Girish Kumar, K; Chowdary, K P R; Devala Rao, G(Indian Journal Of Pharmaceutical Sciences, January 8, 1999)
[+]
[-]
Abstract:
Two simple and sensitive spectrophotometric methods (A and B)in the visible region have been developed for the determination of nimesulide in bulk and in dosage forms.Method A is based on the reaction of reduced nimesulide with nitrous acid followed by its coupling with phloroglucinol to yield an yellow colored azo dye with an absorption maximum of 400 nm and method B is based on the reaction of reduced nimesulide with p-dimethylamino benzaldehyde(PDAB) to form an yellow colored chromogen wiht an absorption maximum of 415 nm.When pharmaceutical preparations (Tablets and suspension) were analysed, the results obtained by the proposed methods are in good agreement with the labelled amounts and are comparable with the results obtained by a reported method.recovery in both the method is 98-101 %.
Sugunan, S; Bindhu, Jacob(Indian Journal of Chemistry, October , 1999)
[+]
[-]
Abstract:
The acidity of the various rare-earth exchanged zeolite-Y
catalysts has been examined by titration method using Hammett
indicators and is correlated with the catalytic activity of the
samples in the benzylation of 0-xylene.
Sugunan, S; Seena, C R Kumaree(Indian Journal of Chemistry, November , 1999)
[+]
[-]
Abstract:
The changes in surface acidity/basicity and catalytic activity of cerium oxide due to surface modification by sulphate ion have been
investigated. Electron donor properties of both the modified and unmodified oxides have been studied using electron acceptors of
various electron affinity values, viz. 7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrachloro--l, 4-benzoquinone. p-dinitrobenzene and
m-dinitrobenzene in order to find out whether the increase in acidity on suphation is due to the generation of new acidic sites or they are
formed at the expense of some of the basic sites. The surface acidity/basicity has been determined using a set of Hammett indicators.
The data have been correlated with the catalytic activity of the oxides for esterification of acetic acid using l-butanol, reduction of
cyclohexanone with 2- propanol and oxidation of cyclohexanol using benzophenone.
Sugunan, S; Sherly, K B; Devika Rani, G(React. Kinet.Catal.Lett., 1993)
[+]
[-]
Abstract:
The limit of electron transfer in electron affinity from
the oxide surface to the electron acceptor (EA) are reported
from the adsorption of EA on DY203, mixed oxides
of DY203 with alumina and mixed oxides of Y203 with y-alumina.
The extent of electron transfer is understood
from magnetic measurements.
Sreekumar, K; Raja, T; Kiran, B P; Sugunan, S; Rao, B S(Elsevier, 1999)
[+]
[-]
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.
Sankara Raman, S; Nampoori, V P N; Vallabhan, C P G; Ambadas, G; Sugunan, S(American Institute of Physics, 1995)
[+]
[-]
Abstract:
The thermal diffusivity of y-alumina is determined by the photoacoustic method. The method is
calibrated by determining the thermal diffusivity of copper and aluminum. The effect of the
chemisorbed hydroxyl groups or thermal diffusivity is studied by degassing the sample at different
temperatures.
Sugunan, S; Kumaree Seena, C R(Indian Journal of Chemistry, May , 1998)
[+]
[-]
Abstract:
We have investigated the changes in surface acidity/basicity
and catalytic pro~erties of samarium oxide due to surface modification
by SO42- ion. The acidity/basicity of the catalysts is
determined by titration method using Hammett indicators.
Esterification of acetic acid by n-butanol is chosen as a test
reaction. Sm203, owing to its high basicity and low acidity, does
not catalyze the reaction. But sulphated Sm20J catalyzes the
esterification reaction effectively. Activation temperature does
not have much effect on the acidity of sulphated samaria.
Sugunan, S; Kumaree Seena, C R(Indian Journal of Chemistry, August , 1998)
[+]
[-]
Abstract:
The surface electron donor properties of sulphate modified stannic oxide have been determined from the
adsorption of electron acceptors of various electron affinities on the oxide surface. The acid base properties of
stannic oxide have been determined by titration method using Hammett indicators. Catalytic activities of the
oxide for esterification of acetic acid using n-butanol.reduction of cyclohexanone in 2-propanol and oxidation of
cyclohexanol with benzophenone have been studied. The data have been correlated with the surface electron
donor properties of these oxides. The activity for reduction and oxidation decreases and that for esterification
reaction increases on modification with sulphate ion. It has heen found that electron donating capacity decreased
when stannic oxide was modified with sulphate ion.
Description:
Note:Indian Journal of Chemistry
Vol. 37A, August 1998, pp. 669 - 673
Jyothi, T M; Rao, B S; Sugunan, S; Sreekumar, K(Indian Journal of Chemistry, December , 1999)
[+]
[-]
Abstract:
Alkylation of phenol with methanol has been carried out over
Sn-La and Sn-Sm mixed oxides of varying compositions at 623 K
in a vapour phase flow reactor. It is found that the product
selectivity is greatly influenced by the acid-base properties of the
catalysts. Ortho-cresol formation is favoured over catalysts with
weak acid sites whereas formation of 2,6-xylenol occurs in the
presence of stronger acid sites. The cyclohexanol decomposition
reaction and titrimetric method using Hammett indicators have
been employed to elucidate the acid-base properties of the
catalysts.
Description:
Indian Journal of Chemistry
Vol. 38A, December 1999, pp. 1253-1255
Sugunan, S; Binsy, Varghese(Indian Journal of Chemistry, September , 1998)
[+]
[-]
Abstract:
The electron donating properties, surface acidity/ basicity and catalytic activity of cerium - zirconium mixed
oxides at various compositions have been reported at an activation temperature of 500 degree C. The catalytic activity
for the esterification of acetic acid with n-butanol has heen correlated with electron donating properties and
surface acidity/basicity of the oxides.