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71.
Transition Metal Complexes of the Hexamethyl-trisila-tetraphospha-nortricyclene P4 (Sime 2) 3 P4(Sime2)3 1 reacts with Mo(CO)6, Cr(CO)5THF, and Mn(η-C5H5)(CO)2THF to give crystalline complexes in which 1 functions as a monodentate ligand. In each compound one phophorus atom of the cyclotriphosphane ring coordinates to the metal atom. Using Mn(η-C5H5)(CO)2THF, two different P atoms of the P3 Cr(CO)4 norbornadiene and 1 react, yielding the dimeric, red, crystalline compound (CO) 4Cr[μ-P4(Sime2)3]2Cr(CO)4. In this complex the two molecules of 1 are both bonded by two P atoms of the P 3 ring to the two Cr(CO)4 Units, forming a six-memered (CrP2)2ring. 相似文献
72.
William Heilman Ernst Kupfer Walter Keller-Schierlein Hans Zhner Heinz Wolf Heinrich H. Peter 《Helvetica chimica acta》1979,62(1):1-6
From cultures of the Avilamycin (Avilamycin A) producing organism, Streptomyces viridochromogenes, strain ETH 23575, a second antibiotic, Avilamycin C, C61H90Cl2O32 could be isolated in crystalline form. Both Avilamycins belong to the group of the Orthosomycins. By IR., 1H- and 13C-NMR. spectroscopy and by transformation to a common derivative it could be proven that Avilamycin A is a methyl ketone, Avilamycin C the corresponding methyl carbinol. 相似文献
73.
Gert Brandl Fritz Kastner Rainer Fritsch Herbert Zinner Albrecht Mannschreck 《Monatshefte für Chemie / Chemical Monthly》1992,123(11):1059-1069
Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke. 相似文献
74.
Tanaka K Mori M Xu Q Helaleh MI Ikedo M Taoda H Hu W Hasebe K Fritz JS Haddad PR 《Journal of chromatography. A》2003,997(1-2):127-132
In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression. 相似文献
75.
Fritz Theil 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》1992,104(7):943-944
76.
Zusammenfassung In Vorstehendem wurde zunächst die Ausführung der von einem von uns ausgearbeiteten Schwefelsäuretitration mittelst Benzidinchlorhydrats nochmals genau beschrieben, sodann wurden die Bedingungen festgestellt, unter denen verschiedene Schwefelsäuremengen am genauesten zu bestimmen waren. Es hat sich dabei herausgestellt, dass die Schwefelsäure bis zu 0,01g H2SO4 herunter nach der beshriebenen Methode auf 1–2 genau bestimmt werden kann. Die Anwendung der Methode auf verschiedene Fälle (Ammoniumsulfat, Alaun, Zinksulfat-heptahydrat, Mohr'sches Salz, Mangansulfat-tetrahydrat), wobei die Metalle in einigen Fällen vorher ausgefällt wurden, bestätigten die zuvor festgestellten Regeln; ausserdem wurde gezeigt, dass beim Ausfällen von Zink, Eisen und Mangan nach dem angegebenen Verfahren Schwefelsäure nicht mitgerissen wird. Die Zeit, welche eine derartige Bestimmung, auch wenn die beschriebenen Ausfällungen vorgenommen werden müssen, bei einiger Uebung erfordert, ist sehr kurz, weil alles Auswaschen und so weiter in Fortfall kommt, so dass auch hier ein Vortheil gegenüber dem gewichtsanalytischen Verfahren vorhanden ist. 相似文献
77.
A new thiosemicarbazone was prepared, characterized, and used as a complexing reagent for the chromatographic separation and determination of metal complexes by reverse-phase HPLC. The reagent was sufficiently soluble in methanol-water solutions for metal ions to be complexed in this aqueous organic phase, without need for extraction. Many variables affected the retention times of the metal complexes. Several metals were determined selectively by complexation with the reagent and chromatographic separation of the complexes. Interference effects from other metal ions were also investigated. 相似文献
78.
Hans Weidmann Hanns Wolf Oberwalder Egon Wildschek Helmut Schwarz 《Monatshefte für Chemie / Chemical Monthly》1972,103(1):210-217
Zusammenfassung Durch acylierende Dehydratisierung von 1,2-Isopropyliden-d-xylo-und-d-ribo-pentodialdo-furanoseoxim bzw. aus Furanuronsäureestern und-amiden werden über eine Reihe von Zwischenstufen verschiedene 3-O-Acyl-pentofuranuronsäurenitrile synthetisiert und deren Reaktionen untersucht.
Mit 1 Abbildung
Aus den DissertationenH. W. Oberwalder (1970) undE. Wildschek (1967), Technische Hochschule in Graz. 相似文献
Synthesis of xyluronic and riburonic acid derivatives
Various 3-O-acyl-pentofuranurononitrils were synthesized by acylating dehydration of 1,2-isopropylidene-d-xylo- andd-ribo-pentodialdo-furanose oximes, or pentofuranuronic acids via intermediates. Their reactions were investigated.
Mit 1 Abbildung
Aus den DissertationenH. W. Oberwalder (1970) undE. Wildschek (1967), Technische Hochschule in Graz. 相似文献
79.
Paul H. Chen William F. Kuhn Fritz Will Robert M. Ikeda 《Journal of mass spectrometry : JMS》1970,3(2):199-209
The mass spectra of three bicyclic γ-lactones have been studied, and the fragmentation pathways have been proposed with the aid of accurate mass measurements and metastable transitions. An unusually low [M ? CH3] ion and the presence of an abundant [M ? C5H9] ion in the mass spectrum of dihydroactinidiolide were interpreted as a possible rearrangement involving a methyl migration. The eliminations of methyl radical, carbon monoxide and ketene are important processes in many cases. 相似文献
80.
The Conversion of Eperuic Acid into Ethers of the enantio-14, 15-Dinorlabdane Series 5 and 6 are strongly odiferous substances of the ambra-type. Their enantiomers 7 and 8 , hitherto unknown, have been synthesized from eperuic acid (4) and their olfactory properties compared with those of 5 and 6 . 4 was esterified by CH2N2 and dehydrogenated with (C6H5Se)2/H2O2 to the α,β-unsaturated ester 9 (61%). Oxidation by KMnO4 in acetone yielded the ketone 3 (60%). Epoxidation followed by treatment with acid converted 3 into the acetals 7 (61%) and 8 (14%). 7 and 8 differ from 5 and 6 in odor intensity, and 6 and 8 show slightly different odor quality. 相似文献