摘要:

The electrochemical oxidation of copper in the presence of RX (R = CH3, C6H5, C6H5CH2; X = Cl, Br, I, not all combinations) and either 2,2′-bipyridine or (C2H5)4NX gives rise to neutral or anionic copper(I) halide complexes. The current efficiency shows that CuX is produced at the anode; the subsequent solution chemistry influences the complex formation processes.

ISSN:0008-4042    

DOI:10.1139/v81-011

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Several compounds of the title class have been synthesized as small-molecule analogues for the metal-binding sites in such biochemical systems as ADH. The ligands containing pyridine and two thioethers do not bind divalent metals (Co2+, Zn2+, Cu2+, Ni2+), strongly suggesting that thioethers are poorly chelated. However, the analogues containing free SH groups bind divalent metals very strongly, producing complexes with limited solubility at pH values in excess of 6. Titration of the latter ligands in the presence of 1 equiv. Zn2+indicates the consumption of 3 equiv. OH−by pH 6, one for theionization, and one for each S—H bound to Zn2+. On the basis of these data the resulting complexes are considered to neutral bis-thiolates. The relationship of these data to the state of ionization of the Zn2+-cysteine SH's in ADH is discussed.

ISSN:0008-4042    

DOI:10.1139/v81-012

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Irradiation of heptamethylbenzenium ion in a variety of aqueous acids using light of wavelength greater than 350 nm leads to the formation of pentamethylcyclopentadiene and acetone. In 50% HBF4and 70% HClO4this photolysis is very clean and can be used as a convenient preparation of pentamethylcyclopentadiene. A mechanism is proposed for the reaction.

ISSN:0008-4042    

DOI:10.1139/v81-013

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

It is shown that gas-phase heats of formation of homologous odd-electron organic cations can be well represented by an equation of the form ΔHf[ion]+• = A − Bn + C/n, whereA, B, andCare constants andnis the total number of atoms in the molecule. Values forA,B, andChave been determined for the linear homologous series: alkanes, olefins, alkynes, alkanols, aliphatic ethers, aliphatic aldehydes, aliphatic ketones, alkanoic acids, alkyl chlorides, bromides, and iodides. For each of these series, correction terms for chain branching, double-bond position, and asymmetry effects are also given. These equations can be applied to molecules containing 40 or more atoms. The data base for this work is also presented.

ISSN:0008-4042    

DOI:10.1139/v81-014

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The synthesis and physical properties ofN,N′-ethylenebis(salicylideneiminato)chlorogallium(III) andN,N′-ethylenebis(salicylideneiminato)methylgallium(III) are described. Crystals ofN,N′-ethylenebis(salicylideneiminato)chlorogallium(III) dichloromethane are monoclinic,a = 13.049(1),b = 9.525(1),c = 15.459(2) Å, β = 92.452(5)°,Z = 4, space group P21/a. The structure was solved by Patterson and Fourier syntheses and was refined by full-matrix least-squares procedures toR = 0.042 andRw = 0.051 for 1815 reflections withI ≥ 3σ(I). The gallium atom is bonded to one chlorine atom and to the tetradentateN,N′-ethylenebis(salicylideneiminato) ligand to give a coordination geometry which is intermediate between square pyramidal and trigonal bipyramidal. Important bond lengths (corrected for libration) are: Ga—Cl, 2.228(2), Ga—O, 1.868(4) and 1.883(4), Ga—N, 2.019(6) and 2.035(5) Å. The crystal structure consists of discrete (C16H14N2O2)GaCl and CH2Cl2molecules linked by ahydrogen bondto form complex-solvate units.

ISSN:0008-4042    

DOI:10.1139/v81-015

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A series of 5,5-dimethyl-4-aryl-Δ1-1,2,4-triazolin-3-ones (Ar = C6H5,p-C6H4CH3,p-C6H4OCH3,p-C6H4Cl, andp-C6H4Br) were prepared from the corresponding 4-arylsemicarbazones of acetone by oxidative cyclization on alumina. The triazolinones decompose in solution to N2, CO, and isopropylidene aryl amine, with first order kinetics, in the temperature range 148–200 °C. Average activation parameters are ΔH≠ = 35 kcal mol−1and ΔS≠ = 8 cal K−1mol−1. Substituent effects are correlated through σ-constants but the thermolyses are relatively insensitive to substituents, with ρ = −0.17 at 172.5 °C. Solvent effects indicate a transition state that is less polar than the ground state.It is tentatively concluded that the triazolinone fragmentation, like the analogous thermolysis of a Δ3-1,3,4-oxadiazolin-2-one, may be a fully-concerted but nonsynchronous process with a transition state involving little, if any, charge separation. Other mechanisms, except for those involving highly polar (e.g. zwitterionic) transition states, have not been ruled out.

ISSN:0008-4042    

DOI:10.1139/v81-016

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Label from [6-14C]-Δ1-piperideine is incorporated nonrandomly into the carbon skeleton of the quinolizidine alkaloid, matrine, inSophora tetrapteraandS.microphylla. The distribution of radioactivity was determined by a new chemical degradation sequence. On the basis of the results, one of two previously postulated biogenetic schemes must be discarded. A modified biogenetic scheme is presented which is consistent with the present results and also leads to the correct stereochemistry of matrine.

ISSN:0008-4042    

DOI:10.1139/v81-017

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The primary processes in the photoreduction of 2-furaldehyde, 2-furyl methyl ketone, and 2-acetylthiophene by phenol, 2,6-di-tert-butylphenol, and pentachlorophenol, respectively, were studied by esr and time-resolved CIDEP techniques. These furan derivatives, in their excited triplet states, can abstract a hydrogen atom from phenol via either the carbonyl group or the carbon–carbon double bond. The present results suggest that they all behave in the primary processes predominantly as carbonyl compounds. The spin–lattice relaxation times of all transient and polarized radicals observed in these photochemical systems were estimated by the CIDEP technique. The photoreductions of furaldehyde and furyl methyl ketone were also examined by high-field CIDNP. The nuclear polarization is mainly due to the cage products and the results are consistent with triplet carbonyl abstraction mechanism. Secondary radical addition to the carbon–carbon double bond of the furan ring was also observed in the furaldehyde–phenol system.

ISSN:0008-4042    

DOI:10.1139/v81-018

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The vapour pressure lowering, ΔP, of sodium sulphate solutions in water was measured in the concentration range 0.4 to 1.8 mand the temperature range 50 to 150 °C by the use of a differential manometer. ΔPvalues were used to calculate the osmotic coefficient of sodium sulphate solutions. Pitzer's equation for osmotic coefficients was used to evaluate βMX(0), βMX(1), andat each temperature. An attempt has been made to explain the changes in these constants in terms of the ion–ion and ion–solvent interactions. Using these constants, the mean activity coefficients, γ±, of sodium sulphate were calculated at different temperatures and concentrations using Pitzer's equation.

ISSN:0008-4042    

DOI:10.1139/v81-019

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The properties named in the title have been determined by standard methods. Viscosity, molar volume, and orientation polarisation all indicate abnormalities of the nature of association between the components.The most interesting result is that of surface tension which indicates that, in the case of the binary system triethylamine–water, a surface layer of constant composition is formed over a wide range of total composition. When, by a rise in temperature of two or three degrees, this layer becomes unstable, it splits into two phases of different composition. The surface layer may then be instantaneously reformed and so on. A mechanism for the generation of a two-phase system is thus established. The data for the three-phase, isothermal, system are not so convincing, for reasons that are suggested.

ISSN:0008-4042    

DOI:10.1139/v81-020

出版商:NRC Research Press    

年代:1981

数据来源: NRC