摘要:

AbstractSinglet molecular oxygen, O2(1Σ g+), is one of the important intermediate species in the atmospheres of Earth, Mars, and Venus. To elucidate the chemistry of this excited molecular oxygen, a series of kinetic measurements have been undertaken using the flow‐discharge/optical‐emission technique. By monitoring the characteristic emission (762 nm for1Σ g+), the quenching rates for several important molecules have been obtained at room temperature. The following table summarizes measurements.TextQuencherRate Constants (cm3/s)CH2(4.6 ± 0.5) × 10−13H2(7.0 ± 0.3) × 10−13N2(1.7 ± 0.1) × 10−15Cl2(4.5 ± 0.8) × 10−16CO(4.5 ± 0.5) × 10−15O3(2.2 ± 0.3) × 10−112,3 DBM‐2(6.0 ± 0.1) × 10−13The error limits represent one standard deviation. The systematic error is estimated to be about 15%. For CO2and O3molecules, the quenching rate constants were also measured in the temperature range of 245–362 K. In both reactions, negligible temperature dependences (with the activation ener

ISSN:0538-8066    

DOI:10.1002/kin.550171102

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractA discharge‐flow apparatus with resonance fluorescence and chemiluminescence detection has been used to monitor O2(b1σ g+) production from several reactions of the HO2radical at 300 K and 1‐torr total pressure. O2(b), HO2, and OH were observed when F atoms were added to H2O2in the gas phase. Signal strengths of O2(b) were proportional to initial concentrations of H2O2and HO2. These observations were analyzed by using a simple three step mechanism and a more complete computer simulation with 22 reaction steps. The results indicate that the F + HO2reaction yields O2(b) with an efficiency of (3.6 ± 1.4) × 10−3. By monitoring [O2(b)] and [HO2] upon addition of an excess second reactant to HO2, O2(b) yields from the reactions of HO2with O, Cl, D, H, and OH were found to be<1 × 10−2,<5 × 10−4,<2 × 10−3,<8 × 10−3, and<1 × 10−3, respectively. Yields of O2(b) from the HO2± HO2reaction were foun

ISSN:0538-8066    

DOI:10.1002/kin.550171103

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractDecomposition of (R1R2CXON=)2(R1= R2= Ph; R1= R2=pClC6H4; R1= Ph, R2= CH3; X = H or D) in hydrocarbon solvents at 31–75°C afforded R1R2CO in 6–8% lower yield when X = D than when X = H. This result is ascribed to cage escape of secondary alkoxyl radicals in competition with dismutation. Deuterium isotope effects for alkoxyl cage dismutation of 1.35–2.4 are estimated from the data. It is suggested that this same competition may account for the experimentally slower termination rate constants in solution of primary and secondary alkylperoxyl radicals on α‐

ISSN:0538-8066    

DOI:10.1002/kin.550171104

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractLow pressure (4.67 kPa) CH4/O2/Ar flames were seeded with approximately 5300 ppm NH3. The concentration profiles of stable and radical species in lean (ϕ = 0.92) and rich (ϕ = 1.13) flames were determined by molecular beam sampling mass spectrometry. Temperature profiles in these flames were measured with thermocouples whose readings were corrected for radiative losses by the Na‐line reversal method. Regions of the flames were selected where the principal reaction leading to the destruction of NH3wasBy correcting the measured concentrations for diffusion, the net rate of NH3loss rate was determined in the temperature range 2080–2360 K. The rate constantk1was determined from the net loss rate with correction for the reactionusing measured values of (O) andk2values given by Salimian, Hanson, and Kruger [1]. The best‐fit Arrhenius expression fork1in the temperature range 2080–2360 K is 1013.88exp(−4539/T) cm3/mol‐s. The results of this study combined with previous lower temperature data confirm the non‐Arrhenius behavior ofk1suggested by Salimian, Hanson, and Kruger [1]. The best‐fit modified three parameter expression for the range 300–2360 K is 106.33±0.2T2e

ISSN:0538-8066    

DOI:10.1002/kin.550171105

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe rate constants of the reaction between OH and H2S in He, N2, and O2over the temperature range 245–450 K have been determined using the discharge flow‐resonance fluorescence technique. At 299 K,k1= (4.4 ± 0.7) × 10−12cm3molecule−1s−1. The temperature dependence of the rate constant can be fitted either byk1= 5.6 × 10−12exp(−57/T) or byk1= (3.8 × 10−19)T2.43exp(732/T) to within 8 and 9%, respectively. However, the non‐Arrhenius behavior can be confidently confirmed. The absence of the pressure dependence and the third‐body effect at low temperature suggest that the complex formation mechanism is not important over the tempera

ISSN:0538-8066    

DOI:10.1002/kin.550171106

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractAn electron paramagnetic resonance (EPR) technique was used to show that simple alkyl radicals readily abstract hydrogen from 1,4‐cyclohexadiene. Rate constants for the reaction were ca. 104–105M−1s−1at 300 K and activation energies 5–7 kcal mol−1. For the stabilized radicals, allyl and benzyl, the rate constants were<102M−1s−1at 300 K. The data suggest that 1,4‐cyclohexadiene could be used as an effective trap to probe rearrangement reactions of carbon centered radica

ISSN:0538-8066    

DOI:10.1002/kin.550171107

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe reaction of CF3radicals with NH3has been studied over a wide temperature range 298–673 K, using the photolysis and the thermal decomposition of CF3I as the free radical source.It was found that the reaction could not be explained in terms of a simple mechanismin the whole temperature range because a marked pressure dependence on the rate of products formation and the presence of a dark reaction complicate the system at low temperatures. Thus, Arrhenius parameters for reaction (1) have been calculated relative to the CF3recombination from data in the range 523–673 K where pure hydrogen transfer occurs. The rate constant expression is given by\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_H /k_c^{1/2} = (6.17 \pm 0.28) - (57.8 \pm 2.9)/\theta $$\end{document}wherekH/k c1/2is in units of cm3/2/mol1/2s1/2and θ = 2.303 RT/

ISSN:0538-8066    

DOI:10.1002/kin.550171108

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe kinetics of the chlorination of various tertiary alcoholamines by hypochlorite have been studied in alkaline media. A reaction mechanism consistent with the experimental results is put forward, and a relationship is established between the rate constants and the polar parameter (Σσ*) of the substituent

ISSN:0538-8066    

DOI:10.1002/kin.550171109

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550171101

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY