Sugunan, S; Sunitha, Kurur; Anto, Paul(Indian Journal of Chemistry, December , 1994)
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Abstract:
The surface acidity and basicity of oxides of Sm and Zr
and their mixed oxides have been determined using a set of
Hammett indicators. The data have been correlated with
the catalytic activity of these oxides towards the liquid
phase reduction of cyclo-hexanone in 2-propanol.
Sugunan, S; Devika Rani, G; Unnikrishnan, P A(Indian Journal of Engineering & Materials Sciences, October , 1995)
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Abstract:
Acid/base strength distribution of Y2O3 and its mixed
oxides with alumina catalysts are measured on Hammett
acidity function scale and expressed in terms of H0max
value. Basicity of Y2O3 increases with increase in activation
temperature and for mixed oxides the basicity increases
with increase in concentration of Y2O3, in the catalyst.
Sugunan, S; Sherly, K B; Devika Rani, G(React. Kinet.Catal.Lett., 1993)
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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.
Sugunan, S; Binsy, Varghese(Indian Journal of Chemistry, September , 1998)
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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.
The electron donating properties, surface acidity/basicity and catalytic activity of lanthana for various dopant concentrations of strontium are reported at two activation temperatures. The catalytic activity has been correlated with electron donating properties and surface acidity/basicity of the oxide.
Ferrospinels of nickel, cobalt and copper and their sulphated analogues were prepared by the room temperature coprecipitation
route to yield samples with high surface areas. The intrinsic acidity among the ferrites was found to decrease in
the order: cobalt> nickel> copper. Sulphation caused an increase in the number of weak and medium strong acid sites,
whereas the strong acid sites were left unaffected. Electron donor studies revealed that copper ferrite has both the highest
proportion of strong sites and the lowest proportion of weak basic sites. All the ferrite samples proved to be good catalysts
for the benzoy lation of toluene with benzoyl chloride. copper and cobalt ferrites being much more active than nickel ferrite.
The catalytic activity for benzoylation was not much influenced by sulphation, but it increased remarkably with calcination
temperature of the catalyst. Surface Lewis acid sites, provided by the octahedral cations on the spinel surface, are suggested
to be responsible for the catalytic activity for the benzoylation reaction.
Smitha, V K; Suja, H; Joyce, Jacob; Sugunan, S(Indian Journal of Chemistry, February , 2003)
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Abstract:
Preparation and physico-chemical characterization or
phosphate modified zirconia systems and their application to
Friedel-Crafts benzylation and benzoylation of toluene have been
reported. The influence of transition metals on the surface
properties and catalytic activity has also been discussed.
Sugunan, S; Renuka, N K(Indian Journal of Chemistry, February , 2002)
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Abstract:
Sm2O3 - vanadia catalysts have been prepared by wet
impregnation method using NH4VO3 solution. The surface
properties of the prepared catalysts have been studied using FTIR.
XRD. surface area and pore volume data. The acid-base properties
of the system have been investigated by titrimetric method using
Hammett indicators. adsorption of electron acceptors as well as
decomposition of cyclohexanol. Phenol alkylation reaction by
methanol has been carried out to investigate the catalytic activity.
It has been observed that the selectivity of the products depends
upon the composition of the supported system
Mohammed Yusuff, K K; Mayadevi, S(Taylor & Francis, 1997)
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Abstract:
Some new transition metal complexes of the Schiff base
quinoxaline-2-car boxalidene-2-aminophenol (HQAP) have been
synthesized and characterized by elemental analyses, conductance
and magnetic measurements and IR and UV-Visible spectral studies.
The complexes have the following empirical formulae: [Mn(QAP121,
[Fe(QAPl2C1I, [Co(QAPl21, [Ni(QAP121 and [Cu(QAP121. A tetrahedral
structure has been assigned for the manganese(=), cobalt(II1,
nickel(II1 and copper(II1 complexes. For the iron(IIIl complex an
octahedral dimeric structure has been suggested
Sreesha, Sasi; Prathapachandra Kurup, M R; Suresh, E(Springer, January 1, 2007)
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Abstract:
The cobalt(III) complex, [Co(L)2(N3)2]2(ClO4)2, L being a Schiff base N-[phenyl(pyridin-2-yl)methylene]aniline has been synthesized and the crystal structure determined using X-ray crystallography. The complex crystallizes in triclinic system, space group P-1 with unit cell parameters a=10.9367(9) , b=18.0817(17) , c=20.1629(16) , α=111.341(2), β=91.622(2), γ=107.5030(10), V=3499.1(5) 3 and Z=2. It crystallizes with two independent molecules in the asymmetric unit. The two cobalt atoms are hexa-coordinate and have a distorted octahedral geometry, satisfied by four nitrogen atoms from two molecules of the Schiff base and two nitrogen atoms from the monodentate azide group. The perchlorate ions are non-coordinating.
A series of nonelectrolytic lanthanide(III) complexes,
[
ML
2
Cl
3
]
·
2
H
2
O, where M is lanthanum(III),
praseodymium(III), neodymium(III), samarium(III), gadolinium(III), terbium(III), dysprosium(III), and
yttrium(III), containing sulfamethoxazole ligand (L) are prepared. The structure and bonding of the ligand are
studied by elemental analysis, magnetic susceptibility measurements, IR,
1
H NMR,
TG
/
DTA
, X-ray diffraction
studies, and electronic spectra of the complexes. The stereochemistry around the metal ions is a monocapped
trigonal prism in which four of the coordination sites are occupied by two each from two chelating ligands, sulfonyl
oxygen, and nitrogen of the amide group and the remaining three positions are occupied by three chlorines.
The ligand and the new complexes were tested in
vitro to evaluate their activity against the bacteria
Escherichia
coli
and
Staphylococcus
aureus.
Rahna, K Shamsudeen; Nisha, K; Sugunan, S(November , 2002)
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Abstract:
Iron pillared Montmorillonite has been synthesised and it is then wet impregnated with vanadia with different vanadia
composition. These catalysts are characterised using conventional techniques such as XRD analysis,FTIR analysis and
surface area and pore volume measurements. Acidity is measured using spectrophotometric monitoring of adsorption of
perylene, thermogravimetric desorption of 2.6 dimethylpyridine and temperature programmed desorption of ammonia.
Activity studies are done in the liquid phase. It has been concluded that Lewis acidic sites are responsible for the benzylation
of toluene when the benzylating agent is benzyl chloride while Bronsted acidic sites are responsible when the reagent is
benzyl alcohol.
Sunajadevi, K R; Sugunan, S(Elsevier, October , 2004)
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Abstract:
Chromia loaded sulfated titania has been synthesized via sol–gel route with different chromia loadings. These catalysts are characterized using conventional techniques such as XRD analysis, FTIR analysis, surface area and pore volume measurements, EDX, SEM and UV–Vis diffuse reflectance spectral analysis. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. Activity studies are done in the liquid phase. It has been concluded that Lewis acid sites are responsible for the benzylation of arenes with benzyl chloride.
A series of rare-earth neodymia supported vanadium oxide catalysts with various V205 loadings ranging from 3 to 15 wt.% were prepared
by the wet impregnation method using ammonium metavanadate as the vanadium precursor. The nature of vanadia species formed on the
support surface is characterized hy a series of different physicochemical techniques like X-ray diffraction (XRD). Fourier transform infrared
spectroscopy (FTIR). BET surface area, diffuse reflectance UV-vis spectroscopy (DR UV-vis), thermal analysis (TG-DTG/DTA) and SEM.
The acidity of the prepared systems were verified by the stepwise temperature programmed desorprion of ammonia (NH3-TPD) and found that
the total acidity gets increased with the percentage of vanadia loading. XRD and FT1R results shows the presence of surface dispersed vanadyl
species at lower loadings and the formation of higher vanadate species as the percentage composition of vanadia is increased above 9 wt.%.
The low surface area of the support. calcination temperature and the percentage of vanadia loading are found to influence the formation of
higher vanadia species. The catalytic activity of the V205-Nd203 catalysts was probed in the liquid phase hydroxylation of phenol and the
result show that the present catalysts are active at lower vanadia concentrations.
Mohammed Yusuff, K K; Anas, K(Elsevier, Applied Catalysis A :General 264 (2004) 213–217, December 25, 2003)
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Abstract:
CoMo/gama-Al2O3 catalysts for hydrodesulphurisation activity were prepared by making use of the molecular designed dispersion (MDD)
method. Molybdenum and cobalt pyrrolidine-N-carbodithioate (Pydtc) complexes were used for the incorporation of metals on the support.
The catalysts were characterized by elemental analysis, low temperature oxygen chemisorption, temperature programmed reduction (TPR)
and laser Raman spectroscopy. The hydrodesulphurisation activity of all the catalysts were carried out and results were compared with those
of the catalysts prepared through the conventional method. Higher molybdenum dispersion, smaller molybdenum clusters, lower reduction
temperature of catalyst and better hydrodesulphurisation activity were observed for the catalysts prepared through the MDD method
The title reaction was undertaken to establish the interaction between amantadine and molybdate at physiological pH. Identical FTIR spectra, TG-DTA curves and CHN data of the complexes formed from three solutions at pH 1.5, 7.4 and 8.0 indicate that the same complex was formed at all the three pHs. The FTIR spectrum shows shift in peaks corresponding to primary amino group of the drug due to coordination to molybdate. An octahedral geometry is assigned to the complex. The kinetics of the complexation has been studied at low concentrations of the reactants using UV-visible spectrophotometry. At pH 7.4, the initial rate varies linearly with [molybdate]. A plot of initial rate versus [drug] is linear passing through origin. These results indicate that the drug and molybdate react at pH 7.4 even at low concentrations. At pH 1.5, the rate increases linearly with increase in [drug] but decreases with [molybdate]. The effect of pH and ionic strength on the rate of the reaction has also been studied. A suitable mechanism has been proposed for the reaction. Reaction between the drug and molybdate even at low concentrations and the fact that the amino group of amantadine required to be free for its function as antiviral, is bound to molybdate in the complex suggests that simultaneous administration of the drug and molybdate supplements should be avoided.
Mohammed Yusuff, K K; Manju, Sebastian; Arun, Vasudevan; Robinson, P P; Leeju, Pally; Digna, Varghese; Varsha, Gopalakrishnan(Taylor & Francis, Journal of Coordination Chemistry, October 15, 2009)
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Abstract:
The mononuclear cobalt(II) complex [CoL2] H2O (where HL is quinoxaline-2-carboxalidine-
2-amino-5-methylphenol) has been prepared and characterized by elemental analysis, conductivity
measurement, IR, UV-Vis spectroscopy, TG-DTA, and X-ray structure determination.
The crystallographic study shows that cobalt(II) is distorted octahedral with each tridentate
NNO Schiff base in a cis arrangement. The crystal exhibits a 2-D polymeric structure parallel to
[010] plane, formed by O-H...N and O-H... O intermolecular hydrogen bonds and pye
stacking interactions, as a racemic mixture of optical enantiomers. The ligand is a Schiff base
derived from quinoxaline-2-carboxaldehyde
Bejoy, Thomas; Prathapan, Sreedharan; Sugunan, Sankaran(Elsevier, May , 2005)
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Abstract:
The synthesis of dimethyl acetals of carbonyl compounds such as cyclohexanone, acetophenone, and benzophenone has successfully been carried out by the reaction between ketones and methanol using different solid acid catalysts. The strong influence of the textural properties of the catalysts such as acid amount and adsorption properties (surface area and pore volume) determine the catalytic activity. The molecular size of the reactants and products determine the acetalization ability of a particular ketone. The hydrophobicity of the various rare earth exchanged Mg–Y zeolites, K-10 montmorillonite clay, and cerium exchanged montmorillonite (which shows maximum activity) is more determinant than the number of active sites present on the catalyst. The optimum number of acidic sites as well as dehydrating ability of Ce3+-montmorillonite and K-10 montmorillonite clays and various rare earth exchanged Mg–Y zeolites seem to work well in shifting the equilibrium to the product side.