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1.
The kinetics of chlorine atom abstraction from the chloromethanes (CM)CCl4, CHCl3, and CH2Cl2 by radiolytically generated cyclohexyl radicals has been studied in the liquid phase by a competitive method. The halogen abstraction data have been put on an absolute basis by comparing the rates of the metathetical reactions with the known rate of addition of cyclohexyl radicals to C2Cl4. The following Arrhenius parameters were obtained:
The error limits are the standard deviations from least mean square Arrhenius plots. The possible application of the Evans–Polanyi relationship to chlorine atom abstraction reaction from CM is considered. 相似文献
CM | log A(CM)/A(C2Cl4) | E(CM)? E(C2Cl4)(kcal/mole) | log A(CM)(1./mole·sec) | E(CM) (kcal/mole) | Temperaure Range(°K) |
---|---|---|---|---|---|
CCl4 | 0.72±0.02 | ?1.42±0.05 | 9.40±0.08 | 5.88±0.15 | 333–453 |
CHCl3 | 0.77±0.06 | 2.86±0.01 | 9.45±0.12 | 10.16±0.11 | 392–492 |
CH2Cl2 | 0.56±0.12 | 6.37±0.27 | 9.42±0.18 | 13.67 ± 0.37 | 463–543 |
2.
The reactions have been studied by a mass-balance method involving the photolysis of small amounts of biacetyl in the presence of a large excess of isobutane containing a small proportion of the unsaturated substrate. The following Arrhenius parameters have been derived:
The results for methyl addition to ethylene are based on previous determinations by other techniques as well as the present studies. The results for methyl addition to acetylene and benzene are derived solely from the present experiments and are calculated relative to a rate constant of log k2(l./mol·sec) = 7.42 - (7.1/θ) for the reference reaction (2), ·H3 + (CH3)3CH → CH4 + ·4H9. 相似文献
Temperature | |||
---|---|---|---|
E | log A | range | |
Reaction | (kcal/mol) | (1./mol·sec) | (°K) |
?H3 + C2H4 → ?3H7 | 7.3 ± 1.0 | 8.32 ± 0.5 | 350 – 500 |
?H3 + C2H2 → ?3H5 | 7.7 ± 1.5 | 8.79 ± 0.8 | 379 – 487 |
?H3 + C6H6 → C7H9 | 7.6 ± 1.0 | 8.79 ± 0.5 | 372 – 484 |
3.
The following Arrhenius parameters have been determined for the hydrogen-abstraction reactions: R + (CH3)4Si → RH + (CH3)3SiCH3
The activation energies are in keeping with the strengths of the bonds formed during the reaction. By comparison with the activation energies for the analogous reactions of neopentane it is estimated that D((CH3)3SiCH2? H) ? 97 kcal/mole. The A factors for the above series of reactions fall within the range predicted by transition-state theory for this type of process and the validity of previous results of Kerr, Slater, and Young is seriously in doubt. 相似文献
R | Temp. (°K) | E (kcal/mole) | Log A (mole?1 cc sec?1) | Log k(400°K) (mole?1 cc sec?1) |
---|---|---|---|---|
CF3 | 330–433 | 7.23 ± 0.09 | 11.90 ± 0.05 | 7.95 |
CH3 | 396–476 | 10.23 ± 0.36 | 11.55 ± 0.18 | 5.68 |
CD3 | 396–496 | 10.36 ± 0.12 | 11.84 ± 0.06 | 6.20 |
C2H5 | 423–522 | 11.40 ± 0.48 | 11.88 ± 0.22 | 5.68 |
4.
Arrhenius parameters have been determined for the hydrogen-abstraction reactions: R + SiHCl3 + RH + SiCl3
The trend in activation energies E < E < E is interpreted as indicating a polar effect in the reaction of CF3 with SiHCl3 and the similar reactivities of all three radicals appear to be due to the high exothermicity of the reactions. The A Factors for the reactions are normal for hydrogen abstraction reactions of free radicals. The previous results of Kerr, Slater, and Young for CH3 abstracting an H atom from SiHCl3 have been amended. 相似文献
R | Temp (°K) | E(kcal/mole) | Log A(mole?1 cc sec?1) | Log k(400°K) (mole?1 cc sec?1) |
---|---|---|---|---|
CF3 | 323–461 | 5.98 ± 0.06 | 11.77 ± 0.03 | 8.50 |
CH3 | 333–443 | 4.30 ± 0.08 | 10.83 ± 0.04 | 4.48 |
C2H5 | 314–413 | 5.32 ± 0.07 | 11.54 ± 0.04 | 8.63 |
5.
The kinetics of reactions involving halogen atom abstraction from haloalkanes by methyl radicals have been studied in the gas phase. Arrhenius parameters for halogen atom transfer were determined relative to those for methyl radical combination:
The rate data obtained are used to provide information on the importance of polar effects for halogen abstraction processes. 相似文献
RX | log10A2(L/mol · s) | E2(kcal/mol) |
---|---|---|
CFCl3 | 8.3 ± 0.2 | 10.7 ± 0.4 |
CF3CCl3 | 7.9 ± 0.3 | 9.7 ± 0.6 |
CF2Cl2 | 9.1 ± 0.4 | 11.3 ± 0.7 |
CF3Cl | 8.8 ± 0.5 | 11.8 ± 1.0 |
CF3CF2Cl | 8.3 ± 0.3 | 10.9 ± 0.7 |
CF3Br | 8.6 ± 0.2 | 9.3 ± 0.5 |
CF3I | 8.1 ± 0.1 | 4.3 ± 0.2 |
CH3CH2I | 8.9 ± 0.3 | 7.4 ± 0.6 |
6.
Rate constants for the gas‐phase reactions of hydroxyl radicals and chlorine atoms with a series of alcohols have been determined by using the relative method. The experiments were performed at 295 ± 2 K and at 1 atmospheric pressure. The obtained values of the rate constants in units of 10?12 cm3 molecule?1 s?1 are as follows:
The above relative rate constants are based on the values (in units of 10?12 cm3 molecule?1 s?1) of k(OH + propane) = 1.08, k(OH + cyclohexane) = 7.22, k(Cl + propane) = 131 and k(Cl + cyclohexane) = 307. The results are compared with previous determinations. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 81–87, 2003 相似文献
Alcohol | Rate Constants for OH with | Rate Constants for Cl with | ||
---|---|---|---|---|
Propane | Cyclohexane | Propane | Cyclohexane | |
Ethyl alcohol | 3.40 ± 0.25 | – | 103 ± 4 | 96 ± 7 |
n‐Propyl alcohol | 5.47 ± 0.44 | – | 153 ± 13 | 147 ± 11 |
Isopropyl alcohol | 5.31 ± 0.39 | – | 73.5 ± 3.7 | 82.7 ± 7.4 |
n‐Butyl alcohol | 8.66 ± 0.66 | – | 211 ± 11 | 223 ± 10 |
Isobutyl alcohol | 9.08 ± 0.35 | 9.59 ± 0.45 | 182 ± 4 | 196 ± 11 |
tert‐Butyl alcohol | 1.11 ± 0.07 | – | 31.5 ± 2.4 | 34.1 ± 2.5 |
n‐Pentyl alcohol | 12.2 ± 1.0 | 12.4 ± 0.5 | 257 ± 25 | 258 ± 12 |
Isopentyl alcohol | 13.8 ± 0.5 | 13.2 ± 1.1 | 237 ± 7 | 235 ± 9 |
7.
The reactions (R = CF3, C2F5, and i,-C3F7) have been studied competitively in the gas phase over the range of 27–231°C. The following Arrhenius parameters were obtained:
The above data lead to bond dissociation energies D(R-I) which are compared with previous published results. The following values are recommended: D,(CF3-I) = 224, D,(C2F5-I) = 219, and D,(i,-C3F7-I) = 215 kJ/mol. 相似文献
log A,(cm3/mol · s) | E,(kJ/mol) | |
---|---|---|
R = CF3 | 13.99 ± 0.21 | 17.1 ± 2.0 |
R = C2F5 | 13.97 ± 0.20 | 11.5 ± 2.0 |
R = i,-C3F7 | 14.18 ± 0.20 | 10.2 ± 2.0 |
8.
Rate constants for the gas phase reactions of hydroxyl radicals and chlorine atoms with a number of ethers have been determined at 300 ± 3 K and at a total pressure of 1 atmosphere. Both OH radical and chlorine atom rate constants were determined using a relative rate technique. Values for the rate constants obtained are as follows.
The above relative rate constants are based on the values of k(OH + pentane)=[3.94 ± 0.98]×10?12 and k(OH + diethyl ether)=[13.6 ± 2.26] × 10?12 cm3 molecule?1 s?1 in the case of the hydroxyl reactions. In the case of the chlorine atom reactions, the above rate constants are based on values of k(Cl + ethane)=[5.84 ± 0.88] × 10?11 and k(Cl + diethyl ether)=[25.4 ± 8.05] × 10?11 cm3 molecule?1 s?1. The quoted errors include ±2σ from a least squares analysis of our slopes plus the uncertainty associated with the reference rate constants. Atmospheric lifetimes calculated with respect to reaction with OH radicals are based on a tropospheric OH radical concentration of (7.7 ± 1.4) × 105 radicals cm?3, and lifetimes with respect to reaction with Cl atoms are based on a tropospheric Cl atom concentration of 1 × 103 atoms cm?3. Observed trends in the relative rates of reaction of hydroxyl radicals and chlorine atoms with the ethers studied is discussed. The significance of the calculated tropospheric lifetimes is also reviewed. © 1993 John Wiley & Sons, Inc. 相似文献
compound | kOH×1012(cm3 molecule?1 s?1) | kC1×1011(cm3 molecule?1 s?1) |
---|---|---|
Hexane | 5.53 ± 1.55 | — |
2-Chloro ethyl methyl ether | 4.92 ± 1.09 | 14.4 ± 5.0 |
2,2-Dichloro ethyl methyl ether | 2.37 ± 0.50 | 4.4 ± 1.6 |
2-Bromo ethyl methyl ether | 6.94 ± 1.38 | 16.3 ± 5.4 |
2-Chloro,1,1,1-trifluoro ethyl ethyl ether | <0.3 | 0.30 ± 0.10 |
Isoflurane | <0.3 | <0.1 |
Enflurane | <0.3 | <0.1 |
Di-i-propyl ether | 11.08 ± 2.26 | 16.3 ± 5.4 |
Diethyl ether | — | 25.8 ± 4.4 |
9.
The photolysis of 1,1,3,3-tetrafluoroacetone has been reinvestigated as a source of CHF2 radicals at temperatures up to 578°K, and the following rate constant ratio was determined for the reactions 1 θ= 2.303 RT in kcal/mole. 1,1-Difluoro- and 1,1,3,3-tetrafluoroacetone were photolyzed in the presence of tetramethylsilane, and Arrhenius parameters were measured for the hydrogen abstraction reactions: R + Me4Si → RH + Me3SiCH2
By comparing with previous data on the CH3 and CF3 reactions, the activation energies were interpreted in terms of the enthalpy changes for the reactions and a polar effect operative between the attacking fluoromethyl radicals and the substrate which tends to reduce the activation energy progressively as the fluorine content of the radical increases. This polar effect, which decreases the activation energy for hydrogen abstraction from SiMe4 along the series CH3, CH2F, CHF2, and CF3, is in marked contrast to the polar repulsion between the fluorinated radicals and SiHCl3 which was tentatively proposed to explain the increase in activation energy observed in the same series of reactions with SiHCl3. 相似文献
R | T(°K) | E (kcal/mole) | log A (mole?1cc sec?1) | log k (500°K) (mole?1cc sec?1) |
---|---|---|---|---|
CH2F | 473–586 | 12.00 ± 0.30 | 11.68 ± 0.12 | 6.44 |
CHF2 | 416–526 | 10.18 ± 0.33 | 11.65 ± 0.15 | 7.21 |
10.
The photolyses of 1,3-difluoro- and 1,1,3,3-tetrafluoroacetone have been reinvestigated as sources of fluoromethyl radicals, and the following rate constant ratios were determined 1 θ= 2.303 RT in kcal/mole. The results are in substantial agreement with the original investigations. The photolyses of the fluoroacetones were used as sources of CH2F and CHF2 radicals, and the following Arrhenius parameters were obtained for the hydrogen abstraction reactions R + SiHCl3 → RH + SiCl3:
The rates of reactions of CH2F and CHF2 radicals toward hydrogen abstraction from SiHCl3 are an order of magnitude lower than the corresponding rates for the CH3, C2H5, and CF3 radicals as a result of increased activation energies for the CH2F and CHF2 reactions. The interpretation of the results is hindered by a lack of accurate thermochemical data on the radicals. The activation energies, as they stand, can be rationalized in terms of a polar repulsion between SiHCl3 and the radicals, increasing regularly and leading to a progressive increase in activation energy with increasing fluorine substitution in the radical. This interpretation is consistent with the estimates D(CH2F? H) ∝ D(CHF2? H) ∝ 97 kcal/mole. On the other hand, there is some indication, from the spread of A-factors in the series of fluoromethyl radicals reacting with SiHCl3, that internal compensation of Arrhenius parameters is occurring in some of the reactions; and when this is taken into account, the interpretation of activation energies is more difficult. 相似文献
R | T(°K) | E (kcal/mole) | log A (mole?1 cc sec?1) | log k (400°K) (mole?1 cc sec?1) |
---|---|---|---|---|
CH2F | 335–443 | 6.06 ± 0.15 | 10.79 ± 0.08 | 7.48 CHF2 |
CHF2 | 334–442 | 6.82 ± 0.09 | 11.32 ± 0.05 | 7.59 |
11.
We present a kinetic study of atomic potassium in its electronic ground state, K(42S½), generated in the “single-shot mode” by pulsed irradiation at elevated temperatures and monitored by time-resolved atomic resonance absorption spectroscopy using the Rydberg doublet at λ = 404 nm (K[52PJ]←K[42S½]). Profiles for the decay of atomic potassium in the presence of various halogenated reactants were recorded at different temperatures, yielding the following Arrhenius parameters (kR = A exp(?E/RT), errors 1σ):
A limited body of data is reported for k(K + C2H5Br) = 3.6 × 10?11 cm3 molecule?1 s?1 for the temperature range 704–733 K. These results for atomic potassium constitute a new body of absolute rate data which are compared with some previous results for reactions of atomic potassium with other reactants, and for reactions of atomic sodium, also determined by time-resolved atomic resonance absorption spectroscopy. The data for HCl and HBr are finally compared with early estimates reported using diffusion flames. 相似文献
R | A/10?10 cm3 molecule?1s?1 | E/kJ mol?1 | Temp. Range |
---|---|---|---|
CH3F | 1.93+1.1?0.7 | 59±3.3 | 822–922 K |
C2H5F | 1.40+2.5?0.9 | 62±6.6 | 694–807 K |
C6H5F | 2.0+1.6?0.9 | 41±3.9 | 705–812 K |
CH3Br | 1.7+0.3?0.2 | 15.9±1.2 | 798–903 K |
HCl | 5.6+3.5?2.1 | 34.7±3.5 | 828–902 K |
HBr | 1.9+0.3?0.3 | 34±1.2 | 836–925 K |
12.
The reactions of some perfluoroalkyl radicals with carbon tetrachloride have been studied using the photolysis of the corresponding perfluoroalkyl iodide as the free radical source. The Arrhenius parameters, based on the value of 2.3 × 1013 cm3 mol?1 s?1 for the self-combination rate constant of all radicals are:
Reaction | log(A/cm3 mol?1 s?1) | E/kcal mol?1 |
---|---|---|
CF3 + CCl4 | 12.8 | 11.3 |
C2F5 + CCl4 | 12.8 | 11.6 |
n-C3F7 + CCl4 | 12.9 | 12.0 |
Citing Literature
Volume 16 , Issue 11 November 1984
Pages 1351-1356 相似文献
13.
The reactions of CF3 radicals with the C3 to C7 cyclanes and spiropentane were studied and the following Arrhenius parameters were obtained for the reaction CF3 + c-RH → CF3H + c-R:
The CF3 radicals were generated by photolysis of hexafluoroacetone or CF3I and a comparison is made of the utility of the two compounds as radical sources. The Arrhenius parameters are compared with those for corresponding reactions of CH3 radicals with cyclanes, and the general reactivity of cyclic compounds toward free radicals is discussed. An Evans-Polanyi treatment is used to derive C? H bond dissociation energies in cyclanes; and these results, based on the reactions of CF3 with cyclanes, agree well with those previously obtained using CH3 plus cyclanes. The final mean values are shown above. 相似文献
c-RH | log A (cm3mole?1sec?1) | E (kcal/mole) | D(c-R—H) (kcal/mole) |
---|---|---|---|
Cyclopropane | 11.54 | 8.73 | 100.7 |
Cyclobutane | 11.66 | 6.48 | 95.7 |
Cyclopentane | 12.30 | 6.18 | 94.3 |
Cyclohexane | 12.12 | 6.26 | 94.9 |
Cycloheptane | 12.43 | 5.89 | 94.0 |
Spiropentane | 11.91 | 8.12 | 98.8 |
14.
Competitive studies of the reactions of ground-state oxygen atoms, generated by mercury-photosensitized decomposition of nitrous oxide, have been carried out with ethylene and all the fluoroethylenes using 2-(trifluoromethyl)-propene as reference compound. From measurements at 25°C and 150°C relative rate constants have been determined and used to calculate the Arrhenius parameters shown in the following table:
Olefin | ΔERef | ΔE | ||
---|---|---|---|---|
CH2? CH2 | 1.10 | ?1.18 | (1.0) | (0) |
CH2? CHF | 1.03 | 0.84 | 0.94 | 2.02 |
CH2? CF2 | 0.71 | 1.49 | 0.65 | 2.67 |
CHF? CHF (cis-) | 1.23 | 1.92 | 1.12 | 3.10 |
CHF? CHF (trans-) | 1.40 | 0.79 | 1.27 | 1.97 |
CF2? CHF | 1.06 | 0.00 | 0.96 | 1.22 |
CF2? CF2 | 0.86 | ?3.22 | 0.78 | ?2.04 |
- a ΔERef = Eolefin ? E2TFMP and ΔE = Eolefin ? E. Units are kJ/mole.
15.
The overall photobromination reactions have been studied using a competitive technique. Relative Arrhenius parameters were obtained for the rate-determining step These were placed on an absolute basis using previous-absolute values of A and E for RFI=CF3I. The activation energies were used to calculate bond dissociation energies D(R? I) with the following results:
RF? | E16 | D(RF?I)(kcal/mole) |
---|---|---|
CF3I a a E16 from [1] | 10.8 | 52.6 |
C2F5I | 8.8 | 50.6 |
n-C3F7I | 7.4 | 49.2 |
i-C3F7I | 7.5 | 49.2 |
n-C4F9I | 6.7 | 48.4 |
- a E16 from [1]
16.
The hydrogen abstraction reactions of tert-butoxyl with germane, phosphine, and trimethylsilane were studied by pyrolyzing di-t-butyl peroxide in the temperature range of 403 to 458 K. From the reported rate constant for the tert-butoxy radical decomposition in the literature, the absolute rate constants were determined from the study of competitive reaction between t-butoxy radical decomposition and hydrogen abstraction reaction. (t-BuO + RH → t-BuOH + R, where RH = GeH4, PH3, and HSiMe3) The Arrhenius parameters are found to be as follows:
Ea(kcal mol?1) | Log A(1.mol?1s?1) | |
---|---|---|
t-BuO + SiHMe3 | 2.1 | 8.5 |
t-BuO + GeH4 | 1.9 | 9.1 |
t-BuO + PH3 | 1.4 | 9.0 |
Citing Literature
Volume 18 , Issue 2 February 1986
Pages 267-279 相似文献
17.
The relative hydroxyl radical reaction rate constants from the simulated atmospheric oxidation of selected acetates and other esters have been measured. Reactions were carried out at 297 ± 2 K in 100-liter FEP Teflon®-film bags. The OH radicals were generated from the photolysis of methyl nitrite in pure air. Using a rate constant of 2.63 × 10?11 cm3 molecule?1 s?1 for the reaction of OH radicals with propene, the principal reference organic compound, the rate constants (×1012 cm3 molecule?1 s?1) obtained for the acetates and esters used in this study are:
Error limits represent 2σ from linear least-squares analysis of data. A linear correlation was observed for a plot of the measured relative rate constants vs. the number of CH2 groups per molecule of the following acetates: methyl acetate, ethyl acetate, n-propyl acetate, butyl acetate, and pentyl acetate. © 1993 John Wiley & Sons, Inc. 相似文献
n–propyl acetate | 3.42 ± 0.87 |
n–butyl acetate | 5.71 ± 0.94 |
n–pentyl acetate | 7.53 ± 0.48 |
2–ethoxyethyl acetate | 10.56 ± 1.31 |
2–ethoxyethyl isobutyrate | 13.56 ± 2.32 |
2–ethoxyethyl methacrylate | 27.22 ± 2.06 |
4–pentene-1-yl acetate | 43.40 ± 3.85 |
3–Ethoxyacrylic acid ethyl ester | 33.30 ± 1.22 |
18.
A kinetic investigation is described of the reaction of ground state atomic carbon, C(2p2(3PJ)), monitored by time-resolved atomic resonance absorption spectroscopy, with a wide range of halogenated olefins and aromatic compounds. Atomic carbon was generated by the repetitive pulsed irradiation (λ > ca. 160 nm) of C3O2 in the presence of excess helium buffer gas and the added reactant gases in a slow flow system, kinetically equivalent to a static system. C(23PJ) was then monitored photoelectrically by time-resolved atomic resonance absorption in the vacuum ultra-violet (λ = 166 nm, 33PJ ← 23PJ) with direct computer interfacing for data capture and analysis. The following absolute second-order rate constants for the reactions of C(23PJ) with the following reactants are reported:
These results, constituting the first reported body of absolute rate data for reactions of ground state carbon with these reactants, are compared with the analogous body of absolute rate data for atomic silicon in its Si(3p2(3PJ)) ground state, also determined hitherto by time-resolved atomic resonance absorption spectroscopy and demonstrating similar kinetic behavior. © 1993 John Wiley & Sons, Inc. 相似文献
Reactant | kR/cm3 molecule?1 s?1 (300 K) |
---|---|
C2F4 | (1.9 ± 0.1) × 10?10 |
C2Cl4 | (10.6 ± 0.5) × 10?10 |
CH2CF2 | (4.3 ± 0.2) × 10?10 |
CHClCCl2 | (7.9 ± 0.4) × 10?10 |
C6H6 | (4.8 ± 0.3) × 10?10 |
C6F6 | (4.9 ± 0.3) × 10?10 |
C6HF5 | (5.0 ± 0.3) × 10?10 |
C6H2F4 | (4.4 ± 0.2) × 10?10 |
C6H5—CH3 | (5.5 ± 0.3) × 10?10 |
C6F5—CF3 | (5.4 ± 0.3) × 10?10 |
19.
We present a kinetic study of the reaction of ground state silicon atoms with halogenated unsaturated organic compounds (R). Si(33PJ) was generated by the repetitive pulsed irradiation of SiCl4 in the presence of excess helium buffer gas and the reactant R in a slow flow system, kinetically equivalent to a static system. The ground state atom was monitored by time-resolved atomic resonance absorption spectroscopy at λ = 252 nm [Si(43PJ) ← Si(33PJ)] on time scales by which the optically metastable tates,Si(31D2) and Si(31S0) had relaxed to the 3P state, using signal averaging methods. Computerized fitting of the resulting atomic decay traces in the presence of the various reactants, R, yielded the following new body of absolute second-order rate constants (kR, T = 300 K, errors = 2sigma;):
These data are compared, where appropriate, with analogous data for unsaturated hydrocarbon organic compounds. They are also discussed within the general context of nuclear recoil measurements involving 31Si. 相似文献
R | kR/cm3 molecule?1 s?1 |
---|---|
C2F4 | 1.6 ± 0.2 × 10?10 |
C2Cl4 | 9.9 ± 1.7 × 10?10 |
CH2CF2 | 4.0 ± 0.6 × 10?10 |
CHClCCl2 | 7.0 ± 1.1 × 10?10 |
CF3CH? CH2 | 4.6 ± 0.5 × 10?10 |
C6H6 | 4.4 ± 1.0 times; 10?10 |
C6F6 | 4.4 ± 0.6 × 10?10 |
C6HF5 | 4.6 ± 1.3 × 10?10 |
C6H2F4 | 3.9 ± 0.8 × 10?10 |
C6F5—CF3 | 5.1 ± 0.6 × 10?10 |
20.
Rate constants for the reactions of OH radicals and Cl atoms with CH3ONO, C2H5ONO, n-C3H7ONO, n-C4H9ONO, and n-C5H11ONO have been determined at 298 ± 2 K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute rate technique of pulse radiolysis combined with kinetic spectroscopy and a relative rate method involving simultaneous measurement of the loss of the nitrite and the reference compound. The Cl rate constants were measured using the relative rate method. Values of the rate constants in units of 10?13 cm3 molecule?1 s?1 are:
When compared to rate data for the corresponding alkanes the results show that the -ONO group decreases the rate constant for H atom abstraction by the OH radical from groups bonded to the -ONO group and also decreases that for groups in the β position. Similar results were found for the reaction of Cl atoms with these compounds. The results are discussed in terms of reactivity trends. 相似文献
Relative Cl | Relative OH | Absolute OH | |
---|---|---|---|
CH3ONO | 94.4 ± 7.4 | 3.0 ± 1.0 | 2.6 ± 0.5 |
C2H5ONO | 295 ± 13 | 7.0 ± 1.5 | 7.0 ?1.1 |
n-C3H7ONO | 646 ± 58 | 11.0 ± 1.5 | 12.0 ± 0.5 |
n-C4H9ONO | 1370 ± 58 | 22.7 ± 0.8 | 27.2 ± 6.0 |
n-C5H11ONO | 2464 ± 444 | 37.4 ± 5.0 | 42.5 ± 8.0 |