摘要:

Pulse radiolysis of tetrahydrofuran (THF), dimethoxyethane (DME), diglyme (DG), and triglyme (TG), results in the formation of solvated electrons, es−, with optical band maxima λmax ≥ 1840 nm. In the presence of alkali metal salts transient optical bands are observed with λmaxat ∼900 and ≥1600 nm. The latter bands are assigned to the formation of 'monomeric' species of stoichiometryMconsidered to be 'tight' and 'loose' ion-pairs, respectively. The proportion of 'loose' ion-pairs increases with decreasing temperature and increasing coordination of the solvent in the orderThese results demonstrate a good correlation with established electron spin resonance data in alkali metal solutions and substantiate the coexistence of at least two 'monomeric' species in DME and the glymes.

ISSN:0008-4042    

DOI:10.1139/v77-470

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The apparent molal volumes and heat capacities of nine amino acids were measured in water at 25 °C with a flow densimeter and a flow microcalorimeter. It is shown that the poor additivity of the standard partial molal quantities of amino acids in water are attributable to the ionization of the two groups NH2and COOH. The hydration of these ionic groups interfere with each other when they are separated by less than three carbon atoms.

ISSN:0008-4042    

DOI:10.1139/v77-471

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The heat capacities per unit volume at 25 °C and densities from 10 to 55 °C of sodium phenyl carboxylates were measured with a flow microcalorimeter and a flow densimeter. The apparent molal heat capacities and volumes were used to derive standard partial molal heat capacities, volumes, and expansibilities. The CH2contribution tois the same as that usually observed for aliphatic solutes but the contribution toandis not constant and significantly different. No simple explanation can be offered for this anomaly.

ISSN:0008-4042    

DOI:10.1139/v77-472

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Prompted by the experimental investigation of Betts and Buchannon a thorough analysis of CS2vapor pressure isotope effects has been made in the context of the theory of isotope effects in condensed phases and the available spectroscopic information. The agreement between the calculated and experimental results is satisfactory. The calculated results may be empirically described by the equationsandThe analysis indicates that the principal contribution to the13C isotope effect is due to the shift on condensation of the asymmetric stretching frequency Δν3, and quantitatively corroborates the theoretical conclusion reached earlier by Akopyan, Girin, and Bakshiev and others of the magnitude of the dielectric correction for this band. The34S effects are principally determined by the hindered rotation and translation in the liquid and the shift in the symmetric stretching motion Δν1

ISSN:0008-4042    

DOI:10.1139/v77-473

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The electrical conductivity dependence on temperature measurements for three metal basic chlorides are reported. The conductivity results yield energy values which are interpreted in terms of active solid state processes leading up to, and including, the decomposition step.

ISSN:0008-4042    

DOI:10.1139/v77-474

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The widely-used halothane anaesthetic CF3CHBrCl exhibits a proton magnetic resonance signal in CCl4solution which is strongly deshielded by addition ofN-methylpyrrolidone. This is interpreted as a hydrogen-bonding interaction with halothane C—H as donor and carbonyl as acceptor. From the temperature dependence of the halothane C—H proton chemical shift in the presence of varying concentrations ofN-methylpyrrolidone, thermodynamic parametersΔH0 = −4.7 kcal mol−1and ΔS0 = −14 cal mol−1deg−1were obtained. The carbon magnetic resonance spectrum of the two components in CCl4shows desheilding of the carbonyl carbon at higher concentrations of CF3CHBrCl the halocarbons (1-H) undecafluorobicycloheptane and (1-H,4-H)decafluorobicycloheptane show similar H-bonding behaviour which is comparable with that exhibited by CHCl3.These results are discussed in relation to their possible relevance to the mechanism of action of halocarbon anaesthetics.

ISSN:0008-4042    

DOI:10.1139/v77-475

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Under electron impact, the two isomers resulting from tricarbonylchromium complexation ofN-benzylideneaniline decarbonylate completely before the chromium-ring bond is broken and the azomethine ligand undergoes further fragmentation. The loss of two CO molecules is favored over the competitive process involving elimination of a single CO molecule, especially at high ionizing voltage. In both cases the highly stable benzylideneanilinechromium cations decompose primarily through fission of the metal-ring bond, although additional fragmentation pathways of minor importance are also observed. The decay patterns of the benzylideneaniline ligand cation are identical in the spectra of both complexes and very nearly coincide with that shown by benzylideneaniline itself under the same conditions of electron impact.

ISSN:0008-4042    

DOI:10.1139/v77-476

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Prototype formulations are considered for the reaction pathways commonly encountered for the electrolytic reduction of organic compounds in aqueous and nonaqueous media on the basis that the essential feature is severance of a chemical bond which requires transfer into the reaction site of one or two electrons; multiple electron processes result from instability at the applied potential of initially produced species or their chemically altered products. To obtain electrical neutrality, uptake of electrons may have to be accompanied by that of a cation, generally a proton. Pertinent factors in the path followed in the overall electrode process may include a sequence of free radical or radical anion going to dimeric or carbanion species (depending on the relative rates of chemical and charge-transfer steps), possible interaction of intermediate products with their progenitors, proton donor activities, medium properties (e.g in respect to rates of chemical reactions accompanying charge-transfer and control of the chemical states of reactants and intermediates), stereochemical factors inherent in reactant and intermediate species, and chemical interaction with the electrode material. Application of the general mechanistic considerations are illustrated by various types of electrolytic reductions: aromatic hydrocarbon, nitrogen heterocycle, carbon–halogen bond, ketone carbonyl group, and beta halogenated and/or unsaturated acids.

ISSN:0008-4042    

DOI:10.1139/v77-477

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Infrared and Raman spectra were obtained for 2-bromopentane, 3-bromopentane, 2-bromohexane, and 3-bromohexane. Vibrational assignments were made for several conformers of each compound with the aid of normal coordinate calculations. A 48 parameter modified valence force field was obtained that fit 221 frequencies of three conformers of 2-bromopentane, 4 conformers of 3-bromopentane, and 1 conformer of 2-bromobutane with an average error of 4.1 cm−1. This force field was transferred to the bromohexanes, with good results.

ISSN:0008-4042    

DOI:10.1139/v77-478

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Effective non-adiabatic potential curves were constructed for the ground states of the deuterium molecule and of the hydrogen and deuterium molecule-ions by scaling our empirical non-adiabatic coupling correction for hydrogen according to the approximate rules given by Bunker. These effective potentials were refined by the techniques we have described previously, and were then used to generate the rotation–vibration energy-level spectra for H2+and D2+; tables of these energy levels, which we consider to be the best available at the present time, are presented.

ISSN:0008-4042    

DOI:10.1139/v77-479

出版商:NRC Research Press    

年代:1977

数据来源: NRC