摘要:

The binary gaseous diffusion coefficients of air with methane, methyl chloride, methylene chloride, chloroform, and carbon tetrachloride at 298.2 °K and 1 atm have been determined. A simple diffusion cell was used, in which concentration changes of the diffusing gas were followed by infrared spectrophotometry.

ISSN:0008-4042    

DOI:10.1139/v71-011

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Anodic oxidation of ethylene glycol (EG) has been examined on platinum in 1 NH2SO4by means of potentiostatic and potentiodynamic techniques. Experimental results consist of steady-state, potential-current relationships, reaction order derivatives, inhibition inflections, potentiodynamic profiles, and product analysis. Reaction mechanism has been proposed by combining these results with the previous information on the adsorption of EG on platinum, and on the pHeffects in the anodic oxidation of EG. An analysis of these data has been presented in terms of kinetics under both Langmuir and Temkin conditions of electrode coverage. Inhibition inflections have been interpreted in terms of the kinetic theory of passivation effects proposed by Gilroy and Conway. It has been suggested that a chemical step of the type Pt.EG + Pt.OH → Pt.R + H2O + Pt is the likely rate-determining-step (r.d.s.). The data indicate that quasi-equilibria prior to the r.d.s. are probably different in the ascending and descending direction of potentials (on the potential–current curves), owing to the presence of different extents of oxygenated (Pt.OH or Pt.O) adsorbed species and the associated effects of coverage on kinetics.

ISSN:0008-4042    

DOI:10.1139/v71-012

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Precise analyses of the p.m.r. spectra of 1,3-dithiole-2-thione and 1,3-dithiole-2-one containing13C at positions 4 and 2 yield all proton–proton and proton–carbon spin–spin coupling constants. The two-bond proton–carbon couplings are discussed relative to directly bonded proton–carbon couplings in terms of hyperconjugative effects and it is suggested that d orbital participation in sulfur bonding is unimportant in these compounds. A linear correlation of two-bond proton–carbon withcisoidproton–proton couplings in some ethylene derivatives and aromatic compounds indicates that the above two compounds behave like ethylene derivatives in this respect, in contrast to benzene, furan, and thiophene. Practical use of the correlation in the analysis of complex13C resonance spectra is indicated.

ISSN:0008-4042    

DOI:10.1139/v71-013

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The p.m.r. spectrum of a 15 mole % solution ofp-fluorotoluene in acetone-d6is analyzed at 100 MHz using LAOCN3 and LAME computer programs. The resulting spectral parameters satisfactorily reproduce the methyl proton resonance at 60 MHz. The coupling over six bonds between the fluorine nucleus and the methyl protons is 1.15 ± 0.02 Hz and is taken as a measure of the π electron contribution to the coupling over five bonds between the fluorine nucleus and the proton inp-fluorobenzene. The σ electron contribution to this coupling is discussed for some fluorobenzene derivatives and is shown to depend on the electronegativity of the substituents in a manner completely analogous to proton–proton and other proton–fluorine couplings in benzene and pyridine derivatives.

ISSN:0008-4042    

DOI:10.1139/v71-014

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The electronic spectra of some substituted pyridine complexes of copper(II) have been studied. The effects of bonding on the spectroscopic data are discussed, and compared with theRπvalues determined from infrared measurements.

ISSN:0008-4042    

DOI:10.1139/v71-015

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Six 3,3,4,5-tetrasubstituted pyrazolines have been prepared and the product distribution from their pyrolysis reactions have been determined. This has permitted for the first time the unambiguous evaluation of the stereochemical fate of C-3 and -5 of the pyrazolines on conversion to cyclopropanes. A stereoselectivity is noted for these systems which can be related to the structure of the initial pyrazoline. This suggests that the transition state for reaction retains many of the stereochemical factors present in the pyrazoline. Such a condition would be the case for concerted breaking of the two C—N bonds with a developing overlap of the new bonds being formed at the transition state. That this reaction is not restricted by symmetry constraints suggests that the three carbon fragment can act as a symmetric or antisymmetric unit and that these are not separated by more than a few kcal of energy.

ISSN:0008-4042    

DOI:10.1139/v71-016

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The1H and19F n.m.r. spectra of the α- and β-anomers of 3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-D-glucopyranosyl fluoride and of the correspondingD-manno derivatives have been fully analyzed. The signs of most of the19F–1H and of all thel9F–19F couplings have been determined by a heteronuclear double-resonance method. The vicinal19F–19F couplings are absolutely negative in sign, withJa,a = – 20.0 Hz, andJa,eandJe,e = – 13.5 to – 18.8 Hz. Sizeablelong-rangecouplings (4J) between an axial fluorine and an axial proton are absolutely positive in sign.

ISSN:0008-4042    

DOI:10.1139/v71-017

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The isolation and structure of a new tetrahydroprotoberberine alkaloid fromC.caseanais reported. This alkaloid, named caseanadine, has a phenolic hydroxyl at C-1 and methoxyls at C-2, -9, and -10. Its structure has been deduced from an analysis of its p.m.r. mass, and i.r. spectra. The alkaloid has a substitution pattern different from other members of this group of alkaloids of established structure.

ISSN:0008-4042    

DOI:10.1139/v71-018

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The secondary deuterium isotope effect is reported for the decomposition of benzyl-α-d2-phenyldimethylammonium bromide in both chloroform and acetone solvent, over a temperature range of 25 to 30°. The magnitudes of the rate ratios are compared to literature values for SN1 reactions, from which it is concluded that the mechanism of the decomposition involves a carbonium ion or ion-pair. The variation of the isotope effect with solvent is rationalized in terms of specific solvent interaction with the benzyl group.

ISSN:0008-4042    

DOI:10.1139/v71-019

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The photolyses of several acylsilanes and one acylgermane in carbon tetrachloride have been shown to involve Norrish Type I cleavage of the metalloid-acyl bond to give metalloidal radicals. These radicals readily abstract chlorine from the solvent.

ISSN:0008-4042    

DOI:10.1139/v71-020

出版商:NRC Research Press    

年代:1971

数据来源: NRC