摘要:

The γ-radiolysis of homogeneous solid solutions of SF6and N2O in cyclohexane has been examined at 77 °K. With SF6, yields of the major products, hydrogen, bicyclohexyl, and cyclohexene, were all reduced, and no large yields of other products were observed. Thus, since SF6reduces hydrogen yields by capturing electrons, combination of the SF6anion and cyclohexane cation does not lead to bond breaking. Experimental evidence suggests that the ratio of disproportionation to combination of cyclohexyl radicals in solid cyclohexane at ~ 186 °K is 0.3 ± 0.2.With N2O, hydrogen yields are decreased to 3.5 Gunits, but large yields of cyclohexene, bicyclohexyl, and cyclohexanol (4.7, 2.0, and 1.0 Gunits respectively) are produced. Thus combination of O−and the cyclohexane cation leads to a great deal of bond breaking. The yields are explained by a mechanism similar to Dyne's mechanism for the radiolysis of hydrocarbons. It was, however, necessary to assume that excited states of cyclohexane formed directly behave differently from those formed by electron–cation combination.

ISSN:0008-4042    

DOI:10.1139/v68-018

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The room temperature, liquid phase radiolysis of cyclohexane in the presence of three solutes, per fluorocyclohexane (PCH), perfluoromethylcyclohexane (PMCH), and perfluorocyclobutane (PCB) has been examined. All decrease the hydrogen yield from 5.6 to 2.6 Gunits by capturing electrons. However, with PMCH and PCB the yields of cyclohexene and bicyclohexyl are not decreased as much as the hydrogen yield and with PCH, dimer and olefin yields are increased. Furthermore, large yields of monohydrofluorocarbon (e.g. undecafluorocyclohexane) are produced, indicating that a carbon–fluorine bond has been broken. It is concluded that electron capture by these fluorocarbon compounds causes dissociation; possible mechanisms are discussed, but it was not possible to reach a clear conclusion on the basis of our results.The radiolysis of homogeneous solid solutions of these solutes at 77 °K has also been studied, but only PMCH was studied in detail. Under these conditions there is no evidence for dissociative electron capture and apparently the combination of solute anion and hydrocarbon cation on warming does not lead to bond breaking.

ISSN:0008-4042    

DOI:10.1139/v68-019

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The ion–molecule reactions in ethylene have been studied under conditions where C2H4+was the only primary ion. In addition to the expected secondary ions C3H5+and C4H7+, the C3H4+, C2H2+, and C2H3+ions have been detected, presumably formed by the reactionsReactions [b] and [c] are endothermic for ground state reactants and it has been shown that the kinetic energy of the reactant ion plays a major role in determining the relative importance of these endothermic reactions.The C5H9+ion has been shown to originate by further reaction of the C3H5+secondary ion rather than by reaction of the (C4H8+)* collision complex. The reversion of the (C4H8+)* complex to reactants has been confirmed by the observation of isotopically mixed ethylene ions in C2H4–C2D4mixtures.

ISSN:0008-4042    

DOI:10.1139/v68-020

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The theory of nucleation in solid state reactions is formulated in a general way and a solution to the problem of multi-step nucleation obtained. Two special cases of the general formulation are considered: the second of these corresponds to Bagdassarian's approximate model and some corrections to his treatment are pointed out. A new equation describing the kinetics of a solid state reaction, which involves multi-step nucleation followed by a constant and isotropic rate of growth, is derived. This equation is termed the generalized Avrami equation since it removes the restriction, in Avrami's treatment, of a single-step nucleation process. Erofeev's analysis of the problem is shown to be valid only in the limit of short times: the generalized Avrami equation reduces to Erofeev's equation in this limit.

ISSN:0008-4042    

DOI:10.1139/v68-021

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Crystalline complexes of norbornadiene with silver tetrafluoroborate have been obtained both from anhydrous and aqueous solution. While both solutions yield complexes of stoichiometry AgBF4•C7H8and 2AgBF4•3C7H8, those from the aqueous solutions also contain water of crystallization. The infrared spectra show that norbornadiene is similarly complexed in both the anhydrous and hydrated complexes but that the coordination in the 1:1 complex is different from that in the 2:3 complex. The anhydrous and hydrated 1:1 complexes have the same X-ray diffraction powder patterns while those of 2:3 complexes are different.

ISSN:0008-4042    

DOI:10.1139/v68-022

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The first order rate constants for the solvolysis of benzyl chloride in a series of mixtures of methyl, ethyl,i-propyl, andt-butyl alcohols with water are reported at 40.05 and 60.50 °C. The ΔH* and ΔS* values are calculated using these rate constants and those previously reported at 50.25 °C (1, 2). The dependence of these parameters on solvent composition is discussed.

ISSN:0008-4042    

DOI:10.1139/v68-023

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The nature of the coordination bond in some metal complexes of 4-substituted pyridines has been investigated by thermodynamic and infrared spectroscopic methods. The effects of the substituents upon the coordination bond strength in the copper(II) complexes of these ligands have been found by direct measurement of the heats of coordination. These effects have been further described by the substituent effect upon the change in free energy of the coordination center in the ligands. A new parameter,Rπ, measuring the relative π bonding in the complexes of 4-substituted pyridines has been introduced. For this purpose a series of complexes of the types [M(4—R—C5H4N)2Cl2] and [(4—R—C5H4N)•HCl] (R = CH3, CH2OH, H, COCH3, CONH2, COOCH3, CN; M = Cu(II), Zn(II)) has been isolated, and the infrared spectra of these complexes and the free ligands have been examined.

ISSN:0008-4042    

DOI:10.1139/v68-024

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Infrared spectra, including the lower frequency region, of copper (II) complexes of the type [CuL2Cl2], where L = 4-methylpyridine, 4-carbinylpyridine, pyridine, 4-acetylpyridine, 4-pyridinecarboxamide, 4-carbomethoxypyridine, and 4-cyanopyridine have been measured. The substituent effect upon the copper–nitrogen (ligand) and copper–chlorine stretching frequencies has also been examined. It was found that the substituents on the pyridine ring not only affected the nature of copper–nitrogen bond, but also the copper–chlorine bond. It appears that an entirely delocalized system exists, involving the chlorine atoms and the substituents in the complexes. Force constants associated with the coordination bond between copper and the nitrogen of the ligands have been calculated by means of an IBM 1620 computer. By comparison of the copper–nitrogen stretching frequencies with the corresponding force constants, and the heats of coordination, it may be concluded that the magnitude of the metal–ligand stretching frequency is directly related to the metal–ligand coordination bond strength for the systems under study.

ISSN:0008-4042    

DOI:10.1139/v68-025

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Colored solutions of selenium in fluorosulfuric, sulfuric, and disulfuric acids have been investigated by conductometric, cryoscopic, spectrophotometric, and magnetic methods. Evidence is presented for the new species Se42+and Se82+in the yellow and green solutions respectively.

ISSN:0008-4042    

DOI:10.1139/v68-026

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reaction between allene and hydrogen over pumice-supported metals of the eighth group has been investigated in a constant volume reactor for a wide range of temperature and reactant ratios. The shape of the pressure–time curves were found to be dependent upon the reactant ratios and their order of admission. The reaction over nickel–pumice is principally a selective formation of propylene with small yields of propane and reduced polymers of allene. The orders of hydrogenation reaction are first, or slightly higher, and zero with respect to hydrogen and allene respectively. The apparent activation energies for Pd, Pt, Co, Fe, Ni, Rh, Ir, Ru, and Os are 13, 17.4, 10.8, 9.4, 7.8, 9.6, 5.3, 3.0, and 4.6 kcal/mole respectively. The catalytic activities of the metals are in the sequenceWhile selectivity was found to decrease with increasing initial hydrogen pressures, it increased with increasing temperatures.

ISSN:0008-4042    

DOI:10.1139/v68-027

出版商:NRC Research Press    

年代:1968

数据来源: NRC