摘要:

The Scaled Particle Theory (SPT) is probably the most powerful theory presently available, that enables the calculation of the thermodynamic functions relative to the formation of cavities in liquids. We give the general relationship between the enthalpy of vaporization and the enthalpy of formation of a molecular cavity in a pure normal liquid; the good agreement with the experimental data constitutes one of the strongest arguments justifying the application of SPT to real liquids. However, we show that SPT can lead to uncertain cavity terms if the molecular diameters of the studied liquids are not well-known. We compare, on the other hand, the cavity terms (GandH) calculated from Sinanoglu's theory, since this theory has been used to that end recently, with those obtained from SPT.

ISSN:0008-4042    

DOI:10.1139/v81-001

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A1H dnmr study has been performed on a series of addition compounds formed from the gaseous reactions of di- and trimethyl amine and triethyl amine with sulfur dioxide in the presence of a small amount of water in a liquid sulfur dioxide solvent. The dynamic system involves an equilibrium of the general form: amine•The activation parameters for the exchange process were calculated. Large positive entropies of activation were found in the present systems that strongly suggest the formation of an ion pair in the transition state in which the activation process is controlled largely by solvation effects.

ISSN:0008-4042    

DOI:10.1139/v81-002

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Photolytic oxidation of aliphatic acids with aqueous H2O2has been studied. Formic acid gives CO2and H2O. Acetic acid gives products containing CO2, methane, formic, glycolic, and tartaric acids. Propionic acid gives CO2, methane, ethane, acetic, formic, lactic, β-hydroxypropionic, malonic, and glycolic acids. A mechanism involving an initial H-atom abstraction by HO•formed via photo-dissociation of H2O2is postulated and discussed.

ISSN:0008-4042    

DOI:10.1139/v81-003

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The aim of this investigation was to assess the possible use of sulfuric lignins for the purification of industrial liquid wastes. The adsorption of anionic (SDS), cationic (CPC), and non-ionic (NPPO) surfactants on charred plant material was carried out under various pH and temperature conditions. Ionic and hydrophobic interactions are involved in the adsorption process. The analysis of the adsorption kinetics in aqueous and alcoholic media allowed the mode of adsorption to be characterized. The plot of the surfactant uptake against the square root of time led to the determination of the mode of diffusion. The effect of the chain length of alkylsulfates on their adsorption corroborated the involvement of hydrophobic interactions and could be correlated with the values of their cmc.

ISSN:0008-4042    

DOI:10.1139/v81-004

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Tris(aminomethyl)phosphine oxide (6) can be synthesized from octakis(hydroxymethyl)diphosphonium sulfate (1b) in an overall yield of 54.6% via the methyl carbamate derivatives2b,3, and4. On a preparative scale, the last step is complicated by the formation of a cyclic by-product8in amounts up to 20% of the total. The triamine6forms a 1:1 adduct (11) with carbon dioxide, whose structure, established by1H and13C nmr, consists of equimolar amounts of carbamateAand dicarbamateBC. The componentsA,B, andCcan be separated by ion exchange. Thermolysis of11regenerates6smoothly, providing a convenient method for purifying the triamine.

ISSN:0008-4042    

DOI:10.1139/v81-005

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The major alkaloids ofPodopetalum ormondiihave been shown to be (−)-podopetaline, (−)-ormosanine, and 6-epipodopetaline. A constant-melting substance, mp 160–161 °C, isolated from the extract proved to be a quasiracemate of (−)-podopetaline and (−)-ormosanine; the absolute configuration of (−)-ormosanine consequently followed from the established absolute configuration of (−)-podopetaline. Both (−)-6-epipodopetaline, mp 118–119 °C, and its racemic form, mp 174–175 °C, were isolated from the extract. A constant-melting ternary mixture, mp 178–179 °C, of the three major alkaloids has also been isolated.

ISSN:0008-4042    

DOI:10.1139/v81-006

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The solid state properties of poly-β-hydroxybutyrate (PHB) were investigated for samples with degrees of polymerizationfrom 4 to 994. The observed melting points ranged from 47 °C to 180 °C. Electron diffractograms on carefully prepared single crystals of a high molecular weight sample provided data which confirmed the reportedaandbparameters from X-ray fiber diffraction and provided clear justification for theP212121space group. The observed intensities in the electron diffractogram, corresponding to (hk0) reflections, were compared with the predicted intensities for two proposed structures in the literature. The observed and calculated structure factors for both structures were in good agreement. Small angle X-ray diffraction of the meridional maximum for annealed "cold drawn" and "hot drawn" fibers showed a distinctly different dependence on temperature than the maximum for stacks of lamellar single crystals. For oligomers a long spacing was observed which was about twice the length of the samplemultiplied by the crystalline advance per monomer.

ISSN:0008-4042    

DOI:10.1139/v81-007

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

In aqueous sodium hydroxide solutions at 25 °C, 3-penten-2-one undergoes retroaldol cleavage to acetone and acetaldehyde. The kinetics can be followed spectrophotometrically, and show two exponential phases with rather different rate constants. By a new analysis of the mathematical solution to this system we have been able to derive an improved method for calculating the microscopic rate constants. These rate constants arekhyd = 2.89 × 10−3 M−1 s−1,kdehyd = 4.04 × 10−4 M−1 s−1, andkretro = 3.36 × 10−4 M−1 s−1. The equilibrium constant for hydration of 3-penten-2-one (standard state for water is the pure liquid) is 7.13.

ISSN:0008-4042    

DOI:10.1139/v81-008

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v81-009

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

31P nmr has been used to show that, in MeNO2, M(SbF6)2(M = Sn or Pb) forms 1:1 complexes with Ph2P(CH2)2PPh2, PhP[(CH2)2PPh2]2, MeC(CH2PPh2)3,P[(CH2)2PPh2]3, and Ph2P[(CH2)2PPh]2(CH2)2PPh2. The phosphonium ligands are formed in situ. Spectra characteristics of slow inter- and intramolecular exchange were obtained in all cases except, perhaps, those involving the last two ligands, which may be involved in rapid intramolecular exchange. For the first five ligands, the maximum denticity is achieved and unambiguous one-bond M(II)—31P (M = 117/119Sn or207Pb) coupling constants are reported and discussed. In the presence of M(SbF6)2 (M = Sn or Pb). PPh3is protonated in MeNO2, while in acetone Sn(SbF6)2forms a 1:1 complex with PPh3which appears to be solvent-inserted, [Sn—O—CMe2PPh3]2+.Reduced temperature31P nmr spectroscopy has allowed the detection of 1:2 and 1:3 (M:L) complexes of OPPh3, and 1:1 complexes of Ph2P(O)(CH2)2P(O)Ph2, PhP(O)[(CH2)2P(O)Ph2]2, and (O)P[(CH2)2P(O)Ph2]3, with both tin(II) and lead(II). The 1:1 complexes with polydentate ligands are isolable; nmr shows that the maximum denticity occurs except with the last ligand which behaves in a tridentate manner. Several two-bond M—O—P coupling constants have been obtained. Also, the changes which complexation produces in the P—P couplings are compared with changes produced in the analogous phosphine complexes.The synthesis and characterization of Ph2P(E)[(CH2)2P(E)Ph]2(CH2)2P(E)Ph2(E = S or Se) and (Se)P[(CH2)2P(Se)Ph2]3are reported. The31P nmr spectra of these compounds are compared with those of the parent tetraphosphines and other members of the corresponding tetraoxide–tetrachalcogenide series.

ISSN:0008-4042    

DOI:10.1139/v81-010

出版商:NRC Research Press    

年代:1981

数据来源: NRC