Thermodynamic properties of the species resulting from the phenyl radical with O2 reaction system

Phenyl radicals are formed in combustion and oxidation systems by abstraction of the phenyl—hydrogen from benzene or aromatics by active radical species and by oxidation and thermal reactions of the benzylic carbon on alkyl‐substituted aromatics. The reaction of phenyl with O₂ leads to chain‐branching reactions and a number of unsaturated oxygenated hydrocarbon intermediates that may need to be included in detailed combustion models. Thermochemical parameters and structures on important species resulting from the phenyl radical + O₂ association and reaction are reported in this study. Enthalpies, Δ_f H, of a series of stable molecules, radicals, and transition state structures are calculated using ab initio (G3MP2B3 and G3) and density functional (DFT, B3LYP/6–311g(d,p) calculations, group additivity (GA), and literature data. The ab initio and density functional calculations are combined with isodesmic reaction analysis, whenever possible, to improve the accuracy of the enthalpy values. Entropies, S, and heat capacities, Cp_f298 (T), are calculated using density functional calculations, group additivity, and literature data. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 583–604, 2008     

ESR Study of Nitroxide Radicals Generated from Triaz-2-en-1-ols

The triazenols 4-R¹? C₆H₄? N?N? N(OH)? R² ( 1 ), oxidized with t-BuO radicals, produced nitroxide radicals R¹? C₆H₄? N(O^?)? N?N(R²) ⁺O^? ( 5 ). The suggested radical structure was confirmed by ¹⁵N-labeling. The reaction of triazenols 1 with PbO₂ proceeded under N₂ elimination, in which case nitroxides R¹? C₆H₄? N(R₂)? O^?( 2 ) were observed as the final radical products. The intermediate R¹? C₆H radicals were identified by spin-trapping.     

Effects of CH3OH‐H2O and CH3OH solvents on rate of reaction of phthalimide with piperidine

Pseudo‐first‐order rate constants (k_obs) for the cleavage of phthalimide in the presence of piperidine (Pip) vary linearly with the total concentration of Pip ([Pip]_T) at a constant content of methanol in mixed aqueous solvents containing 2% v/v acetonitrile. Such linear variation of k_obs against [Pip]_T exists within the methanol content range 10%–∼80% v/v. The change in k_obs with the change in [Pip]_T at 98% v/v CH₃OH in mixed methanol‐acetonitrile solvent shows the relationship: k_obs = k[Pip]_T + k[Pip], where respective k and k represent apparent second‐order and third‐order rate constants for nucleophilic and general base‐catalyzed piperidinolysis of phthalimide. The values of k_obs, obtained within [Pip]_T range 0.02–0.40 M at 0.03 M NaOH and 20 as well as 50% v/v CH₃OH reveal the relationship: k_obs = k₀/(1 + {k_n[Pip]/k_OX[⁻OX]_T}), where k₀ is the pseudo‐first‐order rate constant for hydrolysis of phthalimide, k_n and k_OX represent nucleophilic second‐order rate constants for the reaction of Pip with phthalimide and for the XO⁻‐catalyzed cyclization of N‐piperidinylphthalamide to phthalimide, respectively, and [⁻OX]_T = [NaOH] + [⁻OX_re], where [⁻OX_re] = [⁻OH_re] + [CH₃O_re⁻]. The reversible reactions of Pip with H₂O and CH₃OH produce ⁻OH_re and CH₃O_re⁻ ions. The effects of mixed methanol‐water solvents on the rates of piperidinolysis of PTH reveal a nonlinear decrease in k with the increase in the content of methanol. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 33: 29–40, 2001     

Disproportionation-to-combination ratios for cyclohexyl-h11 and -d11 radicals in the gas phase as determined by the radiolysis of water vapor–cyclohexane mixtures

In the radiolysis of water vapor containing small concentrations of cyclohexane, the principal products which account for about 98% of all end products are found to be hydrogen, cyclohexene, and bicyclohexyl. Cyclohexene and bicyclohexyl yields were determined over a range of temperatures (70–200°C), total pressures (50–2400 torr), and total doses (0.15–2.0 Mrad). The disproportionation–combination ratio k/k for c-C₆H₁₁ radicals could be determined as 0.56 ± 0.01 from the ratio of cyclohexene to bicyclohexyl yield. By using c-C₆D₁₂, the ratio k/k for c-C₆D₁₁ radicals is found to be 0.38 ± 0.01. Comparison of the reactivity pattern of C₆H₁₁ and C₆D₁₁ radicals leads to (k)/(k)/(k/k) = 1.47 ± 0.02. The corresponding values for the reactions of c-C₆H₁₁ with c-C₆D₁₁ were also determined.     

Chemistry of Superoxide Ion as Revealed by the Differential Oxidation of Arylpyruvates

Superoxide ion apparently reacts with acidic substrates via species such as O₂, HO₂, O, HO and H₂O₂. Arylpyruvates give arylacetates and arylaldehydes indicating competing nucleophilic and free radical oxidation. Benzaldehyde is further oxidized by free radical and nucleophilic dioxygen species giving benzoic acid. p-Hydroxybenzaldehyde gives the corresponding benzoic acid which is best accounted for by HO₂, since O and O₂ are without effect. Hydroquinone is also produced presumably by nucleophilic attack of HO. Replacement of the acidic hydrogen atoms by sodium changes the product distribution in accord with these findings.     

The kinetics of the interaction of peroxy radicals. I. The Tertiary Peroxy Radicals

Existing data on the self-reactions of tertiary peroxy radicals RO₂ has been reanalyzed and corrected to deduce Arrhenius parameters for both termination and nontermination paths. For R = t-Butyl, these are logk_t(M^?1sec^?1) = 7.1 - (7.0/θ) and logk_nt(M^?1sec^?1) = 9.4 - (9.0/θ), respectively, different from those recommended by other authors. The higher magnitudes observed for termination processes of tertiary peroxy radicals like those of cumyl and 1,1-diphenylethyl have been discussed in terms of a much greater cage recombination of cumyloxy radicals as contrasted with t-butoxy radicals. It is shown that for benzyl peroxy radicals, the R—O bond dissociation energy is sufficiently low (18–20 kcal) that reversible dissociation into R^˙ + O₂ opens a competing second-order path to fast recombination R^˙ + RO → ROOR. This path is probably not important for cumyl peroxy radicals under usual experimental conditions but can become important for 1,1-diphenyl ethyl peroxy radicals at (O₂) < 10^?3M. At very low RO concentrations (<10^?5M), in the absence of added O₂, an apparent first-order disappearance of RO can occur reflecting the rate determining breaking of the cumyl—O bond followed by the second step above. The thermochemistry of RO is used to show that the reaction of R₂O₄ → 2RO + O₂ must be concerted and cannot proceed via RO which is too unstable and cannot form even from RO^˙ + O₂.     

Oxygenation of Co(II) Complexes with Tripodal Ligands

The kinetics of O₂-uptake of five-coordinated Co²⁺/tren complexes (tren = 2,2′, 2″-tris(2-aminoethyl)amine) have been studied extensively. The kinetics of formation of (tren)Co(O₂, OH)Co(tren)³⁺ exhibits two steps. The rate law of O₂-addition, the first step, was of the form: rate = (k[H⁺] + kK_a)/([H⁺] + K_a) [Co(tren)²⁺][O₂]. Second-order rate constants k = 220 ± 19 M ^?1s^?1 and k = 1.8 ± .035 · 10³M ^?1s^?1 agreed well from O₂-uptake and (stopped-flow) spectrophotometric measurements. The protonation constant of the hydroxo complex obtained by equlibrium measurements (spectrophotometric and by pH-titration) in anaerobic conditions (pK_a = 10.03) agreed well with that derived from kinetic data (p K_a = 9.93); k and k are about a factor 100 smaller than those for the pseudooctahedral Co(trien) (H₂O). This and the fact that several other Co(II) complexes with five-coordinated geometry do not exhibit oxygen affinity led to the proposal that the oxygenation mechanism for Co²⁺/tren complexes involves fast preequilibria between Co(tren) (H₂O)²⁺ and Co(tren) (H₂O) and only the latter is assumed to be reactive. The enhanced rate at high pH is explained by rate determining H₂O-exchange in the O₂-addition step and the ability of coordinated OH^? to labilize the neighbouring H₂O. This mechanism is furthermore supported by the formation of one kinetically preferred isomer of the peroxo-bridged dicobalt(III) complex (O₂ cis to the tertiary N-atom) and the large negative activation entropy (?30 eu). The second step is the intramolecular bridging reaction: is independent of [Co(tren)²⁺] and [O₂] but exhibits a pH-dependence of the form k₃ = k′₃[H + ]/(K_a + [H⁺]); k_?3 ( = 5 · 10^?5 s^?1) was determined independently and from the two rate constants the equilibrium constant was calculated as ≈ 10⁵. The ligand combination as in Co(tren)²⁺ was shown to provide an excellent balance to form a reversible oxygen carrier; possible reasons for this are discussed.     

Kinetics and mechanism of oxidation of aliphatic aldehydes by peroxomonosulphate

The kinetics of the oxidation of aliphatic aldehydes, formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, and trichloroacetaldehyde by Peroxomonosulphate (PMS) was carried out in aqueous perchloric acid medium (0.1–1 M H⁺) at constant ionic strength of 1.2 M in the temperature range 10°–60°C. The reactions of all the aldehydes were found to obey a total second-order kinetics, first order each with respect to [Peroxomonosulphate] and [aldehyde]. Acetaldehyde, propionaldehyde, and n-butyraldehyde exhibited acid catalysis with the concurrent occurrence of acid-independent reaction path conforming to the rate law Formaldehyde was found to undergo oxidation only by acid-dependent path (k_b = 0) and trichloroacetaldehyde exhibited only the acid-independent reaction path (k_a = 0). The products of oxidation were found to be the respective carboxylic acids in each case. The stoichiometry of the reaction, [Peroxomonosulphate]:[Aldehyde] = 1:1, indicated the absence of carbonyl-assisted decomposition and self-decomposition of peroxomonosulphate. The kinetic and thermodynamic parameters evaluated pointed to the mechanism of a fast nucleophilic attack of the oxidant on the aldehyde followed by slow acid catalyzed and/or uncatalyzed decomposition of the intermediate to product. A sharp comparison is made with the corresponding reactions of the similar peroxides, S₂O and H₂PO.     

Temperature and pressure effects on the kinetics of the Bromate ion-iodide ion-L-ascorbic acid clock reaction

The kinetics of the bromate ion-iodide ion-L-ascorbic acid clock reaction was investigated as a function of temperature and pressure using stopped-flow techniques. Kinetic results were obtained for the uncatalyzed as well as for the Mo(VI) and V(V) catalyzed reactions. While molybdenum catalyzes the BrO-I^? reaction, vanadium catalyzes the direct oxidation of ascorbic acid by bromate ion. The corresponding rate laws and kinetic parameters are as follows. Uncatalyzed reaction: r₂ = k₂[BrO] [I^?][H⁺]², k₂ = 38.6 ± 2.0 dm⁹ mol^?3 s^?1, ΔH? = 41.3 ± 4.2 kJmol^?1, ΔS? = ?75.9 ± 11.4 Jmol^?1 K^?1, ΔV? = ?14.2 ± 2.9 cm³ mol^?1. Molybdenum-catalyzed reaction: r′₂ = k₂[BrO] [I^?] [H⁺]² + k_Mo[BrO] [I^?] [ H⁺]²[M₀(VI)], k_Mo = (2.9 ± 0.3)10⁶ dm¹² mol^?4 s^?1, ΔH? = 27.2 ± 2.5 kJmol^?1, ΔS? = ?30.1 ± 4.5 Jmol^?1K^?1, ΔV? = 14.2 ± 2.1 cm³ mol^?1. Vanadium-catalyzed reaction: r′₁ = k_V[BrO] [V(V)], k_V = 9.1 ± 0.6 dm³ mol^?1 s^?1, ΔH? = 61.4 ± 5.4 kJmol^?1, ΔS? = ?20.7 ± 3.1 Jmol^?1K^?1, ΔV? = 5.2 ± 1.5 cm³ mol^?1. On the basis of the results, mechanistic details of the BrO-I^? reaction and the catalytic oxidation of ascorbic acid by BrO are elaborated. © 1995 John Wiley & Sons, Inc.     

Gas phase rate coefficients and activation energies for the reaction of butanal and 2‐methyl‐propanal with nitrate radicals

Rate coefficients have been determined for the reaction of butanal and 2‐methyl‐propanal with NO₃ using relative and absolute methods. The relative measurements were accomplished by using a static reactor with long‐path FTIR spectroscopy as the analytical tool. The absolute measurements were made using fast‐flow–discharge technique with detection of NO₃ by optical absorption. The resulting average coefficients from the relative rate experiments were k = (1.0 ± 0.1) × 10⁻¹⁴ and k = (1.2 ± 0.2) × 10⁻¹⁴ (cm³ molecule⁻¹ s⁻¹) for butanal and 2‐methyl‐propanal, respectively. The results from the absolute measurements indicated secondary reactions involving NO₃ radicals and the primary formed acyl radicals. The prospect of secondary reactions was investigated by means of mathematical modeling. Calculations indicated that the unwanted NO₃ radical reactions could be suppressed by introducing molecular oxygen into the flow tube. The rate coefficients from the absolute rate experiments with oxygen added were and k = (1.2 ± 0.1) × 10⁻¹⁴ and = (0.9 ± 0.1) × 10⁻¹⁴ (cm³ molecule⁻¹ s⁻¹) for butanal and 2‐methyl‐propanal. The temperature dependence of the reactions was studied in the range between 263 and 364 K. Activation energies for the reactions were determined to 12 ± 2 kJ mole⁻¹ and 14 ± 1 kJ mole⁻¹ for butanal and 2‐methyl‐propanal, respectively. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 294–303, 2000     

Kinetics of acid catalyzed and Ag(I) catalyzed decomposition of peroxodisulfate in aqueous medium

The mechanism of acid catalyzed decomposition of peroxodisulfate, (S₂O) in aqueous perchlorate medium involves the hydrolysis of the species H₂S₂O₈ and HS₂O and the homolysis of the species H₂S₂O₈, HS₂O and S₂O at the O? O bond. The overall rate law when 1.4M > [HClO₄] > 0.1M is The constants k′ and k″ contain the hydrolysis and homolysis rate constants of HS₂O₈^? and H₂S₂O₈, respectively. With added Ag(I), the acid catalyzed and Ag(I) catalyzed reactions take place independently. Ag(I) catalyzed decomposition appears to involve the species AgS₂O (aq).     

Scope for Accessing the Chain Length Dependence of the Termination Rate Coefficient for Disparate Length Radicals in Acrylate Free Radical Polymerization

A method that utilizes reversible addition fragmentation chain transfer (RAFT) chemistry is evaluated on a theoretical basis to deduce the termination rate coefficient for disparate length radicals k in acrylate free radical polymerization, where s and l represent the arbitrary yet disparate chain lengths from either a “short” or “long” RAFT distribution. The method is based on a previously developed method for elucidation of k for the model monomer system styrene. The method was expanded to account for intramolecular chain transfer (i.e., the formation of mid-chain radicals via backbiting) and the free radical polymerization kinetic parameters of methyl acrylate. Simulations show that the method's predictive capability is sensitive to the polymerization rate's dependence on monomer concentration, i.e., the virtual monomer reaction order, which varies with the termination rate coefficient's value and chain length dependence. However, attaining the virtual monomer reaction order is a facile process and once known the method developed here that accounts for mid-chain radicals and virtual monomer reaction orders other than one seems robust enough to elucidate the chain length dependence of k for the more complex acrylate free radical polymerization.     

Theoretical study of electrical and electrochemical properties of cyclopentanepentaone and its dicyanomethylene derivatives

Theoretical studies on anions of 1,2‐dihydroxycyclopentenetrione (croconic acid, H₂C₅O₅) and the whole series of dicyanomethylene derivatives in gas phase and in dimethyl formamide (DMF) solution are carried out using density functional theory (DFT) and self‐consistent reaction field (SCRF)‐DFT method at the B3LYP theory level for the first time. Natural bond orbital (NBO) analyses indicate that π‐electron delocalization in the series is quite strong. Based on the most stable conformations, linear correlations are observed between the oxidation potential measured by cyclic voltammetry and the highest occupied molecular orbital (HOMO) energy as well as ionization potential (Ip), which supports experimental results that systematic substitution of the oxygen atoms in the C₅O structure with C(CN)₂ groups causes a shift of both the oxidation potentials E and E toward more positive values. The correlations are also observed between experimental diffusion coefficient D and E_bind calculated in gas phase and DMF solution, the experimental electrochemical reducing potentials (E_R) and the electron affinity (Ea). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Non‐transition metal‐catalyzed living radical polymerization of vinyl chloride initiated with iodoform in water at 25 °C

Non‐transition metal‐catalyzed living radical polymerization (LRP) of vinyl chloride (VC) in water at 25–35 °C is reported. This polymerization is initiated with iodoform and catalyzed by Na₂S₂O₄. In water, S₂O dissociates into SO that mediates the initiation and reactivation steps via a single electron transfer (SET) mechanism. The exchange between dormant and active propagating species also includes the degenerative chain transfer to dormant species (DT). In addition, the SO₂ released from SO during the SET process can add reversibly to poly(vinyl chloride) (PVC) radicals and provide additional transient dormant ～SO radicals. This novel LRP proceeds mostly by a combination of competitive SET and DT mechanisms and, therefore, it is called SET‐DTLRP. Telechelic PVC with a number‐average molecular weight (M_n) = 2,000–55,000, containing two active ～CH₂? CHClI chain ends and a higher syndiotacticity than the commercial PVC were obtained by SET‐DTLRP. This PVC is free of structural defects and exhibits a higher thermal stability than commercial PVC. SET‐DTLRP of VC is carried out under reaction conditions related to those used for its commercial free‐radical polymerization. Consequently, SET‐DTLRP is of technological interest both as an alternative commercial method for the production of PVC with superior properties as well as for the synthesis of new PVC‐based architectures. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6267–6282, 2004     

Reaction of CF3 radicals with H2O and D2O

The reaction of CF₃ radicals with H₂O (D₂O) has been studied over the range of 533–723 K using the photolysis and the pyrolysis of CF₃I as the free radical source. Arrhenius parameters for the reactions where X = H or D, relative to CF₃ radical recombination are given by where k/k is in cm^3/2/mol^1/2·s^1/2 and θ = 2.303RT/cal/mol. The activation energy and the primary kinetic isotope effect have been compared with those derived from the BEBO method.     

Visible light induced free radical promoted cationic polymerization using thioxanthone derivatives

The free radical promoted cationic polymerization cyclohexene oxide (CHO), was achieved by visible light irradiation (λ_inc = 430–490 nm) of methylene chloride solutions containing thioxanthone‐fluorene carboxylic acid (TX‐FLCOOH) or thioxanthone‐carbazole (TX‐C) and cationic salts, such as diphenyliodonium hexafluorophosphate (Ph₂I⁺PF) or silver hexafluorophosphate (Ag⁺PF) in the presence of hydrogen donors. A feasible initiation mechanism involves the photogeneration of ketyl radicals by hydrogen abstraction in the first step. Subsequent oxidation of ketyl radicals by the oxidizing salts yields Bronsted acids capable of initiating the polymerization of CHO. In agreement with the proposed mechanism, the polymerization was completely inhibited by 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy and di‐2,6‐di‐tert‐butylpyridine as radical and acid scavengers, respectively. Additionally polymerization efficiency was directly related to the reduction potential of the cationic salts, that is, Ag⁺PF (E = +0.8 V) was found to be more efficient than Ph₂I⁺PF (E = ?0.2 V). In addition to CHO, vinyl monomers such as isobutyl vinyl ether and N‐vinyl carbazole, and a bisepoxide such as 3,4‐epoxycyclohexyl‐3′,4′‐epoxycyclohexene carboxylate, were polymerized in the presence of TX‐FLCOOH or TX‐C and iodonium salt with high efficiency. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

The Catalytic Oxidative Coupling of Methane

One of the great challenges in the field of heterogeneous catalysis is the conversion of methane to more useful chemicals and fuels. A chemical of particular importance is ethene, which can be obtained by the oxidative coupling of methane. In this reaction CH₄ is first oxidatively converted into C₂H₆, and then into C₂H₄. The fundamental aspects of the problem involve both a heterogeneous component, which includes the activation of CH₄ on a metal oxide surface, and a homogeneous gas-phase component, which includes free-radical chemistry. Ethane is produced mainly by the coupling of the surface-generated CH radicals in the gas phase. The yield of C₂H₄ and C₂H₆ is limited by secondary reactions of CH radicals with the surface and by the further oxidation of C₂H₄, both on the catalyst surface and in the gas phase. Currently, the best catalysts provide 20% CH₄ conversion with 80% combined C₂H₄ and C₂H₆ selectivity in a single pass through the reactor. Less is known about the nature of the active centers than about the reaction mechanism; however, reactive oxygen ions are apparently required for the activation of CH₄ on certain catalysts. There is spectroscopic evidence for surface O^? or O ions. In addition to the oxidative coupling of CH₄, cross-coupling reactions, such as between methane and toluene to produce styrene, have been investigated. Many of the same catalysts are effective, and the cross-coupling reaction also appears to involve surface-generated radicals. Although a technological process has not been developed, extensive research has resulted in a reasonable understanding of the elementary reactions that occur during the oxidative coupling of methane.     

Determination of Propagation Rate Coefficient of Acrylates by Pulsed‐Laser Polymerization in the Presence of Intramolecular Chain Transfer to Polymer

Unusual difficulties are faced in the determination of propagation rate coefficients (k_p) of alkyl acrylates by pulsed‐laser polymerization (PLP). When the backbiting is the predominant chain transfer event, the apparent k_p of acrylates determined in PLP experiments for different frequencies should range between k_p (propagation rate coefficient of the secondary radicals) at high frequency and k at low frequency. The k value could be expressed from kinetic parameters: , where k_fp is the backbiting rate coefficient, k_p2 is the propagation rate coefficient of mid‐chain radicals, and [M] is the monomer concentration.

Apparent propagation rate coefficients determined for different frequencies by simulating the PLP of n‐butyl acrylate at 20 °C. Horizontal full lines show the values of k_p and k.     

SP–PLP–EPR Investigations into the Chain‐Length‐Dependent Termination of Methyl Methacrylate Bulk Polymerization

Termination kinetics of methyl methacrylate (MMA) bulk polymerization has been studied via the single pulsed laser polymerization–electron paramagnetic resonance method. MMA‐d₈ has been investigated to enhance the signal‐to‐noise quality of microsecond time‐resolved measurement of radical concentration. Chain‐length‐dependent termination rate coefficients of radicals of identical size, k, are reported for 5–70 °C and up to i = 100. k decreases according to the power‐law expression . At 5 °C, k_t for two MMA radicals of chain‐length unity is k = (5.8 ± 1.3) · 10⁸ L · mol⁻¹ · s⁻¹. The associated activation energy and power‐law exponent are: E_A(k) ≈ 9 ± 2 kJ · mol⁻¹ and α ≈ 0.63 ± 0.15, respectively.

     

Rate constants and conversion ratios for aqueous‐phase reactions of SO with CnF2n+1C(O)O− (n = 4–7) at 298 K

Kinetic data for aqueous‐phase reactions of sulfate anion radicals (SO) with perfluorocarboxylates (C_nF_2n+1C(O)O^?) are needed to evaluate removal and transformation processes of C_nF_2n+1C(O)O^? species in the environment, but rate constants for the reactions of SO with C_nF_2n+1C(O)O^? (k_n) have been reported only for short‐chain C_nF_2n+1C(O)O^? species (n = 1–3). Since C_nF_2n+1C(O)O^? reacted with SO to form C_mF_2m+1C(O)O^? (m < n), we determined relative rates k_n?1/k_n for the reactions of SO with C_nF_2n+1C(O)O^? (n = 4–7), along with conversion ratios for conversion of C_nF_2n+1C(O)O^? into C_n?1F_2n?1C(O)O^? (α_n) and into C_n?2F_2n?3C(O)O^? (β_n) at 298 K. SO was photolytically generated from S₂O by use of sunlamps (λ ≈ 310 nm). Even if k_n and k_n?1 change with increasing ionic strength, k_n?1/k_n can be determined when k_n?1/k_n and α_n remain almost constant during the reaction. The values of k_n/k₁ for n = 4–7 were nearly equal, and their average was 0.82 ± 0.04 (2σ). Conversion ratios of α_n and β_n were mostly independent of n for n = 4–7, and their averages were 0.77 ± 0.07 (2σ) and 0.13 ± 0.08, respectively. Branching ratios of reactions of a possible intermediate (C_nF_2n+1O^?), reaction of C_nF_2n+1O^? with H₂O, and fission of the C? C bond of C_nF_2n+1O^?, seemed to determine α_n and β_n. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 735–747, 2009