摘要:

AbstractMagnetic nonequivalence of methylene protons in some 1,1,2‐trisubstituted ethanes of the type XCH2CHXY was studied in the medium of various solvents over the temperature range of 0–95°C. Asymmetry effect and rotamer populations have been considered to be two major contributions to magnetic nonequivalence of methylene protons in the title compounds. A graphic method has been proposed to determine the asymmetry effect for methyl 2,3‐dibromopropionate, ethyl 2,3‐dibromopropionate, methyl 2,3‐dichloropropionate, and (1,2‐dibromoethyl) benzene in vari

ISSN:0009-4536    

DOI:10.1002/jccs.198100033

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractA general method to find the rate constant and particle self‐diffusion coefficient is suggested for a heterogeneous isotopic exchange reaction which is controlled by surface mass reaction or controlled by a combination of surface mass reaction and intraparticle diffusion. The values of the kinetic parameter, ξ1(ratio of the forward surface mass reaction rate to the intraparticle diffusion rate), particle self‐diffusion coefficientDand rate constantkare obtained by the proposed method for the isotopic exchange reaction systems CaCO3(s)/Ca2+(aq) and CaC2O4(s)/Ca2+

ISSN:0009-4536    

DOI:10.1002/jccs.198100034

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe structure of macrocyclic ligand complex, (5, 7, 12, 14‐tetraethyl‐7, 14‐dimethyl‐1, 4, 8, 11‐tetraazacyclotetra decane)·NiII·(ClO4)2has been determined by X‐ray diffraction with three dimensional counter data. This compound, C20H44N4NiII·(ClO4)2, crystallizes in orthorhombic space group Pbca, with cell parametersa=14.369,b=11.752,c=16.207A,V=2736.8A3, determined from Syntex Pl autodiffractomter. The formula weight (598.21) and a measured density of 1.45gm cm−3(by flotation) indicate the presence of four molecules per unit cell (Dc=1.452gm cm−3). The structure was solved, using Patterson and Fourier methods and refined by full‐matrix least‐squares techniques to a reliability index,R(F) of 0.09, based on 1480 independent observed data corrected for absorption, L‐p factors. In this molecule, in addition to the usual covalent and ionic bonds, there exist two hydrogen bonds between the perchlorate ions and the amine groups. The Ni and the four N atoms are coplanar. The six membered ring subtends a larger angle (93.5(3)°) over the Ni atom than the five membered ring (86.5(3)°) does. The former belongs to the chair form and the latter p

ISSN:0009-4536    

DOI:10.1002/jccs.198100035

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe X‐ray diffraction data of cubic BN were reanalyzed by aspherical electron charge distribution model. The valence‐charge densities of nitrogen atom and boron atom were represented by a finite multipole deformations. A least‐squares refinement of the model charge was computed by fitting population parameters and thermal parameters. The result showed that there is a tendency toward a ionic bond in going from IV‐IV compouds to III‐V

ISSN:0009-4536    

DOI:10.1002/jccs.198100036

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractIodide ion‐selective electrode were studied, prepared and applied for the complex formations and solubility product determination. The thermodynamic formation constant of PbI+and the solubility product of PbI3were found to be 54 and 9.2 × 10−9, respectively. The formation constant of PbNO3+was calculated to be 4.6 from the different formation constant of PbI+in perchlorate and nitrate m

ISSN:0009-4536    

DOI:10.1002/jccs.198100037

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractA facile and generally applicable procedure for acetylation of hindered phenols using tetra‐n‐butylammonium bromide as phase transfer catalyst and acetic anhydride as acetylation agent has been developed. The isolation yield is 85

ISSN:0009-4536    

DOI:10.1002/jccs.198100038

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractUsingN,N′‐Dicyclohexylcarbodiimide (DCC) as a condensing agent,32P‐cyanoethylphosphate and NH3were combined to yield32P‐cyanoethylphosphoramidate. Treatment with NaOH resulted in a β‐elimination step to yield32P‐phosphoramidate and acrylonitrile. The phosphoramidate was purified via DEAE‐cellulose chromatography. AtpH 7.4 the histidine residues of histone H4 were chemically phosphorylated using32P‐phosphoramidate as the phosphoryl donor. The nucleophilic nitrogen of the imidazole ring is attracted to the phosphorus of phosphoramidate resulting in the displacement of NH3and formation of the protein phosphoryl‐nitrogen linkages.Chromatin monomers (nucleosomes) were prepared by a mild digestion of chromatin with micrococcal nuclease. This report also presents the chemical phosphorylation of these nucleosomes by3

ISSN:0009-4536    

DOI:10.1002/jccs.198100039

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractA fancy emission behavior was found in the light carrier of the commercial Cyalume light stick, 9,10‐bis (phenylethynyl) anthracene (BPEA). The yellowish‐orange emission is noted from BPEA in methylcyclohexane matrix. Nitrogen laser time‐resolved spectroscopy and excitation luminescene studies of BPEA in methylcyclohexane showed that the different emission behavior is probably due to the different conformation of the ground state of the BPEA in solid and in sol

ISSN:0009-4536    

DOI:10.1002/jccs.198100040

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractOne kinetic model for the oxidation of iodide ion by peroxydisulfate ion in aqueous solution is proposed. The reaction is regarded as\documentclass{article}\pagestyle{empty}\begin{document} {\rm S}_2 {\rm O}_8^{2 -} + {\rm I}^ - {\rm IS}_2 {\rm O}_8^{3 -} \end{document}, followed by the reaction\documentclass{article}\pagestyle{empty}\begin{document} {\rm IS}_2 {\rm O}_8^{3 -} + {\rm I}l_2 + 2{\rm SO}_4^{2 -} \end{document}. If the initial ratesVare obtained from the formation of the iodine molecules, the reaction rate constantk1and the ratiok2/k‐1can be estimated by plotting the values of [S2O82−][I−]/Vagainst that of 1/[I−]. The extrapolated value fork1is 2.20×10−2L/mol‐secandk2/k‐1is calculated to be 4.25×102mol/Lat 27°C in a solution with an ionic s

ISSN:0009-4536    

DOI:10.1002/jccs.198100041

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractBis (η5‐cyclopentaienyl)N,N‐disubstituted dithiocarbamato chloro oxotungsten (VI) complexes of the type η5‐Cp2WO(S2CNR2)Cl and η5‐Cp2WO(S2CNRR')Cl (where R=Me, Et andi‐Pr and R'=Cyhx) have been prepared by the reaction of bis (η5‐cyclopentadienyl) oxotungsten (VI) dichloride with sodium salts of dithiocarbamic acids in refluxing tetrahydrofuran. Infrared spectral studies demonstrate that in these complexes dithiocarbamate ligands are bidentate. Therefore, tungsten (VI) atom may be assigned a coordination number 6 in all these complexes. Elemental analyses of these compounds have also been carried out. Electronic spectra have been recorded for all th

ISSN:0009-4536    

DOI:10.1002/jccs.198100042

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY