摘要:

AbstractA new extraction method for ginsenosides from ginseng roots, ginseng leaves and ginseng drug preparations by Sep‐Pak C18cartridges has been studied. Ginsenoside extraction by Sep‐Pak cartridges is a rapid, efficient, reproducible method. In addition, the extracts were analyzed by high performance thin layer chromatography (HPTLC) and reverse phase high performance liquid chromatography (HPLC). The major components of ginseng saponins were effectively separated using an ODS‐120T c

ISSN:0009-4536    

DOI:10.1002/jccs.198700001

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractA simple and improved gas chromatographic method has been developed for the quantitative analysis of nalidixic acid. The method is based on the derivatization of nalidixic acid with pentafluorobenzyl bromide in acetone, using potassium carbonate as a base‐catalyst. The derivative obtained was chromatographed on an OV‐101 column and the pentafluorobenzyl ester of cinoxacin was used as an internal standard. The method was satisfactorily applied to the analysis of nalidixic acid in tablets, and the results agree well with those obtained using the UV absorption spectrophotometric met

ISSN:0009-4536    

DOI:10.1002/jccs.198700002

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe stepwise formation constants ofN‐antipyrinyl‐N′‐3‐phenyl‐2‐propenoyl‐thiourea (I) complexes with metal ions of the first transition series, Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) have been determined in 70% (V/V) ethanol‐water medium. The formation constants for the chelates follow the Irving‐Williams series:Zn(II)Mn(II)The effect of ionic radius and electronegativity on the chelate formation are discussed. Complexes of Cu(II) and Ni(II) have been synthesised and characterised by elemental analysis, electrolytic conductance, IR spectra and magnetic susceptibility measurements. The ligand formsbis‐complexes with Cu(II) and Ni(II). The binding sites are oxy

ISSN:0009-4536    

DOI:10.1002/jccs.198700003

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reactions ofN‐phenylhydroxylamine in the presence of dry hydrogen chloride to form azoxybenzene, aniline, 2‐chloroaniline and 4‐chloroaniline were studied. The molar ratio of the azoxybenzene and aniline obtained was very close to one. A similar reaction was also observed for 2‐methyl‐ and 4‐methyl‐N‐phenylhydroxylamine. A reasonable explanation is thatN‐phenylhydroxylamine undergoes a self oxidation reduction reaction to give aniline and nitrosobenzene, and the latter subsequently reacts withN‐phenylhydroxylamine to give azoxybenzene. The reaction ofN‐phenylhydroxylamine, catalyzed by trifluoroacetic acid to yield azoxybenzene, was previously studied by Okamotoet al. and was suspected to undergo a similar reaction. We repeated the reaction and evidence for the same self oxidation reduction reaction was found. A mechanism involving the anilenium ion is proposed to acco

ISSN:0009-4536    

DOI:10.1002/jccs.198700004

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reduction and nitration of 1‐keto and 4‐keto‐1,2,3,4‐tetrahydrophenanthrene were investigated. The structures of the products were confirmed by spectroscop

ISSN:0009-4536    

DOI:10.1002/jccs.198700005

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe physical properties of theN‐oxides prepared by the oxidation of tertiary isoquinoline alkaloids withm‐chloroperbenzoic acid are presented and are compared with those of their parent alkalo

ISSN:0009-4536    

DOI:10.1002/jccs.198700006

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

Abstract(4S‐5R)‐ and (4S‐5S)‐dihydroxy‐n‐decanoic acid‐4‐lactones have been synthesized in a stereocontrolled manner by a chemomicrobiol

ISSN:0009-4536    

DOI:10.1002/jccs.198700007

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reactions of methylphenylvinylsulfonium tetrafluoroborate (1) with the lithium enolates of 1,3‐dicarbonyl compounds, acyclic ketones and cyclic ketones have been studied. Cyclopropanes and cyclic ethers are obtained. The reaction mechanisms are also discusse

ISSN:0009-4536    

DOI:10.1002/jccs.198700008

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractSensitized photooxygenation of 2,5‐di‐teri‐butylfuran was carried out in methylene chloride at −75°Cto give a labile ozonide 4a, which was heated in methylene chloride under reflux to afford six products after puri

ISSN:0009-4536    

DOI:10.1002/jccs.198700009

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractA series of polyurethanes based on hydroxyl‐terminated polybutadiene (HTPBD) and cured withBis‐(‐hydroxy ethyl)‐terephthalate (BHET) have been synthesized. Mechanical, microscopic and kinetic studies were carried out to elucidate the structure‐property relationships from the view point of phase separation. We studied the effects of the polymerization method, varying the hard to soft segment ratio and changing the hard‐segment domain structure on the properties of the subject materials.Dynamic mechanical responses showed that the Tg of the soft‐segment at −60°Cwas independent of the hard‐segment content, which indicates that the copolymers were well phase separated. A higher hard‐segment content brought about a slight increase in the modulus, a moderate increase in the tensile strength and a decrease in the ultimate elongation.The size of the hard‐segment domain, as estimated from electron micrographs, ranged from 60A to 100A. It was observed that a higher content of hard‐segments causes an increase in the hard‐segment domain size. In addition, a general survey of the reaction rate indicated that BHET is less reactive with diphenyl methyl diisocya

ISSN:0009-4536    

DOI:10.1002/jccs.198700010

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY