摘要:

Equations for enthalpies and volumes of mixing are derived from thermodynamic association theory for complex binary liquid mixtures containing self-associating species and binary complexes. The various species can interact through general non-specific interactions of the simple mixture type.The equations, along with equations for the excess Gibbs energy, are applied to experimental data on excess Gibbs energies, heats, and volumes of mixing for the three binary systems formed from acetonitrile, carbon tetrachloride, and chloroform. The data require a theoretical model that involves two types of self-association of acetonitrile, one type of self-association of chloroform and formation of a binary complex CH3CN•2CHCl3. Thermodynamic parameters for the various types of association and interaction are derived by constrained least-squares methods, and provide a unified picture of the thermodynamic properties of these mixtures.

ISSN:0008-4042    

DOI:10.1139/v77-415

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Starting from the Diels–Alder adduct of furan and methyl β-nitroacrylate, the synthesis of the title compound is described.

ISSN:0008-4042    

DOI:10.1139/v77-416

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Starting from teloidinone5a, 2-(2′α,3′α-dihydroxy-4′β-hydroxymethyl-N-carbomethoxypyrrolidin-1β-yl)maleimide1b, a showdomycin analogue in which the ribofuranosyl ring oxygen is replaced by anN-carbomethoxy group, has been synthesized in 7% overall yield.

ISSN:0008-4042    

DOI:10.1139/v77-417

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Published values for the potential parameters σ and ϵ/kof the Lennard–Jones (12–6) and Stockmayer (12–6–3) potentials as based on viscosity measurements are reviewed, with particular reference to the problem of indeterminacy inherent to such calculations. A number of correlation techniques, calibrated on viscosity-based potential parameters, are critically reviewed; where possible, priority rules for the use of these correlations have been developed. In addition, several other criteria (i.e. not based on viscosity data) for the acceptance or rejection of σ and ϵ/kparameter values are also discussed. Upon application of the various criteria and priority rules it has been possible to give recommended σ and ϵ/kparameter values for 75 molecules.

ISSN:0008-4042    

DOI:10.1139/v77-418

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The1H and13C resonances of methane have been measured at 298 K, both as pure CH4in the gas phase as function of the density as well as at low concentration in solution, using polar, non polar, isotropic, as well as magnetically anisotropic solvents. It is found that both the gas and the solution proton shift data can be readily understood in terms of the Van der Waals shielding σwand the mean-square field due to the dispersive interactions:. Either a macroscopic reaction field model or a binary collision statistical mechanical model forcan be used with an approximately equal degree of success. Whereas the13C gas phase shifts of CH4are also proportional to the density, the13C gas-to-solution shifts indicate that, apart from σw, there exists even in non-polar isotropic solvents another effect which is not proportional to. The present study also includes a new proposal regarding, a discussion of anisotropy shielding σain magnetically anisotropic solvents and a discussion of the effectiveBparameters (1H and13C) of CH4in the gas and the solution state.

ISSN:0008-4042    

DOI:10.1139/v77-419

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The reaction of XeF2with aryl and alkyl sulfides and thiols has been investigated. Oxidative-fluorination of diphenyl sulflde andtert-butylphenyl sulfide gives diphenylsulfur difluoride andtert-butylphenylsulfur difluoride, respectively. The presence of an α-hydrogen substituent leads to α-fluorination and, in some cases, to olefin formation while reaction of XeF2with thiols gives disulfldes. HF catalyzed decomposition of products and intermolecular fluorine exchange is inhibited by the addition of [(CH3)3Si]2NH.On a étudié la réaction de XeF2avec des sulfures et des thiols d'aryles et d'alkyles. La fluoration oxydative du sulfure de diphényle et du sulfure detert-butylphényle conduisent respectivement au difluorure de diphénylsulfure et au difluorure detert-butylphénylsulfure. La présence d'un hydrogène comme substituant en α conduit à une α fluoration et dans quelques cas à la formation d'oléflne; la réaction de XeF2avec les thiols conduit aux disulfures. La décomposition catalysée par HF des produits et l'échange intermoléculaire du fluorure sont inhibés par l'addition de [(CH3)3Si]2NH. [Traduit par le journal]

ISSN:0008-4042    

DOI:10.1139/v77-420

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Salicylic acid forms a 1:1 complex with boric acid, the reaction involving both the fully protonated ligand, and the salicylate ion. The kinetics of this reaction have been studied by the stopped-flow method. The stability constant for the reaction involving salicylate ion has been calculated from measurements of the absorbances of solutions at equilibrium and is the same as that obtained from the kinetic data. The kinetic results at pHvalues in the range 3.45–4.63 suggest that, when salicylic acid is the ligand, the complex is formed in two steps. A similar process may also occur with salicylate ions.

ISSN:0008-4042    

DOI:10.1139/v77-421

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The virial partitioning of a molecular electronic charge distribution, ρ(r), divides a molecule into a collection of chemically identifiable atomic-like fragments. When two fragments interact strongly the distribution of charge in the region between their nuclei contains a saddle pointThe gradient paths (paths of steepest ascent through ρ(r), as traced by the vectors) whichterminateat this internuclear saddle point, define the virial partitioning surface which lies between the fragments. The two gradient paths whichoriginateat the internuclear saddle point and terminate at each of the fragment nuclei define abond path: the path which follows the ridge of maximum charge density between a pair of bonded nuclei. When the internuclear axis does not coincide with a symmetry axis, the internuclear stationary point will, in general, lie off the axis, and the bond path joining the nuclei will deviate or curve from this axis. The magnitude and direction of this 'bond curvature' as determined by the bond path agrees well with chemical expectations.

ISSN:0008-4042    

DOI:10.1139/v77-422

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The influences of nitrogen, hydrogen, and pyridine on the conversion of 3-carene into various products over chromia catalyst at 450 °C and over chromia–alumina at 400 °C have been investigated. Nitrogen acts as a diluent over these catalysts; hydrogen at low partial pressures enhances the formation of cymenes over chromia, but suppresses its formation over chromia–alumina. Increase of the partial pressure of hydrogen increases the proportion of men thanes over chromia–alumina, but decreases it over chromia catalyst. Pyridine suppresses the over-all conversion of 3-carene and the formation of cymenes over chromia and chromia–alumina; however, it increases the formation of menthadienes over chromia–alumina. These observations are explained in terms of the acidity of chromia and chromia–alumina, the diluting effects of nitrogen, hydrogen, and pyridine, and their ability to adsorb and desorb over the catalyst surfaces.

ISSN:0008-4042    

DOI:10.1139/v77-423

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The transition-state activity coefficientapproach has been applied to the acid-catalyzed hydrolysis of benzamide and itsN-alkyl derivatives. For all systems (with the exception of theN-tert-butyl derivative which reacts via carbon–nitrogen bond cleavage) a uniform type of medium dependence ofis observed. The reaction shows a pronounced destabilization of S≠over the whole region of acidity studied, practically identical to that found for the AAc-2 type of ester hydrolysis. This is interpreted in terms of an AoT2 mechanism of amide hydrolysis, that is the rate-determining formation of the oxonium-type tetrahedral intermediate from the O-protonated form of substrate conjugate acid.

ISSN:0008-4042    

DOI:10.1139/v77-424

出版商:NRC Research Press    

年代:1977

数据来源: NRC