15454-33-8Relevant articles and documents
Rate Coefficient for the Reaction of CH2OH Radicals with Cl2 and Infrared Spectra of Chloromethanol and Dichloromethanol
Tyndall, Geoffrey S.,Wallington, Timothy J.,Hurley, Michael D.,Schneider, William F.
, p. 1576 - 1582 (1993)
Quantitative infrared spectra have been recorded for chloromethanol and dichloromethanol, formed from the reactions of Cl2 with CH2OH and CHClOH, respectively.Chloromethanol decomposes quantitatively to HCHO and HCl, probably via a heterogeneous mechanism.The lower limit for the homogeneous gas-phase lifetime thus measured is 660 s.The rate coefficient for the reaction of CH2OH with Cl2 has been determined by measuring the products formed in experiments where O2 was allowed to complete with Cl2 for the CH2OH radicals.The rate coefficient is (2.7 +/- 0.7) x 10-11 cm3 molecule-1 s-1 at 295 +/- 2 K.The rate coefficient for the reaction of Cl atoms with chloromethanol was estimated to be (4 +/- 2) x 10-12 cm3 molecule-1 s-1 at 295 +/- 2 K.
Rate coefficients for the reactions of chlorine atoms with methanol and acetaldehyde
Tyndall,Orlando,Kegley-Owen,Wallington,Hurley
, p. 776 - 784 (1999)
Rate coefficients have been measured for the reactions of Cl atoms with methanol (k1) and acetaldehyde (k2) using both absolute (laser photolysis with resonance fluorescence) and relative rate methods at 295±2 K. The measured rate coefficients were (units of 10-11 cm3 molecule-1s-1): absolute method, k1 = (5.1±0.4), k2 = (7.3±0.7): relative method k1 = (5.6±0.6), k2 = (8.4±1.0). Based on a critical evaluation of the literature data, the following rate coefficients are recommended: k1 = (5.4±0.9)×10-11 and k2 = (7.8±1.3)×10-11 cm3 molecule-1s-1 (95% confidence limits). The results significantly improve the confidence in the database for reactions of Cl atoms with these oxygenated organics. Rate coefficients were also measured for the reactions of Cl2 with CH2OH, k5 = (2.9±0.6)×10-11 and CH3CO, k6 = (4.3±1.5)×1011cm3 molecule-1s-1, by observing the regeneration of Cl atoms in the absence of O2. Based on these results and those from a previous relative rate study, the rate coefficient for CH3CO±O2 at the high pressure limit is estimated to be (5.7±1.9)×10-12cm3molecule-1s-1.
Photochemical Processes on Chloromethyl Formate and Vinyl Formate in Low-Temperature Matrices: Infrared Spectra and ab Initio Calculations on Chloromethanol and Vinyl Alcohol
Kunttu, Henrik,Dahlqvist, Martti,Murto, Juhani,Raesaenen, Markku
, p. 1495 - 1502 (1988)
The UV photodecomposition of chloromethyl formate and vinyl formate has been studied in low-temperature noble-gas matrices at wavelengths between 200 and 260 nm.Two distinct channels in cage photolysis were observed: (i) ClH2COCHO -> ClH2COH+CO; H2CCHOCHO -> H2CCHOH+CO. (ii) ClH2COCHO -> H2CO+HCl+CO; H2CCHOCHO -> CH3CHO+CO.There is a well-established wavelength dependence influencing the product ratios in these photochemical processes.Decomposition due to irradiation at wavelength near 250 nm prefers channel i, where the formic acid esters decompose to the corresponding alcoholic species, chloromethanol (a new compound), and vinyl alcohol.On the other hand, at shorter wavelengths, channel ii dominates.Neither chloromethanol nor vinyl alcohol were observed to decompose at wavelengths above 200 nm.The photoprocesses of vinyl formate were also studied in NO-doped Ar matrices as well as in solid Xe in order to get information concerning the mechanisms of photochemical decomposition of formic acid esters.The assignment of the vibrational spectra is based on ab initio calculations performed at the Hartree-Fock 6-13G level for chloromethanol and at the MP2/6-13G** level for vinyl alcohol.A detailed vibrational analysis is given for chloromethanol, chloromethanol-O-d, and vinyl alcohol.
Stability and infrared spectra of mono-, di-, and trichloromethanol
Wallington,Schneider,Barnes,Becker,Sehested,Nielsen
, p. 97 - 102 (2000)
CH2ClOH, CHCl2OH, and CCl3OH were prepared by UV irradiation of CH3OH/Cl2/N2 gas mixtures. Absorption cross-sections (base e) of σ(CH2ClOH) at 1093 cm-1=6.16×10-1
Kinetic study of hydrolysis of benzoates. Part XXIII - Influence of the substituent and temperature on the kinetics of the alkaline hydrolysis of alkyl benzoates in aqueous 2.25 M Bu4NBr and 80% DMSO
Nummert, Vilve,Piirsalu, Mare
, p. 353 - 361 (2007/10/03)
The second-order rate constants k2 (M-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates, C6H5CO(O)R (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3), were measured in aqueous 2.25 M n-Bu4NBr and in 80% (v/v) DMSO solution at several temperatures. The log k values were analyzed using the equation log k = log k0 + ρσ + δEsB. The EsB scale has been proposed for the steric effect of alkyl substituents in the alkyl part of esters: EsB = (log kR - log kCH(3))H+, where k is the rate constant for the acidic hydrolysis of substituted alkyl benzoates or acetates in water. As polar substituent parameters, both Taft σ* and σI constants were used. The dual parameter treatments of the log k values with σ and EsB constants gave excellent correlations (R = 0.997). For 2.25 M n-Bu4NBr, 80% (v/v) DMSO and pure water at 25 °C, calculated susceptibilities to the inductive effect of alkyl substituents ρ* were found to be 2.07, 2.21 and 1.64, respectively. The corresponding ρI values were 4.64, 4.94 and 3.64. The dependence of ρI on solvent and temperature in the alkaline hydrolysis of substituted alkyl benzoates was similar to that observed earlier for meta- and para-substituents in the alkaline hydrolysis of substituted phenyl benzoates and tosylates. The substituent dependence of the activation energy, E, was found to be completely caused by the polar effect. Susceptibility to steric effect in the alkaline hydrolysis of alkyl benzoates (δ ≈ 1) appeared to be independent of the solvent and temperature. Copyright
The return of the succinimidyl radical
Merenyi, Gabor,Lind, Johan,Eberson, Lennart
, p. 62 - 66 (2007/10/03)
The aqueous kinetics of the succinimidyl radical, S., has been re-examined in the presence of oxidizable substrates and oxygen. The results indicate a rapid equilibrium between S. and its ring-opened analogue, the β-(isocyanato-carbonyl)ethyl radical, PI.. The equilibrium constant K1 is ca. 10, with k1 ≈ 107 s-1 and k-1 ≈ 106 s-1. The glutarimidyl radical, G., was produced by one-electron reduction of N-chloroglutarimide, GCl. The rate constants of several oxidation and hydrogen abstraction reactions with S. and G. have been determined. Furthermore, halogen abstraction reactions from haloimides by some selected alkyl radicals were also scrutinised. Most striking is the finding that the 2-cyanoethyl radical abstracts Br from SBr ca. 25 times slower than does the ethyl radical. This demonstrates a strong β-effect and rationalises a relatively slow Br abstraction rate by PI. from SBr. While the closure rate of the PI' radical appears to be solvent-insensitive, the ring opening rate of S., k1, is estimated to be ca. 100 times faster in, e.g., CH2Cl2 than in water. This suggests hydrogen-bonded stabilisation of S.. Acta Chemica Scandinavica 1998.
Kinetics of the cross reactions of CH3O2 and C2H5O2 radicals with selected peroxy radicals
Villenave, Eric,Lesclaux, Robert
, p. 14372 - 14382 (2007/10/03)
The kinetics of the reactions of selected peroxy radicals (RO2) with CH3O2 and with C2H5O2 have been investigated using two techniques: excimer-laser photolysis and conventional flash photolysis, both coupled with UV absorption spectrometry. Radicals were generated either by photolysis of molecular chlorine in the presence of suitable hydrocarbons or by photolysis of the appropriate alkyl chloride. All such cross-reaction kinetics were investigated at 760 Torr total pressure and room temperature except for the reaction of the allylperoxy radical with CH3O2, for which the rate constant was determined between 291 and 423 K, resulting in the following rate expression: k15 = (2.8 ± 0.7) × 10-13 exp[(515 ± 75)/T] cm3 molecule-1 s-1. Values of (2.0 ± 0.5) × 10-13, (1.5 ± 0.5) × 10-12, (9.0 ± 0.15) × 10-14, -12, (2.5 ± 0.5) × 10-12, and (8.2 ± 0.6) × 10-12 (units of cm3 molecule-1 s-1) have been obtained for the reactions of CH3O2 radicals with C2H5O2, neo-C5H11O2, c-C6H11O2, C6H5CH2O2, CH2ClO2, and CH3C(O)O2, respectively, and (1.0 ± 0.3) × 10-12, (5.6 ± 0.8) × 10-13, (4.0 ± 0.2) × 10-14, and (1.0 ± 0.3) × 10-11 (units of cm3 molecule-1 s-1) for the reactions of C2H5O2 with CH2=CHCH2O2, neo-C5H11O2, c-C6H11O2, and CH3C(O)O2 radicals, respectively. These rate constants were obtained by numerical simulations of the complete reaction mechanisms, which were deduced from the known mechanisms of the corresponding peroxy radical self-reactions. A systematic analysis of propagation of errors was carried out for each reaction to quantify the sensitivity of the cross-reaction rate constant to the parameters used in kinetic simulations. The rate constant for a given cross reaction is generally found to be between the rate constants for the self-reactions of RO2 and CH3O2 (or C2H5O2). However, when the RO2 self-reaction is fast, the cross reaction with CH3O2 (or C2H5O2) is also fast, with similar rate constants for both reactions, suggesting that these particular peroxy radical cross reactions can play a significant role in the chemistry of hydrocarbon oxidation processes in the troposphere and in low-temperature combustion. Relationships between cross-reaction and self-reaction rate constants are suggested.
Kinetics and mechanisms of the acid-catalysed methanolysis of halogen-substituted carboxylic esters
Kanerva,Liisa, T.
, p. 329 - 334 (2007/10/02)
The methanolysis of chloromethyl dichloroacetate in HClO4/NaClO4 solutions of aqueous methanol at cw 1.30, 2.60 and 5.56 mol/L both at variable and at the constant ionic strengths of 0.5 and 1.0 mol/L and the methanolysis of ethyl trichloroacetate in anhydrous methanol up to 0.1 mol/L hydrogen chloride solutions were studied.The acid-catalysed methanolysis of ethyl trichloroacetate and that of the esters with one or two halogen substituents is proposed to proceed by the normal AAC2 mechanism even in the case when the acid-catalysed hydrolysis in water takes place by the exceptional A-BAC3 mechanism.Under the experimental conditions, the acid catalysed methanolysis of chloromethyl dichloroacetate seems to proceed simultaneously by the AAC2 and A-BAC3 mechanisms.The involvement of the A/BAC3 mechanism in the case of chloromethyl dichloroacetate agrees with the observation that water acts as an effective general base catalyst in the rate-limiting step of the A-BAC3 reactions and that a chloro-substituent in the alkyl component retards the rate of its AAC2 reaction more than in the acyl group, at least in the case of ester hydrolysis.
Kinetics and Mechanisms of the Neutral and Acid-catalysed Hydrolyses of Chloro-substituted Alkyl Acetates in Aqueous Solutions of Constant Ionic Strength
Euranto, Erkki K.,Kanerva, Liisa T.,Cleve, Nils J.
, p. 2085 - 2092 (2007/10/02)
The simultaneous neutral and acid-catalysed hydrolyses of different chloro-substituted alkyl acetates in water and in aqueous acetone solutions have been studied using electrolyte solutions of constant ionic strength.The mechanism of the acid-catalysed hydrolyses of monochloroesters is AAC2.When an ester has two chloro-substituents the acid-catalysed hydrolysis takes place simultaneously by the AAC2 and A-BAC3 mechanisms and in the case of trihalogenated esters the mechanism is A-BAC3, a mechanism with an unsymmetrically catalysed partition of the intermediate formed from the water-catalysed addition of water to the carbonyl group of the ester.Structural and solvent effects of these reactions are discussed.
