ISSN:0268-2605    

DOI:10.1002/aoc.590050602

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractReaction of the Nicalon polycarbosilane with the n‐BuLi/Me3COK reagent resulted in metalation of approximately one CH2group in four. Reaction of the metalated polymer with Me2(CH2= CH)SiCl gave a Me2(CH2= CH)Si‐substitued Nicalon polycarbosilane. The polymer was heated with different amounts of the [(MeSiH)∼0.8(MeSi)∼0.2]npolysilane in the presence of azobisisobutyronitrile in refluxing benezene. Hydrosilylation by the SiH‐containing polysilane of the CH2CH groups of the Me2(CH2CH) Si‐substituted Nicalon polycarbosilane gave a new hybrid polymer (when appropriate quantities of reactant polymers were used) whose pyrolyis in a stream of argon to 1000°C left a ceramic residue in 77% yield whose elemental analysis indicated a nominal composition of 91% by w

ISSN:0268-2605    

DOI:10.1002/aoc.590050603

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of ferrocene additive concentrations on the stability of polythylene polymers under atmospheric ageing and ultraviolet irradiation is reported. At concentrations underca5 × 10−3mol kg−1polymer the ferrocene compound is shown to diminish polymer resistance to light, whereas above this concentration such a compound stabilizes the polymeric matrix. Another purpose of the work is to look into the photo‐oxidative destruction of polyethylene doped with ferrocene compound by using an EPR technique. A mechanism of photo‐oxidative destruction of polyethylene polymers in the presence of ferrocene compounds is

ISSN:0268-2605    

DOI:10.1002/aoc.590050604

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThepara‐substituted diphenylzirconocenes [(t‐BuCp)2Zr(p‐C6H4R)2; R = Br, NMe2] (A) were easily obtained from the reaction of the appropriate organolithium reagent with bis(t‐butylcyclopentadienyl)zirconium dichloride. Elimination of bromobenzene orN,N‐dimethylaminobenzene from A by slight heating led to arynezirconocenes into which were inserted two equivalents of elementary chalcogens. As a result dichalcogenated zirconacycles [(t‐BuCp)2ZrY2C6H3R; Y = S, Se] (B) were obtained. Complexes B constitute useful potential synthons in organic synthesis and a large family of new functionalized dichalcogenated benzenic compounds was prepared by reacting electrophiles.The structure of complexes B as well as related benzenic derivatives has been confirmed by microanalysis,1H NMR and mass s

ISSN:0268-2605    

DOI:10.1002/aoc.590050605

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral organisms used for biomonitoring in the mercury‐contaminated Wabigoon–English River System, Ontario, Canada (sport fish, forage fish, crayfish and others) were examined for their utility as bioindicators. Causes for spatial and temporal variability in mercury concentrations in biota are reviewed. The significance of intertrophic and intratrophic biotic relationships is evaluated on both a site‐specific and intersite basis. Larger mature fish are the most effective integrators as these organisms are the most buffered from site‐specific and seasonal variations in mercury concentrations and bioavailability. Where there are no physical barriers preventing movement of biota between contaminated and uncontaminated parts of the watercourse, younger, smaller organisms can better ‐ ical zones of contamination because of their restricted range. Because many organisms can provide information on mercury contamination, the choice of the most suitable indicator depends upon the purpose of the study, the pharmacokinetics of mercury uptake by the organisms in question, and the chemodynamics of methyl and inorganic mercury species in

ISSN:0268-2605    

DOI:10.1002/aoc.590050606

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe synthesis of dimethyl‐, diethyl‐ and/or di‐t‐butyl‐tin(IV) derivatives of substituted salicylic acids of the type a, (X‐Y‐2‐OH‐C6H2COO)2SnR2(X, Y  H, H; H, 5‐CH3; H, 5‐Cl; H, 5‐F; H, 3‐CH3O; H, 5‐CH3O; 3‐CH3, 6‐(CH3)2CH; 3,5‐[(CH3)2CH]2and 4,5‐benzo) and b {[R2(X‐Y‐2‐OH‐C6H2COO)Sn]2O}2(X, Y  H, 3‐CH3O; H, 5‐CH3O: 3‐CH3, 6‐(CH3)2CH; 3,5‐[(CH3)2CH]2and 4,5‐benzo) is reported. Their characterization by1H,13C and119Sn NMR, Mössbauer and mass spectrometry is described. Thein vitroantitumor activity of selected derivatives agains

ISSN:0268-2605    

DOI:10.1002/aoc.590050607

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe relationship between the four components, (1) fluorescence intensity, (2) arsenic concentration, (3) pH and (4) total dissolved solids, (TDS) measured in well waters from areas in Taiwan where blackfoot disease (BFD) is endemic was studied, as well as the relationships between the four degrees of BFD and each of the above four symptomatic components, in order to evaluate the etiological factors of BFD more progressively. The following 95% confidence intervals were obtained in well water samples (n= 1189): fluorescence intensity, 26.837–32.570; arsenic concentration, 0.103–0.127 mg dm−3; pH, 7.466–7.519; and TDS 733.063–801.647 mg dm−3. Fluorescence intensities of the four degrees of BFD were not all the same (F= 64.54,P<0.001), and nor were arsenic concentrations (F= 72.03,P<0.001), pH values (F= 7.30,P<0.001), nor TDS values (F= 10.76,P<0.001). In addition, multiple comparisons indicate that the higher the epidemical degree, the higher the fluorescence intensities, arsenic concentrations and pH values become; however, such a relationship is not found for TDS values. Moreover, the fluorescence intensities have positive linear correlations with arsenic concentrations (r= 0.49,P<0.001), pH (r= 0.25,P<0.001), and TDS (r= 0.18,P<0.001), as do the arsenic concentrations with pH (r= 0.22,P<0.001). Of the four epidemical degree groups, pairs are not significantly different from one another in correlation coefficients between fluorescence intensity and arsenic concentration, which implies a steady relationship between fluorescent compounds and arsenic. We conclude that fluorescent compounds in well water, as possible etiological factors of BFD, are closely related to arsenic along with pH and TDS values in the areas where BFD is endemic. In addition, we infer that a complex is formed by fluorescent compounds, arsenic and o

ISSN:0268-2605    

DOI:10.1002/aoc.590050608

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractVarious esters are conveniently prepared by direct esterification of the corresponding carboxylic acids with alcohols catalyzed by a triphenylstibine oxide–phosphorus(V) sulfide combined system (Ph3SbO/P4S10) under mild conditions (25–80

ISSN:0268-2605    

DOI:10.1002/aoc.590050609

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractMono‐substituted triphenyl‐phosphine, ‐arsine and ‐stibine derivatives of phenylmethinyltricobalt enneacarbonyls PhCCo3(CO)8L (where L  PPh3, AsPh3and SbPh3) were synthesized. The Co(2p3/2) binding energy (Eb) was lowered from 781.3 eV in PhCCo3(CO)9, to 780.0 eV in PhCCo3(CO)8PPh3, to 780.3 eV in PhCCo3(CO)8AsPh3and to 780.5 eV in PhCCO3(CO)8SbPh3. Hydroformylation selectivity to total aldehyde and alcohol of the substituted clusters PhCCo3(CO)8L was about 100%, but that of the parent cluster PhCCo3(CO)9was 93.8%. Hydroformylation products of styrene and di‐isobutene were the completely normal aldehyde when using PhCCo3(CO)8AsPh3

ISSN:0268-2605    

DOI:10.1002/aoc.590050610

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe conversion of adamantane exclusively to 1‐adamantyl trifluoroacetate in a refluxing trifluoroacetic acid solution of palladium acetate at 1 atm of air or nitrogen was confirmed. The conversion can be made quantitative. The 1‐adamantyl trifluoroacetate was hydrolysed to yield 1‐adamantanol in 90% isolated yield. The adamantane functionalization is accompanied by concomitant formation of a palladium m

ISSN:0268-2605    

DOI:10.1002/aoc.590050611

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY