摘要:

The carbon-13 n.m.r. spectra of 26 α,β-unsaturated methyl esters and 16 substituted acrylic acids have been determined and the13C shieldings are discussed. These data are compared with the recently reported values for several α,β-unsaturated carboxylic acids. Linear regression analysis of the olefinic shielding data for several α,β-unsaturated carbonyl derivatives yields a set of parameters which correlate the results with reasonable precision. The solvent dependence of the13C shieldings of acrylic acid and methyl acrylate has been examined briefly. The proton results for the methyl esters are discussed briefly.

ISSN:0008-4042    

DOI:10.1139/v72-095

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The structure of the dimer formed from acetonylacetone and hydrazine has been re-examined. On the basis of chemical and spectroscopic data, a covalent tricyclic structure is proposed.

ISSN:0008-4042    

DOI:10.1139/v72-096

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The deuterionorborneols2a,b,c, andehave been prepared and converted to the brosylates1a,b,c, ande. The deuterium isotope effects determined spectrophotometrically for solvolysis in HOAc–KOAc are 1.00 ± 0.01, 1.01 ± 0.01, 0.99 ± 0.01, and 1.11 ± 0.01, respectively. These data establish that: (a) a steric deuterium isotope effect does not operate at C-5 and therefore probably not at C-6; (b) hyperconjugative stabilization of the norbornonium ion to the C-5 hydrogens is confirmed to be not important, and (c) provides the first experimental evidence that the hydrogen (deuterium) shift – internal return pathway contribution to the γ-deuterium isotope effects observed for1dandeis minor.

ISSN:0008-4042    

DOI:10.1139/v72-097

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The i.r. and Raman spectra of 3-chloro-1,2,5-thiadiazole have been recorded. Assignments have been made for all 15 fundamental vibrations on the basis of these observations plus some data from the vapour-phase u.v. absorption spectrum.

ISSN:0008-4042    

DOI:10.1139/v72-098

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The phase space theory of chemical reaction in which all accessible channels are uniformly weighted was shown to be inappropriate for describing exothermic reactions. Modification to the theory was introduced by a concept of partial statisticity in which only that portion of the phase space available to each vibrational level was treated statistically. The product rotational and translational distributions of the reaction, Cl + HI, and its isotopic variant, Cl + DI, were computed by this modified formulation and compared with that obtained from a straight application of the phase space theory. The implication of the profound differences found from these two formulations was discussed in light of experimental data.

ISSN:0008-4042    

DOI:10.1139/v72-099

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The causes of inaccuracy in the values of the successive formation constants for 1:2 metal:ligand complex systems for whichK1 ≤ K2are discussed. The experimental error in thepLdata has been shown to become increasingly important asK1/K2decreases. It has been concluded that the successive constants cannot be determined ifK1/K2 < 10−2.4. Their product,K1K2, can, however, be determined. It is also shown that the value ofK2cannot be determined for the iron complexes with bipyridyl and 1,10-phenanthroline.

ISSN:0008-4042    

DOI:10.1139/v72-100

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The electronic transition energies and ionization potentials of formaldehyde have been calculated by a semi-empirical molecular orbital method, using several different ways of evaluating the diagonal matrix elements, in an attempt to adapt the Pariser–Parr–Pople method to the calculation of σ electron properties. The use of theoretically computed penetration integrals in this semi-empirical calculation lead to incorrect relative separation of the π-, σ-, and nonbonding molecular orbital energies, and hence to failure in predictingn →π* andn → σ* transition energies. A method is developed which reproduces the spectrum of formaldehyde (which includesn–π*, π–π*, andn–σ* electronic transitions) satisfactorily. In paper II of this series, this method is applied to study the spectrum of HCN and CO2.

ISSN:0008-4042    

DOI:10.1139/v72-101

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

All valence electron molecular orbital calculations have been carried out on hydrogen cyanide and carbon dioxide using a minimum basis set of Slater-type orbitals by a semi-empirical SCF-LCAO-MO method described earlier for formaldehyde. Since many of the excited states of these molecules are bent, a series of calculations is carried out on hydrogen cyanide in the linear configuration and in bent configurations with H—C—N angles of 150°, 120°, and 90°, and on carbon dioxide in the linear configuration and bent configuration with O—C—O angle of 90°. The binding energy changes in various molecular orbitals on bending are used to interpret electronic spectra and are also compared with Walsh's curves.

ISSN:0008-4042    

DOI:10.1139/v72-102

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The solubility of carbon tetrachloride in compressed helium, hydrogen, nitrogen, argon, methane, carbon dioxide, and ethylene has been measured over pressure ranges of 1–60 atm at temperatures ranging from −10 to 75 °C. Second cross virial coefficients representing carbon tetrachloride – gas interactions are evaluated from the data. It is shown that when allowance is made for the effects of quantum deviations and quadrupolar interaction on the critical temperatures and volumes of helium, hydrogen, and carbon dioxide, respectively, ordinary combining rules produce pseudocritical parameters which reduce all of the measured cross virial coefficients to a single function of reduced temperature. When reduced on a Boyle point basis, it is found that the data are best represented by virial coefficients corresponding to a 7-28 Mie type potential or a Kihara core potential having a core radius somewhat smaller than the carbon–chlorine bond length in carbon tetrachloride.

ISSN:0008-4042    

DOI:10.1139/v72-103

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The preparations and reactions of a series of 1,3,5-triaryl-2,4-diaza-1,3-pentadienes (1) have been investigated. Products of cyclization (2and4), prototropy3and addition–elimination (5,6, and7) have been characterized. Also, the preparations and reactions of3, a new isomer of1, have been studied.

ISSN:0008-4042    

DOI:10.1139/v72-104

出版商:NRC Research Press    

年代:1972

数据来源: NRC