摘要:

The photochemical loss of cyanide from Mo(CN)84−is shown to be sensitized by common organic triplet donors naphthalene, phenanthrene, anthraquinone, and benzophenone, but not by biacetyl. This suggests that the reactive state may be3B1, not the lower lying3A2. The quantum yields for sensitized photolysis (near 0.25) are larger than for the direct reaction (near 0.15). This is unlike the behavior of Co(CN)63−where the similarity of the two yields leads to the conclusion that higher excited states are efficiently converted to "the lowest triplet".Naphthalene irradiated at 286 nm leads to a quantum yield of 0.4 which is, perhaps, associated with a new process involving sensitized production of a solvated electron.Thermal solvolysis rates in several media are also reported. The medium dependence of solvolysis is small.

ISSN:0008-4042    

DOI:10.1139/v71-114

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Activities of CoO in CoO–SiO2melts were measured at 1450–1500 °C by equilibrating the melts, held in Pt–Rh containers, with atmospheres of known oxygen potential. Activities were calculated by the relationshipwhereaCo, the activity of cobalt in the container, was determined in separate experiments.The results were compared with theoretical activity–composition curves based on the application of polymer theory to silicate melts. The results were in good agreement with theoretical curves calculated on the assumption of linear chains. In contrast, for all other binary silicate melts so far investigated the results are best represented in terms of theory in which all chain configurations are allowed. Ionic distributions and number average and weight average molecular weights were calculated as functions of the silica content from the experimental data. The calculated proportions of monomeric ion, SiO44−, dimer Si2O76−, and trimer Si3O108−were in reasonable agreement with experimental values based on trimethylsilylation and gas-chromatographic separation of the ionic constituents in quenched melts.

ISSN:0008-4042    

DOI:10.1139/v71-115

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A new apparatus is described in which the solubility of deuterium sulfide in deuterium oxide and of hydrogen sulfide in water have been determined with 0.1 % accuracy between 0 and 50 °C. Solubility equations are derived and the solubility standard thermodynamic function changes, together with their standard errors, are tabluated. Equal solubilities would occur at −1 °C. The solubility of hydrogen sulfide in water is greater than for deuterium sulfide in deuterium oxide, the solubility difference increases to a maximum at 40 °C and thence decreases at higher temperatures.

ISSN:0008-4042    

DOI:10.1139/v71-116

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Carbon disulfide has been shown to undergo insertion reactions with [Ni(aziridine)4,6]2+and [Ni(2-methylaziridine)4]2+. The diamagnetic products are formulated as planar dithiocarbamate complexes in which the heterocyclic ring remains intact. The complexes have properties which are atypical of all dithiocarbamate complexes heretofore reported, and infrared and optical spectral measurements suggest that the insertion products may be the first examples of N,S-bonded dithiocarbamate ligands. In methanol the products slowly rearrange to give S,S-bonded complexes in which the aziridine rings have been opened.

ISSN:0008-4042    

DOI:10.1139/v71-117

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The Raman spectrum of gaseous TeCl2Br2at 310 °C is reported for the first time. The gas phase data is consistent with the presence of a monomolecular species hayingC1symmetry. A synthetic route for the preparation of penta- and hexa-co-ordinate mixed halide anions of tellurium(IV), under anhydrous conditions, is described for the first time. The infrared and Raman spectra for solid [Et4N]TeCl2Br3and [Et4N]2TeCl2Br4are reported. A stereochemistry based on a square pyramid, is favored for [Et4N]-TeCl2Br3. In the case of [Et4N]2TeCl2Br4the vibrational data strongly suggests the presence of acis-octahedral anion, havingC2vsymmetry.

ISSN:0008-4042    

DOI:10.1139/v71-118

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Activity coefficients for aqueous sodium and potassium tetraborate, sodium metaborate, sodium and potassium fluoroborate, and orthoboric acid were derived from their freezing points. The measurements confirmed in general the behavior of these salts at 25° except that the tetraborates showed different low concentration behavior from that predicted from isopiestic data. Because of this difference, the 25° activity coefficients reported earlier for sodium and potassium tetraborates have been revised. The new values for 0.15 msolutions of the tetraborates are 0.345 at 25° and 0.303 at the freezing point.

ISSN:0008-4042    

DOI:10.1139/v71-119

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Dielectric constants and losses of the four butyl alcohols have been measured at concentrations of 0.02–0.12 mol fraction inp-xylene solution over the frequency range 1–35 GHz at 25 °C. The data for the most dilute solutions can be represented by a symmetrical distribution of relaxation times. For the mole concentrated solutions the Cole–Cole plots indicate a separation into two absorption regions and the data can be analyzed in terms of two relaxation times both of which lengthen with increased alcohol concentration. The contribution from the long relaxation time and the apparent dipole moment for each butanol, is independent of alcohol concentration and decreases in the ordern-butanol > iso-butanol > sec-butanol > t-butanol. The results are discussed in terms of previous dielectric relaxation studies of pure liquid aliphatic alcohols and their solutions in non-polar solvents.

ISSN:0008-4042    

DOI:10.1139/v71-120

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The synthesis and properties of 5-hydroxymethyldeoxyuridine (6) and its α-anomer7are described. Treatment of 5-hydroxymethyluracil (2) with trimethylchlorosilane in the presence of triethylamine gave 2,4,5-tris(trimethylsilyl)-5-oxymethyluracil (3) in excellent yield (92%) which, upon condensation with 3,5-di-(O-p-toluoyl)-2-deoxy-D-ribofuranosyl chloride in acetonitrile at room temperature, furnished an anomeric mixture of substituted nucleosides β-anomer (4) and α-anomer (5) in high yield 90% (by a fusion method (12) yield of blocked nucleosides was 70%). Compound4was the major product formed by both methods and was recovered as a crystalline solid in high yield. However, condensation of3with chlorosugar in benezene with mercuric chloride as a catalyst at room temperature gave a mixture of protected nucleosides; the amount of5formed was appreciably higher (34%) and was isolated as a microcrystalline solid from mother liquors in low yield (without the catalyst nucleosides were formed in low yield 30%). Removal of the blocking groups by alcoholysis gave6and7in high yields. The structure was confirmed by n.m.r. studies, u.v. and i.r. absorption spectra, elemental analysis, and by conversion of4to β-thymidine (8).

ISSN:0008-4042    

DOI:10.1139/v71-121

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

γ-Radiolysis of a mixed disulfide, cysteine-cysteamine disulfide, in unbuffered aqueous solution (0.3 mM) was investigated in the presence and absence of oxygen. The principal products were the thiols (cysteine and cysteamine), the corresponding sulfinic and sulfonic acids, the symmetrical disulfides (cystine and cystamine) and ammonia. Cystine and cystamine were formed in very high yields in deaerated solution; (G(CySSCy) ~ 15) but addition of oxygen reduced the yield sharply and it was inversely proportional to the oxygen concentration except at very low oxygen levels. In aerated solutionG(CySSCy) = 0.8. These observations were attributed to a chain reaction which was suppressed by oxygen:In the case of proteins, it was concluded that although chain reactions between RS• radicals and protein disulfide bonds were possible, they should be inhibited by oxygen.

ISSN:0008-4042    

DOI:10.1139/v71-122

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The broad line p.m.r. spectra of the alkali metal oleates have been observed from 77 °K up to or beyond the crystalline to waxy phase transition. Lower phase transition temperatures are observed in the oleates than in the stearates. This fact is attributed to larger entropies of transition in the oleates than in the stearates. The n.m.r. second moments indicate that in the stearates the packing of chains is probably not closer than in the oleates and consequently that the barriers to chain reorientation are not significantly higher in the stearates than in the oleates. Sodium oleate and stearate both appear to behave irregularly in the series of alkali metal soaps. Spin-lattice relaxation times have been measured by adiabatic rapid passage methods for both alkali metal oleates and stearates. Values ofT1and of the activation energy barrier for the reorientation of end methyl groups are compared with values obtained by other workers. No significant difference is seen between relaxation processes in stearates and oleates, at least in the lower temperature range. Soaps which seem to have some amorphous character have a second relaxation mechanism, in addition to end methyl group rotation, which is evidently important in the region of about 150–250 °K.

ISSN:0008-4042    

DOI:10.1139/v71-123

出版商:NRC Research Press    

年代:1971

数据来源: NRC