摘要:

A 4-O-methylglucuronoxylan has been isolated in almost quantitative yield from the wood of trembling aspen (PopulustretmuloidesMichx.) The hemicellulose was electrophoretically homogeneous and had a number-average degree of polymerization of 212. Partial hydrolysis gaveD-xylose, galacturonic acid, 4-O-methylglucuronic acid, and 2-O-(4-O-methyl-α-D-glucopyranosyluronic acid)-D-xylopyranose. Methanolysis and hydrolysis of the fully methylated polysaccharide, which contained 108 xylose residues per average molecule, gave 2-O-methylxylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and methyl 2-O-(2,3,4-tri-O-methyl-α-D-glucopyranosyluronic acid) -3-O-methyl-D-xylopyranoside in a mole ratio of 0.2:95:1:11. It is concluded that the hemicellulose contained a linear framework of approximately 200 (1 → 4)-linked β-D-xylopyranose residues and that, on the average, every ninth xylose unit carried a (1 → 2)-linked 4-O-methyl-α-D-glucuronic acid residue directly attached to the xylan backbone. The polysaccharide is evidently similar to the 4-O-methylglucuron-oxylans occurring in the wood of all arborescent angiosperms so far investigated.

ISSN:0008-4042    

DOI:10.1139/v61-131

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The structures of extracellular polysaccharides produced by the plant pathogensAgrobacterium tumefaciens(2 strains),A.rhizogenes,A.radiobacter,A.ruhi,A.gypsophilae, andA.pseudotsugaewere investigated. Polymeric material was formed in good yield from all organisms exceptA.gypsophilae. Periodate oxidations of the polysaccharides and their sodium borohydride reduction products indicated linear 1,2-glucopyranose structures forA.tumefaciens(2 strains),A.rhizogenes,A.radiobacter, andA.rubipolymers. Optical rotational considerations led to the assignment of β-configurations. The linear structure for theA.radiobacterpolysaccharide was confirmed by the isolation, after partial acid hydrolysis, of five 1,2-linked oligosaccharides with chain lengths of two to six. Periodate and chromatographic data indicated that the polysaccharide fromA.pseudotsugaecontained glucose and galactose and 1,6- as well as 1,2-glycopyranose links. It is noteworthy that the polysaccharides from the genusAgrobacteriurmare shown to be mainly 1,2-β-glucans, a structure not yet found in other genera.Treatment of linear 1,2-β-glucans fromA.tumefaciens,A.radiobacter, andA.rhizogeneswith sodium hydroxide – dimethyl sulphate, followed by silver oxide in methyl iodide dimethyl formamide, did not cause full methylation. Some of the 3-hydroxyl groups were not substituted and possible reasons for this unreactivity are discussed.

ISSN:0008-4042    

DOI:10.1139/v61-132

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

When organic compounds are added to active nitrogen, the red and violet bands of the CN radical are emitted. The relative intensities of these red bands have been measured for a variety of added compounds, temperatures, and pressures. It is shown that there are at least three processes producing electronically excited CN radicals, two yielding CN(A2II) and one yielding CN(B2∑). The behavior of the flames indicates that a chain mechanism is involved. Adding ammonia, which does not react with nitrogen atoms, quenches the CN emission and inhibits the consumption of nitrogen atoms. It is concluded that a second reactive species in active nitrogen, possibly metastable N2(A3∑) molecules, initiates the reactions which result in light emission.

ISSN:0008-4042    

DOI:10.1139/v61-133

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Two additional acids, 10-hydroxydecanoic andp-hydroxybenzoic, have been isolated from the ether-soluble fraction of royal jelly. A sterol, 24-methylenecholesterol, has been found in the ether-insoluble, methanol-soluble fraction of royal jelly.

ISSN:0008-4042    

DOI:10.1139/v61-134

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Seven alkaloids have been isolated fromL.clavatumLinn. collected in Jamaica, clavolonine C16H25NO2, fawcettiine C18H29NO3, base A (now named fawcettimine), lycopodine, dihydrolycopodine, and L.2 (acetyldihydrolycopodine). Fawcettimine is a secondary amine now shown to be C16H25NO2. The isolation of deacetylfawcettiine C16H27NO2in quantity from a later extraction indicated that there was a seasonal variation in the alkaloid content of the plant. These bases differ from those obtained fromL.clavatumof Canadian or European origin.

ISSN:0008-4042    

DOI:10.1139/v61-135

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The effect of pressures up to 3 kbar on the rate of the acid-catalyzed hydrolysis of methyl, ethyl, andt-butyl acetates in dilute aqueous acid and of ethyl acetate in concentrated hydrochloric acid has been measured. The volume of activation fort-butyl acetate is zero within experimental error, showing that the mechanism is unimolecular. Those for methyl and ethyl acetates are near –9 cm3mole−1in both dilute and concentrated acid. We deduce from this that the mechanism is the same in 9.2-Mhydrochloric acid as in dilute acid, that the transition state is not highly polar, and that if the proton in the reactive protonated ester is on the carbonyl oxygen then the attacking water molecule adds, and if the proton is on the ether oxygen then the attacking water molecule substitutes.

ISSN:0008-4042    

DOI:10.1139/v61-136

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The effect of pressures up to 3 kbar on the rate of the acid-catalyzed hydrolysis of acetamide and benzamide in both dilute and concentrated perchloric acid has been measured. The volumes of activation in dilute acid are consistent with a transition state that is not highly polar. It follows from this that if the attacking water molecule adds to the amidium ion then the reactive amidium ion is the O-protonated form, and if the attacking water molecule substitutes then the reactive amidium ion is the N-protonated form.The volume of activation for acetamide in concentrated acid provides no additional information about the mechanism. That for benzamide in concentrated acid is tentatively interpreted as favoring the O-protonated benzamidium ion as the reactive ion.

ISSN:0008-4042    

DOI:10.1139/v61-137

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A rapid spectrophotometric method for the determination of small amounts of aluminum in uranium metal and uranium compounds is described. The method makes use of the yellow-colored complex formed between aluminum and 8-hydroxyquinoline (oxine) at pH 9.5–10; the complex is extracted with carbon tetrachloride. Elements which interfere are extracted with 8-hydroxyquinaldine. The method is suitable for the determination of up to 0.1% aluminum.

ISSN:0008-4042    

DOI:10.1139/v61-138

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Argon–nitrogen mixtures (9/1) were inoculated with traces of Cr(CO)6(0.026%) and shocked to temperatures in the range 3500 °K to 5700 °K. The intensities of a violet line (7P2 → 7S3) and a triplet of green lines (5P3,2,1 → 5S2) were measured concurrently, with a dual-channel spectrograph. Exclusive of runs for whichT > 5000 °K, the variation of intensity with temperature was brought to agreement with theoretical predictions under the assumption that the N2vibrations, the dissociation of Cr(CO)6, and the ionization of Cr attained their equilibrium states, but allowance had to be made for self-absorption. The dependence of the rise times on temperature suggest that the excitation and ionization of Cr is predominantly due to collisions with electrons. The over-all shapes of the recorded light pulses were qualitatively accounted for. It is suggested that extraneous background radiation contributed to the measured intensities for samples shocked to temperatures above 5000 °K.

ISSN:0008-4042    

DOI:10.1139/v61-139

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The ultraviolet absorption spectra of bromobenzene in various solvents, and the spectra of a series of substituted bromobenzenes in cyclohexane solution, are reported. TheB-band spectral data confirm the hypotheses postulated for theB-band spectra of chlorobenzenes in the previous part of this series of papers. That is, the bromine atom usually gives rise to greater steric effects than the chlorine atom and the apparent mesomeric interaction as judged from these spectra increases with the size of the halogen substituent.Both bromobenzene and chlorobenzeneC-band intensities are unusually small, and this is assumed to account for the frequentC-band similarity between the spectrum of a mono-substituted benzene derivative PhX, where X = OH, OCH3, NH2, and the spectrum of the corresponding chloro- or bromo-substituted PhX derivative.

ISSN:0008-4042    

DOI:10.1139/v61-140

出版商:NRC Research Press    

年代:1961

数据来源: NRC