摘要:

The previously reported fragments and a new fragment, FeC2+, have been observed in the mass spectrum of iron pentacarbonyl. The electron impact appearance potentials for the minor fragments of Fe(CO)5are (in eV): FeC3O2+, 18.2; FeC2O+, 20.2; FeC2+, 29.9; FeO+, 22.5; and Fe(CO)32+, 24.0. Electron energy calibration was carried out using existing data for the major fragments of Fe(CO)5.

ISSN:0008-4042    

DOI:10.1139/v78-428

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The exchange ofN,N-dimethylformamide (DMF) between M(NH3)5DMF3+and solvent in acidic DMF solutions proceeds with pseudo-first-order kinetics governed by the parameterskex(55 °C) = 8 × 10−5and 1.1 × 10−4 s−1, ΔHex* = 113 and 99 kJ mol−1, ΔSex* = +22 and −20 J K−1mol−1, and ΔVex* = +3.2 and −1.4 cm3mol−1for M = Co and Rh respectively. For M = Co (but not Rh), the exchange rate was much faster in the absence of acid, and reduction of Co(III) to Co(II) was significant at low acidities. Solubility problems precluded the measurement of meaningful rate data for the reactions of M(NH3)5DMF3+with nucleophiles X−in acidic DMF solution except for the case M = Co with X = Br−, for which a limiting first-order rate coefficient 2.5 timeskexwas obtained for the formation of Co(NH3)5Br2+at high [Br−] at 55 °C. Despite this last result, the mechanism of simple substitution reactions is evidently dissociative interchange (Id) for pentaamminecobalt(III) complexes in general, but associative interchange (Ia) for pentaamminerhodium(III) analogues.

ISSN:0008-4042    

DOI:10.1139/v78-429

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Phase transformation studies on pure Na2SO4revealed four phases only; phase IV was not observed.Electrical conductivity measurements have been made on polycrystalline undoped and K-doped Na2SO4and on single crystals of undoped Na2SO4. Kinetic measurements on II → III transformation in undoped Na2SO4show rate of conversion to be time independent and inversely related to temperature.The presence of K in Na2SO4effects a lowering of both the transition temperature and the enthalpy of transition along with an alteration from the "athermal" kinetic behavior to first-order kinetics.

ISSN:0008-4042    

DOI:10.1139/v78-430

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The relative volatilities of cyclohexylamine and morpholine in dilute aqueous solution have been measured in the temperature range 150 to 300 °C at the corresponding equilibrium vapour pressure of the solution. Cyclohexylamine strongly prefers the steam phase while morpholine has a relatively volatility close to that of water. In both cases an azeotrope of the amine and water, with a vapour pressure higher than that of either component, must exist; however, with morpholine and water azeotrope formation only occurs above 175 °C. The concentration dependence of the distribution between the steam and solution phases of both amines is explained in terms of their partial ionization in solution.

ISSN:0008-4042    

DOI:10.1139/v78-431

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The effect of a number of organic compounds on the rate of formation of 1Sn(II)–4Sn(IV) charge transfer complex in acidic stannous sulphate solutions and on the stability of these solutions has been determined by measuring, spectrophotometrically, the change of absorption of these solutions with time. From the results, it is possible to classify these organic compounds into three broad categories in terms of how they affect the formation of the charge transfer complex and the stability of the solution.These results have been interpreted taking into account that the formation of the 1Sn(II)–4Sn(IV) complex depends on the initial concentration of stannic ions present as an impurity in the stannous sulphate solution, the rate of oxidation of the stannous ions, the rate of hydrolysis of the stannic ions, and the stability of stannic colloids that are formed.

ISSN:0008-4042    

DOI:10.1139/v78-432

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A systematic study of the pressure effects on the quantum yields of some products between 0.1 and 600 Torr (13 and 80 000 N m−2) was carried out in the 7.6 and 8.4 eV photolysis of normal, iso- andcis-2-butenes. The propylene quantum yield (s-C4H9* → C3H6 + CH3) decreased with the increase in then-butene pressure and a good linearity of S/D (stabilization/decomposition) vs. pressure plot, over a broad pressure region, was observed. It is concluded that hydrogen atoms involved in the s-C4H9* radical formation are produced with a relatively narrow energy distribution. The slope of S/D vs. pressure lines decreased with the increase in photon energy, indicating the trend in the kinetic energy of the H-atoms.In the case of isobutene andcis-2-butene photolysis, the Stern–Volmer plots for allene formation were nonlinear. It is concluded that the formation of two different allene precursors is needed to account for this result. By the use of a simple RRK-type formalism we also conclude that the excess energy of the photon in the primary photoexcited butene molecules is far from being randomized before their fragmentation occurs.

ISSN:0008-4042    

DOI:10.1139/v78-433

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Attempts were made to study the kinetics of the reaction of atomic H with (CF3)2CO vapour (HFA). Atomic H was generated from H2by mercury photosensitization in the presence of C2H4and HFA but the system was complicated by the loss of C2H5radicals by addition to HFA and the kinetic results were intractable. When atomic H was generated from C3H8, the kinetics again were obscured by some unidentified reaction(s) which became more important at higher [HFA]/[C3H8]. An estimate of the rate constant for the addition of H to HFA obtained at low [HFA]/[C3H8] yieldedk9 = 8.5 × 105 lmol−1s−1. Trifluoroacetaldehyde was identified with some reliability but many of the other heavier products formed in the H2 + HFA reaction could not be identified. Quenching cross-sections were determined for C2H4, C3H8, C4H10, and HFA relative to that for N2O.

ISSN:0008-4042    

DOI:10.1139/v78-434

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Oxidation ofo-,m-, andp-hydroxyacetophenone with peracetic acid ortert-butyl hydroperoxide, oxidants relatively readily monitored by nmr, failed to generate isolable intermediates though an intermediate was detected for thep-ketone. Attempted oxidation of a number of related ketones under Dakin conditions failed either to react, or to generate a detectable intermediate. However, with delicate adjustment of pH and careful timing of the isolation procedure, hydroquinone monoacetate has for the first time been successfully isolated from an alkaline aqueous hydrogen peroxide oxidation (Dakin oxidation) ofp-hydroxyacetophenone.

ISSN:0008-4042    

DOI:10.1139/v78-435

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Turbidity measurements, circular dichroism spectra, electron micrographs and thermal denaturation profiles of complexes between sonicated DNA and either poly(L-lysyl-L-alanine) or poly(L-lysyl-D-alanine) show significant differences which might be related to the primary or secondary structure of the polypeptides.

ISSN:0008-4042    

DOI:10.1139/v78-436

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Turbidity measurements, circular dichroism spectra, electron micrographs, and thermal–optical measurements have been made on complexes between sonicated DNA and several polypeptides with the following structure: poly-(L-lysine-L-X) where X = Gly, Ala, Val, Leu, Phe. The results are influenced by any method of polypeptide synthesis which results in chain branching of the polypeptide. When polypeptides prepared by the same synthetic route are incorporated into the complexes the results also depend on the polypeptide used. Five possible explanations are offered as sources of the latter observations.

ISSN:0008-4042    

DOI:10.1139/v78-437

出版商:NRC Research Press    

年代:1978

数据来源: NRC