摘要:

The title compound crystallizes in the space groupP21/cwith four formula units in a cell of dimensionsa = 10.146(6) Å,b = 10.593(4) Å,c = 26.31(1) Å, β = 103.14(3)°. Using 1496 observed reflections (I = 2.3σ(I)) in the range 0° < 2θ < 40° measured on a Picker FACS-1 automatic diffractometer with Mo-Kα radiation, the structure was solved (symbolic addition) and refined (full-matrix least-squares procedure) toR = 0.062 (Rw = 0.058), with all hydrogen atoms included and all non-hydrogen atoms having anisotropic thermal parameters. The dimensions within the cation are consistent with a delocalized electronic structure which is intermediate between valence formulations involving benzenoid or quinonoid structures for the (4-diethylaminophenyl)diazenyl residue. Some important bond lengths are N3—C22 1.336(7) Å, N2—C19 1.356(7) Å, N1—N2 1.308(6) Å, and P—N1 1.648(5) Å.

ISSN:0008-4042    

DOI:10.1139/v78-148

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The hydrogenolysis of aspen lignin using rhodium-on-charcoalas catalyst has been studied. The maximum yield of chloroform-soluble lignin degradation products was obtained at a reaction temperature of 195 °C. Analysis of this chloroform-soluble fraction revealed that the monomeric fraction was composed essentially of the four compounds,1–4, only, and in a total yield representing at least 40% of the original lignin.Solvent extraction was shown to be preferred over thermal distillation as a preparative procedure for the separation of these phenolic derivatives. The significance of the isolation of these lignin degradation products is discussed.

ISSN:0008-4042    

DOI:10.1139/v78-149

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The effect of reaction conditions on the hydrogenolysis of spruce wood lignin over a rhodium-on-charcoal catalyst has been studied and monitored by the yields of the three major degradation products,1,2, and5. Variables included: initial pressure of hydrogen, amount of catalyst, and acidity–basicity of the media. Little variation occurred under moderate acidic or basic conditions with yields of 18–20% of lignin recovered as monomers. Under strongly acidic or basic conditions both yields and relative abundances changed appreciably. Initial hydrogen pressures less than 500 psig resulted in slightly decreased yields in some cases. In strongly alkaline media similar results were obtained with or without added hydrogen provided the catalyst were present.

ISSN:0008-4042    

DOI:10.1139/v78-150

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The photolysis of benzylic sulfonyl compounds (XSO2CH2Ph) gives products which are explained in terms of the chemistry of the benzyl and sulfonyl (XSO2•) radicals. The synthetic applications of this photocleavage have been examined for two general cases: (i) preparation of sulfones from disulfone precursors, R1SO2CHR2SO2CH2Ph to R1SO2CH2R2(yields ∼ 90%); (ii) preparation of sulfinic acids and sulfonyl chlorides from mono sulfone precursors, R3SO2CH2Ph to R3SO2H and R3SO2Cl (yields ∼ 55%).

ISSN:0008-4042    

DOI:10.1139/v78-151

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The theory of galvanostatic transients is extended to include the formation of a three-dimensional crystalline layer. The mechanism of formation of this layer is assumed to be one of nucleation and subsequent growth of randomly distributed nuclei on the electrode surface. The resulting crystallization overvoltage is shown to be a complex function of the applied current density, as well as being related to the potential-dependence of the rate constants for lattice growth and the potential-dependence of the nucleation rate constant. The completeE–tresponse is calculated numerically and also certain limiting cases are described which have exact analytical solutions. A method of testing the model experimentally is briefly discussed.

ISSN:0008-4042    

DOI:10.1139/v78-152

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

For studies on effects of pressure on kinetics of electrode processes (Parts I, II), reversible reference electrodes suitable for use in a completely enclosed high-pressure bomb are required. The electrodes must exhibit reversible behaviour over the pressure range employed in the experiments, i.e., their changes of emf with increasing and decreasing changes of pressure must be reproducible and correspond to the respective volume changes in the reactions.A series of reversible reference electrodes is examined over a range of pressures up to ca. 2500 bars. The Pd–H/H+and Ag, AgCl/Cl−reference electrodes are found to behave very satisfactorily at elevated pressures; the Pt,H2/H+electrode is, however, less satisfactory, due to problems associated with dissolved H2.The results enable the volume of Pd–H and of H sorbed into Pd to be evaluated, together with estimates of the partial molar volume of H2in aqueous HCl. These data enable the pressure-coefficients of metal–solution potential differences at individual reference electrodes to be evaluated. Such information is required for interpretation of effects of pressure on kinetics of electrode processes.

ISSN:0008-4042    

DOI:10.1139/v78-153

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

1/1 adducts from oxiranes or thiiranes and cadmium, zinc, or magnesium α,β,γ,δ-mesotetra-phenylporphyrins were obtained in benzene and complexation constants determined. Results agree with the theory of 'hard and soft' acids and bases.Demetallation of the metaloporphyrins of Cd, Zn, and Mg is achieved with thiols. The cadmium porphyrin reacts with sulfur heterocycles which contain a β hydrogen to yield the free porphyrin and a thiolate of cadmium. If this heterocycle is methylthiirane, the organocadmium compound formed may initiale the subséquentin situstereospecific polymerization of methylthiirane.

ISSN:0008-4042    

DOI:10.1139/v78-154

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The rates of hydrolysis of seven meta- andpara-substituted ethyl thiolbenzoates and seven meta- andpara-substituted ethyl thionbenzoates in various concentrations of sulfuric acid above 48% have been determined. The Yates–McClellandrand the Hammett ρ parameters indicate that substituted ethyl thiolbenzoates hydrolyze by an AAc1 mechanism but substituted ethyl thionbenzoates by an AAc2 mechanism.

ISSN:0008-4042    

DOI:10.1139/v78-155

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The rates of hydrolysis of thioacetic, thiobenzoic, and three substituted thiobenzoic acids increase with concentration of solvent sulfuric or perchloric acid to a maximum in 30–40% acid and then decrease. Yates–McClellandr, Bunnett–Olsen, and Hammett ρ parameters, and entropies of activation indicate an AAC2 mechanism over this range of acid concentrations. In acid concentrations above 50–60% the rates increase sharply and the same mechanistic criteria now indicate an AAc1 mechanism. The difference between the rate–acidity profile of thiobenzoic acid and that of ethyl thiolbenzoate can be explained by the different response of the activity coefficients of their transition states to increase in sulfuric acid concentration.

ISSN:0008-4042    

DOI:10.1139/v78-156

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The primary reaction in sodium diffusion flames, Na + RX = NaX + R, has been investigated as a possible source of free radicals for kinetic studies. A number of different alkyl halides were investigated as possible radical sources. Optimum conditions were found to minimize wall reactions and hydrogen abstraction from the halide, the two factors which invalidated previous work using this method. Rate constants were derived from product analyses by the numerical solution of simultaneous non-linear differential equations based on a spherical model involving diffusion. Values were obtained for the two modes of decomposition ofn-C3H7, the abstraction of primary and secondary H atoms from C3H8by CH3, and the addition of CH3to C2H4. These are in reasonably good agreement with values determined by more conventional methods.

ISSN:0008-4042    

DOI:10.1139/v78-157

出版商:NRC Research Press    

年代:1978

数据来源: NRC