摘要:

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M(KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

ISSN:0008-4042    

DOI:10.1139/v77-362

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Solid state synthesis of thirteen ammonium fluorolanthanates is reported. Two main types of fluorolanthanates appeared in the primary synthesis reaction,viz. NH4LnF4and (NH4)3Ln2F9.The final decomposition product of the fluorolanthanates is LnF3with NH4Ln2F7appearing as an intermediate in (NH4)3Ln2F9decomposition.Infrared absorption spectra and X-ray diffraction data for the stable fluorolanthanates are presented.

ISSN:0008-4042    

DOI:10.1139/v77-363

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The solid state reaction Eu2O3–NH4F leading to the formation of NH4EuF4was studied by thermal analyses and X-ray diffraction.The heat of decomposition of NH4EuF4and the kinetics of thermal decomposition of NH4EuF4are reported.

ISSN:0008-4042    

DOI:10.1139/v77-364

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Vanadium metal dissolves rapidly in a cell Pt/X2in CH3CN/V (anode) (X = Cl, Br, I) under applied voltages of 5–50 V. The solution phase yields crystalline VCl2. 2CH3CN, VBr2. CH3CN, or VI2; the acetonitrile adducts decompose to VX2on heating in vacuo. Overall yields of VX2, based on weight of metal dissolved, are 80–90%.

ISSN:0008-4042    

DOI:10.1139/v77-365

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A controlled thermal explosion in which methyl isocyanide isomerises quantitatively to methyl cyanide has been studied in a calorimeter at 300 K. The enthalpy of isomerisation ΔH = −23.70 ± 0.14 (2 sdm) kcal mol−1, from which values of the enthalpies of formation of both gaseous and liquid methyl isocyanide are calculated.Similar measurements for ethyl isocyanide yield ΔH = −21.5 ± 1.0 kcal mol−1.

ISSN:0008-4042    

DOI:10.1139/v77-366

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Ionization potentials (IP) of HX, CH3X, C2H5X, andi-C3H7X, where X is a substituent with non-bonded electrons, are directly proportional to ionization potentials of 4-substituted quinuclidines. This is taken as evidence that in general the energy required to remove an electron from a substituent X, as is the case in HX, CH3X, C2H5X, andi-C3H7X, is directly proportional to the energy required to remove an electron from a site remote from the substituent, as in the quinuclidines in which an electron is lost from the ring nitrogen. Furthermore, the IP's of the HX-i-C3H7X series are directly proportional to inductive substituent constants, σI, providing a valuable correlation between gas and solution phase behavior.

ISSN:0008-4042    

DOI:10.1139/v77-367

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The effect of substituents at the 3-position in a series ofN-methyl 5,6-dihydro-7H,12H-di-benzo[c,f]azocines on the geminal coupling constants of the C-12 methylene protons has been determined. The slope of the Hammett plot of2J vs. σ has been found to be +0.20. The orientation of the methylene protons with respect to the π orbitals of the benzene ring bearing the substituent is such that no hyperconjugative effect should be present. The value of +0.20 is in contrast to a previously measured slope of −1.9 for compounds having a geometry ideal for hyperconjugative effects and substantiates the predictions of theoretical MO calculations. As a result, the reliability of this conformational dependence of ρ for use in conformational analysis has been strengthened.A comparison of the data for the azocines with those in the literature indicates the difference between the minimum and maximum effects of a phenyl substituent on a geminal coupling constant of an attached methylene group is 5.5 Hz.

ISSN:0008-4042    

DOI:10.1139/v77-368

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The free energies of activation for hindered rotation around the C—N bond have been determined for a series ofN,N-disubstituted thioamides by means of13C and1H dynamic nmr.A comparison between barriers for 20 amides and the corresponding thioamides, studied under similar conditions, has been drawn up using both our results and data obtained from the literature. An excellent linear correlation has been obtained. The same correlation also holds for primary (thio)amides and seems to be of general significance. Substituent effects on the barrier heights of thioamides and amides are discussed in connection with some particular cases.

ISSN:0008-4042    

DOI:10.1139/v77-369

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The reaction between 1-chloro-2,4,6-trinitrobenzene (picryl chloride) and diethylmalonate anion in benzene–DMSO 7:1 v/v solvent has been investigated by means of stopped-flow and uv–visible spectrophotometers. The results support a simple bimolecular aromatic substitution with a fast formation of a Meisenheimer-like coloured intermediate, followed by a slower decomposition to the picryl ester. The latter is rapidly deprotonated by the excess base. The steps of the reaction were followed separately and the rate constants and activation parameters have been measured.

ISSN:0008-4042    

DOI:10.1139/v77-370

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The reaction of picryl bromide with sodium diethylmalonate has been studied in benzene–DMSO 7:1 v/v by means of stopped-flow and uv–visible spectrophotometers. A Meisenheimer-like intermediate was detected, decomposing to yield the stable violet anion of the substitution product. The rate constants of the individual steps have been measured and the activation parameters calculated. Comparison with those obtained for picryl chloride support a bimolecular substitution via the 1,1-complex. The reaction with 1,3,5-trinitrobenzene is too fast to be measured in the same solvent system. The equilibrium constant is estimated to be of the order of 104–105.

ISSN:0008-4042    

DOI:10.1139/v77-371

出版商:NRC Research Press    

年代:1977

数据来源: NRC