31 research outputs found
Asia Behind the News 1979. Program 3
No full textInterviews produced by the ANU Instructional Resources Unit for 2XX FM. -- Tape 3 of 42. Revolution in Iran: Implications of the Iranian situation for India, with Martin Rudner and Sukhdev Muni. Recorded 28/02/197
Oxidation of tricyclic antidepressant drugs with chloramine-T in acidic solutions: Kinetic, mechanistic and thermodynamic studies
No full textThe kinetics of the oxidation of two tricyclic antidepressants (TCA) namely, imipramine (IMP) and clomipramine (CLM) with sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in HClO4 medium was studied at 300 K. The two reactions followed identical kinetics with a first-order dependence of rate on CATo and fractional order dependence on TCAo. The reaction is catalyzed by H+ ions with a fractional order dependence. The reaction was studied at different temperatures and activation parameters were evaluated. The reaction constants involved in the mechanism were computed. The solvent isotope effect was studied using D2O. Addition of p-toluenesulfonamide retards the reaction rate. The rate increased with decreasing dielectric constant of the medium. Variation of ionic strength of the medium and addition of halide ions (Cl- or Br-) showed no effect on the rate. The stoichiometry of the reaction was found to be 1:1 and the oxidation products were identified as imipramine-5-N-oxide and clomipramine-5-N-oxide. The rate of oxidation of IMP is faster than CLM. The observed results have been explained in terms of a mechanism and a relevant rate law has been deduced. © 2013 Sukhdev and Puttaswamy; licensee Springer
Hands-on guide to clinical pharmacology / Christopher Tofield, Alexander Milson, Sukhdev Chatu.
No full textChatu's name appears first on the earlier edition.Includes index.viii, 200 pages
Oxidation of mephenesin and guaifenesin with chloramine-B in hydrochloric acid medium: Design of kinetic model
No full text339-345Kinetics of oxidation of mephenesin and guaifenesin by sodium N-chlorobenzenesulfonamide (CAB) have been investigated in HCl medium at 303 K. The oxidation behaviour is similar for both the substrates. The rate shows a first order dependence on both [CAB]₀ and [HCl], and is fractional in [substrate]₀. The orders individually in [H⁺] and [Cl⁻] are fractional. The variation of ionic strength and addition of the reduction product, benzenesulfonamide, has no significant effect on the reaction rate. The solvent isotope effect has been studied using D₂O, and the oxidation products have been identified. Composite activation parameters for the reaction have been determined from Arrhenius plots. Michaelis-Menten type of kinetics is observed and activation parameters for the rate limiting steps have also been computed. The proposed mechanism assumes the simultaneous catalysis by H⁺ and Cl⁻ ions. The reaction is found to be moderately faster in guaifenesin in comparison with mephenesin, which may be attributed to the involvement of methoxy and methyl groups of the substrate. The observed results have been explained by a plausible mechanism and the related rate law has been proposed
Oxidative Decolorisation of Eriochrome Black T with Chloramine-T: Kinetic, Mechanistic, and Spectrophotometric Approaches
No full textThe kinetics and mechanism of oxidative decolorisation of Eriochrome Black T (EBT) with sodium N-chloro-p-toluenesulfonamide or Chloramine-T (CAT), catalysed by osmium tetroxide [Os(VIII)] in alkaline medium and uncatalysed in acid medium, have been spectrophotometrically investigated at 303 K. The reaction exhibited a first-order dependence of rate on [CAT]0 and [EBT]0 in both media, and also with respect to [H+]. The order with respect to [OH-] and [Os(VIII)] was fractional. Activation parameters were deduced. It was observed that the uncatalysed decolorisation reaction was ca. eightfold faster in acid medium in comparison with alkaline medium, while the Os(VIII)-catalysed reaction was ca. sevenfold faster than the uncatalysed reaction. Mechanisms and rate laws were determined. The chemical oxygen demand of Eriochrome Black T dye was also determined. Importantly, the developed oxidative decolorisation method is simple, efficient, inexpensive, requires less time, and is environmentally benign. Hence, it can be adapted for treating Eriochrome Black T present in industrial and laboratory wastewater
Oxidative decolorization of methyl red dye with chloramine-T ─ Kinetic and mechanistic chemistry
No full text416-422<span style="font-size:9.0pt;mso-bidi-font-size:
12.0pt" lang="EN-GB">A simple and expeditious oxidative decolorization technique has been
developed for the removal of Methyl Red dye (MR; C.I. Acid Red 2) present in
the wastewater. The kinetic and mechanistic aspects of the present redox system
have also been investigated. Kinetics and oxidative decolorization of MR dye
with sodium N-chloro-p-toluenesulfonamide
or chloramine-T (CAT) in HClO4 medium at 303 K has been investigated
spectrophotometrically at λmax 524 nm. The reaction shows a
first-order dependence of rate each on [CAT]o and [MR]o.
The reaction is catalyzed by [HClO4] and the order with respect to
[H+] is found to be fractional (0.75). Activation parameters have
been evaluated. The oxidation products of MR dye are identified as N-(4-dimethylamino-phenyl)-hydroxylamine
and 4-nitroso-benzoic acid by GC-MS analysis.
The observed results have been explained by a plausible mechanism and the
related rate law is deduced. Further, the present redox system can be adopted
for treating MR dye present in industrial effluents with suitable modifications
to reduce the toxicity caused by MR dye.
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Oxidative cleavage of β-lactam ring of cephalosporins with chloramine T in alkaline medium: a kinetic, mechanistic, and reactivity study
No full textCephalosporins are β-lactam antibiotics, and the important drugs of this group are cephalexin, cefadroxil and cephradine. In the present research, the kinetics and mechanism of oxidn. of cephalexin (CEX), cefadroxil (CFL), and cephradine (CPD) with chloramine-T (CAT) in alk. medium were investigated at 301 K. All the three oxidn. reactions follow identical kinetics with a first-order dependence each on [CAT]o and [substrate]o. The reaction is catalyzed by hydroxide ions, and the order is found to be fractional. The dielec. effect is neg. Proton inventory studies in H2O-D2O mixts. with CEX as a probe have been made. Activation parameters and reaction consts. have been evaluated. Oxidn. products were identified by mass spectral anal. An isokinetic relation was obsd. with β = 378 K, indicating that enthalpy factors control the rate. The rate increases in the following order: CPD > CFL > CEX. The proposed mechanism and the derived rate law are consistent with the obsd. kinetics
The Rediscovery of Yakṣa and the Problem of Attribution
No full textThe Nighaṇṭu–Nirukta occupies a singular position in the early intellectual history of South Asia. As the oldest surviving work of linguistic analysis and conceptual reflection, it stands at the threshold between the ritual-poetic world of the Vedic hymns and the emergence of systematic philosophical reasoning. Yet the identity of its author—Yakṣa—has remained obscured for almost two millennia by a long-standing error of attribution that conflated him with the later scholastic figure Yāska. The recovery of Yakṣa’s authorship is therefore not a philological nicety but an interpretive necessity: without him, the conceptual foundations of early Indian dialectics, hermeneutics, and naturalistic philosophy remain misunderstood. The central argument of this research is that Yakṣa must be restored as the true author of the Nirukta, dated securely between 625–525 BCE, and distinguished sharply from the later grammatical tradition that retroactively absorbed his work. This reattribution clarifies the conceptual originality of the Nirukta, situates it in its proper intellectual horizon, and reveals Yakṣa as the earliest known philosopher of language whose method laid the foundations for later dialectical thought across India and the world
