摘要:

A general procedure for the analysis of complex n.m.r. spectra has been developed in terms of simpler sub-spectra. The method is applicable to all possible combinations of magnetically equivalent and non-equivalent, strongly and weakly coupled groups of nuclei. It includes the special case of the composite particle model as well as the effective frequency method.The method is applied, as an example, to the ABB′XX′ spectrum of pyridine where the parametersJAB,JAX, the sum ofJBX + JBX′, δAB, and δAXare derived without complete analysis of the spectrum, from the AB2sub-spectra of the problem.

ISSN:0008-4042    

DOI:10.1139/v65-011

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The conversion of tetra-O-acetyl-α-D-glucopyranosyl bromide (I) to 2-acetoxy-D-glucal triacetate (II) was found to be catalyzed by secondary amines containingn-alkyl groups. Substitution at the α-positions of the amine reduced the catalysis. Although triethylamine and tri-n-propylamine did not serve as useful catalysts, the less hindered and strongly basic 1,4-diazabicyclo[2,2,2]octane was more effective than diethylamine. The reaction is strongly promoted by polar solvents and added salts—especially tetra-n-butylammonium bromide. The course of the reaction involves direct elimination of hydrogen bromide and this reaction is in competition with the formation of acetylatedN-glucosides. A kinetic study of the reaction using a variety of amines led to the conclusion that the first stage of the reaction is dissociation of I to glycosyloxocarbonium ion strongly solvated by the amine. Depending on the structure of the amine, the second stage of the reaction may involve transfer of the 2-proton to the amine to form 11 at a faster or slower rate than the formation of the N to C1bond of the acetylatedN-glucoside. Conditions were established for the near quantitative conversion of I to II in about 1/100th the reaction time reported in the literature.

ISSN:0008-4042    

DOI:10.1139/v65-012

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The reactions of methylene radicals with acetaldehyde and propionaldehyde have been studied over the temperature range 48–118 °C and over a range of pressures of aldehyde and carbon dioxide. From acetaldehyde, the main products were carbon monoxide, methane, ethane, and acetone, with small amounts of ethylene at low pressures of acetaldehyde. With carbon dioxide present, small amounts of propylene oxide were formed, but propionaldehyde was not observed. The main products from the reaction with propionaldehyde were carbon monoxide, methane, ethane, and ethylene, with small amounts of methyl ethyl ketone, butene oxide, and isobutyraldehyde. The relation of the results to the relative rates and mode of attack of methylene on the various bonds is discussed.

ISSN:0008-4042    

DOI:10.1139/v65-013

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The reaction between adrenochrome and glutathione has been studied. The main products result from the 1,4-addition of glutathione to the C5unsaturated carbonyl systems in adrenochrome involving the C6—C7and the C4—C9double bonds, and are probably 7-S-glutathionyl-5,6-dihydroxy-N-methylindole and 9-S-glutathionyl-2,3,6,9-tetrahydro-3,5-dihydroxy-6-oxo-N-methylindole respectively. 5,6-Dihydroxy-N-methylindole is also formed during the interaction of glutathione and adrenochrome. The mechanisms by which these compounds are formed are discussed.

ISSN:0008-4042    

DOI:10.1139/v65-014

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Methyl benzoate (p-tolylsulfonyl)hydrazone (I) was prepared from the reaction between (p-tolylsulfonyl)hydrazide and either methyl benzimidate hydrochloride or methyl orthobenzoate. When the potassium or sodium salt of this hydrazone was decomposed, thermally or photochemically, in the presence of alcohols, benzaldehyde mixed acetals could be isolated in good yields and of high purity. When the decomposition was carried out in the presence of piperidine, there was produced 1(α-methoxybenzyl) piperidine (II) and α,α-dipiperidinotoluene (III). The reaction products can be explained by assuming the initial formation of phenylmethoxydiazomethane.

ISSN:0008-4042    

DOI:10.1139/v65-015

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The utilization of one-carbon precursors in the biosynthesis of hydrastine and berberine was investigated by tracer experiments with plants ofHydrastiscanadensisL. The lactone group of hydrastine and the bridge carbon of berberine are shown to be derived from theS-methyl group of methionine.

ISSN:0008-4042    

DOI:10.1139/v65-016

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The17O n.m.r. spectra from aqueous solutions containing both chromate and dichromate ions have been obtained over a range of concentrations. Signals from both the bridging oxygen and the terminal oxygens in the dichromate ion have been observed. The line widths for the dissolved species were found to be concentration dependent. The variations in line width have been ascribed to a rapid reaction occurring at equilibrium between chromate and dichromate ions. The bimolecular rate constant for the reaction is 2.3 ± 0.4 × 103 1 mole−1s−1at 27 °C. The reaction mechanism is discussed in the general context of nucleophilic attack on dichromate ion. A comparison of this rate constant with those for the analogous reaction using different nucleophiles indicates that it is polarizability rather than basicity which determines nucleophilic reactivity towards Cr2O7−.

ISSN:0008-4042    

DOI:10.1139/v65-017

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The solubility data in light and heavy water of Swain and Thornton and of Taft and coworkers are reinterpreted to show that they support primarily the initial state origin for the kinetic solvent isotope effect. Other recent data, including the effect fort-butyl and α-phenethyl fluorides, are also shown to be compatible with the same hypothesis.

ISSN:0008-4042    

DOI:10.1139/v65-018

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

A pulsed ion source has been constructed for use with a magnetic-deflection mass spectrometer. With this source the time between ion formation and withdrawal for analysis can be controlled and varied in a known manner. The design and operating characteristics of the source are discussed and a technique is described for the measurement of ion withdrawal times using the pulsing technique. The rate constant for the ion molecule reactionhas been determined for the reaction of thermal energy ions using reaction time as the experimental variable. The equivalent reactions in the deuteriomethanes have also been studied. Preliminary results obtained in the study of the unimolecular fragmentation of the cyclohexadiene, toluene, and spiroheptadiene parent ions are presented.

ISSN:0008-4042    

DOI:10.1139/v65-019

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Evidence for a dihydrate of zinc fluoride ZnF2•2H2O from dehydration studies is reported. The structural changes accompanying the decomposition of the hydrate were followed by X-ray diffraction. The heating of the dihydrate in air was found to yield as residues (a) mixture of ZnF2and its hemihydrate, (b) mixture of ZnF2and ZnO, (c) the hemihydrate, and (d) ZnO.

ISSN:0008-4042    

DOI:10.1139/v65-020

出版商:NRC Research Press    

年代:1965

数据来源: NRC