排序方式: 共有105条查询结果,搜索用时 15 毫秒
31.
Chimatadar Shivamurti A. Koujalagi Sangappa B. Nandibewoor Sharanappa T. 《Transition Metal Chemistry》2001,26(6):662-667
The CrVI oxidation of HgI in an aqueous acid medium occurs to a modest extent only in presence of PdII and in H2SO4 above ca. 0.20 mol dm–3. The reaction is first order in [CrVI] in the presence of PdII catalyst. The order in [HgI] is less than unity, whereas that in [PdII] is unity. Increase in [H2SO4] accelerates the reaction rate. The added products, CrIII and HgII, do not significantly effect the reaction rate. A mechanism involving HCrO4
– and PdCl+ as the reactive species of oxidant and catalyst respectively, is proposed. The reaction constants involved in the mechanism have been evaluated. 相似文献
32.
Abdulazizkhan L. Harihar Mohammedsaleem R. Kembhavi Sharanappa T. Nandibewoor 《Monatshefte für Chemie / Chemical Monthly》2000,131(11):1129-1137
Summary. The title reaction was investigated in aqueous alkaline medium. A first order dependence on both [diperiodatonickelate(IV)]
and [OH−] and an apparent fractional order in [1,10-Phenanthroline] was obtained. Addition of the reaction product has no effect on
the reaction. The effects of dielectric constant, ionic strength, and temperature on the rate of the reaction were studied.
A mechanism based on the experimental results is proposed, and the constants involved in the mechanism were evaluated. A good
agreement between the observed and calculated rate constants at varying experimental conditions was obtained.
Received May 26, 2000. Accepted (revised) July 27, 2000 相似文献
33.
34.
Rahamatalla M. Mulla Gurubasavaraj C. Hiremath Sharanappa T. Nandibewoor 《Journal of Chemical Sciences》2005,117(1):33-42
Kinetics of ruthenium (III) catalyzed oxidation of atenolol by permanganate in alkaline medium at constant ionic strength
of 0.30 mol dm3 has been studied spectrophotometrically using a rapid kinetic accessory. Reaction between permanganate and atenolol in alkaline
medium exhibits 1 : 8 stoichiometry (atenolol : KMnO4). The reaction shows first-order dependence on [permanganate] and [ruthenium (III)] and apparently less than unit order on
both atenolol and alkali concentrations. Reaction rate decreases with increase in ionic strength and increases with decreasing
dielectric constant of the medium. Initial addition of reaction products does not affect the rate significantly. A mechanism
involving the formation of a complex between catalyst and substrate has been proposed. The active species of ruthenium (III)
is understood as [Ru(H2O)5OH]2+. The reaction constants involved in the different steps of mechanism are calculated. Activation parameters with respect to
the slow step of the mechanism are computed and discussed and thermodynamic quantities are also calculated. 相似文献
35.
Deepak S. Munavalli Praveen N. Naik Shivamurti A. Chimatadar Sharanappa T. Nandibewoor 《Reaction Kinetics and Catalysis Letters》2008,94(2):359-366
The effect of La2O3, K2O and Li2O on the properties and catalytic performance of silica-supported nickel catalysts for the hydrogenation of m-dinitrobenzene was investigated. The catalysts promoted with La2O3, Li2O and K2O showed better catalytic performance than the catalyst without promotion, especially the ones co-promoted with La2O3 and K2O or Li2O. 相似文献
36.
The oxidation of L-isoleucine by alkaline diperiodatoargentate(III) (DPA) at 298 K and a constant ionic strength of 0.80 mol dm−3 was studied spectrophotometrically. The stoichiometry is [L-isoleucine]: [DPA] = 1:2. The reaction is first order in [DPA] and has less than unit order in both [L-isoleucine] and [alkali] and retarding effect in The oxidation reaction in alkaline medium has been shown to proceed via a L-isoleucine–DPA complex, which further reacts with one molecule of DPA in a rate determining step followed by other fast steps
to give the products. Spot test and IR were used to identify the main products. The reaction constants involved in the different
steps of the mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed
and discussed, and thermodynamic quantities are also determined. The probable active species of oxidant have been identified.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
37.
Praveen N. Naik Shivamurti A. Chimatadar Sharanappa T. Nandibewoor 《Transition Metal Chemistry》2008,33(4):405-410
The oxidation of tyrosine by chromium(VI) in aqueous perchloric acid medium has been studied spectrophotometrically at 30 °C
and at a constant ionic strength I = 3.10 mol dm−3. The main reaction products were identified as chromium(III) and 4-hydroxyphenylacetaldehyde. The stoichiometry is 2:3, i.e.,
two moles of chromium(VI) react with three moles of tyrosine. The reaction is first order with respect to both chromium(VI)
and tyrosine. Increase in perchloric acid concentration increased the rate of reaction. The order with respect to acid concentration
was found to be two. Added products, ionic strength and dielectric constant of the medium did not have any significant effect
on the reaction rate. A suitable mechanism is proposed. The activation parameters were determined with respect to the slow
step of the mechanism. The thermodynamic quantities were also determined and discussed. 相似文献
38.
Deepak S. Munavalli Shivamurti A. Chimatadar Sharanappa T. Nandibewoor 《Transition Metal Chemistry》2008,33(5):535-542
The kinetics of oxidation of l-lysine by diperiodatoargentate(III) (DPA) in aqueous alkaline medium at a constant ionic strength of 0.50 mol dm−3 was studied spectrophotometrically. The oxidation products are aldehyde, 5-aminopentanal and Ag(I). The main products were
identified by spot test, IR and GC-MS. The stoichiometry is [l-lysine]:[DPA] = 1:1. The reaction is first order with respect to diperiodatoargentate(III) concentrations, whereas the order
with respect to l-lysine and alkali concentrations changes from first order to zero order as the l-lysine and alkali concentrations are increased. The effects of added products, periodate, ionic strength, and dielectric
constant of the reaction medium were investigated. Based on the experimental results, a mechanism involving complex formation
between DPA species and l-lysine is proposed. The reaction constants involved in the mechanism were evaluated. The activation parameters with respect
to the slow step of the mechanism were determined and discussed. 相似文献
39.
Electro‐oxidation and Determination of Tripelennamine Hydrochloride at MWCNT‐CTAB Modified Glassy Carbon Electrode
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An electrochemical method for the determination of tripelennamine hydrochloride (TPA) using cetyltrimethylammoniumbromide‐multiwalled carbon nanotubes modified glassy carbon electrode (MWCNT‐CTAB/GCE) was developed. Because of good electrical conductivity of MWCNT and catalytic behavior of CTAB, new electrode significantly enhances the sensitivity for the detection of TPA. Parameters such as amount of modifier suspension, scan rate, pH of measure solution, heterogeneous rate constant were investigated. The electrode exhibits a linear potential response in the range of 1.0×10?8 M to 3.0×10?6 M with a detection limit of 2.38× 10?9 M. The modified electrode was successfully applied to the determination of TPA in pharmaceutical and real samples. 相似文献
40.
Kiran A. Thabaj Deepak S. Munavalli Shivamurti A. Chimatadar Sharanappa T. Nandibewoor 《Transition Metal Chemistry》2007,32(7):902-912
The micro amounts of iodide (10−7) (mol dm−3) and chloride (10−2) (mol dm−3) mediated oxidation of antimony(III) by cerium(IV) in an aqueous sulphuric acid medium have been studied spectrophotometrically
at 25 °C and μ = 3.10 mol dm−3. The stoichiometry is 1:2 in chloride and iodide mediated reactions. i.e. one mole of antimony(III) requires two moles of cerium(IV). In the case of chloride mediated reaction, the reaction was
first order in cerium(IV) and halide concentrations, whereas in the case of iodide mediated reaction the order with respect
to [cerium(IV)] was unity and with respect to iodide concentrations was more than unity (ca. 1.4). In both chloride and iodide mediated reactions the order with respect to antimony(III) concentrations was less than
unity. Increase in sulphuric acid concentration increased the rate. The order with respect to H+ ion concentration was less than unity. Added products, cerium(III) and antimony(V) did not have any significant effect on
the reaction rate. The active species of oxidant was understood to be
, whereas that of reductant as SbCl3 in the case of chloride and SbI2+ in case of iodide mediated reactions. The possible reaction mechanisms were proposed and the activation parameters were determined
and discussed. 相似文献