摘要:

AbstractThe electrooxidation of Bilirubin (BR) inN, N′‐dimethylformamide (DMF) and DMF + H2O mixed solvent is investigated by voltammetry techniques,in siturapid scan thin layer spectroelectrochemistry and insituESR spectroscopy. The data reveal that the oxidation process of BR undergoes many stages, which are all sped up by the introduction of water. The species of bilirubin taking part in the reaction is found to be changed from BR in DMF into BR' in the mixed solvents and the anodic peak potential is shifted correspondingly from +0.58 V to +0.026−+0.35 V (vs. Ag/AgCl, 1.0 M KCl). Free radicals and the dimerization of them are observed during the oxid

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120101

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractA strategy for the synthesis of polymer‐protective bimetallic sols is proposed which has the advantage of the strong protective effect of the polymer agent on one of the composites to stabilize the bimetallic colloidal particles. This strategy is certified to be useful to the predication of the formation of stable bimetallic colloids protected by polymer and to the control of the particle size to a certain extent. A series of new PVP‐protective bimetallic colloidal dispersions containing noble metal element (Pt, Rh, Pd), light transition metal element (Co, Fe), and boron are obtained from the corresponding salts by the methods of reduction by stage and coreduction, using the NaBH4 as reductant. The TEM, XRD and EPMA measurements indicate the formation of bimetallic colloids. An interesting kind of coil aggregation is observed in the systems of PVP‐Pt‐Co and PVP‐Rh‐Co prepared by the method of reducti

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120102

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe equilibrium molalities of In3+in extraction reaction: In3+(aq)+3HOx(org) = In(Ox)3(org) + 3H+(aq) were measured at ionic strengths from 0.13 to 2.54 mol·kg−1in the aqueous phase containing Na2SO4as the supporting electrolyte and at constant initial molality of extractant, HOx, in the organic phase at temperatures from 278.15 to 308.15 K, where HOx and Ox mean 8‐hydroxy‐quinoline and its anion, respectively. The standard extraction constantsKat various temperatures were obtained by two methods proposed in our previous

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120103

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe reaction of singlet oxygen with ethylene has been studied at theab initiolevel with both HF/3–21G and HF/6–31G* basis sets, fully optimizing the geometries of the critical points. The transition state leading to the intermediate peroxirane from the initial reactants is found, located at 81.71 kJ/mol above the dissociation limit The vibrational analysis is done with two basis sets. From the results it can be seen that the frequencies have not been made an improvement obviously with augmented 6–31G* compared to 3–21G basis; it follows that main reason for too high HF/3–21G frequency could mainly be the vibrational anharmonicity. The eigenvector corresponding to the single imaginary vibrational frequency is dominated by the larger O—O distance. The finding of the transition state confirms that the peroxirane minimum can be reachable passing through a peroxirane‐like saddle point. In addition, the mechanisms of the reaction forming oxirane are disc

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120104

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractTwo new coenzyme B12analogues, 2′,5′‐dideoxycytidylcobalamin (2a) and 2′,5′‐dideoxyuridinylcobalamin (2b), and two others, 2′,5′‐dideoxyadenosylcobalamin (2c), and 5′‐deoxythymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV‐vis and 2D1H NMR spectroscopy. The comparisons and discussion about their spectroscop

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120105

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractA new μ3‐O triiron(III) complex [Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2(HOBZ = benzoic acid) has been synthesized, its structure has been determined and variable temperature magnetic susceptility has also been measured. In the molecule, three iron atoms formed an equilateral triangle with μ3‐O in center. The fitting to the magnetic susceptibility showed that an intramolecular antiferromagnetic exchange interaction occurred between iron atoms withJ=‐25.51 cm−1, and a weaker intermolecular autiferromagnetic exchange interaction occurred withzJ'=

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120106

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis of adamantane from tetrahydrodicyclopentadiene on zeolites with different framework structures was studied. The adamantane yield on HY zeolites is higher than on HM and HZSM‐5 zeolites. Among various types of dealuminated HY zeolites the HEY and HUSY zeolites give higher adamantane yields than conventional HY zeolite. The changes in activity and selectivity of the main and side reactions are correlated with the acidity and the pore structure of the zeolites. To ion‐exchange the HY and HUSY zeolites with Ni2+and La3+cations may further improve the activity and selectivity of the zeolite cataly

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120107

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractTheoretical consideration was proposed for the frequency response of a series piezoelectric sensor to the properties of liquid and verified experimentally. This kind of sensor has sensitive and selective frequency response to the permittivity and specific conductivity of solution with excellent stability, and was applied to the determination of micro‐content of water in organic solvents. The detection limit is 0.01 g/L in dioxan

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120108

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractElectron transfer reaction between vitamin A (1) and tris(p‐bromophenyl)aminium bexachloroantimonate (2) in dichloromethane (DCM) has been investigated by means of UV‐VIS absorption and ESR spectroscopy. The title radical cation formed in the reaction was characterized by a new absorption band around 600 nm and a singlet unresolved ESR spectrum withgfactor of 2.0038–2.0039 and line width of 20 G. Further studies indicated that ESR pattern and parameters of the radical cation generated by γ‐irradiation of 1 in CFCl3matrix at 77 K are consistent with that resulted in the chemical oxidation in DCM at ambient tem

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120109

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe reaction of 2′‐hydroxychalcones with I2‐H2SO4‐DMSO system has been studied. The results obtained by us are entirely different from those reported in the literature. The mechanism of this reaction has also been inves

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120110

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY