摘要:

Reactions between niobium(V), tantalum(V), and protactinium(V) chlorides and bromides and sodiumN,N-diethyldithiocarbamate (Nadtc) have been examined in non-aqueous, non-oxygenated organic solvents. Complexes obtained are of the types Mdtc4X, Mdtc3X2, Mdtc3S, Mdtc2X3, and Mdtc2X3.nC6H6(n = 0.7–1.0); not all complexes have been isolated for each metal. Within each group the niobium(V) and tantalum(V) complexes are isostructural; possible structures are discussed in the light of results from infrared (i.r.) and nuclear magnetic resonance (n.m.r.) spectra, molecular weight, and electrical conductivity measurements.

ISSN:0008-4042    

DOI:10.1139/v71-191

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Defocussed metastable peaks have been used to elucidate the hitherto apparently complex fragmentation of the molecular ion of 1,2-cyclohexanediol. It was shown that the predominant mode of water loss from the molecular ion involved "scrambling" of six hydrogen atoms, those in the 4- and 5-methylene groups and the hydroxyl pair. A minor water elimination involves simple hydroxyl–hydroxyl interaction.

ISSN:0008-4042    

DOI:10.1139/v71-192

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Diphenylcyclopropenone reacts with a variety of heteroaromatic nitrogen compounds to give in good yield either (a) 1,2-diphenyl-3-indolizinylcis-1,2-diphenyl acrylates and aza analogs, (b) 5,6-diphenyl-7-hydroxypyrrolo[1,2-b]pyridazines and similar structures, or (c) adducts in which cycloaddition takes place to an N=N bond. Proof of structure of the new heterocycles is based on deuterium labelling experiments, hydrogenolysis to known compounds, and the preparation of chloro and iminoether derivatives. Cycloheptenocyclopropenones in the examples studied form heterocycles of typeb.

ISSN:0008-4042    

DOI:10.1139/v71-193

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

D-Idurone was prepared by periodate oxidation ofD-glycero-D-ido-heptonolactone.

ISSN:0008-4042    

DOI:10.1139/v71-194

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The reaction of osmic acid with 1,6-anhydro-3,4-dideoxy-β-DL-erythro-hex-3-enopyranose and its 2-O-methyl and 2-O-acetyl derivatives in either pyridine or dioxane solution has produced 1,6-anhydro-β-DL-allopyranose and 1,6-anhydro-β-DL-galactopyranose and the corresponding 2-O-methyl and 2-O-acetyl derivatives. These or their fully acetylated derivatives could be hydrolyzed to α,β-DL-allose and α,β-DL-galactose and the 2-O-methyl derivatives. The proportion ofallotogalactoproduct obtained varies widely with the solvent used in hydroxylation, showing that attack by osmic acid is subject to steric control.

ISSN:0008-4042    

DOI:10.1139/v71-195

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A cell is described that permits a model phospholipid membrane and the two adjacent aqueous compartments to be irradiated with a collimated beam of X-rays. During a 2 h irradiation a marked increase in [H+] in the aqueous phases is observed. A protonmotive force, given by the H+Nernst potential, is generated when one compartment only is irradiated or when both compartments separated by a membrane made structurally asymmetric by the adsorption of alamethicin, are irradiated equally.The results of irradiations in N2O, N2, and O2indicate that the membrane scavenges the superoxide O2−. The effect is discussed in terms of a clearing field that is derived from the potential at the membrane interfaces.

ISSN:0008-4042    

DOI:10.1139/v71-196

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

2,4-Dihydroxy-3-(3-methyl-2-butenyl)benzaldehyde was obtained from 2,4-dihydroxybenzaldehyde with either 3-hydroxy-3-methyl-1-butene or 1-bromo-3-methyl-2-butene. Oxidation of the product in neutral medium withm-chloroperoxybenzoic acid gave (±)-2,3-dihydro-2-(1-hydroxy-1-methylethyl)-4-hydroxybenzofuran-5-aldehyde, whose condensation product with malonic acid was (±)-3-carboxy-columbianetin. Oxidation in acidic medium gave (±)-2,2-dimethyl-3,5-dihydroxybenzopyran-6-aldehyde, whose condensation product with malonic acid was (±)-3-carboxylomatin. (±)-Columbianetin and (±)-lomatin were obtained by decarboxylation.

ISSN:0008-4042    

DOI:10.1139/v71-197

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Dipole moments are reported for trimethylene sulfite and 11 alkyl derivatives in a variety of solvents (C6H12, CCl4, C6H6, dioxan). The variation of dipole moment with solvent for one of the 5-t-butyltrimethylene sulfite isomers is confirmed, but this behavior is not shown by the other compounds. This latter fact is used to rule out rapid chair–chair interconversion for these compounds. Recent ultrasonic absorption experiments are reinterpreted in the context of vicinal electron pair interactions and their effect on conformational analysis of sulfites and similar six-membered compounds. The result is a general scheme which is consistent with available information and which we believe is preferable to analysis of these compounds by analogy with cyclohexane.

ISSN:0008-4042    

DOI:10.1139/v71-198

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The n.m.r. spectra of 11 tetra-substituted ethanes have been obtained in a number of solvents. Changes in the vicinal coupling constants of 1-phenyl-1,2,2-trihaloethanes with solvent do not fit the electrostatic model for solvent effects. It is concluded that the theory breaks down because solute–solvent hydrogen bonding specifically favors thetransrotamers of these compounds. The conditions under which the theory would be expected to break down are also discussed in more general terms.

ISSN:0008-4042    

DOI:10.1139/v71-199

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The role of substituted anilines as second coordination sphere ligands of cobalt(II) complexes has been investigated. Chemical shifts of the ligand nuclear magnetic resonance (n.m.r.) spectra arising from pseudo-contact interaction with the paramagnetic cobalt complex have been utilized for this purpose. It has been found that in each case the aniline preferentially occupies a position perpendicular to the three fold symmetry axis of the complex and tends to be aligned with the amino group directed towards the cobalt atom. Electron withdrawing substituents para to the amino group enhance the second coordination sphere binding and electron donating substituents diminish it. These results are consistent with the idea that the structure of the second coordination sphere is determined by electrostatic interaction with the negatively charged ligands comprising the first coordination sphere. There is competition between aniline molecules and solvent molecules for a position in the second sphere with the solvent competing with increasing effectiveness in the series carbon tetrachloride, benzene, and methylene chloride.

ISSN:0008-4042    

DOI:10.1139/v71-200

出版商:NRC Research Press    

年代:1971

数据来源: NRC