Sugunan, S; Benny, Thomas(Indian Journal of Chemistry, February , 1995)
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Abstract:
The Setschenow parameter and thermodynamic
parameters of transfer of 2- and 4- hydroxybenzoic acids
from water to salt solutions have been reported. The data
have been rationalised by considering the structure
breaking effects of the ions of the salts, the localized
hydrolysis model, the internal pressure theory and the
theory of water structure due to Symons.
The Setschenow parameter and thermodynamic parameters of transfer of 2-, 3-, and 4-methylbenzoic acids
from water to salt solutions have been reported. The data have been rationalized by considering the structure breaking
effects of the ions of the salts, the localized hydrolysis model, and the internal pressure theory.
Sugunan, S; Benny, Thomas(Journal of Solution Chemistry, 1994)
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Abstract:
The Setschenow parameter and thermodynamic parameters of transfer of
2-, 3- and 4-fluorobenzoic acid from water to salt solution are reported.
The data have been rationalized by considering the structure breaking effects of the ions of the salts, the localized hydrolysis model and the internal
pressure theory.
Sugunan, S; Anantaraman, R(Indian Journal of Chemistry, December , 1982)
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Abstract:
Kinetics of mercuric chloride catalysed solvolysis of l-butyl
chloride, benzyl chloride. p-methylbenzyl chloride, l-phenylethyl
chloride and triethylcarbinyl chloride have been studied in aq.
DMSO, aq. acetonitrile and aq. ethanol. The kinetic data fit a second
order rate equation in aq. DMSO. The calculated values of the
second order rate coefficients increase in the case of aq. acetonitrile
and aq. ethanol. The order in catalyst in 95%(v/v) aq. DMSO is less
than unity.
Nishamol, K; Rahna, K S; Sugunan, S(Elsevier, 2004)
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Abstract:
Various compositions of chromium manganese ferrospinels were tested as catalysts for the vapour phase alkylation of aniline with methanol. The samples were prepared by room temperature co-precipitation technique and characterized by various physico-chemical methods. The acidity–basicity determination revealed that the samples possess greater amount of basic sites than acidic sites. All the ferrite samples proved to be selective and active for N-monoalkylation of aniline leading to N-methyl aniline; Cr0.6Mn0.4Fe2O4, Cr0.8Mn0.2Fe2O4 and CrFe2O4 exhibited cent percent selectivity for N-methyl aniline. Neither C-alkylated products nor any other side products were detected for all catalyst samples. The catalytic activity of the samples studied in this reaction is related to their acid–base properties and also on the cation distribution. Under the optimized reaction conditions all the systems showed constant activity for a long duration.
Iron and mixed iron aluminium pillared montmorillonites prepared by partial hydrolysis method was subjected to room temperature exchange with transition metals of the first series. The materials exhibit good structural as well as thermal stability. Exchanged metals were found to be present inside the porous network, in the environs of the pillars. Mixed pillaring resulted in the intercalation of Al 13 like polymers in which Al is partially substituted by Fe. The acidic structure was followed by temperature programmed desorption of ammonia and cumene cracking test reaction. Weak and medium sites overshadow the strong sites in all systems. However, exchange with metals increases the number of strong sites. The prepared materials are efficient catalysts for gas phase MTBE synthesis. The catalytic activity can be well correlated with the total amount of weak and medium acid sites.
Sreekumar, K; Raja, T; Kiran, B P; Sugunan, S; Rao, B S(Elsevier, 1999)
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Abstract:
The reaction of aniline with methanol was carried out over Zn1-xNixFe2O4 (x= 0, 0.2, 0.5, 0.8 and 1) type systems in a
fixed-bed down-flow reactor. It was observed that systems possessing low ``x'' values are highly selective and active for mono
N-alkylation of aniline leading to N-methyl aniline. Selectivity for N-methyl aniline over ZnFe2O4 was more than 99% under
the optimized reaction conditions. Even at methanol to aniline molar ratio of 2, the yield of N-methyl aniline was nearly
55.5%, whereas its yield exceeded 67% at the molar ratio of 7. The Lewis acid sites of the catalysts are mainly responsible for
the good catalytic performance. Cation distribution in the spinel lattice influences their acido-basic properties, and hence,
these factors have been considered as helpful to evaluate the activity and stability of the systems.
Sreekumar, K; Jyothi, T M; Talawar, M B; Kiran, B P; Rao, B S(Elsevier, 2000)
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Abstract:
A series of ferrites having the general formula Zn1-xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0)were prepared by soft
chemical route. The materials were characterized by adopting various physico-chemical methods. The reaction of aniline
with methanol was studied in a fixed-bed reactor system as a potential source for the production of various methyl anilines.
It was observed that systems possessing low ‘ x’ values are highly selective and active for N-monoalkylation of aniline
leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining
N-methylaniline selectively and in better yield. Among the systems Zn0.8Co0.2Fe2O4 is remarkable due to its very high
activity and excellent stability. Under the optimized conditions N-methylaniline selectivity exceeded 98%. Even at a
methanol to aniline molar ratio of 2, the yield of N-methylaniline was nearly 50%, whereas its yield exceeded 71% at the
molar ratio of 5. ZnFe2O4, though executed better conversion than Zn0.8Co0.2Fe2O4 in the initial period of the run,
deactivates quickly as the reaction proceeds. The Lewis acidity of the catalysts is mainly responsible for the good
performance. Cation distribution in the spinel lattice influences their acido-basic properties and, hence, these factors have
been considered as helpful parameters to evaluate the activity of the systems.
The 2,4,6-triphenylthiapyrylium ion has been obtained imprisoned inside the supercages of the tridirectional,
large pore zeolites Y and beta via ship-in-a-bottle synthesis from chalcone and acetophenone in the presence of
hydrogen sulfide. The resulting solids are efficient and robust photocatalysts that are able to degrade phenol and
aniline in water with a higher efficiency than the P-25 TiO2 standard. Preliminary tests have shown that these
encapsulated dye materials are also efficient photocatalysts for the oxidative degradation of malodorous sulfurcontaining
molecules.
The quantum yields of singlet oxygen production and
lifetimes at the gas–solid interface in silica gel material
are determined. Different photosensitizers (PS) are encapsulated
in parallelepipedic xerogel monoliths (PS-SG). PS were chosen according
to their known photooxidation properties: 9,10-dicyanoanthracene
(DCA), 9,10-anthraquinone (ANT), and a benzophenone
derivative, 4-benzoyl benzoic acid (4BB). These experiments
are mainly based on time-resolved 1O2 phosphorescence detection,
and the obtained FD and tD values are compared with
those of a reference sensitizer for production, 1H-phenalen-1-
one (PN), included in the same xerogel. The trend between their
ability to oxidize organic pollutants in the gas phase and their efficiency
for production is investigated through photooxidation
experiments of a test pollutant dimethylsulfide (DMS). The
FD value is high for DCA-SG relative to the PN reference, whereas
it is slightly lower for 4BB-SG and for ANT-SG. FD is related to
the production of sulfoxide and sulfone as the main oxidation
products for DMS photosensitized oxidation. Additional mechanisms,
leading to C!S bond cleaveage, appear to mainly occur
for the less efficient singlet oxygen sensitizers 4BB-SG and ANTSG.
Rare earth metal ion exchanged (La3+, Ce3+, RE3+) KFAU-Y zeolites were prepared by simple ion-exchange methods and have
been characterized using different physico-chemical techniques. In this paper a novel application of solid acid catalysts in the dehydration/
Beckmann rearrangement of aldoximes; benzaldoxime and 4-methoxybenzaldoxime is reported. Dehydration/Beckmann
rearrangement reactions of benzaldoxime and 4-methoxybenzaldoxime is carried out in a continuous down flow reactor at
473K. 4-Methoxybenzaldoxime gave both Beckmann rearrangement product (4-methoxyphenylformamide) and dehydration product
(4-methoxybenzonitrile) in high overall yields. The difference in behavior of the aldoximes is explained in terms of electronic
effects. The production of benzonitrile was near quantitative under heterogeneous reaction conditions. The optimal protocol allows
nitriles to be synthesized in good yields through the dehydration of aldoximes. Time on stream studies show a fast decline in the
activity of the catalyst due to neutralization of acid sites by the basic reactant and product molecules.
Sugunan, S(Indian Journal of Chemistry, February , 1983)
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Abstract:
Solubilities of 4-nitrobenzoic acid at 25°, 35° and 42°C have
been determined in water and in the presence of several concentrations
of electrolytes. The free energies, enthalpies and entropies
of transfer are also reported. The data have been rationalized
by considering the structure-breaking effects of the ions of
the salts and the requirement of the localized hydrolysis model.
The theory of Symons is not satisfactory to rationalise the
experimental data.
Seena, E B; Prathapachandra Kurup, M R(Elsevier, 2007)
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Abstract:
Three copper(II) complexes of salicylaldehyde N(4)-phenyl thiosemicarbazone (H2L1) and two copper(II) complexes of N(4)-cyclohexyl thiosemicarbazone (H2L2) have been synthesized and characterized by different physicochemical techniques like magnetic studies and electronic, infrared and EPR spectral studies. The complexes View the MathML source and [(CuL2)2] (4) having dimeric structure. The thiosemicarbazones bind to the metal as dianionic ONS donor ligand in all the complexes, except in the complex [Cu(HL1)2] · H2O (2). In complex 2, the ligand moieties are coordinated as monoanionic (HL−) ones. Two of the complexes [CuL1dmbipy] · H2O (3) and [CuL2dmbipy] (5) have been found to possess the stoichiometry [CuLB], where B = 4,4′-dimethyl-2,2′-bipyridine (dmbipy). The coordination geometry around copper(II) in 5 is trigonal bipyramidal distorted square based pyramidal (TBDSBP), as obtained by X-ray diffraction studies.
Girish Kumar,K; Muthuselvi,R(Department of Applied Chemistry, March 30, 2005)
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Abstract:
A spectrophotometric method employing 2-hydroxybenzaldiminoglycine (HBIG) is proposed for
the determination of chromium(III). The results of the determinations are compared with the standard diphenyl
carbazide method. The presently developed method is direct, simple, rapid, selective, sensitive and precise.
Girish Kumar,K; Devala Rao, G; Chowdary, K P R(Indian Journal Of Pharmaceutical Sciences, February 7, 2001)
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Abstract:
Two simple and sensitive spectrophotometric methods(A and B) in the visible region have been developed for the determination of cefotaxime sodium (DFTS) in bulk and in dosage forms. Method A is based on the reaction of CFTS with nitrous acid under alkaline conditions to form a stable violet colored chromogen with absorption maximum of 560 nm and method B is based on the reaction of CFTS with1,10-phenanthroline and ferric chloride to form a red colored chromogen with the absorption maximum of 520 mm.The color obeyed Beer’s law in the concentration range of 100-500 µg/ml for method A and 1.6-16 µg/ml for method B, respectively.When pharmaceutical preparations containing CFTS were analysed, the results obtained by the proposed methods are in good agreement with the labeled amounts and are comparable with the results obtained using a UV spectrophotometric method.
Rice husk silica was utilized as the promoter of ceria for preparing supported vanadia catalysts. Effect of vanadium content was investigated with 2–10 wt.% V2O5 loading over the support. Structural characterization of the catalysts was done by various techniques like energy dispersive X-ray (EDX), X-ray diffraction (XRD), BET surface area, thermal analysis (TGA/DTA), FT-infrared spectroscopy (FT-IR), UV–vis diffused reflectance spectroscopy (DR UV–vis), electron paramagnetic spectroscopy (EPR) and solid state magnetic resonance spectroscopies (29Si and 51V MASNMR). Catalytic activity was studied towards liquid-phase oxidation of benzene. Surface area of ceria enhanced upon rice husk silica promotion, thus makes dispersion of the active sites of vanadia easier. Highly dispersed vanadia was found for low V2O5 loading and formation of cerium orthovanadate (CeVO4) occurs as the loading increases. Spectroscopic investigation clearly confirms the formation of CeVO4 phase at higher loadings of V2O5. The oxidation activity increases with vanadia loading up to 8 wt.% V2O5, and further increase reduces the conversion rate. Selective formation of phenol can be attributed to the presence of highly dispersed active sites of vanadia over the support.
Seven bis(ligand) Co(III) complexes {[CoL21] NO3 · H2 O (1), [CoL21] Cl · 2 H2 O (2),[CoL21] ClO4 (3), [CoL22] NO3 (4), [CoL22] Cl · 2 H2 O (5), [CoL23] Br · 2 H2 O (6), [CoL23] ClO4 · H2 O (7)} of three thiosemicarbazone ligands {pyridine-2-carbaldehyde-N(4)-p-methoxyphenyl thiosemicarbazone [HL1], pyridine-2-carbaldehyde-N(4)-2-phenylethyl thiosemicarbazone [HL2] and pyridine-2-carbaldehyde-N(4)-(methyl),N(4)-(phenyl) thiosemicarbazone [HL3]} were synthesized and physico-chemically characterized. All complexes are assigned octahedral geometries on the basis of spectral studies. The ligands deprotonate and coordinate by means of pyridine nitrogen, azomethine nitrogen, and thiolate sulfur atoms. The single crystal X-ray structures of HL3 and two nitrate compounds are discussed. The structural studies corroborate the spectral characterization.
Manoj, N(American chemical society, August 7, 2006)
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Abstract:
A combined experimental and theoretical study of the absorption spectra of a group of closely related pyrylium
perchlorates 1-11 are presented. Minor changes in the position of the substituents lead to drastic changes in
the absorption spectra in this series of compounds. We have attempted to explain the observed changes using
the x,y-band notation developed by Balaban and co-workers. Absorption spectra of all compounds are compared
with results from time-dependent density functional theory (TDDFT) and Zerner’s intermediate neglect of
differential overlap (ZINDO/S) level calculations. Results of the calculations are in good agreement with
experimental observations and an interesting correlation between Balaban’s notations and the MO transitions
are obtained for simple derivatives. It is suggested that for more complex systems such as R- and â-naphthyl
substituted systems, the empirical method is not appropriate.