摘要:

Water vapor, and mixtures of water vapor with radical and electron scavengers, have been irradiated with fission fragments at temperatures from 170 to 365 °C and densities from 1–50 mg/ml. The unimolecular hydrogen yield is the same as in γ-ray irradiations. In D2O–C6H12mixtures the HD yield and HD/H2ratio are lower than in γ-ray irradiations and N2O and SF6have little effect. The HD yield reaches a limiting value (G(HD) ~4) with increasing linear energy transfer suggesting that a fraction of the D atoms formed are hot.

ISSN:0008-4042    

DOI:10.1139/v68-627

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The new complexes GaCl3(bipy), GaBr3(bipy)2MeCN, GaBr3(bipy)2, Gala(bipy), and the related compounds [GaCl2(bipy)2]BF4, [GaCl2(bipy)2]PF6, [GaBr2(bipy)2]PF6(bipy = 2,2′-bipyridyl) have been prepared and characterized. Conductivity and far-infrared measurements suggest the structures [GaCl2(bipy)2][GaCl4], [GaBr2(bipy)2]Br, and [GaI2(bipy)2][GaI4] for the trihalide adducts.

ISSN:0008-4042    

DOI:10.1139/v68-628

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The thermal emission of negative azide ions from a heated filament operating in gases of both HN3and CH3N3has been studied in a magnetron cell and the temperature variation of this current used to deduce the C—N bond dissociation energies in both molecules. Results indicate higher values than previous estimates. They are:D0(H—N3) = 90 ± 8 kcal/mole andD0(CH3—N3) = 88 ± 8 kcal/mole at 0°K.

ISSN:0008-4042    

DOI:10.1139/v68-629

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The photolysis of HBr has been studied at 77 °K. The photodecomposition of solid state HBr is an inefficient process which is strongly inhibited by a reaction product, probably Br atoms, or by added Br2ortrans-butene-2. The results suggest H2is formed by abstraction from HBr by thermal H atoms, the activation energy for the abstraction being ~350 cal mole−1. The photolysis of both pure HBr and HBr with added Br2ortrans-butene-2 can be described by an absorber complex mechanism similar to that inferred by Hughes and Purnell in the photolysis of HI. The absorption tail of solid HBr extends beyond the gas phase absorption into the wavelength region in which trapped radicals are generated in HBr–olefin mixtures but where there is no H2evolution. The solid state absorption spectrum of Br2is contrasted with that of gaseous Br2; an absorption peak is observed at 2725 Å which may be associated with (Br2)naglomerates.

ISSN:0008-4042    

DOI:10.1139/v68-630

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A detailed study of the reactions of the acetone•BF3complex in excess acetone has been carried out by "F nuclear magnetic resonance (n.m.r.) spectroscopy. It is shown that rapid reversible fluorine exchange processes occur in solution, in addition to the slower aldol condensation–dehydration reaction. Two of the new19F absorptions which appear during the reaction are shown to arise from BF3complexes of donors which are formed by condensation and dehydration of acetone. The rate of the aldol condensation reaction is shown to fall off markedly as an increasing proportion of the BF3becomes complexed with water; thus BF3catalysis of the reaction appears to depend on the existence of a ketone–BF3donor–acceptor bond.1H and19F n.m.r. studies of the acetone•BF3complex in methylene chloride throw some light on the apparent greatly decreased reactivity of the complex in this solvent. Evidence is presented for the reversibility of the first step of the condensation reaction.

ISSN:0008-4042    

DOI:10.1139/v68-631

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Vinyl proton chemical shifts of styrene and six 4-substituted styrenes have been determined at infinite dilution in cyclohexane. It is shown that changes in the chemical shift difference of the β protons, Δ(δC − δB) can be accounted for by electric field effects. Reasonable values of the constant in the Buckingham equation of(−3.11 ± 0.50) × 10−12and (−4.77 ± 0.83) × 10−12are obtained from two different types of field effect calculations. Residual chemical shift changes for β protons after correction for electric field effects can be explained in terms of mesomeric and possibly inductive mechanisms. α-Proton chemical shift values cannot be satisfactorily rationalized. Small concentration effects are noted, usually resulting in high field shifts with increasing concentration. Previous results are reexamined in order to resolve a conflict in the literature.

ISSN:0008-4042    

DOI:10.1139/v68-632

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v68-633

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v68-634

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The lattice parameters and the quadrupole splittings of the room-temperature Mössbauer spectra of the cubic A2FeSbO7pyrochlores (A = Sm, Eu, Gd, Tb, Y, Er, Lu) have been found to vary linearly with the Templeton–Dauben radii of the A3+ions. The variation of the quadrupole splitting can be correlated with the positional parameter of the majority oxygen atom,x(O2), which determines the degree of distortion of the BO6octahedron in cubic A2B2O7pyrochlores. An increase of 0.1 Å inr(A3+) corresponds to a decrease of ca. 0.20 mm/s in the quadrupole splitting in the A2FeSbO7series, and to an estimated increase of ca. 0.005 inx(O2). The isomer shift and quadrupole splitting at room temperature are typical of Fe3+(high spin) in octahedral coordination of relatively high distortion. Y2FeSbO7at 4.2°K was found to exhibit magnetic order with a hyperfine magnetic field of approximately 400 kOe. An attempt to prepare a cubic La2FeSbO7, pyrochlore by the standard procedure was not successful.

ISSN:0008-4042    

DOI:10.1139/v68-635

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Tertiary alkyl and cyanoalkyl free radicals prepared fromt-butyl peroxypivalate and azobisisobutyronitrile were reacted with 4-vinylcyclohexene (1) for comparison with results previously obtained in the reaction of certain alkyl, alkoxy, peroxy, and thiyl radicals with this model olefin. The (CH3)3C• and (CH3)2(CN)C• radicals (like thiyl but in contrast tot-butoxy andt-butyl peroxy radicals) added to the vinyl double bond with subsequent abstraction of hydrogen by the resulting secondary alkyl radicals to give RH adducts along with higher molecular weight material.Vinylcyclohexenyl radicals formed by hydrogen abstraction from1reacted mainly by coupling to form dehydro dimers. They also formed substituted products by coupling with cyanoisopropyl radicals, but not witht-butyl radicals. The presence of both stabilized and unstabilized alkyl radicals of both secondary and tertiary types in these reactions with1permitted the observation of differences in the relative tendencies of these types of radicals to participate in addition, hydrogen abstraction, disproportionation, and coupling reactions. The observed effect of temperature (60 and 90°) on product distribution, together with estimated bond dissociation energies, suggest that the addition of cyanoisopropyl radicals to1is a reversible process.

ISSN:0008-4042    

DOI:10.1139/v68-636

出版商:NRC Research Press    

年代:1968

数据来源: NRC