摘要:

AbstractThe Hg(63P1) photosensitized decompositions of 3‐methyl‐1‐butene, 2‐methyl‐2‐butene, 3,3‐dimethyl‐1‐butene, and 2,3‐dimethyl‐1‐butene have been used to generate 1‐methylallyl, 1,2‐dimethylallyl, 1,1‐dimethylallyl, and 1,1,2‐trimethylallyl radicals in the gas phase at 24 ± 1°C. From a study of the relative yields of the CH3combination products, the relative reactivities of the reaction centers in each of these unsymmetrically substituted ambident radicals have been determined. The more substituted centers are found to be the less reactive, and this is ascribed primarily to greater steric interaction at these centers during reaction. Measurement of the ratio oftrans‐ tocis‐2‐pentene formed from the 1‐methylallyl radical, combined with published values for this ratio at higher temperatures, enabled the differences in entropy and heat of formation of thetrans‐ andcis‐forms of this radical to be calculated as 0.62 ± 0.85 J mol−1K−1and ‐ 0.63 ± 0.25 kJ mol−1, respectively, at 298K. Approximate values of the disproportionation/combination ratios for reaction of CH3with 1,1‐dimethylallyl and 1‐methylallyl have been estimated and used to compute rate constants for the recombinations oftert‐butyl and isopropy

ISSN:0538-8066    

DOI:10.1002/kin.550050402

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe photolysis of 3,3‐dimethylbutan‐2‐one (MTBK) has been studied in the gas phase at 408 and 326 K, mainly with light of 313 nm wavelength. At the higher temperature, the major products were methane, ethane, isobutane, isobutene, neopentane, tetramethylbutane, and carbon monoxide. At 326 K, in addition to these products, appreciable quantities of acetaldehyde, acetone, and biacetyl were detected. Quantum yields were determined using acetone and pentan‐3‐one as actinometers. A conventional mechanism is able to explain most of the experimental data. At 326 K, the results may be interpreted to yield a value for the rate constant for decomposition of the acetyl radical. Some theoretical calculations are reported on the acetyl radical decomposition and some earlier experimental work on this radical re

ISSN:0538-8066    

DOI:10.1002/kin.550050403

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe hydrogen abstraction from the chlorinated ethanes by chlorine atoms has been investigated in the liquid phase. Rate constants relative to that for hydrogen abstraction from chloroform have been measured between 267° and 333°K using a competition technique. The results are compared with gas‐phase d

ISSN:0538-8066    

DOI:10.1002/kin.550050404

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe kinetics of decomposition of trimethylene sulfide to ethylene and thioformaldehyde was investigated in a single‐pulse shock tube using the «relative rate» technique. The extent of reaction was measured in the reflected shock regime from 860° to 1170°K, but experimental difficulties limited the useful data to the temperature range of 980°–1040°K. The first‐order rate constant was found to bek= 1013.0exp (−48,200/RT) sec−1. This result sets an upper limit of 50 kcal/mole for the standard enthalpy of formation of CH2S, with 35 kcal/mole as a more likely value. The isomerization of cyclopropane to propene was used for the reference reaction; in turn, this was checked, in a relative rate experiment, against the pyrolysis

ISSN:0538-8066    

DOI:10.1002/kin.550050405

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractMeasurements have been made which provide information concerning the rate of energy transfer between vibrationally excited HF and atomic fluorine. It was found that HF (v= 1) deactivates about seven times slower than was determined in previous experiments. The deactivation rate constant for HF (v= 2) is about six times larger than for HF (v= 1).

ISSN:0538-8066    

DOI:10.1002/kin.550050406

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractDetection of atoms by mass spectrometry has been used to study the reactions of hydrogen azide, HN3, with H atoms and active nitrogen, in a fast flow reactor at pressures of about 1 torr. Stoichiometry and products of the H + HN3reaction have been determined and the rate constant of the initial step, assumed to be H + HN3→ NH2+ N2, was found to be 2.54 × 10−11exp (−4600/RT) cm3molecule−1s−1, in the temperature range of 300–460K. The formation of NH3and H2products has been discussed from the different secondary steps which may occur in the mechanism. For the reaction of active nitrogen with HN3, evidence has been found for the participation of excited nitrogen molecules produced by a microwave discharge through molecular nitrogen. The influence of excited nitrogen molecules has been reduced by lowering the gas flow velocity. It was then possible to study the N + HN3reaction for which the rate constant of the initial step was found to be 4.9 × 10−15cm3molecule−1s−1at room temperature. Finally, the occurrence of these elementary reactions has been discussed in the mechanism of the decompo

ISSN:0538-8066    

DOI:10.1002/kin.550050407

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractIn the study of chemical kinetics, many integrated reaction rate equations have the form In [f(A) +a] =bt+c, wherea,b, andcare constants andf(A) is some function of the concentration of a reactant (or product) which can be calculated from the data. The left‐hand side of this equation cannot be graphed versus time if the constantais unknown. However, it is shown thatf(A2) varies linearly withf(A1) if A2is the concentration of reactant measured at a constant time interval later than A1. The constantsaandbcan be determined from the linear graph. A number of specific examples are considere

ISSN:0538-8066    

DOI:10.1002/kin.550050408

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of dimethyl sulfoxide at small extent of reaction has been studied at temperatures of 297‐350°C and pressures of 10–400 Torr. The major products CH4, C2H4, and SO2were shown to follow first‐order kinetics. The activation energies for production of each was about 48 kcal·mole−1. A chain mechanism has been postulated in the light of the results of isotopic substitution ex

ISSN:0538-8066    

DOI:10.1002/kin.550050409

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractOxygen added in amounts of 0.01‐0.1% was found to cause the explosion of an acetylene–chlorine mixture at temperatures as low as −78°C. Explosion occurrence and nature depend on the mode of mixing the reactants, the effect of oxygen being associated with concentration limits. The dependence of explosion‐inducing oxygen amounts on temperature, pressure, concentrations of reactants, reactor surface type and area, additions of inert gases, and reaction products were investigated. The effect of light on the C2H2+ Cl2+ O2was studied. The composition of gaseous products resulting from acetylene–chlorine mixture explosion in the presence of minute amounts of oxygen, from a slow reaction inhibited and noninhibited by oxygen, and also from explosion at 400°C in the absence of oxygen, was determined. The results obtained point to the fact that any acetylene–chlorine mixture flash caused by small amounts of oxygen is a branched chain reaction involving activated particles, chain branching presumably being associated with the decomposition of radical CHCl=CHOO* →

ISSN:0538-8066    

DOI:10.1002/kin.550050410

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractMeasurements of the rate coefficient of the reaction (O3P) + NO2→ O2+ NO have been made at 296°K and 240°K, using the technique of NO2* chemiluminescent decay. Values of 9.3 × 10−12cm3molec−1sec−1at 296°K and 10.5 × 10−12cm3molec−1sec−1at 240°K were obtained, in excellent agreement with the recent results of Davis, Herron, and Huie [1]. The earlier lower values may have resulted from los

ISSN:0538-8066    

DOI:10.1002/kin.550050411

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY