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61.
Albert Günter Herrmann und Doris Knake 《Fresenius' Journal of Analytical Chemistry》1973,266(3):196-201
Zusammenfassung Für die Bestimmung von Gesamt-, Carbonat- und Nichtcarbonat-Kohlenstoff in magmatischen, metamorphen und sedimentären Gesteinen (auch bei höheren Anteilen an organischem C) ist ein Verfahren nach dem Prinzip der coulometrischen Titration geeignet. Der Gesamt-Kohlenstoff wird ermittelt durch Erhitzung der auf <0,125 mm zerkleinerten Probe bei etwa 1250°C im Sauerstoffstrom ohne irgendwelche Zusätze. Zur Bestimmung von Nichtcarbonat-Kohlenstoff wird eine bestimmte Menge Gesteinspulver mit Salzsäure versetzt und auf einem Aluminiumblock HCl abgeraucht. Der Carbonat-Kohlenstoff entweicht als CO2. Zurück bleibt der Nichtcarbonat-Kohlenstoff, welcher wie der Gesamt-Kohlenstoff coulometrisch bestimmt wird. Der Carbonat-Kohlenstoff bzw. die äquivalente Menge CO2 ergibt sich dann aus der Differenz von Gesamt- zu Nichtcarbonat-Kohlenstoff. Das Verfahren ist anwendbar auf Kohlenstoffgehalte in Gesteinen von etwa 10 ppm bis 20 Gew.-% bei mittleren Standardabweichungen von etwa 0,0002–0,05% C (Richtwerte). Die Analysendauer für eine Probe beträgt etwa 3–5 min.
Coulometric method for the determination of total, carbonate, and non-carbonate carbon in igneous, metamorphic, and sedimentary rocks
For the measurement of total carbon the sample, ground finer than 0.125 mm and without the addition of any reagents, is ignited in a current of oxygen at about 1250°C. Non-carbonate carbon can be analysed after another portion of the sample is treated with conc, hydrochloric acid and evaporated on a hot plate; the carbonates are decomposed and the carbonate carbon is removed as carbon dioxide. The residue is non-carbonate carbon which is also determined by the coulometric method. The difference between total carbon and non-carbonate carbon corresponds to carbonate carbon or its equivalent as carbon dioxide. The method is applicable to carbon contents in rocks from 10 ppm to 20 wt.-%. The standard deviation is approximately 0.0002 to 0.05% C. Each carbon analysis takes about 3 to 5 min.相似文献
62.
Stasch A Roesky HW Vidovic D Magull J Schmidt HG Noltemeyer M 《Inorganic chemistry》2004,43(12):3625-3630
The carbaalane halogen derivatives [(AlX)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (6) and BF(3).OEt(2), BX(3) (X = Br, I), Me(3)SnF, and Me(3)SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH)(2)(AlX)(4)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (12) (X = Cl (approximately 40%), Br (approximately 60%)) was obtained from 5 and impure BBr(3). [(AlH)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (5) was converted to [(AlX)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (X = F (13), Cl (14), Br (15), I (16)) using BF(3).OEt(2) and Me(3)SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11.C(6)H(6), 12.3C(7)H(8), 13.6C(7)H(8), and 15.4C(7)H(8) were determined. Compounds 7 and 9-11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents. 相似文献
63.
Metallcarbonyl-Synthesen,XIV. Neuartige Vanadium-, Niob- und Tantal-Komplexe mit Wasserstoff-Brücken
Wolfgang A. Herrmann Helmut Biersack Barbara Balbach Peter Wülknitz Manfred L. Ziegler 《欧洲无机化学杂志》1984,117(1):79-94
Syntheses of Metal Carbonyls, XIV. Novel Vanadium, Niobium, and Tantalum Complexes Having Hydrido Bridges The novel homo- and heterodinuclear organometallic μ-hydrido compounds 3a – c of vanadium, niobium, and tantalum have been synthesized by light-induced reactions of the hydridoniobium complex (η5-C5H5)2NbH3 ( 1 ) with the half-sandwich complexes (η5-C5H5)M(CO)4 ( 2a : M = V; 2b : M = Nb; 2c : M = Ta). These compounds have the general composition LxM – H – Nb(CO)(η5-C5H5)2. The formation of the M – H – Nb moieties is a dark-reaction preceded by two photoreactions that are independent from each other elimination of CO from 2a – c and elimination of H2 from 1 , with the extruded carbon monoxide being transfered to the (η5-C5H5)2NbH fragment; subsequent fixation of the species (η5-C5H5)2Nb(CO)H thus generated to the photogragments (η5-C5H5)M(CO)3 results in donor stabilization of these latter groups. The structural architecture of the derivatives 3a und b was established by X-Ray diffraction. The hydrogen bridges are to be considered as three-center two-electron functions that are responsible for a serious lengthening of the otherwise by at least 40 pm shorter metal-to-metal distances amounting to 371.3 pm in 3a and 373.3 pm in 3b (mean values). 相似文献
64.
Wolfgang A. Herrmann Jo o D. G. Correia Georg R. J. Artus Richard W. Fischer Carlos C. Rom o 《Journal of organometallic chemistry》1996,520(1-2):139-142
Methyl(oxo)bis(η2-peroxo)rhenium(VII)1, the active species of the system CH3ReO3/H2O2 in the catalytic oxidation of different organic and organometallic compounds, is stabilized by a water molecule attached to the rhenium center. This water molecule can be removed and substituted by hexamethylphosphoramide (HMPA) to yield (hexamethylphosphoramide)methyl(oxo)bis(η2-peroxo rhenium(VII) (3). The synthesis, crystal structure (X-ray difraction study), and catalytic properties of which compound are reported. Crystal data are as follows: monoclinic, space group P21/n, A = 900.76(7) pm, B = 1229.80(11) pm, C = 1318.57(11) pm, β = 90.251(7)°, Rw = 0.034 for 1878 reflections. The catalytic properties of compound 3 in the oxidation of olefins with H2O2 are similar to those of 1. 相似文献
65.
66.
Jorge Casas-Sanchez M. Asuncion Alsina Mathias K. Herrlein Concepció Mestres 《Colloid and polymer science》2007,285(12):1351-1360
Oleuropein, a secoiridoid glycoside extracted from the olive tree, Olea europaea L., has been described as showing antibacterial properties. However, the exact mechanism of these antimicrobial properties
is not yet well understood. In the present study, we have studied the interaction of oleuropein with phosphatidylglycerol
(PG) as a model membrane for Staphylococcus aureus (S. aureus) (Gram-positive bacteria) and phosphatidylethanolamine and Escherichia coli (E. coli) lipid extract as a model membrane for E. coli (Gram-negative bacteria). The study has been carried out using monolayers as model membranes and using kinetics at constant
area and compression isotherms with Brewster angle microscopy (BAM) observations. The results show that oleuropein interacts
in higher extent with PG monolayers, which is related with its stronger antibacterial effect against Gram-positive bacteria.
The effects on the membrane are probably produced at the cell surface because oleuropein did not form stable mixed monolayers
with the lipids assayed at the air/water interface. 相似文献
67.
Herrmann H Jacobi HW Raabe G Reese A Zellner R 《Analytical and bioanalytical chemistry》1996,355(3-4):343-344
Nitrate radical (NO(3)) reactions with benzene (R-1), toluene (R-2), p-xylene (R-3), p-cresol (R-4) and mesitylene (R-5) have been studied by laser photolysis/long path laser absorption (LP-LPLA) in aqueous solution. Rate constants of k(1)=(4.0+/-0.6). 10(8), k(2)=(1.2+/-0.3). 10(9), k(3)=(1.6+/-0.1). 10(9), k(4)= (8.4+/-2.3). 10(8) and k(5)=(1.3+/-0.3). 10(9) lmol(-1)s(-1) were obtained at T=298 K. In addition, reaction rate coefficients for SO(-)(5)+Fe(2+)-->prod. (R-6) and SO(-)(5)+Mn(2+)-->prod. (R-7) of k(6)=(4.3+/-2.4). 10(7) lmol(-1)s(-1) and k(7)=(4.6+/-1.0). 10(6) lmol(-1)s(-1) (T=298 K, I-->0) have been obtained by the application of laser photolysis/UV-VIS broadband diode array spectroscopy. A new laser photolysis/UV-long path laser absorption experiment has been applied to study the reaction of the Cl(-)(2) radical anion with dissolved sulfur(IV). For the reactions Cl(-)(2)+HSO(-)(3)-->2Cl(-)+H(+)+SO(-)(3) (R-8) and Cl(-)(2)+SO(2-)(3)-->2Cl(-)+SO(-)(3) (R-9) rate coefficients of k(8)=(1.7+/-0.2). 10(8) lmol(-1)s(-1) (T=298 K, I-->0) and of k(9)=(6.2+/-0.3). 10(7) lmol(-1)s(-1) (T=279 K, I-->0) were obtained. 相似文献
68.
Linda K. Bell Wolfgang A. Herrmann Gangolf W. Kriechbaum 《Journal of organometallic chemistry》1982,240(4):381-393
An unexpected novel coordination mode of diazoalkanes has been verified via addition of 2-diazopropane to the metal—metal triple bond of bis[dicarbonyl(η5-pentamethylcyclopentadienyl)molybdenum] (MoMo). The dinuclear 1:1 addition product isolated in nearly quantitative yield is structurally characterized by a bent, 4-electron type η1:η2-diazoalkane ligand, with the terminal nitrogen atom symmetrically bridging the metal-metal “single bond” (d(MoMo) 305.0(2) pm; d(Mo---N(1)) 212.0(12) and 212.6(10) pm, respectively) and the second nitrogen atom being bonded to one molybdenum atom only (d(Mo---N(2)) 213.4(13) pm). 相似文献
69.
N-Activated 2-phenylazetidines were opened regioselectively at the benzylic carbon with various allylsilanes or propargylsilane in the presence of BF3·Et2O, providing amino olefins, precursors of biomolecules such as phenyl-homo-kainoids. 相似文献
70.
Wolfgang A. Herrmann Ricardo Serrano Adolf Schäfer Ulrich Küsthardt Manfred L. Ziegler Ernst Guggolz 《Journal of organometallic chemistry》1984,272(1):55-71
Short-wavelength photolysis of tricarbonyl(η5-pentamethylcyclopentadienyl)rhenium (1) (λ < 300 nm, quartz-glass) in tetrahydrofuran yields under partial or complete decarbonylation three novel organorhenium compounds, with the relative yields depending upon the irradiation time. Formed by exhaustive oxidative decarbonylation, the complex trioxo(η5-pentamethylcyclopentadienyl)rhenium(VII) (5) represents the first example of the new class of oxo half-sandwich complexes. The derivatives (μ-O)[(η5-C5Me5)Re(CO)2]2 (2; Me = CH3) and (η5-C5Me5)2Re2(CO)2O2 (3; Me = CH3) containing both oxo and carbonyl ligands are formed from 1 at shorter irradiation times. Both compounds are isolable intermediates along the mechanistically not yet fully established sequence 1 → → 5 as they are degraded to 5 under CO2 elimination in the presence of air and/or light. The mixed oxo carbonyl complex 2 has been characterized by means of single-crystal X-ray diffraction techniques (triclinic, space group P-Ci1; a 907.4(2), b 1040.2(3), c 1414.3(4) pm; α 79.99(2), β 88.42(2), γ 66.18(2)°; Riso = 0.068, Raniso = 0.037, Rw = 0.031). The molecular structure centres around an isosceles Re2O triangle whose metal centres exhibit a strongly distorted square-pyramidal geometry; the metal-metal distance recorded at 281.7(1) pm is in agreement with a single bond by the EAN rule. The centrically coordinated, planar five-membered ring ligands are parallel to each other (interplanar angle 2°) and occupy trans-positions with respect to the central Re2O geometry. 相似文献