摘要:

Protonation of bis(glycylglycinato)cobaltate(III) in acidic aqueous solutions has been investigated by proton magnetic resonance spectroscopy. Chemical shift measurements indicate that the site of protonation is the peptide oxygen rather than the Co(III)-coordinated, deprotonated peptide nitrogen as previously proposed, and that the two peptide linkages are protonated in a stepwise fashion rather than simultaneously. Equilibrium constants for the stepwise protonation equilibria have been derived from the n.m.r. data. The equilibrium constant for the first protonation step has also been determined by pHtitration.

ISSN:0008-4042    

DOI:10.1139/v71-629

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The X-ray crystal structure analysis of the chloroform adduct of the bis(triphenylphosphine) platinum di-oxygen complex (PPh3)2PtO2•2CHCl3is reported. The crystals belong to the monoclinic Systema = 15.492(7),b = 13.520(5),c = 19.187(6) Å; β = 98.97(6)°. Space groupC2/c.Z = 4 molecules per cell.A total of 2740 independent X-ray reflections were measured and refinement gave a final conventionalRof 6.6%.The molecule has a two-fold axis of symmetry through the Pt atom with O—O normal to the axis. The O—O distance of 1.505(16) Å is in accord with that found with other transition elements when oxygen is taken up irreversibly to form di-oxygen complexes.

ISSN:0008-4042    

DOI:10.1139/v71-630

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The vapor phase decomposition of isopropyl alcohol has been studied from 210 to 365 °C on manganese(II) oxide. Rates of conversion to acetone and propylene were measured with partial pressures of isopropyl alcohol from 0.3 to 22 mm. The catalyst selectivity towards dehydrogenation was around 0.80 between 320 and 365 °C while at 306 °C it was somewhat less and depended on the alcohol partial pressure. Propylene and hydrogen additions had no effect on the reaction rate while the reaction order with respect to isopropyl alcohol partial pressure was 0.4 to 0.6 except at 306 °C when it decreased with increase in the alcohol partial pressure. The effects of acetone and water additions were shown respectively to be exerted mainly on the dehydrogenation and dehydration reactions while at acetone pressures above 4 mm, considerable amounts of by-products including mesityl oxide and heavier ketones were clearly detected. The apparent activation energy of the overall decomposition as calculated from the experimental rates was 26 ± 0.5 kcal mol−1. The results have been interpreted to be in general agreement with the concept that the rate-limiting step is linked to the direct interactions on the catalyst surface and it has been established that the reaction is significantly more complex than previously recognized. The physical properties of the manganese(II) oxide were determined by X-ray and nitrogen adsorption techniques while infrared, n.m.r., and gas chromatographic methods were used to analyze the products of catalysis.

ISSN:0008-4042    

DOI:10.1139/v71-631

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Raman and infrared spectra of crystalline OF2indicate that this solid is not centro-symmetric and contains at least two molecules per primitive cell, on sites of symmetryCsorC1.

ISSN:0008-4042    

DOI:10.1139/v71-632

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Gaseous acetylene at pressures of about 200 Torr was irradiated with γ-rays at doserates between about 1011and 1012 eV/cc s, with and without an electric field applied. The deposition of cuprene on the bottom of the reaction vessel was markedly affected by the field, but the rate of cuprene formation as measured by the pressure decrease was unchanged. Examination of the cuprene deposit with an electron microscope showed it to consist of rather uniform spheres averaging about 3000 Å in diameter, with each containing an estimated 2 × 108molecules of acetylene. The mechanism of cuprene formation is discussed, and it is suggested that it does not proceed through a direct polymerization of acetylene, but involves a secondary polymerization of polyene intermediates, in the gas phase and after their condensation in liquid droplets.

ISSN:0008-4042    

DOI:10.1139/v71-633

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The —NH2group causes an intensive band pair in the i.r. spectra of DNA, r.RNA, poly (A + U), and poly (G + C). One band occurs at 3330, another at 3180 cm−1. This band pair is due to the NH stretching vibration of the hydrogen-bonded NH group as well as to the harmonic vibration of the —NH2bending vibration, whereby these vibrations are coupled via Fermi resonance. This follows on comparison with papers on amines. The weak shoulder in the 3500–3400 cm−1range is to be assigned to the stretching vibrations of the non hydrogen-bonded NH groups. The doublet structure disappears to a large extent in the denaturated DNA, since the strength of the Fermi resonance depends on the strength of the hydrogen bonds and the hydrogen bonds are of differing strength, due to the bending and stretching. The relative intensities of the two bands are interchanged in the corresponding band pair of the —ND2groups, for which an explanation can also be given.

ISSN:0008-4042    

DOI:10.1139/v71-634

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A study of the u.v., i.r., and n.m.r. spectra of 5-hydroxy-2-pentanone and of 6-hydroxy-2-hexanone has shown that in most organic solvents there is a slight preference for the open-chain form of the hydroxyketone over the cyclic hemiketal. Increase in temperature and in polarity of solvent further favors the open-chain tautomer; in water there was no evidence of any cyclic form.

ISSN:0008-4042    

DOI:10.1139/v71-635

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A distillate containing 25% vinylacetic acid has been obtained fromtrans-crotonic acid. Pure vinylacetic acid has been obtained from this by successive thermal equilibrations and distillations. Vinylacetic acid has been subjected to tautomerization conditions in acidic, neutral, and basic media, the latter in normal and in heavy water. These observations are coordinated in an attempt to arrive at plausible pathways for the various transformations observed.

ISSN:0008-4042    

DOI:10.1139/v71-636

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The i.r. spectra of 2-nitroethanol in the three physical states were measured between 4000 and 250 cm−1. The liquid and the crystal were also studied in Raman effect. In all three states the molecules exist asgaucheandtransisomers, the former being stabilized by a weak intramolecular hydrogen bond. Definite evidence for a third isomer, previously reported in dilute CCl4solutions, could not be ascertained from the vapor spectra as a function of temperature. On the other hand this study revealed appreciable decomposition of the vapor above 80 °C, with formation of nitroethylene and also some aldehyde. For that reason it was not possible to evaluate the enthalpy of isomerization. The difficulty of securing a pure sample of 2-nitroethanol is emphasized. Only one crystalline phase was obtained.

ISSN:0008-4042    

DOI:10.1139/v71-637

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The reaction oftrans-[IrI(CO)(PPh3)2Cl] (1) with AgNO3in acetone leads to two products. If a small excess of AgNO3is present, [IrI(CO)(PPh3)2(NO3)] is isolated; while if a larger excess of AgNO3is present, the novel compound [Ir(CO)(PPh3)2(NO3)2Ag] is isolated as product. The characterization, and some reactions of these complexes are discussed.

ISSN:0008-4042    

DOI:10.1139/v71-638

出版商:NRC Research Press    

年代:1971

数据来源: NRC