{"title":"Micellar Effects on the Chromium(VI) Oxidation of d (+)-Xylose","authors":"Kabir-ud-din, A. Morshed, Z. Khan","doi":"10.1080/1028662021000003865","DOIUrl":"https://doi.org/10.1080/1028662021000003865","url":null,"abstract":"Chromic acid oxidation of d (+)-xylose in water and in presence of surfactants has an induction period followed by autoacceleration. The kinetics and mechanism of the induction period have been studied spectrophotometrically in both media. Due to precipitate formation, the effect of cetyltrimethylammonium bromide (CTAB, cationic) cannot be studied whereas the oxidation rate increased with increase in sodium dodecyl sulphate (SDS, an-ionic) and octylphenoxypolyethoxy ethanol (TX-100, nonionic) concentration. Reaction is routed through the same mechanism as shown by the kinetic study in the absence and presence of surfactants. Micellar catalysis has been traced to partitioning of the chromic acid species and xylose between the aqueous and micellar pseudo-phases. Rate enhancement in SDS micelles is decreased by ammonium, lithium and sodium ions. Micellar binding/association constants and activation parameters were evaluated and discussed. A mechanism consistent with the results is proposed.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"3 1","pages":"255-266"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59826918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kinetics and Mechanism of Oxidation of Bromate by Diperiodatonickelate(IV) in Aqueous Alkaline Medium--A Simple Method for Formation of Perbromate","authors":"D. Bilehal, Raviraj M. Kulkarni, S. Nandibewoor","doi":"10.1080/1028662021000020244","DOIUrl":"https://doi.org/10.1080/1028662021000020244","url":null,"abstract":"The kinetics of oxidation of bromate by diperiodatonickelate(IV) (DPN) in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between DPN and bromate in alkaline medium exhibits 1:1 stoichiometry (DPN:bromate). The reaction shows first order dependence on [DPN] and zero order dependence in [bromate] and less than unit order dependence in alkali concentrations. Periodate has a retarding effect on the rate of reaction. Reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Initial addition of reaction products did not affect the rate significantly. A mechanism involving the monoperiodatonickelate(IV) (MPN) as the reactive species of the oxidant has been proposed. The reaction constants involved in the mechanism are evaluated. The activation parameters were computed with respect to the slow step of the mechanism.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"4 1","pages":"103-109"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/1028662021000020244","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59826926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Jackson, Leigh J. McJames, P. Newitt, Kerrina Wells
{"title":"Probing Memory Effects in Octahedral Substitution Reactions: New Handles on Rearrangement Processes","authors":"W. Jackson, Leigh J. McJames, P. Newitt, Kerrina Wells","doi":"10.1080/1028662021000062554","DOIUrl":"https://doi.org/10.1080/1028662021000062554","url":null,"abstract":"The rates and steric course for the Me 2 SO substitution reactions for cis - and trans -[Co(en) 2 (OSMe 2 )(N 3 )] 2+ in solvent Me 2 SO have been investigated by 1 H NMR and Vis./UV spectroscopy. Isomerisation, racemisation, solvent exchange and NH scrambling experiments for selectively-deuterated complexes are reported which provide a wider picture on the octahedral substitution process and the nature of the intermediates than previously possible. The results show that the traditional accounts appearing in standard texts are in need of revamping.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"26 1","pages":"141-157"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59827368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Saha, M. Ali, S. Gangopadhyay, Nizamuddin Shaikh, P. Banerjee
{"title":"Electron Transfer Reactions Between Peroxodisulfate-and Iron(II) and Nickel(II)-oxime-imine Complexes--a Kinetic Study","authors":"B. Saha, M. Ali, S. Gangopadhyay, Nizamuddin Shaikh, P. Banerjee","doi":"10.1080/10286620210353","DOIUrl":"https://doi.org/10.1080/10286620210353","url":null,"abstract":"The kinetics of the oxidation of complexes, [Fe(H 2 L) 2+ and [Ni(HL')] 2+ (H 2 L u = u 3,14-dimethyl-4,7,10,13-tetraazadeca-3,13-diene-2,5-dione-dioxime, (I)) and HL'=15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-ene-2-one-oxime, (II)) by peroxodisulfate ion was studied spectrophotometrically under pseudo-first-order conditions keeping the complexes as minor components, within the pH range 3.0-7.93 at I =0.20 u mol u dm m 3 (NaClO 4 ) for the former and I =0.25 u mol u dm m 3 for the latter complex at 303 u K. At a particular pH, plots of k obs vs. [S 2 O 8 2 m ] yield ascending curves with decreasing slope values for both the reactions, and the general rate law: d/d t [complex]=2 kQ [S 2 O 8 2 m ]/(1+ Q [S 2 O 8 2 m ]) is followed. A pre-equilibrium ion-pair formation between the reactants prior to electron transfer is proposed. A plot of m [log( k 12 / W 12 ) m 1/2 u log u k 22 ] vs. 1/2 u log( K 12 f 12 ) for such reactions yields a straight line with slope m (0.73 - 0.10) which deviates significantl...","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"3 1","pages":"173-180"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59827662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kinetic and Mechanistic Study of Oxidation of Sulfamethoxazole by Alkaline Permanganate","authors":"Raviraj M. Kulkarni, D. Bilehal, S. Nandibewoor","doi":"10.1080/10286620290034728","DOIUrl":"https://doi.org/10.1080/10286620290034728","url":null,"abstract":"The kinetics of the oxidation of sulfamethoxazole (SMZ) by permanganate in aqueous alkaline medium at constant ionic strength of 0.41 mol dm m 3 was studied spectrophotometrically. The reaction is of first order in [permanganate ion] and has apparent less than unit order in both [SMZ] and [alkali]. Addition of products have no significant effect on the reaction rate. However, increasing ionic strength and decreasing dielectric constant of the medium increase the rate. The oxidation in alkaline medium has been shown to proceed via an alkali-permanganate species, which forms a complex with SMZ. The latter decomposes slowly, followed by a fast reaction between a free radical of SMZ and another molecule of permanganate to give the products. The reaction constants involved in the mechanism were evaluated and there is a good agreement between observed rate constants and the calculated rate constants. The activation parameters were computed with respect to the slow step of the proposed mechanism.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"3 1","pages":"239-247"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/10286620290034728","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59827781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Catalytic Effect of Polyoxyethylene t -octylphenol (Triton X-100) Surfactant on the Oxidation of EDTA by Chromic Acid","authors":"Kabir-ud-din, M. Akram, Z. Khan","doi":"10.1080/1028662021000062572","DOIUrl":"https://doi.org/10.1080/1028662021000062572","url":null,"abstract":"The effect of nonionic Triton X-100 (TX-100) micelles on the pseudo-first order rate constants ( k ) for the oxidation of EDTA by chromic acid has been studied at different perchloric acid concentrations. The micellar-mediated reaction was independent of chromic acid concentration whereas first- and complex-order dependence on [EDTA] and [HClO 4 ], respectively, were observed. Increase in the total concentration of TX-100 from 0.0 to 60.0 2 10 m 3 mol dm m 3 caused the k to increase by nearly 4-fold at constant temperature and [HClO 4 ]. The observed catalytic effect has been explained on the basis of pseudo-phase kinetic and Piszkiewicz models. The higher rate of EDTA oxidation in the micellar pseudo-phase is attributed to association of the reactants with the nonionic micellar head groups through hydrogen bonding. A mechanism is proposed in accordance with the experimental results obtained.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"4 1","pages":"187-196"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59827893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Kitamura, Kohji Hyodoh, Yoshihiko Nagawo, Y. Sasaki, N. Azuma
{"title":"Kinetic Study of the Acid-catalysed Hydrolysis of Cobalt(III) Carbonato Complexes with Nonlabile Tetrakis(methylamine), Tetrakis(ethylamine), Fac ( N )-(ethylenediamine)(glycinato), Mer ( N )-(ethylenediamine) (glycinato) or Bis(1,3-propanediamine) Ligands","authors":"Y. Kitamura, Kohji Hyodoh, Yoshihiko Nagawo, Y. Sasaki, N. Azuma","doi":"10.1080/1028662021000062608","DOIUrl":"https://doi.org/10.1080/1028662021000062608","url":null,"abstract":"Acid-catalysed hydrolysis kinetics were studied for 14 cobalt(III) carbonato complexes involving the title five at oxonium ion concentration of 0.01-1.0 M, ionic strength of 2.0 (NaClO 4 ) and 15-45°C (M=mol dm m 3 ). Preprotonation constant, about 1 M m 1 , was estimated from a non-linear acidity dependence of an experimental rate constant for the ring-opening of the didentate hydrogencarbonato intermediate. Acidity constant, 0.003-0.7 M, and basicity constant, 0.1-0.9 M m 1 , of the ring-opened aquahydrogencarbonato intermediate were estimated from an acidity dependence of an experimental rate constant for the decarboxylation. Concerning the widely ranging ring-opening rate constants (0.05-126 s m 1 at 25°C), we demonstrate labilizing effects of a reduced charge and of small tetrakis(amine) ligand, correlating with a high activation entropy, as well as of the trans five-membered chelate correlating with a low activation energy. The charge effect may be understood by the solvational change during the dis...","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"4 1","pages":"221-232"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59827643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Boukhalfa, F. Thomas, G. Serratrice, C. Béguin
{"title":"Kinetics of Aqueous Acid Hydrolysis of Iron(III) 5-Substituted-8-Hydroxyquinoline Complexes: Mechanistic Implications","authors":"H. Boukhalfa, F. Thomas, G. Serratrice, C. Béguin","doi":"10.1080/10286620210351","DOIUrl":"https://doi.org/10.1080/10286620210351","url":null,"abstract":"Synopsis : The acid-driven stepwise dissociation kinetics of tris (8-hydroxy-5-sulfonated-quinoline) iron(III) complex and two other 8-hydroxyquinoline derivatives are reported and compared to literature data. The main finding is that, in the rate determining step, the iron-oxygen bond cleavage (oxygen of the hydroxyl group of the ligand) occurs in the transition state with proton transfer to the oxygen of the incipient free ligand oxine in relation with its structure (C-OH). Comparison with literature data shows that for the hydroxamate ligand with its coordinating oxygen involved in C=O, there is no proton transfer during the iron-oxygen bond cleavage in the transition state.The acid hydrolysis reaction rate constants of the mono -oxine iron(III) complexes, with oxine=8-hydroxyquinoline, sulfoxine=8-hydroxy-5-sulfonated-quinoline and fluoro-oxine=5-fluoro-8-hydroxyquinoline, were measured in aqueous solution, 2.0 u M in NaClO 4 at 25°C. Under these conditions, for iron(III)-sulfoxine, the dissociation r...","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"3 1","pages":"153-172"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59828060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Kitamura, Kohji Hyodoh, Masayuki Hayashi, Yoshihiko Nagawo, Y. Sasaki, A. Shibata
{"title":"Effect of Nonlabile Quadridentate Ligand on the Acid-catalysed Hydrolysis Velocity of Cobalt(III) Carbonato Chelates","authors":"Y. Kitamura, Kohji Hyodoh, Masayuki Hayashi, Yoshihiko Nagawo, Y. Sasaki, A. Shibata","doi":"10.1080/713931736","DOIUrl":"https://doi.org/10.1080/713931736","url":null,"abstract":"Acid-catalysed hydrolysis kinetics were studied for 10 cobalt(III) complexes bearing a bidentate carbonato ligand at oxonium ion concentration of 0.02-1.0 u M, ionic strength of 2.0 (NaClO 4 ) and 15-45°C (M=mol u dm m 3 ). Preprotonation constant, about 1 u M m 1 , was estimated from a non-linear acidity dependence of the ring-opening velocity of the bidentate hydrogencarbonato intermediate. Acidity constant, 0.005-0.4 u M, and basicity constant, about 0.4 u M m 1 , of the ring-opened aquahydrogencarbonato intermediate were estimated from an acidity dependence of the decarboxylation velocity. Between analogous complexes, ring-opening is faster; activation parameters of ring-opening are lower; and acidity of an aquahydrogencarbonato intermediate is weaker, when the nonlabile quadridentate forms five-membered chelates on the Co(III) center. We believe that a five-membered chelate, especially trans to the hydrogencarbonato, labilizes the hydrogencarbonato chelate by reinforcing the steric strain and that it...","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"3 1","pages":"197-211"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/713931736","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60390020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kinetics and Mechanism of the Reaction of Copper(II)-tryptophan Complex with Ninhydrin in Aqueous and Micellar Media","authors":"Kabir-ud-din, M. Akram, Z. Khan","doi":"10.1080/1028662021000020235","DOIUrl":"https://doi.org/10.1080/1028662021000020235","url":null,"abstract":"Kinetics of the title reaction has been investigated spectrophotometrically in aqueous solution as well as in the presence of cetyltrimethylammonium bromide (CTAB) cationic micelles. The reaction rate is first- and fractional-order with respect to [substrate] and [ninhydrin], respectively, both in the absence and presence of cationic micelles. Whereas SDS addition shows formation of a different product, the reaction of copper(II)-tryptophan complex with ninhydrin is catalyzed by CTAB: the maximum rate enhancement being ca . 5-fold. The data are interpreted in terms of the pseudo-phase model (assuming the association/incorporation of both the reactants at the micellar surface). The binding constants of copper(II)-tryptophan ( K S ) and ninhydrin ( K N ) with CTAB micelles have been calculated. The presence of inorganic salts (NaCl, NaBr, NaNO 3 and Na 2 SO 4 ) leads to a decrease in the rate followed by an increase and it is found that tightly bound/incorporated anions are most effective.","PeriodicalId":54977,"journal":{"name":"Inorganic Reaction Mechanisms","volume":"4 1","pages":"77-87"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59826922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}