 

Rate constants involved in each step of the reaction have been evaluated along with their thermodynamic parameters.

 

 

 

1619


Surface properties and oxydehydrogenation of ethylbenzene over molybdenum doped ceria systems

 

 

 

 

 

 

 

 

P Fincy Jose & S Sugunan*

 

 

 

Pure cerium hydroxide has been prepared by pseudo-template method and sulphate modification has been carried out by wet impregnation method using H2SO4. Modified catalysts have been prepared by incorporating varying amounts of molybdenum (5, 10 and 15%) into pure as well as sulphated cerium hydroxide. The oxydehydrogenation of ethyl benzene proceeds efficiently over molybdenum incorporated pure as well as sulphated ceria systems yielding styrene as the major product. Benzene, toluene and
C-oxides are also formed as byproducts.

 

 

 

1626


Kinetics and mechanism of oxidation of aliphatic alcohols by oxone catalyzed by Keggin type
12-tungstocobaltate(II)

 

 

 

 

 

 

 

 

D S Rajmane, K V Kapashikar & G S Gokavi*

 

 

 

The oxidation of various aliphatic alcohols by oxone catalyzed by Keggin type [CoIIW12O40]6- has been studied.

 

 

 

 

 

1631

 

Effect of temperature on the viscosities of some divalent transition metal sulphates and magnesium sulphate in water and water+ethylene glycol mixtures

 

 

 

 

 

M L Parmar* & R C Thakur

 

 

 

Relative viscosities for the solutions of some divalent transition metal sulphates at different concentrations have been determined in water and in water + ethylene glycol mixtures. The data have been analysed using
the Jones-Dole equation. The transition metal
sulphates and magnesium sulphate act as structure makers/promoters in water and in ethylene glycol + water mixtures.

 

 

1638

 

Synthesis, spectroscopic (IR, electronic and FAB-mass) and magnetic studies of some mixed ligand complexes of chromium (III)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

 

 

Some new mixed ligand complexes of chromium (III) of the type [Cr(L)2(L˘)Cl].2H2O [where LH = Schiff bases derived from the condensation of
2-aminopyridine, 2-aminophenol, o-toludine,
p
-toludine, aniline, 3-nitroaniline and anthranilic
acid with salicylaldehyde/vanillin and substituted benzimidazole/benzoxazole or mercaptobenzi-
midazole; L=pyridine] have been synthesized.

 

 

 

 

 

Notes

 

 

1643

 

Substituent effects on catalytic activity of transition metal phthalocyanine complexes

 

 

 

 

 

Hassan Hosseini Monfared*,   Saeid Dini,

Naser Safari & Mahtab Pirouzmand

 

 

 

 

 

 

 

The effects of chloro substituents on catalytic activityof Fe(II), Co(II), and Cu(II) phthalocyanine (MCl16Pc and MCl8Pc)complexes in olefin epoxidation are reported. Performance of these catalystshas been tested for the oxidation of cyclohexene, cyclooctene and styrenewith iodosylbenzene. In cyclohexene oxidation, epoxide selectivity (22-56%for MCl8Pc and 32-55% for MCl16Pc) follows the order: Fe(II)>Co(II)>Cu(II)complexes. In the catalytic oxidation of cyclooctene and styrene, only thecorresponding epoxides are obtained.

 

 

 

1646

 

Hydrogenation of cinnamaldehyde over Pt/ZrO2 catalyst modified by Cr, Mn, Fe, Co, Ni and Sn

 

 

 

 

 

 

 

 

 

 

 

Xiaoxiang Han, Renxian Zhou* & Xiaoming Zheng

 

 

Hydrogenation of cinnamaldehyde has been studied over Pt/ZrO2 and PtM/ZrO2 catalysts (M= Cr, Mn, Fe, Co, Ni, Sn) in ethanol at 343 K and 2.0 MPa.

 

 

 

 

 

1651

 

Solid phase extraction and spectrophotometric determination of gold

 

 

 

 

 

 

Jishou Zhao, Jinsong Li, Zhangjie Huang,

Qunyan Wei, Jing Chen & Guangyu Yang*

 

 

A sensitive, selective and rapid method for the determination of gold based on the rapid reaction of gold with 5-(p-aminobenzylidene)-thiorhodanine and the solid phase extraction of the colored chelate has been developed. This method has been applied for determination of gold in water and ore with good results.

 

 

1655

 

6-Chloro-3-hydroxy-2-[2'-(5'-methylfuryl)]-4H-chromen-4-one as an analytical reagent for the spectrophotometric determination of tungsten(VI)

 

 

R Agnihotri, N Agnihotri & J R Mehta*

 

 

A 1:2 light yellow complex of tungsten(VI) is formed with 6-chloro-3-hydroxy-2-[2'-(5'-methylfuryl)]-4H-chromen-4-one in 0.18-0.32 M HClO4 medium. The complex is extractable into chloroform and absorbs maximally at
435 nm. The method has been satisfactorily applied to analysis of tungsten in various synthetic and technical samples.

 

 

1659

 

Spectrophotometric determination of copper(II) in alloys and edible oils using 2-acetylthiophene thiosemicarbazone

 

 

 

 

 

M Sayaji Rao, N B L Prasad, & K Hussain Reddy*

 

 

 

The reagent, 2-acetylthiophene thiosemicarbazone has been synthesized and characterized. It gives intense yellowish green coloured complex (λ max = 370 nm) with copper(II) in sodium acetate-acetic acid buffer (pH 5-7) medium. The molar absorptivity and Sandell’s sensitivity of the copper(II) complex are 1.83 ´ 104 L. mol-1 cm-1 and 0.0034 μg of Cu(II) cm-2, respectively. The method has been used for the determination of copper(II) in alloys, edible oils and seeds.

 

 

 

1663

 

TLC separation of l-tryptophan using microemulsion mobile phase and its spectrophotometric determination

 

 

 

 

 

 

 

 

 

Ali Mohammad*, Sufia Hena &

Showkat Ahmad Bhawani

 

 

The TLC system comprising silica gel as the stationary phase, and water-in-oil microemulsion (SDS + water + heptane + n-pentanol; as the mobile phase, has been used for selective separation of L-tryptophan from other amino acids in the presence of metal cation impurities. The proposed method is applied to L-tryptophan in drug samples. The quantitative estimation of L-tryptophan by spectrophotometry (lmax 570 nm) after separation from other amino acids has been done. The recovery of tryptophen is around 98%  and its limit of detection on silica gel layer is 0.13 mg.

 

 

 

 

1667

 

Solubility enhancement of rofecoxib in water in the presence of hydrophilic polymers, surfactants,
co-solvents, and small molecules at 310.15 K

 

 

 

 

 

K H Desai, A R Kulkarni, S A Agnihotri,
K B Gudasi & T M Aminabhavi*

 

 

Solubility enhancement of rofecoxib in water has been studied in presence of different concentrations of hydrophilic polymers like polyethylene glycol-4000 polyethylene glycol-6000 and polyvinylpyrrolidone (PVP- K30); surfactants like Span-20, Tween-80 and sodium lauryl sulfate (SLS); co-solvents like ethanol, propylene glycol and glycerol and small molecules like urea, mannitol and b-cyclodextrin at 310.15 K. Drug analysis has been carried out by HPLC method using UV detector at 254 nm. Drug solubility is greatly enhanced in the presence of PVP-K30, SLS, and ethanol. In the presence of small molecules, urea enhances the solubility much more than mannitol or b-cyclodextrin.

 

 

 

1670

 

Announcement

 

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

AUTHOR INDEX

 

Agnihotri N

1655

Agnihotri R

1655

Agnihotri S A

1667

Aminabhavi T M

1667

Bhawani Showkat Ahmad

1663

Brar A S

1605

Desai K H

1667

Dini Saeid

1643

Dubey R K

1638

Dubey U K

1638

Fincy Jose P

1619

Furtula Boris

1601

Gokavi G S

1626

Gudasi K B

1667

Gutman Ivan

1601

Han Xiaoxiang

1646

Hen Jing C

1651

Hena Sufia

1663

Huang Zhangjie

1651

Kapashikar K V

1626

Kulkarni A R

1667

Li Jinsong

1651

Mehta J R

1655

Mishra C M

1638

Mohammad Ali

1663

Monfared Hassan Hosseini

1643

Parmar M L

1631

Pirouzmand Mahtab

1643

Prasad N B L

1659

Qunyan Wei

1651

Rajmane D S

1626

Rao M Sayaji

1659

Reddy Ch Sanjeeva

1611

Reddy K Hussain

1659

Safari Naser

1643

Singh Pravin Kumar

1605

Sugunan S

1619

Thakur R C

1631

Turković Nedžad

1601

Vijaya Kumar T

1611

Yang Guangyu

1651

Zhao Jishou

1651

Zheng Xiaoming

1646

Zhou Renxian

1646

 

 

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1601-1604

 

On distribution of π-electrons in rhombus-shaped benzenoid hydrocarbons

Ivan Gutman, Nedžad Turković  & Boris Furtula

Received 20 April 2006; accepted 12 May 2006

The distribution of π-electrons into rings of rhombus-shaped benzenoid hydrocarbons is reported here. In this class of benzenoid systems, the (unique) Clar formula represents only a minute fraction of the total number of Kekulč structures, and therefore a breakdown of the Clar model could be expected. It is found that the π-electron distribution follows a pattern different from what is predicted by the Clar model: the greatest π-electron content is in the two "full" peak hexagons (around 4.5 electrons). In the other boundary hexagons, the π-electrons are distributed almost uniformly (around 3 electrons per hexagon). In the internal hexagons, the π-electrons are also distributed in an almost uniform manner (around 2 electrons per hexagon), the π-electron content of the "full" hexagons insignificantly exceeding the π-electron contents of the "empty" hexagons.

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1605-1610

 

NMR and thermal studies of N-acryloylcarbazole/methacrylonitrile copolymers

A S Brar & Pravin Kumar Singh

Received 5 April 2006; revised 22 May 2006

Copolymers with different compositions of N-acryloylcarbazole (A) and methacrylonitrile (M) are reported here. Composition of the copolymer has been determined by 1H NMR spectrum. The comonomer reactivity ratios, determined by both Kelen-Tudos (KT) and non-linear error-in-variables (EVM) methods are rA= 1.27 ± 0.13, rM= 0.69 ± 0.06, and rA= 1.30, rM = 0.69, respectively. Complete spectral assignments of the 1H and 13C{1H} NMR spectra of the copolymers is done by Distortionless Enhancement by Polarization Transfer (DEPT) and Heteronuclear Single Quantum Coherence (HSQC) techniques. The methylene carbon signals of both (A and M) units have been found to be sequence sensitive. The signals obtained are broad, pertaining to the restricted rotation of bulky carbazole group and the quadrupolar effect of nitrogen present in carbazole moiety. The thermal stability and glass transition temperatures (Tg) of the copolymers are dependant on polymer composition and characteristic of rotational rigidity of the polymer chain. Variation in the values of Tg with the copolymer composition has been found to be in good agreement with theoretical values obtained from Johnston and Barton equations.

IPC Code: Int. Cl.8 C07C255/08; C07D209/82; G03C1/04; G01N24/08

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1611-1618

 

Homogeneous catalysis of aquachlororuthenium(III) complex and
evaluation of individual kinetic and thermodynamic parameters of
bromate-mandelic acid reaction

Ch Sanjeeva Reddy & T Vijaya Kumar

Received 24 September 2005; accepted 8 May 2006

Aquachlororuthenium(III) complex catalysed and uncatalysed acid bromate oxidation of mandelic acid (MA) is reported here. Uncatalysed oxidation exhibits first order each in [MA] and [bromate], and second order in [acid]. Primary kinetic isotope effect (kH/kD = 1) has been found to be absent. However, an inverse solvent isotope effect is observed. The assumed mechanism includes slow formation of a mandelic ester of bromic acid due to the nucleophilic attack by the alcoholic/hydroxyl group at the bromine atom of HOBr+O(OH), which dissociates rapidly through C-C bond cleavage to form benzaldehyde and CO2. Aquachlororuthenium(III) complex catalysed MA-bromate reaction exhibits second order in [bromate], first order in [catalyst], fractional order in [MA] and a dualistic effect in [acid]. The envisaged mechanism involves complex formation between the substrate and the catalyst, which in turn forms a ternary complex with two moles of the oxidant. The slow decomposition of the ternary complex to form products constitutes the rate-determining step. The rate constants involved in each step of the reaction have been evaluated along with their thermodynamic parameters.

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1619-1625

 

 

Surface properties and oxydehydrogenation of ethylbenzene over molybdenum doped ceria systems

 

P Fincy Jose & S Sugunan

Received 29 April 2005; revised 12 April 2006

Pure cerium hydroxide has been prepared by pseudo-template method and sulphate modification has been carried out by wet impregnation method using H2SO4. Modified catalysts have been prepared by incorporating varying amounts of molybdenum (5, 10 and 15%) into pure as well as sulphated cerium hydroxide and characterized by XRD, FT-IR, BET surface area and DRS techniques. The acid structural properties have been determined by temperature programmed desorption of ammonia and thermodesorption studies using 2, 6-dimethylpyridine. Study on catalytic activity of the systems towards oxydehydrogenation of ethylbenzene shows the formation of styrene as the major product. Reaction conditions such as air flow, temperature of the reaction and flow rate of ethylbenzene have been optimised.

 

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

 

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1626-1630

 

 

Kinetics and mechanism of oxidation of aliphatic alcohols by oxone catalyzed by Keggin type 12-tungstocobaltate(II)

D S Rajmane, K V Kapashikar & G S Gokavi

Received 30 November 2005; revised 26 April 2006

The oxidation of various aliphatic alcohols by oxone catalyzed by Kegin type [CoIIW12O40]6- has been studied in a buffer medium of pH= 4.  The reaction proceeds by the oxidation of [CoIIW12O40]6- to [CoIIIW12O40]5- by oxone which then oxidizes the alcohol in a rate determining step generating alcohol free radical. The reaction is accelerated by increase in the pH of the solution due to the protonation equilibria of the oxidant. The reaction between oxone and [CoIIW12O40]6- has also been studied and is found to proceed in two one-electron steps, involving  formation  HSO52-  free radical in a slow first step followed by its reaction with  reductant in a fast step. The reaction rate is inhibited by the [ H+ ] due to protonation equilibria of HSO5-  which is the active species. Decreasing the relative permittivity of the medium increases the rate of the reaction which is attributed to the formation of an outer-sphere complex between the reactants. The activation parameters determined for both the reactions support the proposed mechanisms.

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1631-1637

Effect of temperature on the viscosities of some divalent transition
metal sulphates and magnesium sulphate in water and
water+ethylene glycol mixtures

 

M L Parmar & R C Thakur

Received 6 January 2006; revised 15 April 2006

Relative viscosities for the solutions of some divalent transition metal sulphates, viz. manganese sulphate, cobalt sulphate, nickel sulphate, copper sulphate and zinc sulphate; and magnesium sulphate at different concentrations have been determined in water and in water + ethylene glycol (EG) [5, 10, 15, 20 and 25% by weight of EG] mixtures at 303.15 K, and in water and in 5% (w/w) EG + water at five different temperatures. The data have been analysed using the Jones-Dole equation and the obtained parameters have been interpreted in terms of ion-ion and ion-solvent interactions. The activation parameters of viscous flow have been obtained which depicts the mechanism of viscous flow. The transition metal sulphates and magnesium sulphate act as structure makers/promoters in water and in EG + water mixtures.

 

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1638-1642

 

Synthesis, spectroscopic (IR, electronic and FAB-mass) and magnetic
studies of some mixed ligand complexes of chromium (III)

 

R K Dubey, U K Dubey & C M Mishra

Received 31 October 2005; revised 18 May 2006

Some new mixed ligand complexes of chromium (III) of the type [Cr(L)2(L1)Cl].2H2O [where LH = Schiff bases (derived from the condensation of 2-aminopyridine, 2-aminophenol, o-toludine, p-toludine, aniline, 3-nitroaniline and anthranilic acid with salicylaldehyde/vanillin and substituted benzimidazole/benzoxazole, or mercaptobenzimidazole; L=pyridine] have been synthesized by the interactions of chromium (III) chloride with corresponding ligand in 1:2 molar ratio in refluxing pyridine solution. The resulting products have been characterized by elemental analysis and spectral as well as magnetic susceptibility measurements. Structures of the chromium (III) complexes are also proposed.

IPC Code: Int. Cl.8  C07F11/00

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1643-1645

 

Substituent effects on catalytic activity of transition metal phthalocyanine complexes

Hassan Hosseini Monfared, Saeid Dini, Naser Safari & Mahtab Pirouzmand

 

Received 13 December 2004; revsied 19 April 2006

This study investigates the effects of 16- and 8-chloro substituents on catalytic activity of Fe(II), Co(II), and Cu(II) phthalocyanine (MCl16Pc and MCl8Pc) complexes in olefin epoxidation. The catalytic performance of these substituted catalysts has been tested for the oxidation of cyclohexene, cyclooctene, and styrene with iodosylbenzene and results have been compared with those of unsubstituted catalysts. In cyclohexene oxidation, epoxide selectivity (22-56% for MCl8Pc and 32-55% for MCl16Pc) is in order Fe(II) > Co(II) > Cu(II) complexes. In the catalytic oxidation of cyclooctene and styrene, only the corresponding epoxides have been obtained.

IPC Code: Int. Cl.8 B01J8/00

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1646-1650

 

 

Hydrogenation of cinnamaldehyde over Pt/ZrO2 catalyst modified by Cr, Mn,Fe, Co, Ni and Sn


Xiaoxiang Han, Renxian Zhou & Xiaoming Zheng

Received 30 December 2005; revised 11 May 2006

Hydrogenation of cinnamaldehyde (CMA) has been studied over Pt/ZrO2 and PtM/ZrO2 catalysts (M= Cr, Mn, Fe, Co, Ni, Sn) in ethanol at 343 K and 2.0 MPa. The catalytic properties are shown to increase upon introduction of metals to Pt/ZrO2 catalyst. Catalytic activities of the catalysts are enhanced except PtCr/ZrO2 catalyst. PtMn/ZrO2, PtCo/ZrO2 and PtFe/ZrO2 catalysts show good yield of cinnamyl alcohol (CMO), and PtNi/ZrO2 PtSn/ZrO2 catalysts show good yield of hydrocinnamaldehyde (HCMA). In the presence of NaOH and H2O, rate of the hydrogenation of CMA increases significantly and side reaction is remarkably inhibited. PtCo/ZrO2 catalyst shows best catalytic activity (TOF 7.4´10-2 s-1) and yield of CMO (84.1 mol%). PtNi/ZrO2 catalyst shows best yield of HCMA (62.8 mol%). More active sites for the hydrogenation of C=O group on PtCo/ZrO2 catalyst surface are the main reason of good selectivity of CMO.

IPC Code: Int. Cl.8  B01J23/42; B01J27/135

 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1651-1654

 

Solid phase extraction and spectrophotometric determination of gold

Jishou Zhao, Jinsong Li, Zhangjie Huang, Qunyan Wei, Jing Chen & Guangyu Yang

Received 10 August 2005; revised 8 May 2006.

A sensitive, selective and rapid method for the determination of gold based on the rapid reaction of gold with 5-(p-aminobenzylidene)-thiorhodanine (ABTR) and the solid phase extraction of the colored chelate has been developed. In 0.05-0.5 mol L-1 hydrochloric acid and emulsifier-OP medium, ABTR reacts with gold to form a red chelate of molar ratio 1:3 (gold to ABTR). This chelate has been preconcentrated by solid phase extraction with polymer-based C18 cartridge and eluted from cartridge with dimethyl formamide to attain an enrichment factor of 100. In DMF medium, the molar absorptivity of the chelate is 1.23 ´ 105 L. mol-1. cm-1 at 550 nm. Beer’s law is obeyed in the range of 0.01-3 mg mL-1 of gold. The relative standard deviation for eleven replicate samples of 0.5 mg L-1 gold is 2.18%. The detection limit, based on three times of standard deviation, is 0.02 mg L-1 in the original sample. This method has been applied to the determination of gold in water and ore with good results.

IPC Code: Int. Cl.8 G01N21/00; G01N30/00

 

Indian Journal of Chemistry
Vol. 45A, July 2006, pp. 1655-1658

 

 

-Chloro-3-hydroxy-2-[2'-(5'-methylfuryl)]-4H-chromen-4-one as an analytical reagent for the spectrophotometric determination of tungsten(VI)

R Agnihotri, N Agnihotri & J R Mehta

Received 14 November 2005; revised 16 May 2006

A 1:2 light yellow complex of tungsten(VI) is formed with 6-chloro-3-hydroxy-2-[2'-(5'-methylfuryl)]-4H-chromen-4-one (CHMFC) in 0.18-0.32 M HClO4 medium. The complex is extractable into chloroform and absorbs maximally at 435 nm. The absorbance remains constant for more than 1 h with molar absorptivity, detection limit and Sandell’s sensitivity as 2.16 ´ 104 L mol-1 cm-1, 0.131 mg mL-1 and 0.0085 mg W cm-2, respectively. Beer’s law is obeyed in the concentration range of 0-2.6 mg W mL-1; the correlation coefficient is, r =1.001. Oxalate interferes in the tungsten determination. The method has been satisfactorily applied to the analysis of tungsten in various synthetic and technical samples.

IPC Code: Int. Cl.8 G01N21/00; G01N33/20

 

Indian Journal of Chemistry
Vol. 45A, July 2006, pp. 1659-1662

Spectrophotometric determination of copper(II) in alloys and edible oils using 2-acetylthiophene thiosemicarbazone

M Sayaji Rao, N B L Prasad & K Hussain Reddy

Received 27 July 2005; revised 5 April 2006

The reagent, 2-acetylthiophene thiosemicarbazone (ATT) has been synthesized and characterized based on spectral data. The reagent gives intense yellowish green coloured complex (λ max = 370 nm) with copper(II) in sodium acetate-acetic acid buffer (pH 5-7) medium. The colour reaction has been investigated in detail. The molar absorptivity and Sandell’s sensitivity of the copper(II) complex of ATT are 1.83 ´ 104 L. mol-1 cm-1 and 0.0034 μg of Cu(II) cm-2 respectively. The method has been used for the determination of copper(II) in alloys, edible oils and seeds.

IPC Code: Int.Cl.8 

Indian Journal of Chemistry

Vol. 45A, July 2006, pp. 1663-1666

 

 

TLC separation of l-tryptophan using microemulsion mobile phase and its spectrophotometric determination

 

Ali Mohammad, Sufia Hena & Showkat Ahmad Bhawani

Received 6 December 2005; revised 11 May 2006

The TLC system comprising silica gel as the stationary phase, and water-in-oil microemulsion (SDS+water+heptane+n-pent­anol; (160 g + 8 mL + 16 mL + 25 mL) as the mobile phase, has been identified as the most favourable system for selective separation of l-tryptophan from other amino acids in the presence of metal cation impurities. The proposed method is applicable to the identification and separation of l-tryptophan from drug samples such as Astymin-m (Forte), Astymin (liquid) and Alamin (Forte). The separation up to 10 mg of l-tryptophan from milligram quantities (up to 0.77 mg) of other amino acids has also been realized. The quantitative estimation of l-tryptophan by spectrophotometry (lmax 570 nm) after separation from other amino acids has been done. The recovery of tryptophan is around 98% and its limit of detection on silica gel layer is 0.13 mg.

 

IPC Code: Int. Cl.8 G01N21/00

 

Indian Journal of Chemistry
Vol. 45A, July 2006, pp. 1667-1669

 

 

Solubility enhancement of rofecoxib in water in the presence of hydrophilic polymers, surfactants, co-solvents, and small molecules at 310.15 K

K H Desai, A R Kulkarni, S A Agnihotri, K B Gudasi &
T M Aminabhavi

Received 6 January 2006; revised 16 March 2006

Solubility enhancement of rofecoxib in water has been studied in presence of different concentrations of hydrophilic polymers like polyethylene glycol-4000 polyethylene glycol-6000 and polyvinylpyrrolidone (PVP- K30); surfactants like Span-20, Tween-80 and sodium lauryl sulfate (SLS); co-solvents like ethanol, propylene glycol and glycerol and small molecules like urea, mannitol and b-cyclodextrin at 310.15 K. Drug analysis has been carried out by HPLC method using UV detector at 254 nm. Drug solubility is greatly enhanced in the presence of PVP-K30, SLS, and ethanol. In the presence of small molecules, urea enhances the solubility much higher than mannitol or b-cyclodextrin.

IPC Code: Int. Cl.8 A61K