摘要:

Thermometric measurement of vapor pressure equilibria in reaction mixtures containing borate ion andcis-3,4-dihydroxytetrahydrofuran (I) orD-glucose 5,6-carbonate (II) indicate that complexing involves at least three different equilibria. Borate complexing by I is characterized by a gross change in n.m.r. spectral characteristics, most striking being a strong overall decoupling effect. Alterations in the spectrum of II and of 5-O-methylD-glucose in the presence of borate, when compared with those ofD-glucose, suggest that complex formation by the latter sugar proceeds with a pyranose-to-furanose interconversion. The O—C—C—O dihedral angle, within the range 0° to about 40°, does not appear to be a factor determining the stability of borate complexes. Crystalline spirane-type complexes of I, II, and ofD-threose have been prepared, illustrating the usefulness of borate complexing for the isolation of some furanose sugars and derivatives.Solutions of alkali tetraborates are found by thermometric vapor pressure measurements to behave as equimolecular mixtures of alkali borate and boric acid.

ISSN:0008-4042    

DOI:10.1139/v63-354

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

In the reaction of isobutane with Hg3P1atoms, cleavage of the tertiary C—H bond is about seven times as frequent as cleavage of a primary C—H bond. This ratio is greatly changed by deuterium substitution in the tertiary position. Cleavage of the tertiary C—D bond in (CH3)3CD occurs only about 0.6 times as frequently as cleavage of a primary C—H bond. In (CD3)3CH, no cleavage of a primary C—D bond could be detected, and only the tertiary H-atom is removed.

ISSN:0008-4042    

DOI:10.1139/v63-355

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The action onD-quinic acid of hot 95% acetic acid containing mineral acid gave, after complete acetylation, 1,4,5-tri-O-acetyl-epi-quinide consisting of approximately equal portions of the (−)- and (±)-isomers, and tetra-O-acetyl-scyllo-quinic acid. The stereochemistry of the products and their derived free polyols were determined by nuclear magnetic resonance (n.m.r.) spectroscopy and synthesis.Elimination of the tosyloxy group in 5-tosyl-epi-quinicol was shown to take place readily in aqueous acetic acid with participation of the primary carbinol group to give an anhydro quinicol derivative and epi-quinicol.

ISSN:0008-4042    

DOI:10.1139/v63-356

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

(CH3)2AsSC2H5, prepared from (CH3)2AsCl and Pb(SC2H5)2, and ((CH3)2As)2S2react with RfI at 100° to give the compounds (CH3)2AsRf(Rf = CF3, C3F7). The compounds AS2Sx(x = 2, 3) do not react with CF3I at 100°. ((CF3)2As)2S, prepared from (CF3)2AsI and Ag2S or from (CF3)2AsH and S, reacts with Hg to give ((CF3)2As)2, decomposes at 175° to give (CF3)3As, and reacts with CF3I at 125° to give mainly (CF3)3As. Some (CF3)2AsI and CF3SAs(CF3)2is also produced from this last reaction.

ISSN:0008-4042    

DOI:10.1139/v63-357

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A2B2spectra of 1,1 -disubstituted cyclopropanes have been calculated over a range of values of the spectral parameters. The sign of the geminal coupling is opposite to that of the vicinal couplings. Since this is also the case with other saturated ring systems the theoretical spectra should be useful in studies of other saturated ring systems.The shifts and coupling constants are given for the protons in 1-phenylcyclopropylcarboxylic acid in solution in carbon disulphide, chloroform, and benzene as an example of the A2B2analysis. The ring protons in 1-phenylcyclopropylcarbinol were found to be equivalent in different solvents, with insignificant coupling to the protons in the methylene and phenyl groups. A qualitative discussion of the shifts of the various protons in various solvents is given.

ISSN:0008-4042    

DOI:10.1139/v63-358

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

After repeated and vigorous treatments, a fully methylated glucan was obtained. Hydrolysis of the methylated glucan with sulphuric acid gave tetra-, tri-, di-, and mono-O-methyl-D-glucoses in a 5:5:3:1 ratio. Both the furanose and pyranose tetramethyl isomers were identified. Nearly all of the possible pyranose and furanose cyclic trimethylglucoses were positively identified. An attempted resolution of the dimethylglucoses was relatively unsuccessful. The monomethylglucoses were identified by electrophoresis.

ISSN:0008-4042    

DOI:10.1139/v63-359

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The problem of current distribution at an electrode of linear geometry having a significant ohmic resistance is examined for conditions where the ohmic potential drop along the electrode material is of the same order of magnitude as the metal–solution potential difference. This problem is of practical significance in primary and secondary cells at high current drains and in certain types of fuel cell electrodes. The current distribution and metal–solution potential profiles are calculated as limiting cases of a general theory. The true and apparent current–potential relations are compared theoretically.

ISSN:0008-4042    

DOI:10.1139/v63-360

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The photolysis of acetone in the presence of methyl alcohol and of methyl-d3alcohol has been studied between 406 and 472° K. The rates and Arrhenius parameters for the following abstraction reactions have been determined:At 182°C the rate of reaction [b] is found to be approximately four times greater than the rate of reaction [c].

ISSN:0008-4042    

DOI:10.1139/v63-361

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Some dinitrophenyl glycyl peptides have been prepared from dipeptides and from dinitrophenyl glycyl chloride, and the products suitably characterized. Electrophoresis gave good separation of those differing by more than two carbon atoms.

ISSN:0008-4042    

DOI:10.1139/v63-362

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The cryoscopic and conductimetric behavior of solutions of hexamethyldisiloxane, trimethylethoxysilane, dimethyldiethoxysilane, methyltriethoxysilane, and tetraphenylsilane in 100% sulphuric acid has been investigated. The measurements show that stable non-electrolytes such as (CH3)3Si·HSO4and (CH3)2Si(HSO4)2are formed from the tri- and di-alkyl compounds. Species such as CH3Si(HSO4)3, which are presumably formed in the reaction of monoalkyl compounds, and Si(HSO4)4, which it is reasonable to suppose is the initial product from the cleavage of tetraphenylsilane, are unstable and polymerize to give polymers containing Si—O—Si bridging groups. No evidence was obtained for the formation of siliconium ions or for the formation of compounds containing silicon with a coordination number greater than four.

ISSN:0008-4042    

DOI:10.1139/v63-363

出版商:NRC Research Press    

年代:1963

数据来源: NRC