摘要:

The rate of the elementary dissociation of ethane into two methyl radicals has been measured in its pressure-dependent region at temperatures from 913–999 °K and at pressures from 1–200 mm. The high-pressure first-order rate constant obtained by extrapolation was in agreement with that obtained at lower temperatures,Comparison with calculated Kassel curves showed that the best fit of the data was obtained with the Kassel parameters = 12 ± 1. The high-pressure first-order rate constant for the decomposition of the ethyl radical was obtained by extrapolation of the data reported in Part I, assuming the rate constant for combination of ethyl radicals is independent of temperature.From the measured constant for the dissociation of ethane, the rate constant for the combination of methyl radicals was calculated and compared with the values measured in a lower temperature region. Differences in the values of the rate constants and in the shapes of the unimolecular falloff curves are discussed.

ISSN:0008-4042    

DOI:10.1139/v66-357

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The kinetics of the secondary reactions producing methane, butane, and butene-1 in the pyrolysis of ethane have been investigated over the temperature range 550–726 °C and at pressures from 600–10 mm. The rate of secondary methane production was second order in ethylene at high pressures but was first order in ethylene at low pressures and high temperatures. In the latter region it is concluded that isomerization of then-butyl radical tosec-butyl with subsequent decomposition to CH3 + C3H6was the main source of methane. The rate of butane formation increased with time at low temperatures and decreased with time at high temperatures. It is shown that the decrease in rate was mainly due to the thermal dissociation of butane. The main source of butene-1 was probably decomposition of then-butyl radical.

ISSN:0008-4042    

DOI:10.1139/v66-358

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The relative rates of hydrogen atom abstraction from ten substituted toluenes byt-butoxy radicals in carbon tetrachloride at 40 °C have been measured and the data fitted to the Hammett equation. A much better correlation is obtained with the σ+constants than with the σ constants of the substituents. In this respect, therefore, the reaction is similar to the majority of hydrogen atom abstraction reactions by radicals of moderate and high electron affinity. That is, the polar properties of the substituents are much more important than their stabilizing effect on the benzyl radical formed in the reaction.The cumyloxy radical has a similar reactivity to thet-butoxy radical. Thep-nitrocumyloxy radical appears to be slightly more reactive and also slightly more susceptible to the polar effects of substituents than aret-butoxy or cumyloxy radicals.

ISSN:0008-4042    

DOI:10.1139/v66-359

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Studies were made of the relative rates of rotation around the benzene-to-carbonyl, carbonyl-to-nitrogen, and nitrogen-to-benzene bonds in some α-naphthamides,o-substituted benzamides, and related compounds. In general bulky substituents on the nitrogen atom tend to increase the rate of rotation around the carbonyl-to-nitrogen bond, but to decrease the rate around the benzene-to-carbonyl bond. Naphthanilides witho-substitution in the benzene ring have a rapid rate of rotation around the naphthalene-to-carbonyl bond compared with other naphthamides. Relative rates of rotation can be rationalized on the basis of combined steric and electronic effects.

ISSN:0008-4042    

DOI:10.1139/v66-360

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Activity coefficient data for ten substituted benzamides and two benzamide salts have been obtained from solubility measurements in 0–70% sulfuric acid. The ionic activity coefficients have been referred to a standard ion, the tetraethylammonium ion. The variations of activity coefficient with acid concentration are discussed and compared with available data for anilines and anilinium ions. Estimates have been made of the relative importance of the various terms contributing to the total acidity function for sulfuric acid. Up to 40% acid the order of importance of these terms isand in more concentrated acids becomes.

ISSN:0008-4042    

DOI:10.1139/v66-361

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The charge-transfer transition energies for a series of methylbenzene–tetracyanoethylene complexes in four solvents are reported. The charge-transfer transition energies are found to decrease with increasing solvent refractive index. The magnitude of the decrease appears to be a function of donor strength. It is inferred that the excited state dipole moment decreases with increasing donor strength for these complexes.

ISSN:0008-4042    

DOI:10.1139/v66-362

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The thicknesses of oxide films formed in aqueous borate solutions were obtained by the spectrophotometric method after developing the interference colors by evaporating a very thin film of gold or bismuth onto the oxide. The refractive index of the stripped films was determined by the Becke immersion method as 1.57 to 1.58 at 5 900 Å wavelength. The dielectric constant was estimated as 9.8 ± 0.5. Experimental data on the steady state ionic current density,I, through the oxide as a function of the field strength,E, in the oxide could be represented byI = I0exp −(W − qaE)/kTwhereI0 = 2.24 × 107 A cm−2,W = 1.3 ± 0.15 eV,q = 3e,a = 2.95 ± 0.15 Å.

ISSN:0008-4042    

DOI:10.1139/v66-363

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The rates of solvolysis of 1-(p-alkylphenyl)ethyl chlorides (Alk = Me, Et,i-Pr, andt-Bu) in the presence and absence of mercuric chloride have been measured in aqueous acetone and ethanol solvents. In all cases, the Baker–Nathan order is followed. For all normal reactions and for the catalyzed reactions in 90% aqueous acetone and 90% aqueous ethanol there is an increase in the heats and entropies of activation as the series is ascended, while for the catalyzed reaction in 75% and 80% aqueous acetone, there is a decrease. It is suggested that in the more aqueous acetone solvents the catalyst calls into play an inductomeric effect. The effect of added chloride ions on the rate of hydrolysis has been studied and the results are discussed.

ISSN:0008-4042    

DOI:10.1139/v66-364

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

In the measurement of electromotive forces at temperatures over 1 000° spurious contact potentials, which may be asymmetric, are sometimes encountered. As an example of these, contact potentials between solid oxides and electrically grounded portions of their environment were measured at temperatures between 1 000° and 1 450°. Their variation with temperature, gaseous environment, and impedance of the measuring circuit is presented and interpreted in terms of thermionic emission.

ISSN:0008-4042    

DOI:10.1139/v66-365

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The preparation of tetraphenylcyclopentadienone rhodium chloride, tetraphenylcylopentadienone rhodium carbonyl chloride, duroquinone rhodium chloride, and 2,3,5,6-tetraethyl-p-benzoquinone rhodium chloride from rhodium dicarbonyl chloride dimer and the appropriate organic ligand are described. The properties of these complexes and some of their reactions are discussed.

ISSN:0008-4042    

DOI:10.1139/v66-366

出版商:NRC Research Press    

年代:1966

数据来源: NRC