摘要:

The rate constant for the irreversible dehydration of a number of aromatic aldehyde hydrates has been measured. The hydrates were generated by constant potential electrolysis of the respective aromatic acid at a rotating disc electrode. The aldehydes are then further reduced to the alcohol. The rate constant can be calculated from the ratio of the concentration of intermediate aldehyde to the total concentration of products.The theory was further extended to include the reverse hydration of the aldehyde to the hydrate and applied in the case ofm-chlorobenzaldehyde. A value for the equilibrium constant ofK = 1.30 ± 0.25 was obtained for this reaction.

ISSN:0008-4042    

DOI:10.1139/v74-236

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Relatively stable radical cations of 9,10-diphenylanthracene (DPA) were formed by controlled potential electrolysis of solutions in acetonitrile. The rates of decay of the ions were measured in the absence and presence of substituted styrenes, including α-methylstyrene,trans-β-methylstyrene,p-methylstyrene, and styrene. In rigorously dried solvent the radical cation was relatively stable, and its rate of decay was independent of its initial concentration. In the presence of monomers the rates of decay were increased greatly and were related to the position of the methyl substituent in the styrene structure.The rate was proportional toA mechanism is suggested and interpreted to show that the rates of cation decay are indicative of the rates of propagation in the polymerization process.

ISSN:0008-4042    

DOI:10.1139/v74-237

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The electron impact induced fragmentation pattern of four aliphatic imines are reported. These are derived from studies involving deuteriated imines and from the observed metastable transitions. The elimination of the R1•radical fromappears to be preferred provided R1•and R2•are methyl or ethyl radicals. The ionization potentials of the compounds studied have been determined.

ISSN:0008-4042    

DOI:10.1139/v74-238

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The synthesis of novel cardenolides, closely related to naturally-occurring cardiotonic agents, is described. They were obtained from 17β-[3-furyl]androstanes derived from digitoxigenin, gitoxigenin, digoxigenin, and strophanthidin by hypohalous acid or organic peracid oxidation. The preparation of β-D- and α-L-glycosidic derivatives is also reported.

ISSN:0008-4042    

DOI:10.1139/v74-239

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

CD3radicals from the photolysis of hexadeuteroacetone abstract H atoms from group IV methylsThrough additional work on the Sn and Ge systems, a comparison of the data for CF3or CD3 + (CH3)4M (where M = C, Si, Ge, Sn) leads to the reactivity ratioat 373 K. Arrhenius parameters for the abstraction processes are reported.

ISSN:0008-4042    

DOI:10.1139/v74-240

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The solubility of water in each of benzene, carbon tetrachloride, and cyclohexane, was determined at 5° intervals over the range 10 to 40 °C. The solubilities were converted to Henry's law constants and these constants were interpreted by means of a statistical mechanical theory based on Zwanzig's perturbation theory of fluids. A fitting-parameter in the form of a correction factor to the water–solvent pairwise potential function was required. The values of this parameter for the benzene–water and cyclohexane–water systems could be rationalized on the basis of anisotropy of solvent polarizability. The values of the parameter for the carbon tetrachloride – water system were consistent with a hydrogen-bonding interaction between water and carbon tetrachloride.

ISSN:0008-4042    

DOI:10.1139/v74-241

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The photochemical reactivity of 2- and 3-benzoylthiophene and theirpara-cyano andpara-methoxy derivatives, upon irradiation in the presence of isobutylene, has been studied. All six ketones undergo photocycloaddition at the carbonyl group under these conditions. The resulting oxetanes are thermally unstable; they eliminate formaldehyde and yield the 1-aryl-1-thienyl-2-methylpropene. The existing generalizations, potentially useful for predicting this photochemical reactivity, are reviewed.

ISSN:0008-4042    

DOI:10.1139/v74-242

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Electronic chemiluminescence has been observed for nine reactions of Group IIametal atoms (M = Ca, Sr, Ba) with dihalogen molecules (X2 = F2, Cl2, Br2).In all cases one or more electronically excited states of the monohalide MX* were observed. Continuum emission, presumably due to dihalides MX2*, was seen in all systems, and the emission intensity increased in the order F2 < Cl2 < Br2. Recombination to form MX2* appears thus to be a fairly general process in these systems.From the highest vibrational levels of MX populated in the upper electronic state(s) we have calculated the following lower limits to the ground state dissociation energiesD0°(MX) (in kcal/mol):Information on the vibrational state distributions of the excited MX* is discussed from a qualitative point of view. Accordingly, the fluorides are formed with inverted vibrational distributions, which bear clear evidence of the direct nature of the interaction dynamics. The electronically excited chlorides and bromides, however, tend to be formed with monotonically decreasing, near-statistical distributions. This is consistent with the formation of long lived collision complexes. Reasons for these trends are discussed in terms of the energetics of the complete decomposition.

ISSN:0008-4042    

DOI:10.1139/v74-243

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

During the autoxidation of benzaldehyde catalyzed by lithium chloride, 26% (by weight) dibenzoyl peroxide is formed. The lithium chloride is responsible for the acceleration of the oxygen uptake and the formation of dibenzoyl peroxide.

ISSN:0008-4042    

DOI:10.1139/v74-244

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A compound, obtained in large yields from the reaction of acetylacetone and oxodichloroethoxobis(triphenylphosphine)rhenium(V) in benzene, has been shown by single crystal X-ray diffraction to becis-dichloropentane-2,4-dionato-trans-bis(triphenylphosphine)rhenium(III). The crystals are monoclinic witha = 13.06(1),b = 18.30(1),c = 16.55(1) Å, and β = 112.7(2)°. The space group isP21/cand there are four molecules per unit cell. A total of 3841 independent reflections, of which 2686 were observed, were examined by film methods, the intensities being measured with a microdensitometer. The structure was refined by full matrix least-squares analysis to anR2value of 0.068. The ligands are arranged around the rhenium atom in the manner described by the compound name to give a rough octahedron of nearest neighbours and the Re—Cl (2.369 Å av.), Re—O (2.02 Å av.), and Re—P (2.474 Å av.) distances are as expected.

ISSN:0008-4042    

DOI:10.1139/v74-245

出版商:NRC Research Press    

年代:1974

数据来源: NRC