摘要:

AbstractDark‐phase experiments between isoprene and O3are discussed. UNC outdoor chamber experiments have shown that in high‐concentration systems of isoprene and O3(5 ppm C and 1 ppm) approximately 75% of the reacted carbon can be observed in the product formation of HCHO, CO, methacrolein, methylvinylketone, methylglyoxal, acetaldehyde, and propylene. Mechanisms were developed which gave reasonable fits to dark‐phase chamber experiments of MACR, MVK, isoprene, and O3. Experimental data and modeling results were used to generate O3rates of attack on MVK and MACR. An isoprene–O3rate of 1.67 × 10−2ppm−1·min−1was used and is consistent with other rates reported in the literature. Dark isoprene–O3systems appear to form homogeneously nucleated aerosol. Most of these particles appear and remain at diameters well below the optical cutoff region (0.3–0.5 μm), as opposed to the particles from similar α‐pinene–O3systems, which also form at smaller sizes but then grow into the optical size range (0.5 μm). Lower concentrations of α‐pinene and O3(0.2 ppm C and 0.12 ppm) still generated substantial aerosol, but by comparison, rapid CN nucleation was not observed during a similar side‐by

ISSN:0538-8066    

DOI:10.1002/kin.550140902

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractPyridiniumchlorochromate (PCC) oxidizes aniline and substituted anilines except nitro anilines smoothly in chlorobenzene–nitrobenzene mixtures in the presence of dichloroacetic acid. The reaction has unit dependence on each of the aniline, PCC, and dichloroacetic acid concentrations. Electron‐releasing substituents accelerate the reaction, whereas electronwithdrawing groups retard the reaction, and the rate data obey Hammett's relationship. The reaction constant ρ is ‐3.75. Azobenzene andp‐benzoquinone have been obtained as products. The observed experimental data have been rationalized in terms of the formation of an intermediate complex involving PCC–amine undergoing a rapid decomposition t

ISSN:0538-8066    

DOI:10.1002/kin.550140903

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractTime‐resolved absorption spectra for a reaction mixture ofp‐methoxystyrene and tetracyanoethylene (TCNE) are found to have a band maximum at 325 nm which is assigned to the 1,4‐cycloadduct. The reaction in chloroform at 15, 20, and 25°C is followed by the charge‐transfer band at 600 nm. The 1,4‐cycloadduct, besides the so far known 1,2‐cycloadduct and EDA complex, is taken into account to derive the rate equation for the EDA complex that is a linear second‐order differential equation. The rate constants for the elementary steps involved in the reaction are obtained. The 1,4‐cycloaddition has an activation entropy of ‐63 J/K·mol for the cycloreversion and a reaction constant ρ of ‐4.7, both of which indicate the polar transition state. On the other hand, activation entropy of the 1,2‐cycloaddition is 73 J/K·mol more negative than that of the 1,4‐cycloaddition, supporting the zwitterionic mechanis

ISSN:0538-8066    

DOI:10.1002/kin.550140904

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe reaction of acetylene (A) with cyclohexa‐1,3‐diene (CHD) has been studied between 450 and 592 K. The pressures of A ranged from 25 to 112 torr and those of CHD from 8 to 62 torr. The reaction yields only ethene (E) and benzene (B) instead of bicyclo[2.2.2]octa‐2,5‐diene (BOD), the product that is expected for a 1,4,1′,2′ addition of the Diels–Alder type. It is first order with respect to each reagent. The rate constant (in L/mol·s) is given by\documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k = - (27,150 \pm 120)/4.576T + (7.49 \pm 0.05)$$\end{document}The thermal decomposition of BOD has also been studied. In the ranges of 354–435 K and 0.5–6 torr, the reaction is first order and results in the formation of equal amounts of B and E as the reaction of A with CHD does. Its rate constant (in s−1) is given by\documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k_d = - (32,520 \pm 40)/4.576T + (14.06 \pm 0.02)$$\end{document}The following consecutive reactions are proposed for the reaction between A and CHD:where BOD is the primary product that is too unstable to be detected. This implies that the rate constantkis equal toka. The reaction mechanisms and the strain energy

ISSN:0538-8066    

DOI:10.1002/kin.550140905

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe reactions of stabilized carbonium ions of setoglaucin, methyl violet, and ethyl violet with cyanide ions are largely catalyzed by the cationic micelles of cetyltrimethylammonium bromide (CTAB) in aqueous media. Added counterions (anions in this case) have strong inhibitory effects on the CTAB‐catalyzed reactions in the following order: N 3−>NO 3−>Br−>Cl−>F−>no salt. The inhibitory effects of the counterions have been attributed to the exchange between added anions and reagent (CN−) in the micellar media. The data have been analyzed by the model schemes, and mathematical formulations were developed. Various parameters associated with the exchange process, such as equilibrium exchange constant, number of surfactant molecules per substrate molecule, number of added anions, and a factor related to the binding of additives to the catalytic micellar aggregates, ha

ISSN:0538-8066    

DOI:10.1002/kin.550140906

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics and mechanism of oxidation of iminodiacetic acid andN‐methyliminodiacetic acid by aquasilver(II) and Ag(II)‐2,2′‐bipyridine complexes has been investigated. The results are discussed with reference to the active reaction pathways, the equilibrium quotient of the title reactions, the protolytic equilibria which involve the oxidizing complex, and the intrinsic self‐exchange rates of the

ISSN:0538-8066    

DOI:10.1002/kin.550140907

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe photolysis of carbon tetrachloride in the presence of a number of alkanes has been investigated in the gas phase. The products obtained from the photolysis experiments were those expected from a chain reaction in which trichloromethyl radicals abstract hydrogen atoms from the alkane. The data have been used to determine Arrhenius parameters for hydrogen abstraction from the series of alkanes CH4, C2H6, C3H8, andi‐C4H10by trichloromethyl radicals,The rate data obtained are used to explain why termination reactions involving alkyl radicals become less significant as the alkane becomes more comple

ISSN:0538-8066    

DOI:10.1002/kin.550140908

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractA chemical system, based on the Briggs–Rauscher reaction, which unperturbed undergoes rhythmic activity followed by a long period of iodine production–consumption prior to return of the rhythmic activity, is described. The effect of the various variables on the system is repor

ISSN:0538-8066    

DOI:10.1002/kin.550140909

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550140910

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550140901

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY