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1.
The reaction of dichloro{1-methyl-2-(arylazo)imidazole}palladium(II), Pd(RaaiMe)Cl2 where RaaiMe = p-R–C6H4N=N–C3H2N2-1-Me; R = H(1), Me(2), Cl(3), with pyridine bases [RPY: R = H (a), 4-Me (b), 4-Cl (c), 2-Me (d), 2,6-Me2 (e), 2,4,6-Me3 (f)] has been studied spectrophotometrically in MeCN at 451 nm. The products (4) have been isolated and characterised as trans-Pd(RPy)2Cl2. The kinetics of the nucleophilic substitution has been examined under pseudo-first-order conditions at 298 K. A single phase reaction step has been observed for bases such as Hpy (a), 4-MePy (b) and 4-ClPy (c) and follows the rate law: rate = (a + k[RPy]2[Pd(RaaiMe)Cl2]). The bases 2-MePy (d), 2,6-Me2Py (e) and 2,4,6-Me3Py (f) exhibits a bi-phasic reaction and follows the rate laws: rate–1 = (a + k[RPy][Pd(RaaiMe)Cl2]) and rate–2 = (a + k[RPy][Pd(RaaiMe)-Cl2]), where k is the third-order rate constant; k is the second-order first phase rate constant, k is the second-order second phase rate constant and a/a/a correspond to the solvent dependent constant of the respective reaction path. The rate data supports a nucleophilic association path. External addition of Cl (LiCl) suppresses the rate, which follows the order: k/k/k (3) > k/k,k (1) > k/k,k (2). The k values are linearly related to the Hammett constants. The 2-substituted pyridines (d–f) remarkably reduce the rate and show a bi-phasic reaction behaviour as compared with 4-Rpy (a–c). This is attributed to the steric effect that destabilises the transition state. The rate decreases with increasing steric crowding at the ortho-position and follows the order: (d) > (f) > (e). The 4-substituted pyridines control the rate via an inductive effect and follow the order: (b) > (a) > (c).  相似文献   

2.
    
Zusammenfassung Die Bandenverbreiterung in der Flüssigkeits-Chromatographie, verursacht durch Kolonne, Kolonnenzuleitungen und Detektor, wurde untersucht durch Messung von h-u-Kurven bis zu Kolonneneingangsdrucken von 15 at. Die Einflüsse außerhalb der Kolonne konnten durch eine besondere Formgebung der entsprechenden Bauelemente vermindert werden. Aromatische N-Verbindungen wurden an einer Silicagel-Kolonne getrennt, wobei etwa 1 effektiver Boden pro Sekunde erzielt werden konnte.
Summary Peak broadening effects in liquid chromatography inside and outside the column, i.e. the influence of the column, the connection and the detector were studied, determining experimentaly h vs. u curves up to 15 at. inlet pressure. Geometry for both of the latter is proposed to diminish peak broadening outside the column. Aromatic N-compounds are resolved on silicagel producing about 1 effective plate per second.

Symbolverzeichnis at 1 Kilopond/cm2 Druck - h Bandenverbreiterung in der Kolonne oder HETP [cm] - h exp L(w/4t R)2 = experimentell bestimmte h-Werte - k Verteilungskoeffizient [-] - k = t R/t0 Massenverteilungsverhältnis [-] - t 0 Durchbruchszeit der Inertbande [sec] - t R Retentionszeit [sec] - t R t r-t0 = Reduzierte Retentionszeit [sec] - u Lineare Geschwindigkeit der mobilen Phase [cm · sec–1] - w Bandenbreite, Achsenschnitt der Wendetangenten an der Basislinie [sec] - C Massentransportkoeffizient der van Deemter-Gleichung [sec] - L Länge der Kolonne [cm] - N (4t R/w)2 = effektive Bandenschärfe oder effektive Bodenzahl - V m Volumen der mobilen Phase in der Kolonne [cm3] - V s Volumen der stationären Phase in der Kolonne [cm3] Die Autoren bedanken sich bei der Deutschen Forschungsgemeinschaft, Bad Godesberg, mit deren finanzieller Unterstützung diese Arbeit ausgeführt wurde.  相似文献   

3.
Summary The separation of C1–C4 nitroparaffins on SE-30, PEGA and Porapak R stationary phases was investigated. The nitroparaffin mixture was obtained from a real technological process. The best separation was achieved on Porapak R at 190°C. The fact that each peak obtained from this column corresponded to a single compound was checked by utilizing the linear relationship between the peak widths and the adjusted retention times (t R ). Peak identification was carried out using the chromatographic data only, with help of plots of log t R vs. carbon number and log t R vs. boiling point; some of the results were also confirmed with comparing the retention times with those of pure substances and IR investigation of the collected chromatographic fraction.  相似文献   

4.
Summary Dansyl derivatives of four long-chain primary aliphatic amines and five secondary aliphatic amines were chromatographed in two adsorption systems: heptane+diisopropyl ether — silica and water+methanol — octadecyl cilica. In the normal-phase system RM (log k) values were approximately linearly dependent on the log concentration of diisopropyl ether in the eluent; the separation selectivity of dansyl C8–C12 primary amines was poor. For the reversed-phase system the derivatives of both primary and secondary amines were well separated, the log k values being linearly dependent on per cent concentration of methanol in the eluent.  相似文献   

5.
Treatment of the coordinative unsaturated complexes [M(SRF)3(PMe2Ph)2] (M = Os or Ru; RF = C6F5 or C6F4H-4) with MS2Z (M = Na, S2Z = S2CNEt2; M = K, S2Z = S2COEt) and [Os(SRF)3(PMe2Ph)2] (RF = C6F5 or C6F4H-4) with MS2Z [M = Na; S2Z = S2P(OEt)2] in Me2CO solution, gave the paramagnetic OsIII and RuIII derivatives, [M(SRF)2(S2Z)(PMe2Ph)2]. X-ray crystallography shows that [Os(SC6F5)2(S2CNEt2)(PMe2Ph)2] has an octahedral geometry with trans-fluorothiolates, cis-phosphines and a chelating N,N-diethyldithiocarbamate ligand.  相似文献   

6.
Aliphatische Di- und Polysulfide lassen sich im reverse-phase-Verfahren an einer chemisch gebundenen Octadecylphase (Micro-Pak-CH) mit MeOH-H2O als Eluens sauber trennen. Die qualitative Zuordnung der Peaks wird durch folgende Effekte vereinfacht:
1.  log k nimmt bei konstanter S-Zahl linear mit der C-Zahl zu;
2.  log k nimmt bei konstantem Alkylrest linear mit der S-Zahl zu;
3.  log k fällt linear mit zunehmendem Gehalt des Eluens an MeOH.
Bei Auswahl eines geeigneten Eluensgradienten können homologe Reihen wie R 2 S 2 mit R = Methyl bis R = Hexyl oder R 2 S x mit x = 2–7 mit einer Auflösung Res 2 zwischen allen Komponenten getrennt werden.  相似文献   

7.
A series of fifteen complexes of the type [Fe(RRNCS2)3] with symmetric (R=R=n- C6H13, n-C8H17, CH2–CH=;CH2, C6H5, C6H11 and C6H5CH2), unsymmetric (R = CH3; R = n-C4H9, C6H11, C6H5 and R = C2H5; R = n-C4H9, C6H11, C6H5 and i-C3H7) and ring substituents (RNR=pyrrolidyl and piperidyl) have been synthesized and their magnetic moments and Mössbauer spectra recorded from room temperature (RT) to liquid nitrogen temperature (LNT). Room temperature Mössbauer spectra of all the complexes exhibit an asymmetric doublet, which could be resolved into two doublets, each corresponding to low and high spin states in equilibrium. The crystal structure of tris(N, N-diallyldithiocarbamato)iron(III) shows it to be monoclinic with trigonally distorted octahedral geometry and space group C2/c. Fe–S stretching vibrations in the far i.r. region also show equilibria, HS LS. Depending on the nature of the alkyl group substituent, variable temperature magnetic moment and Mössbauer spectral studies, all the complexes may be divided into three groups; high spin complexes exhibiting spin-crossover (6A1g 2T2g), high spin complexes exhibiting spin transition (6A1g 4T1g) and intermediate spin complexes showing spin transition (4A1g 2T2g). On the basis of areas of the two doublets corresponding to high and low spin states, their percent contributions were calculated. Furthermore, magnetic moments of the equilibrium mixture calculated on the basis of respective areas compare well with the experimentally determined eff values. EQ values for both high and low spin states show linear decrease with increasing temperature.  相似文献   

8.
An analytical procedure for evaluating the conditional stability constants K of aluminum/humic substance complexes, based on 27Al nuclear magnetic resonance spectroscopy, is described. It is well suited for the determination of Al(III) dissociated from dissolved humic substances at slightly acidic pH values. The new procedure offers a good sensitivity and requires neither special preparation of the sample nor the evaluation of complex coupled chemical equilibria. The pK values range from 2.0 to 4.3 depending on the ratio [Alcomplex] to dissolved organic carbon and the pH.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday  相似文献   

9.
-Diimines, RN:C(R)C(R):NR(LL) derived from glyoxal, GLL (R=H) abbreviated as GAA (R= R=4-dimethylaminophenyl) or GHA (R= R=4-hydroxyphenyl), and derived from biacetyl, BLL (R=Me) abbreviated as BDH (R=R= NH2), BOH (R=NH2, R=OH) react with carbonylrhodium(I) compounds to give different products depending on the imino substituents in the ligand and/or the solvent employed. The reaction of -diimines bearing amino groups, such as GAA or BDH with [RhCl(CO)2]2 in acetone yields binuclear [RhCl(CO)2]2(-LL) while in CH2Cl2 ionic [Rh- (CO)2(LL)]+[RhCl2(CO)2] species are obtained. In acetone [RhCl(CO)2]2(-GAA) exists as an equilibrium mixture between two different neutral binuclear species; [Rh(CO)2(BDH)]+ exists as a mixture of two species containing chelate or monodentate bonded diimine respectively. GAA or BDH react in situ with [RhCl(CO)(C2H4)]2 in benzene to yield tetracoordinated monocarbonylated [RhCl(CO)(LL)] compounds. -Diimines (LL) bearing hydroxy groups, such as GHA or BOH react with [RhCl(CO)2]2 or [RhCl(CO)(C2H4)]2 to give pentacoordinated dicarbonylated [RhCl(CO)2(LL)] compounds.  相似文献   

10.
Summary In aqueous solution [Cu(bigH)2]2+ (bigH=biguanide) reacts with 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen) through intermediate formation of ternary complexes [Cu(bigH)(L)]2+ and [Cu(bipy)(phen)]2+ and binary complexes [CuL2]2+ (L=bipy, phen). The rates of the different steps have been followed in borax buffer (pH 8.0±0.1) by stopped-flow spectrophotometry. For each step kobs=k0+kL[L] and the kL path appears to be associative. H and S values for the kL path conform to an isokinetic trend.  相似文献   

11.
Reactions of zirconium isopropoxide-isopropanolate with bifunctional tridentateSchiff bases such as acetylacetone-(2-hydroxy-anil), benzoylacetone-(2-hydroxy-anil) and salicylidene-o-aminophenol and bifunctional tetradentateSchiff bases such as bisacetylacetone ethylenediimine, bisbenzoylacetone ethylenediimine and bissalicylidene ethylenediamine have been investigated in different molar ratios. The resulting products of the type Zr(OPr i)2(SB), Zr(SB)2, Zr(OPr i)2(SB) and Zr(SB)2 (whereSB andSB represent the anions of the bifunctional tridentate and bifunctional tetradentateSchiff bases respectively) have been isolated in almost quantitative yields. I.R. spectral studies of a few representative derivatives have been made and their molecular weights determined ebullioscopically in benzene. Thermogravimetric analysis of the salicylidene-o-aminophenol derivative has also been carried out.

Mit 1 Abbildung  相似文献   

12.
The reactions of benzimidazole (Bimz) with dichloro{2-(arylazo)pyridine}palladium(II), [Pd(aap)Cl2 (3), aap = RC6H4N= N-2-C5H4N; R = H(a), o-Me(b), m-Me(c), p-Me(d), p-Cl(e)] and dichloro{2-(arylazo)pyrimidine}palladium(II), [Pd(aapm)Cl2 (4), aapm = RC6H4N=N-2-C6H3N2; R = H(a), o-Me(b), m-Me(c), p-Me(d), p-Cl(e)] were followed separately. The kinetics were examined under pseudo-first order conditions with reference to Bimz in MeCN at 385 and 390 nm, respectively and at 298 K using a u.v.–vis. spectrophotometer. The product was isolated and characterised as trans-Pd(Bimz)2Cl2. The reaction between Pd(aap)Cl2 and Bimz follows the rate law, rate = K[Bimz]2[Pd(aap)Cl2], a single step process, whereas biphasic behaviour is observed for the reaction between Pd(aapm)Cl2 and Bimz; each step is first order with respect to the concentration of complex and to Bimz. The rate data support a nucleophilic association path and the rate decreases upon addition of Cl(LiCl). The aryl ring substituent of the arylazoheterocycle influences the substitution rate as follows: k(e) > k(a) > k(d) > k(c) > k(b). The k-values are linearly correlated with Hammett constants with usual deviations for the m-Me and o-Me substituents because of their steric crowding. The rate follows the order: k(aap) > k(aapm). This is unusual with reference to the -acidity order of the heterocycles, pyridine < pyrimidine, as the increased -acidity will enhance the nucleophilic association. The charge density calculation by MNDO method shows that in the pyrimidine ring of arylazopyrimidine, the peripheral m-N(uncoordinated) carries a high negative charge which may retard the nucleophilic association rate. This effect is absent in the pyridine ring of arylazopyridine and may be the reason for the faster single step nucleophilic substitution in Pd(aap)Cl2.  相似文献   

13.
Summary The calculation of capacity factors, k, from net retention times, tR, and the corresponding dead times, tM, at different temperatures suffers from the limited accuracy of the tM values. If the temperature coefficient racy of the tM values. If the temperature coefficient d ln k/d (1/T) only is required, it is sufficient to determine net retention times (tR)p at constant inlet pressure pi for different temperatures, since the temperature dependence of (tM)p can be assumed as (tM)p=A·eB/T, with B being approximately independent of the column inlet pressure and of the nature of the carrier gas. The extrapolation and interpolation of (tR)p may be either performed by linear regression or graphically with a nomogram for ln (tR)p versus 1/T. The resolution factor, , of two components, e.g. enantiomers which are resolved on a chiral stationary phase, can be treated in a similar way. Examples are given for the resolution of enantiomers of two non-proteinogenic amino acids on the new polysiloxane phase L-Chirasil-CPG.  相似文献   

14.
Procedures were developed for the photometric determination of tin(II) with pyrogallol azo compounds, 2,3,4-trihydroxyphenylazo-5-sulfonaphthalene (R1) and 2,2,3,4-tetrahydroxy-3-sulfo-5-chlorazobenzene (R2), in the presence of triphenylguanidine and bathophenantroline. The complexation of tin(II) with R1 and R2 was studied. It was found that different-ligand complexes formed in the presence of hydrophobic amines. A bathochromic shift in absorption spectra was observed along with shifts of optimum pH formation. The effect of reagent concentration, time, and temperature on the formation of different-ligand complexes was studied, and their stoichiometry was determined by different methods. It was shown that the determination of tin(II) with R2 in the presence of the third component is highly selective. The developed procedures were used for the photometric determination of tin in Caspian Sea water.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 468–470.Original Russian Text Copyright © 2005 by Nagiev, Gambarov, Mamedov, Chyragov.  相似文献   

15.
The dependence of the fluorescence constantsk f n and the adiabatic twisting constantsk tpof the S1-State upon the solvent polarity, the capacity of hydrogen-bonding, as well as the solvent viscosity, were investigated for donor-acceptor substitutedtrans-stilbenes [4-dimethylamino-4-cyano-stilbene (1 g), 4-dimethylamino-4-diphenylphosphinyl-stilbene (1 b), 4-dimethylamino-4-brom-stilbene (1 h) and 4-dimethylamino-4-methoxistilbene (1 k)] by using the multiparameter model. An increase of the solvent polarity results in the decrease of the fluorescence ratek f n for all these compounds. The specific interaction between the strongly polar stilbenes such as1 g and1 b and a solvent leads to additional decrease ink f n but in the case of a relatively weak polar compound1 k to its growth. The linear combination of universal and specific solvent-solute interactions yields distinct relations fork tp. Both interactions have an influence onk tpfor1 g,1 b, and1 k to an equal degree. The twisting observed for1 g and1 b due to the interaction with solvent is hindered, however it is being supported for1 k. The influence of the investigated small range of viscosity onk tpat simultaneous variable solvent polarity (pure solvent) is only visible for the weak polar1 k. In the other cases the effect of solvent-polarity is predominant.The viscosity dependence ofk tpwas also experimentally proved for1 g,1 b and1 k by applying the obtained different dimethylformamid-acetonitril mixtures. According previous results the radiationless deactivation process is caused by twisting around ethyl-bonding, thereforek tpevidently decreases with an increase of viscosity.
  相似文献   

16.
Bond strengths in RO-OOR, ROO-OH, and ROO-OOR (R, R = H, Me, Et, and Bu) molecules, calculated by the semiempirical quantum-chemical methods, were used to determine the enthalpies of formation of polyoxides RO x R (x = 3, 4) and related radicals and the bond strengths (D/kcal mol–1) in these molecules:D(ROOO-OR) = 33.2±0.9,D(ROOO-OH) = 37.5±0.7,D(R-O x R) = 76.0±1.2,D(H-000) = 58.6,D(R-000) = 42.8±0.8. A new value of Benson's polyoxide thermochemical increment, f H°[O-(O)2] = 11.1±1.0 kcal mol–1, was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2190–2193, September, 1996.  相似文献   

17.
The title compounds26 and32 were prepared by systematic mono- and bisanellation of sixmembered rings to the positions 5,6 and 5,6, resp. of 2,2-spirobiindane.S E acylation and subsequent transformations of the acylgroups afforded many derivatives with substituents in positions 4 and 4 of the parent compounds which were required for testing semiempirical values of chirality functions.5,6,7,8-Tetrahydrobenz[f]indane (9) and several of its 4-substituted derivatives were prepared as models for the anellation and substitution reactions.Tentative preferred conformations of the 4-acylgroups could be deduced from1H-nmr spectra.
  相似文献   

18.
Conclusions Depending on the ratio of the reactants and the reaction temperature, the reaction of benzenesulfonyl chloride with sodium trialkylsilylalkylthiolates R3Si(CH2)nSNa (R=Me, Et; n=1–3) leads either to labile S-phenyl S-trialkylsilylalkyl thiosulfonates or to their mixture with S,S-bis(trialkylsilylalkyl) disulfides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 204–205, January, 1979.  相似文献   

19.
Zusammenfassung Die Geschwindigkeit der Aethylenpolymerisation bei konstantem Druck, in Toluol, unter Verwendung von Katalysator-Systemen der allgemeinen Zusammensetzung Cp2TiRCl/RAlCl2 (Cp=Cyclopentadienyl; R, R=Alkyl) wurde gemessen. Gleiche Geschwindigkeit bei Al/Ti=1,2 und 2,0 beweist einen 1:1 Komplex als katalytisch aktive Spezies.Durch Variieren von R (am Ti) und R (am Al) konnten die Einflüsse dieser Gruppen auf die Polymerisationsgeschwindigkeit getrennt untersucht werden.Zwei Abbruchsreaktionen wurden festgestellt, von denen die eine mit Reduktion Ti(IV)Ti(III) gekoppelt und die andere vermutlich der langsamen Bildung eines inaktiven Komplexes aus einer Titan- und zwei Aluminiumeinheiten zuzuschreiben ist.
Summary Rates of ethylene uptake at constant pressure in toluene, with the use of catalytic systems of the general composition Cp2TiRCl/RAlCl2 (Cp=cyclopentadienyl: R,R=alkyl) have been measured. Equality of the observed rates at Al/Ti=1.2 and 2.0 shows the 1:1 complex to be the active species. On varying R (on Ti) and R (on Al) the influence of these substituents on the rate of polymerization could be determined. Two termination reactions have been observed. The first is due to the reduction Ti(IV)Ti(III), and the second is attributed to the slow formation of an inactive complex including 1 Ti(IV) and 2 Al-alkyls.


Mit 6 Abbildungen und 1 Tabelle

Herrn Prof. Dr.J.W.Breitenbach zum 60. Geburtstag gewidmet.  相似文献   

20.
Zusammenfassung Der Halogenaustausch zwischen festem AgCl und einer Reihe von flüssigen Organosulfenylchloriden des Typs RRRCSCl (R, R, R=F, Cl, CF3, CF3S) wurde mit Hilfe von radioaktivem36Cl untersucht. Die Ergebnisse deuten darauf hin, daß stark elektronegative Substituenten R, R und R eine Polarisierung der S–Cl-Bindung in den Sulfenylchloriden induzieren und dadurch die heterolytische Reaktivität dieser Bindung erhöhen.
Heterogeneous36 Cl exchange between halogenated organosulphenyl chlorides and silver chloride
The halogen exchange between solid AgCl and a number of liquid organosulphenyl chlorides of the type RRRCSCl (R, R, R=F, Cl, CF3, CF3S) has been studied using36Cl as a tracer. On the basis of the results it is suggested that highly electronegative substituents R, R and R, by polarizing the S–Cl bonds in the sulphenyl chlorides, favour the heterolytic reactivity of these bonds.


Mit 3 Abbildungen

12. Mitt. vgl.A. Haas undH. Reinke, Chem. Ber.102, 2718 (1969).  相似文献   

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