bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of primary and secondary butoxy radicals in oxygen at atmospheric pressure
Authors: Heiss A. , De Maleissye J. Tardieu , Viossat V. , Sahetchian K. A. , Pitt I. G. 
Published: January 2005

AbstractThe reaction pathways of n‐butoxy and s‐butoxy radicals have been investigated by TLC and HPLC analysis of end products, particularly peroxides and carbonyl compounds. The butoxy radicals were produced by the pyrolysis of very low concentrations of the corresponding dibutylperoxide in an atmosphere of oxygen and nitrogen, at atmospheric pressure. The decomposition reaction (3) s‐BuO → C2H5 + CH3CHO and the reaction (2) s‐BuO + O2 → HO2 + CH3COC2H5 have been studied, and the ratio k3/k2 has been determined in the temperature range 363–503 K by kinetic modeling of the formation of the observed acetaldehyde and methylethylketone. The rate constant k3 obtained was:

A good agreement was observed between experimental data and RRKM theory. The implications of the results for atmospheric chemistry and combustion are discussed. At room temperature, the reaction with O2, yielding HO2 radicals and methylethylketone is, by far, the main channel for s‐BuO radicals. In the field of low temperature combustion, the decomposition of s‐BuO radicals producing C2H5 and CH3CHO is the main pathway; the route s‐BuO + O2 decreases tremendously in importance as the temperature is raised above 393 K.
Kinetics of the oxidation of phosphinic, phenylphosphinic, and phosphorous acids by N‐bromoacetamide
Authors: Moondra Anu , Mathur Abha , Banerji Kalyan K. 
Published: January 2005

AbstractThe oxidation of phosphinic, phenylphosphinic, and phosphorous acids by N‐bromoacetamide (NBA) in acid solution, results in the formation of corresponding higher oxyacids of phosphorus. The reaction is first order with respect to NBA, second order in the oxyacid and inverse first in hydrogen ions. The oxidation of deuteriated phosphorus oxyacids showed the presence of a substantial primary kinetic isotope effect. The reaction failed to induce polymerization of acrylonitrile. Added acetamide has no effect on the reaction rate. It has been shown that the ‘inactive’ tautomer of the phosphorus oxyacids, RHP(O)OH, participates in the oxidation process. A rate‐determining step involving transfer of a hydride ion from the PH bond to the oxidant has been proposed.
Reactivity of tert‐butoxyl radicals towards substituted indole derivatives
Authors: Encinas M. V. , Lissi E. A. , Majmud C. , Olea A. F. 
Published: January 2005

AbstractTert‐butoxyl radicals react with indole and methyl substituted derivatives by hydrogen abstraction. For those compounds which are unsubstituted at the N‐atom, hydrogen abstraction takes place almost exclusively at the NH bond. The reactivity of these compounds correlates with their donor electron capacity, pointing to significant contribution of charge transfer to the transition state stability. Substitution at the N atom considerably decreases the reactivity.
Kinetics and mechanism of base‐catalyzed hydrolysis of Cu(II)‐malonamide complex
Authors: Niaz M. Arif , Khan A. Aziz 
Published: January 2005

AbstractA kinetic study of base‐catalyzed hydrolysis of Cu(II)‐malonamide complex has been performed in sodium hydroxide solution (0.2–1.25M). The reaction follows an irreversible first‐order consecutive path:

The variation of k1obs and k2obs with alkali concentration was found to be in good agreement with the equations:

where B1, B2, C1, and C2 are empirical constants. The mechanism of hydrolysis of Cu(II)‐malonamide complex has been discussed and rate equations have been derived. Retardation of rate of hydrolysis due to coordination of Cu(II) with malonamide, in alkaline medium, has been explained in terms of comparatively slow breakdown of the CN bond of the tetrahedral intermediate (TI). Thermodynamic parameters have also been evaluated.
Studies of unusual oxidation states of transition metals III‐kinetics and mechanism of oxidation of triethanolamine by diperiodatoargenate(III) ion in aqueous alkaline medium
Authors: Shi Tie‐Sheng , He Jin‐Tian , Ding Tian‐Hui , Wang An‐Zhou 
Published: January 2005

AbstractThe kinetics of oxidation of triethanolamine (TEA) by diperiodatoargenate(III) anion, [Ag(HIO6)2]5−, has been studied in aqueous alkaline medium by conventional spectrophotometry. The reaction is pseudo‐first‐order in [Ag(III)] disappearance with kobs = (k1 + k2[OH−]) K1K2[TEA]/{[H2IO63−]e + K1 + K1K2[TEA]}, where k1 = 8.05 × 10−3 S−1, k2 = 0.46 M−1 S−1, K1 = 6.15 × 10−4 M, and K2 = 537 M−1 at 25°C, and μ = 0.30 M. Based on the inference that an inner‐sphere complex is formed by indirect replacement of a ligand of [Ag(HIO6)2]5− by a TEA molecule, a reaction mechanism has been proposed. The complex undergoes redox by two modes, both internal and one hydroxide ion assisted.
Kinetics and mechanism of intramolecular general base‐catalyzed alkanolysis of phenyl salicylate in the presence of anionic micelles
Authors: Khan M. Niyaz 
Published: January 2005

AbstractThe alkanolysis of ionized phenyl salicylate, PS−, has been studied in the presence and absence of micelles of sodium dodecyl sulphate, SDS, at 0.05 M NaOH, 30 or 32°C and within the alkanol, ROH, (ROH = HOCH2CH2OH and CH3OH) contents of 15–74 or 92%, v/v. The alkanolysis of PS− involves intramolecular general base catalysis. At a constant concentration of SDS, [SDS]T, the observed pseudo first‐order rate constants, kobs, for the reactions of ROH with PS− obtained at different concentration of ROH, [ROH]T, obey the relationship: kobs = k[ROH]T/(1 + KA[ROH]T) where k is the apparent second‐order rate constant and KA is the association constant for dimerization of ROH molecules. Both k and KA decrease with increase in [SDS]T. At a constant [ROH]T, the rate constants, kobs, show a decrease of nearly 2‐fold with increase in [SDS]T from 0.0–0.3M. These results are explained in terms of pseudo‐phase model of micelle. The rate constants for alkanolysis of PS− in micellar pseudophase are insignificant compared with the corresponding rate constants in aqueous‐alkanol pseudophase. This is attributed largely to considerably low value of [ROH] in the specific micellar environment where micellar bound PS− molecules exist. The increase in [ROH]T decrease the value of the binding constant of PS− with SDS micelle. The effects of anionic micelles on the rates of alkanolysis of PS− are explained in terms of the porous cluster micellar structure.
Kinetics of ring‐opening radical polymerization of vinyloxiranes
Authors: Ito Osamu , Ishizuka Tatsushi , Iino Masashi , Matsuda Minoru , Endo Takeshi , Yokozawa Tsutomu 
Published: January 2005

AbstractRing‐opening radical polymerization has been followed by the flash photolysis method. As an initiator radical, the arylthiyl radical (ArS˙) was used; the addition reaction rate constants of ArS˙ to vinyl monomer containing epoxy‐ring such as vinyloxiranes have been determined at first. The rate constant of ring opening reaction of the adduct radical changing to ArSCH2CH  CROCH2˙ were determined in the form of the relative values, which were converted to the absolute values. The ring‐opening reaction rate constants were ca. 106 s−1, which indicates that the ring‐opening rates are faster than usual radical propagation rates. The rate constants for vinyl monomer with 5‐member ring (1,4‐epoxy‐1,4‐dihydronaphthalene) were similarly evaluated.
Gas‐phase oxidation of 1,4‐dioxane
Authors: Battin F. , Scacchi G. , Baronnet F. 
Published: January 2005

AbstractAn experimental investigation in a conventional static apparatus of the oxidation of equimolecular mixtures 1,4‐dioxane‐O2 has shown that 1,4‐dioxane reacts with oxygen more readily than most hydrocarbons. Cool flames and ignitions were observed above 200°C in a pressure range up to 300 torr.The products of the slow reaction and cool flame were analyzed by gas chromatography and GC‐MS; the slow reaction gives only CO, CO2, H2CO, H2, C2H4, and H2O.A radical chain mechanism is suggested and discussed by using an evaluation of the rate constants of the possible elementary steps by the methods of thermochemical kinetics.
Oscillatory kinetics and mechanism of the chromate catalyzed decomposition of hydrogen peroxide
Authors: Beck Mihály T. , Nagy István P. , Székely Gabriella 
Published: January 2005

AbstractOscillatory change of pH occurs during the chromate‐catalyzed decomposition of hydrogen peroxide in a weakly acidic medium at elevated temperature and at high initial concentration of hydrogen peroxide. In a closed system, there are only two or three periods, but sustained oscillation occurs in a CSTR. In a CSTR bistability is also found. In closed systems the temperature exhibits a great maximum (up to 15°C increase), in a CSTR sustained oscillation occurs at a constant stationary temperature.
Rate constants for reactions of perfluorobutylperoxyl radical with alkenes
Authors: Nahor G. S. , Neta P. 
Published: January 2005

AbstractPerfluorobutylperoxyl radicals were produced by radiolytic reduction of perfluorobutyl iodide in aerated methanol solutions. Rate constants for the reactions of this peroxyl radical with various organic compounds were determined by kinetic spectrophotometric pulse radiolysis. The rate constants for alkanes and alkenes were determined by competition kinetics using chlorpromazine as a reference. The results indicate that hydrogen abstraction from aliphatic compounds takes place with a rate constant that is too slow to measure in our system (<105 M−1 s−1), and that abstraction of allylic and doubly allylic hydrogens is slow compared with addition. Addition to alkenes takes place with rate constants of the order of k = 106 − 108 M−1 s−1. Good correlation was obtained between log k and the Taft substituent constants σ* for the various substituents on the double bond. Perfluorobutylperoxyl radical is found to be more reactive than trichloromethylperoxyl and other peroxyl radicals.
Micellar catalysis in the oxidation of acetophenones by Ce(IV)
Authors: Panigrahi Ganesh P. , Sahu Bimal P. 
Published: January 2005

AbstractRate of oxidation of acetophenones by Ce(IV) in aqueous acetic acid 80:20 (v/v) either slows down or remains constant over a range of cetyltrimethyl ammonium bromide (CTAB) concentration exceeding the cmc value. The rate is then found to increase sharply as the surfactant concentration increases with no sign of reaching a maximum or constant value. From Fluorescence quenching, binding constant for p‐nitro acetophenone has been evaluated. The rate data have been rationalized on the basis of a reaction between the acetophenones situated on the micelle surface and active Ce(IV) species in the bulk aqueous phase.
The thermal reaction of HNCO at moderate temperatures
Authors: He Y. , Liu Xiaoping , Lin M. C. , Melius C. F. 
Published: January 2005

AbstractThe thermal reaction of HNCO has been studied in a static cell at temperatures between 873 and 1220 K and a constant pressure of 800 torr under highly diluted conditions. The reaction was measurable above 1000 K by FTIR spectrometry. The products detected include CO, CO2, HCN, NH3, and the unreacted HNCO. In this moderate temperature regime, the rates of product formation and HNCO decay cannot be accounted for by a previously established high‐temperature mechanism, assuming HNCO → NH + CO (1) as the initiation process. Instead, a new bimolecular reaction, 2HNCO → CO2 + HNCNH (2), has been invoked to interpret the disappearance of HNCO as well as the formation of various products, most importantly CO2.The concentration profiles of all measured species can be quantitatively modeled, throughout the temperature range analyzed, by varying k2 using a modified mechanism. The kinetically modeled values of k2 can be effectively represented by

This result agrees closely with that computed with the conventional transition‐state theory using the TST parameters predicted by the BAC‐MP4 method:

The bimolecular reaction takes place via a stable 4‐membered ring intermediate which is isoelectronic with diketene; viz. magnified image
Kinetics studies of reactions of OH radicals with four haloethanes part I. Experiment and BEBO calculation
Authors: Xing Shi‐Ben , Shi Su‐Hao , Qiu Lian‐Xiong 
Published: January 2005

AbstractThe rate constants for reactions of OH with ClCH2CH2Cl, Cl2CHCHCl2, BrCH2CH2Br, CH3CH2Br have been measured by using a discharge flow‐resonance fluorescence (DF‐RF) technique over the temperature range 293–418 K. The rate constants as a function of temperature were fitted to the Arrhenius expression as follows: (k's units are 10−12 cm3 molecule−1 s−1, and Ea's units are cal/mol)

The experimental data have been compared with theoretical calculations of the semi‐empirical BEBO‐transition state method. Life‐times of the four haloethanes in the troposphere have been estimated.
Kinetics and mechanism of the iodine oxidation of hydroxylamine
Authors: Wang Robert T. , Rábai Gyula , Kustin Kenneth 
Published: January 2005

AbstractStudies of the stoichiometry and kinetics of the reaction between hydroxylamine and iodine, previously studied in media below pH 3, have been extended to pH 5.5. The stoichiometry over the pH range 3.4–5.5 is 2NH2OH + 2I2 = N2O + 4I− + H2O + 4H+. Since the reaction is first‐order in [I2] + [I3−], the specific rate law, k0, is k0 = (k1 + k2/[H+]) {[NH3OH+]0/(1 + Kp[H+])} {1/(1 + KI[I−])}, where [NH3OH+]0 is total initial hydroxylamine concentration, and k1, k2, Kp, and KI are (6.5 ± 0.6) × 105 M−1 s−1, (5.0 ± 0.5) s−1, 1 × 106 M−1, and 725 M−1, respectively. A mechanism taking into account unprotonated hydroxylamine (NH2OH) and molecular iodine (I2) as reactive species, with intermediates NH2OI2−, HNO, NH2O, and I2−, is proposed.
Microemulsions as a medium in chemical kinetics, II. The I− + S2O8= and crystal Violet + OH− reactions in different surfactant/oil/water microemulsions
Authors: Izquierdo Carmen , Casado Julio , Rodriguez Amalia , Moyá Maria Luisa 
Published: January 2005

AbstractA kinetic study of the reactions I− + S2O8= and CV+ + OH− (CV = 4, 4′, 4″‐tris(dimethylamino)triphenylmethyl chloride or crystal violet) in different water in oil microemulsions is reported. The dependence of the rate constants on the nature of the surfactant as well as on the molar ratio R = [H2O]/[Surfactant] has been investigated. The results are interpreted on the basis of the electrostatic interactions between the reactants and the surfactant polar heads and considering the water properties inside the aqueous core of the droplets.
Evidences on the intermediacy of furoxan in the flash vacuum thermolysis of some 4‐Nitroisoxazoles
Authors: Wunderlin Daniel A. , Davico Gustavo E. , Perez Jorge D. 
Published: January 2005

AbstractThe kinetic measurements in the Flash Vacuum Thermolysis (FVT) of 3,5‐Dimethyl‐ and 5‐Methyl‐ 4‐Nitroisoxazole confirm the already suggested intermediacy of the isomer 2H‐Azirine in the formation of 1‐ Cyano‐1‐Nitroacetone. Moreover, theoretical calculations of the stabilization energy (Es), at the transition state, using second order perturbation suggest that this azirine is formed through the isomer furoxan rather than directly from the starting isoxazole.
Atmospheric photooxidation of isoprene part I: The hydroxyl radical and ground state atomic oxygen reactions
Authors: Paulson Suzanne E. , Flagan Richard C. , Seinfeld John H. 
Published: January 2005

AbstractThe OH reaction with isoprene is studied. Methyl nitrite photolysis experiments were carried out in an outdoor smog chamber in an attempt to identify as completely as possible OH‐isoprene product distribution. Emphasis was placed on identification and quantification of oxygenated products. A Tenax‐based cryo‐trap thermal desorber used to trap, concentrate, and dry chamber samples for identification on a GC/MS is described. Analysis of the products revealed that O(3P) can form in reaction systems designed to study OH reactions that include high concentrations of NO, and consequently NO2, hence, this reaction is also examined. The yields of methacrolein and methyl vinyl ketone are determined as 25 ± 3 and 35.5 ± 4%, respectively, with an additional 4 ± 2% as 3‐methyl furan, totaling 65 ± 4%. These results, combined with those of previous studies allow 80% of isoprene's products to be explicitly identified, and the general structure of the remaining products to be ascertained. The O(3P) reaction produces 84 ± 8% epoxides, and 8 ± 3% species which result in production of HO2, and subsequently, OH. A heretofore unidentified product of the O(3P) reaction, 2‐methyl 2‐butenal, is identified. The rate constant of the NO2‐isoprene reaction is measured.
Atmospheric photooxidation of isoprene part II: The ozone‐isoprene reaction
Authors: Paulson Suzanne E. , Flagan Richard C. , Seinfeld John H. 
Published: January 2005

AbstractA series of experiments have been performed to study the ozone‐isoprene reaction in a smog chamber by adding externally produced O3 to the hydrocarbon in the dark. A chemical tracer, methyl cyclohexane, was added to probe the OH formation in the system. O(3P) formation was also examined using the known distribution of products that are unique to the O(3P)‐isoprene reaction (part I). The results provide clear evidence that both OH and O(3P) are produced by the O3‐isoprene reaction directly in large quantities; about 0.68 ± 0.15 and 0.45 ± 0.20 per O3‐isoprene reaction, respectively. These additional radicals severely complicate the analysis of the O3 reaction, hence, computer kinetic modeling was necessary to ascertain the products of the O3 reaction itself, corrected for OH and O(3P) reactions. The product distribution, which differs dramatically from that published previously, is: 67 ± 9% methacrolein, 26 ± 6% methyl vinyl ketone, and 7 ± 3% propene, accounting for 100 ± 10% of the reacted isoprene. Applicability of these results to the gas‐phase O3 reaction with other unsaturated hydrocarbons is briefly discussed.
Kinetics and mechanism of the atmospheric oxidation of Ethyl tertiary butyl ether
Authors: Smith D. F. , Kleindienst T. E. , Hudgens E. E. , McIver C. D. , Bufalini J. J. 
Published: January 2005

AbstractEthyl tertiary butyl ether (ETBE) is being proposed as an additive for use in reformulated gasolines. In this study, experiments were performed to examine the kinetics and mechanism of the atmospheric removal of ETBE. The kinetics of the reaction of ETBE with OH radicals were examined by using a relative rate technique with the photolysis of methyl nitrite to generate OH radicals. With n‐hexane as the reference compound, a value of (9.73 ± 0.33) × 10−12 cm3 molecule−1 s−1 was obtained for the rate constant. The OH rate constant for t‐butyl acetate, a product of the oxidation of ETBE, was (4.4 ± 0.4) × 10−13 cm3 molecule−1 s−1 at 298 K.The primary products and molar yields for the OH reaction with ETBE in the presence of NOx were t‐butyl formate (0.64 ± 0.03), t‐butyl acetate (0.13 ± 0.01), ethyl acetate (0.043 ± 0.003), acetaldehyde (0.16 ± 0.01), acetone (0.019 ± 0.002), and formaldehyde (0.53 ± 0.04). Under the described reaction conditions, the formation of t‐butyl nitrite was also observed. From these molar yields, approximately 98% of the reacted ETBE could be accounted for by paths leading to these products. Chemical mechanisms to explain the formation of these products are presented.
The chain mechanism of ozone destruction by CFCl3 in the 214 nm photolysis of its mixtures with oxygen
Authors: Horowitz A. , Schuster G. , Moortgat G. K. 
Published: January 2005

AbstractThe effect of CFCl3 (0.025–0.200 mbar) addition on the formation of ozone in 214 nm photolysis of oxygen (800–2000 mbar) was investigated. Kinetic analysis of the drastic reduction in ozone formation in the presence of CFCl3 shows that it proceeds by a chain mechanism with a chain length of 5.07 ± 0.21(2σ). This chain length is independent of CFCl3 and O2 pressures as well as incident light intensity and the mechanism of the chain reaction is governed by the Cl generating reactions of ClO radicals. A mechanism based only on the self reaction of these radicals: ClO + ClO → Cl2 + O2 (7), Cl + ClO2 (8), and Cl + OClO (9), followed by fast decomposition of ClO2 into Cl and O2, predicts a chain length which is considerably lower than the observed value. Incorporation of the reaction CFCl2O2 + ClO → CFCl2O + ClO2 (11) in the mechanism satisfactorily accounts for the observed chain length. A lower limit of 3 × 10−12 cm3 molecule−1 s−1 for k11 is estimated.
On the reaction of CH with CO studied in high temperature CH4/Ar + CO mixtures
Authors: Markus Michael W. , Roth Paul 
Published: January 2005

AbstractIn this study a ring dye laser spectrometer was employed for in‐situ measurements of CH concentrations in the reaction zone behind shock waves. The time dependent absorption in the Q‐branch of the A2Δ — X2Π band of CH at 431.1311 nm caused by the formation and consumption of CH radicals during the shock induced pyrolysis of a few ppm methane in argon was recorded. The CH concentration could directly be calculated from the measured absorption by applying the Lambert‐Beer law. By adding a few percent CO to the initial mixtures, the CH concentration profiles were significantly perturbed. Both the perturbed and unperturbed CH concentration profiles have been compared with those calculated from reaction kinetic simulations. A reaction mechanism describing the CH concentration history in the CH4/Ar and CH4/CO/Ar systems between 2900 K and 3500 K was developed. By a fitting procedure, a value of k1 = 1.85 × 1011 cm3 mol−1 s−1 was obtained for the most important perturbation reaction CH + CO → C2O + H.
Kinetics of solvolysis of 1‐acetyl‐4‐(1‐ethoxycarbonyl‐1‐cyano) methylene‐1,4‐dihydroquinoline in undried DMSO‐d6· formation of Acetic Anhydride as an intermediate
Authors: Klemm Leroy H. , Lu Jennifer J. , Klemm Richard A. 
Published: January 2005

AbstractThe kinetics of solvolysis of the title compound (QAc) in undried DMSO‐d6 to give 4‐(1‐ethoxycarbonyl‐1‐cyano)methylquinoline (QH) and HOAc at ambient temperature were investigated by 1H nmr spectrometry. With a limited excess of water the solvolysis follows a three‐step process of \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm QAc} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_1} {\rm QH} + {\rm HOAc}, $\end{document} , and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Ac}_{\rm 2} {\rm O} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_3} {\rm 2\,HOAc}, $\end{document} where k2 > k1 and k3 < k1. Addition of pyridine‐d5 to the reaction mixture markedly catalyzes the overall solvolysis, while addition of CF3CO2D to the reaction mixture simplifies the kinetics to pseudo first‐order in [QAc] with k = 4.3 × 10−3 min−1.
Kinetics of a second order reaction involving two intermediate second order reactions
Authors: Klemm Richard A. , Klemm Leroy H. 
Published: January 2005

AbstractWe have studied the kinetics of a reaction in which starting materials A and B react to form the products C and D directly, as well as by way of two additional intermediate reactions. In the first intermediate reaction, A and C react to form D and E, and in the second intermediate reaction, B and E react to form 2C. There are three conservation laws, which effectively reduce the number of variables to two, resulting in nonlinear coupled first order differential equations for [A](t) and [B](t). These equations are readily solved by standard numerical procedures, for various values of the relative reaction rates and starting concentrations. Our results are used to fit experimental data for the case in which A and B are 1‐acetyl‐4‐(1‐ethoxycarbonyl‐1‐cyano)methylene‐1,4‐dihydroquinoline and water, for which the first and third reverse reactions can be neglected.