摘要:

AbstractUpon irradiation at room temperature, the title compound1isomerized selectively and quantitatively into a cyclobutanedione2which underwent quantitatively bisdecarbonylation to afford a cyclohexadiene3. Thermolysis of2produced1and a bicyclo[2.2.1]heptenone4. Compound4was prepared in 70% yield by irradiation of1in refluxing dry toluene.

ISSN:0009-4536    

DOI:10.1002/jccs.199500001

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractCapillary electrophoresis in ultradilute derivatized solutions is used to separate nucleic acid fragment mixtures. Pulsed field techniques are used to improve resolution. Protocols in which pulse parameters are varied during the course of the separation are used to increase the range of fragment sizes separated. Fluorescence microscopy is used to study the separation mechanism in ultradilute solution.

ISSN:0009-4536    

DOI:10.1002/jccs.199500002

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe reaction of (OC)4Re[μ‐E‐HCC(CO2Me)CS2]Re(CO)4,1with EtNH2yielded two new complexes: Re(CO)4[C(H)C(CO2Me)C(NHEt)S],2, (52%) and Re(CO)3(NH2Et)[C(H)C(CO2Me)C(NHEt)=S],3a(24%) by competitive attack of the EtNH2at the dithiocarboxylate grouping and at the hydrogen substituted olefinic carbon atom in1. In both cases there is a loss of one of the rhenium groupings. The reaction of the sulfurized and oxygenated derivatives of 1, (OC)4Re[EC(H)C(CO2Me)CS2]Re(CO)4,4a(E=S),4b(E=O) with EtNH2yielded Re(CO)4[C(H)=C(CO2Me)C(NHEt)=S],5a, the parent carbonyl of3a, by exclusive attack of the amine at the hydrogen substituted olefinic carbon atom. The reaction of (OC)4Re[μ‐SC(S)C(CO2Me)C(H)S]Re(CO)4,6a(an isomer of4a) with EtNH2produced a similar result. The reaction of4awith Et2NH yielded Re(CO)4[μ‐S2C=C(CO2Me)C=NEt2],5ban N‐ethyl substituted derivative of5a. These results indicate that the addition of certain heteroatoms can have a directing effect upon the reactivity of these compounds with amines. Compounds2and5awere characterized by single crystal x‐ray diffraction analyses. Crystal Data: For2: space group = P1,a= 10.782(1) Å,b= 14.721(2) Å,c= 9.940(2) Å,a= 91.57(1)°, β = 93.61(1)°, γ = 70.774(9)°, Z = 4, 4516 reflections, R = 0.047 and for5a: space group = P21/n,a= 11.389(2) Å,b= 9.660(2) Å,c= 14.756(3) Å, β = 103.36(2)°,

ISSN:0009-4536    

DOI:10.1002/jccs.199500003

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractFluorescence from S2C1 induced by radiation at 488 nm was observed when the parent molecule S2C12was heated. The dependence of the intensity of fluorescence is third order on laser power. The mechanism of excitation is proposed to be dissociation of hot S2C12after two‐photon absorption to yield hot S2CI and one‐photon absorption of the latter to reach the fluoresing states. The fluorescence spectrum consists of two systems, called α and β here. The lower state of the a system is the ground state χ and that of the β system is assumed to be the à state. The upper states of both systems are unknown but may be related to previously observed slates lying about 460 nm and 330 nm. The vibrational structure of the β system was partially analyzed. The vibrational quantum numbers of the v2and the v3modes in the upper state are assessed to be 26 and 0, respectively, from a count of the number of nodes of the curves of the fluorescence intensity distribution. From the abrupt termination of the intensity curve of v2″ progressions, the absolute v2″ quantum numbers were determined. The excitation was in this way assigned to be (p,q + 6,0)′ ← (m,4,n + 3)″, in which p, q, m and n are no

ISSN:0009-4536    

DOI:10.1002/jccs.199500004

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractNitrobenzene, isophorone, 2,6‐dinitrotoluene and 2,4‐dinitrotoluene were removed from aqueous solution by solvent sublation. The separation efficiencies of three solvents (4‐methyl‐2‐pentanone, 1‐octanol and paraffin oil) as the overlaying layer were compared. The rate of separation of these organic pollutants by solvent sublation depends strongly on the size of air bubbles, which is affected by the overlaying solvent, and concentrations of sodium dodecyl sulfate (NDS), inorganic and polar org

ISSN:0009-4536    

DOI:10.1002/jccs.199500005

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe metal‐support interaction in the system of platinum supported on titanium oxides of different crystalline structures was investigated. Titanium oxide powders used as supports were prepared by neutralization of TiOCl2‐analogue solution with either NaOH or NH3base at varied pH. Pt was introduced onto the supports by impregnation. The phenomenon of strong metal‐support interaction (SMSI) was determined by the suppression of chemisorption of H2over samples reduced at 773 K, in comparison with the behavior of samples reduced at 473 K. The loss of adsorption capacity was proved not due to metal sintering by examining the recovery of adsorption capacity after reduction, reoxidation and reduction cycle, accompanied with examination of the size of Pt particle with an x‐ray diffractiometer and a transmission‐electron microscope. The results showed that SMSI phenomenon was common to Pt supported on titanium oxides of all the varied crystalline structures. However, the chemisorption capacity of Pt reduced at 473 K varied greatly with the sodium content in the supports, which in turns affects the crystalline structure of titanium oxide. These results are attributed mainly to electronic effect endowed by th

ISSN:0009-4536    

DOI:10.1002/jccs.199500006

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractSolubilities are reported for psoralen and 8‐hydroxypsoralen in binary aqueous mixtures at ambient pressure and 298 K, with organic cosolvent methanol. Gibb's energies of transfer of there two compounds are calculated from their solubilities. Transfer chemical potentials of both compounds are stabilised by increasing prapartion of organic cosolvent because of their markedly hydrophobic character.Basic hydrolysis of psoralen and 8‐hydroxypsoralen in aqueous methanol mixtures was examines kinetically, yielding Gibb's energies of activation. Derived transfer parameters are used in analysis of kinetic data to describe the influence of solvent composition on initial and transition states. Derived transfer chemical potentials for a single ion such as hydroxide ion lead to an interesting comparison of the effects of extrathermodynamic assumptions, Wells estimates and TATB assumption, on the initial and transition states. The analysis comfirm the important role played by the choice of extrathermodynamic assumption in determining the overall kinetic pattern. We describe misgivings concerning procedures used by wells to derive transfer chemical potential for single i

ISSN:0009-4536    

DOI:10.1002/jccs.199500007

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

Abstract2,2′‐Bipyridyl and some substituted compounds catalyze effectively the oxidation of isopropyl alcohol by chromic acid. The reaction is first order in chromium(VI), alcohol and 2,2′‐bipyridyl; it is first order in hydrogen ions at high acidity and slightly alters to second order at low acidity. The proposed mechanism shows that the rate‐limiting step is mainly the decomposition of a termolecular complex to products. However, at low acidity, the formation step of this complex is a little less reversible and hence somewhat rate‐limiting. Electron‐donating substituents at the 4‐position enhance the catalytic activity. Electron‐withdrawing substituents at the 4‐ and 2‐positions diminish the reaction rates by electron

ISSN:0009-4536    

DOI:10.1002/jccs.199500008

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

Abstract4‐(2‐Pyridylazo) resorcinol, PAR, is shown to be useful for simultaneous determination of cobalt(II) and nickel(II) using second‐derivative spectrophotometric method with controlled experimental parameters. This method allows the determination of 0.20‐1.25 ppm of nickel(II) and 0.25‐1.50 ppm of cobalt(II) in mixtures with good precision and accuracy. This method has advantages of simplicity, speed and requires no prior se

ISSN:0009-4536    

DOI:10.1002/jccs.199500009

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe monomeric rhenium(I) complex with bidentate telluroether ligand Re(CO)3Br(PhTe(CH2)3TePh) (1) was accessible via reaction of the PhTe(CH2)3TePh with Re(CO)5Br. This chelate complex crystallized in triclinic space group\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document}witha= 9.390(5) Å,b= 10.961(3) Å,c= 11.849(4) Åa= 63.30(3)°, β = 87.49(4)° γ = 69.31(4)°, V = 1009.5(7) Å3Z = 2, R = 0.033, and Rw= 0.034. Reaction of Re(CO)5Cl with NaTePh yielded the Re(I) specics PhTeRe(CO)5(2). This complex crystallized in triclinic space group\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document}witha= 7.085(1) Å,b= 9.203(1) Å,c= 11.341(1) Å, α = 107.24(1)°, β = 100.56(1)°, γ = 96.47(1)°, V = 683.2(2) Å3, Z = 2, R = 0.027, Rw= 0.022. Reaction of PhTeRe(CO)5and (PhSe)2in THF at 65 °C yielded a product that was confirmed crystallographically to be the known species Re2(μ‐SePh)2(CO)8(3), in which two phenylselenolate ligands bridge the two Re(I). Compound 3 crystallized in monoclinic space group P21/n witha= 7.210(2) Å,b= 18.862(6) Å,c= 9.083(3) Å, β = 107.48(3)° V = 1178.2(7) Å3, Z = 2, R = 0.046, and Rw= 0.051. Methylation of PhTeRe(CO)5with [Me3O][BF4] afforded Re(I) product [(PhTeMe)Re(CO)5][BF4] (4). This monodentate telluroether species crystallized in monoclinic space group P21/n witha= 8.405(1) Å,b= 13.438(3) Å,c= 15.560(2) Å, β = 92.59(1)° V = 1755.5(5) Å

ISSN:0009-4536    

DOI:10.1002/jccs.199500010

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY