摘要:

AbstractA simple on‐line flow injection analysis pre‐concentration technique has been developed. The flow injection system consisted of a 4‐channel peristaltic pump, two 6‐way rotary injection valves containing a microcolumn of Chelex‐100 resin, and a flame atomic absorption spectrometer, allowing the determination of lead at a concentration as low as ppb. The degree of pre‐concentration depended on the injected sample volume. Lead contained in NBS 1634b and other heavy oil samples was determined using the system. Samples were ashed directly in a furnace at 550°C for two hours, dissolved with perchloric acid and then injected into the system. The sampling frequency also depended on the injected s

ISSN:0009-4536    

DOI:10.1002/jccs.198800059

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractAn iron (III) ion selective PVC membrane electrode based on 1,7‐dithia 12‐crown‐4 as a neutral carrier was prepared. Monovalent responses with a Nerstian slope of 56+1 mV/decade was observed for the Fe (III) ion‐selective electrode within the concentration range 10−3–10−5M Fe (NO3)3. The monovalent responses may be attributed to the formation of Fe (OH)2+or Fe (OH)2(H2O)+4species in aqueous solutions and the absorption of these ions into the PVC electrode membrane. The electrode exhibited good selectivity for Fe (III) in comparison with various alkali, alkali‐earth and some heavy metal ions. The effects of the composition of the membrame, addition of STPB (sodium tetraphenyl borate), the concentration of internal solution of the electrode and anions in the test solutions

ISSN:0009-4536    

DOI:10.1002/jccs.198800060

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe polarography of uranyl ion in 2,3‐cresotic acid solution has been studied at 25°C under varying conditions of ligand concentration and pH. The ligands species were proved to be a 2,3‐cresotate anion. The half‐wave potential vs. pH value interpreted on the basis of pK value for the acid ionization, and resulted in agreement with the deduction.The mole ratio of metal to ligand was found to be 1:1 and 1:2 by conductometric titration. At pH

ISSN:0009-4536    

DOI:10.1002/jccs.198800061

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractSeveral dioxotungsten(VI) complexes of the type WO2L and WO2L.X (where LH2= Schiff base derived from o‐aminothiophenol and salcylaldehyde, 5‐chlorosalicylaldehyde, 5‐bromosalicylaldehyde, and X = dimethyl formamide, dimethyl sulfoxide or pyridine) have been prepared and characterized by elemental analysis, electrical conductance, magnetic and spectral measurements. These complexes are non‐electrolyte, diamagnetic, six‐coordinated and possess an octahedral

ISSN:0009-4536    

DOI:10.1002/jccs.198800062

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe superconductors YBa2Cu3C7‐xhave been prepared via gelation of metal dicarboxylate complexes. Physical measurements such as XRD, Tc, and Xacon these ceramics indicate consistently that a better superconducting behaviors were found than that obtained from previously reported oxalate proces

ISSN:0009-4536    

DOI:10.1002/jccs.198800063

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThree polymers including poly(p‐phenylene), poly(m‐phenylene), and poly(2,5‐thienylene) were synthesized in good yields from the corresponding aryldimagnesium bromide with two equiv of 2,3‐dichloropropene. The polymerization process involving electron transfer from the Grignard reagent to 2,3‐dichloropropene is

ISSN:0009-4536    

DOI:10.1002/jccs.198800064

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA synthesis of phosphocholine 9 was accomplished in 36% yield from isopropylidene glycerol in contrast to 2% yield as reported previously. Since 9 has been converted to platelet activating factor‐analogue 2, this report constitutes a more practical synthesis of

ISSN:0009-4536    

DOI:10.1002/jccs.198800065

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe 2,3‐disulfur‐substituted 1,3‐dienes (1) can be readily prepared from their stable 3‐sulfolene precursors (2) by thermal extrusion of SO2. The Diels‐Alder reaction of diene (1) with several dienophiles has been studied. The substituent effect on the reactivity and regioselectivity follows the order of PhS>PhSO>PhSO2. Lewis acid can greatly increase the regioselectivity of this reaction. The diene (1c), bearing a strong electron‐withdrawing sulfonyl group, also reacted as a

ISSN:0009-4536    

DOI:10.1002/jccs.198800066

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

Abstract3‐Arylsydnone‐4‐carbonitrile oxides (2), which are generated in situ by thermal dehydrochlorination of the corresponding hydroximic acid chlorides (1), undergo 1,3‐dipolar cycloadditions with sydnone‐4‐carbonitriles (6) to give 3‐aryl‐4‐[5‐(3‐arylsydnonyl)‐1,2, 4‐oxadiazol‐3‐yl] sydnones (9). These nitrile oxides (2) also react with alkyl‐ and arylnitriles to give 1,3

ISSN:0009-4536    

DOI:10.1002/jccs.198800067

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

Abstract3‐Arylsydnone‐4‐carbonitrile oxides may undergo 1,3‐dipolar cycloadditions with alkenes to produce the corresponding 3‐aryl‐4‐(5‐substituted‐isoxazolin‐3‐yl)sydnones. The direct reaction of 3‐arylsydone‐4‐carbohydroximic acid chlorides with alkenes may also give the same prod

ISSN:0009-4536    

DOI:10.1002/jccs.198800068

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY