摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v70-551

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

H atoms and•C2H5radicals in the radiolysis of liquid ethane have both ionic and non-ionic precursors. The use of SF6as an electron scavenger leads to very low C2H4yields which is consistent with the addition of•SF5radicals to this product. H and D atoms produced by neutralization of ND3H+can either add to C2H4or abstract from C2H6at 195°K.

ISSN:0008-4042    

DOI:10.1139/v70-552

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The radiolysis of hydrocarbons containing dissolved D2S leads to HD, D2, and H2formation, the total hydrogen yields being greater than those in the absence of D2S. A limiting yield of HD is attained at low D2S concentrations (~5 mole%) in all solvents studied. This limiting yield is equal toG(H•) in ethane at 195°K but not inc-C6H12at 298°K whenG(HD) is much greater than accepted values ofG(H•). D2S behaves as both an electron and a positive ion scavenger, most of the D2and probably some of the HD being formed in these processes. The use of D2S to determine H atom and ion yields in irradiated alkanes is not recommended.

ISSN:0008-4042    

DOI:10.1139/v70-553

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.

ISSN:0008-4042    

DOI:10.1139/v70-554

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The kinetics of the thermal insertion reaction of SnBr2and SnCl2with the metal–metal bonded dimer [π-C5H3Fe(CO)2]2have been studied by following the change in the visible spectrum. The kinetic data are consistent with a two-stage mechanism involving the formation of a carbonyl-bridged intermediate followed by nucleophilic attack by the halides on this intermediate. The formation of the intermediate requires an activation enthalpy of 38.0 ± 1.0 kcal/mole, and an activation entropy of 45.5 + 1.5 cal mole−1 deg−1. The activation energy required to break the Fe—Fe bond is estimated to be about 32 kcal/mole.

ISSN:0008-4042    

DOI:10.1139/v70-555

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The stoichiometry was determined for the oxide formed by bubbling oxygen through thallium amalgam until the wt.% thallium in the amalgam was reduced by about 2%. The composition of the oxide depended upon the wt.% Tl in the amalgam. In the most dilute amalgams the oxide approached the formula Tl2O and as the wt.% Tl increased the oxide became richer in thallium(III). Between 20 and 29 wt.% Tl the oxide approximated Tl3O2and for alloys richer in thallium the oxide became richer in thallium(III). When the wt.% Tl in the alloy was 41.0 the ratio of thallium to oxygen in the oxide was 1.19. It is suggested that the experimental results indicate the existence of shortrange order in the liquid.

ISSN:0008-4042    

DOI:10.1139/v70-556

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Nuclear spin – lattice relaxation timesT1of protons have been measured as a function of concentration at room temperature for H2O/CD3COCD3and CH3COCH3/D2O solutions. The results show thatT1reaches a minimum at ~ 0.8 mole fraction of water in both solutions. This is interpreted in terms of molecular association between water and acetone molecules by hydrogen bonding.Theoretical values for (1/T1)rotand (1/T1)transare also calculated from rotational and translational correlation times using Stokes' model and the microviscosity model. Comparison with the experimentalT1's shows that both models are inadequate to describe the system.Contributions to the overall (1/T1) from (1/T1)rotand (1/T1)transare analyzed. It is found that the rotational motion dominated the relaxation process. The use of two different interaction parameters λ and ηeto describe molecular association is discussed.

ISSN:0008-4042    

DOI:10.1139/v70-557

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Analysis of the products of the pyrolysis of propylene in the initial stages shows that products of molecular weight up to C9are primary products of major significance below about 850 °K and above about 200 Torr. As these products accumulate in the system, their dissociation causes secondary initiation and a rapid increase in pressure. Measurements of the initial rate of decrease in pressure and of the final maximum rate of increase in pressure of the reaction are consistent with this interpretation of the mechanism.

ISSN:0008-4042    

DOI:10.1139/v70-558

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The photolysis of cyclobutanone has been examined at 3260, 3130, and 2537 Å in a variety of solvents and as a pure liquid. Both decarbonylation and photocleavage to C2H4and CH2CO occur with substantial yield in a manner which appears to be somewhat at variance with the currently accepted gas phase mechanism. While C2H4/(cyclopropane + propylene) is relatively insensitive to photon energy, there is a significant wavelength dependence in the rate of propylene formation suggesting that the photoreactions of cyclobutanone occur at rates comparable with relaxation times in solution.

ISSN:0008-4042    

DOI:10.1139/v70-559

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The reaction between allene and hydrogen over unsupported nickel, copper, and their alloys has been investigated in a static constant volume system between 26 and 131 °C for a wide reactant ratios. The orders of reaction with respect to hydrogen and allene were one and zero, respectively, and temperature independent. The reaction over metals and their alloys is largely simple hydrogenation, the early stages being principally a selective formation of propylene, with small yields of reduced polymers of allene. The overall activation energies varied between 4.8 and 11.8 kcal/g-mole. Selectivity was highest with copper and least with nickel. The amount of allene polymerized was not related in any particular way to the copper content of alloy.

ISSN:0008-4042    

DOI:10.1139/v70-560

出版商:NRC Research Press    

年代:1970

数据来源: NRC