摘要:

AbstractA quasi‐thermodynamic model for expansion of polymer configuration in solution is investigated. The model is based on Gaussian distribution of segments and mean field theory of polymer solution. An in‐homogeneous contribution to the free energy of solution is proposed. It arises from the nonhomogeneous distribution of polymer segements. This effects makes the expansion factor α to be larger than those without the effect considered. Some numerical consequence for the case Polydimethylsiloxane+cyclohexane solution is calculated. Our theory predicts a larger value a than the case without inhomogeneous effect being considered. The difference becomes less significant at higher molecular we

ISSN:0009-4536    

DOI:10.1002/jccs.198400001

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractA series of neutral and oxidized π‐bridged biferrocenes (Fc—x—Fc) and biferrocenylenes (FC(—x—)2Fc) (x= —CH=CH—, —CH3,C=CCH3—) were prepared and their physical properties have been studied by means of Mössbauuer and cyclic voltammetry. The electrode reaction of these bridged ferrocene derivatives appears to involve a consecutive two‐step oxidation process. The results also show that the voltage difference between the first and second oxidaton potentials of the bridged biferrocenes was found to be largely exceeded that founded for the corresponding the bridged biferrocenylenes. The Mössbauer data show that the oxidation of doubly bridged Fc(—x—)2Fc with iodine, DDQ, and TCNQ given the corresponding dioxidized salts only and no stable mixed‐

ISSN:0009-4536    

DOI:10.1002/jccs.198400002

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe distribution ratios of two isomeric 5, 7, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, tetcand tetd, in several solvent systems at 25.0°Cas functions of hydrogen ion concentration were determined. The protonation constants and the distribution constants of these macrocyclic ligands and their protonated species were obtained from the variations of the distribution ratios in the range of 6<–log

ISSN:0009-4536    

DOI:10.1002/jccs.198400003

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractInfrared spectrum of amyl amine forming cobalt complex in benzene solution is described. TheD, value and transitions betweendorbitals are identified. Since few transition metal salts are soluble in inert solvent, this paper introduces a special method of making cobalt‐2‐ethyl‐hexanoate which is soluble in be

ISSN:0009-4536    

DOI:10.1002/jccs.198400004

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe reduction of cupric ion in ammonia solution by aqueous sulfur dioxide was studied. Each run was carried out at constant initial cupric concentration, stirred rate and total mixed gas flow rate. The effect of temperature, partial pressure of sulfur dioxide in gas phase and cupric ion concentration of the solution was investigated.The reaction of Cu3++SO2(aq.)→Cu++SO42−was carried out by bubbling mixed gas (SO2/N2) through the aqueous ammonia complex of copper (II). The color change for the system was from deep blue, green, yellow to white. ThepH values in the system changed from 10 to 4. The product of the reaction was identified by the analyses of IR spectrum and X‐ray diffraction, having the formula of 7Cu2SO3· 2CuSO3·3(NH4)2SO3·24H2O.The kinetic model of the reduction was proposed as:–d[Cu2+]/dt=kexp(–E/RT)[Cu2+]α[SO2%]According to the experiments, the parameters were determined as:α=1.64±0.03, þ=1.20,E=13.7Kcal/molandk= (1.77±0.20)×1010(g

ISSN:0009-4536    

DOI:10.1002/jccs.198400005

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe electronic absorption spectrum of orcein is studied in organic solvent of varied polarities and water‐organic solvent mixtures with differentpH. The absorption bands are assigned and the effect of solvent polarity on their position is discussed. Thepkaof the acid‐base equilibria set are determined and commented upon in relation to nature and proportion of the organic solvent added. The main bands of the ir spectrum and signals of the1H nmr spectrum are as well discussed. The mixing of orcein with transition metal ions leads to drastic changes in colour and hence the visible absorption spectra of both organic compound and metal i

ISSN:0009-4536    

DOI:10.1002/jccs.198400006

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractCoordination compounds formed by the interaction of some salicylidene aromatic Schiff bases with Y(III), Ce(III), La(III), and Zr(IV) are prepared and characterized by elemental analysis, electronic and i.r. spectra as well as conductometric methods. The i.r. spectra indicate that coordination takes place through the azomethine nitrogen atoms and OH groups. The structure of such products depend mainly on the type of Schiff base used. Also, the formation constant of the complexes are evaluated.

ISSN:0009-4536    

DOI:10.1002/jccs.198400007

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.198400008

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe cycloadditions of the title compound, 1, a masked 3, 6‐dipropyl‐o‐benzoquinone to various disubstituted (diethyl maleate, diethyl fumarate,trans‐ andcis‐stilbene, and cycloheptene) and monosubstituted alkenes (methyl acrylate, methyl vinyl ketone, styrene, ethyl vinyl ether, and 1‐hexene) have been studied; the yields of the Diels‐Alder adducts, 2, are generally high (>75%) except for stilbenes. These adducts are effectively transformed into the corresponding bicyclo[2.2.2]oct‐5‐ene‐2, 3‐diones, 3, whose stereochemistries are determined from the ring current effect of the respective quinoxalines, 4, on the chemical shifts of the vinyl and the methine protons and/or the lanthanide (Eu(fod)3) induced shift on the pertinent protons of 3. It is interesting to note that the quinoxaline ring current makes the vinyl protons down‐field shifted by 0.15–0.27ppmwhereas the methine protons (R3=H)synto the quinoxaline moiety up‐field shifted by 0.18–0.39ppmas compared to the chemical shifts of the corresponding protons in 3. The transformations of α‐diketones 3 into the corresponding 1, 3‐cyclohexadienes, 5, by irradition with a Hanovia medium pressure lamp through a uranium glass filter are almost quantitative. The present study provides facile and effective methods for the preparation of bicyclo[2.2.2]oct‐5‐ene‐2, 3‐diones and 1, 3‐cyclohexad

ISSN:0009-4536    

DOI:10.1002/jccs.198400009

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractTriphenylphosphine ligand functionality could be readily introduced onto the 2% DVB and 12% DVB cross‐linked polystyrenes. Significant differences in reaction rates and loading capacities were observed in favor of the 2% DVB percentage cross‐linkage. The reaction of iron pentacarbonyl with polymeric ligand gave both monocoordination and biscoordination products. Product distribution analyses indicated that monocoordination was favored for both kind of polymeric ligands. Ratio of biscoordination to monocoordination was higher for the 2% DVB polystyrene ligand than for the 12% DVB polystyrene ligand indicating biscoordination proceeded more easily on the for

ISSN:0009-4536    

DOI:10.1002/jccs.198400010

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY