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941.
Zusammenfassung Leitfähigkeitsmessungen an Et4NCl-Lösungen zeigen die Gültigkeit derBjerrumschen Theorie in PhPOCl2; die Dissoziationskonstante beträgt 1,5·10–2. FeCl3 verhält sich nicht wie eine Ionenverbindung, doch ähnlich wie in POCl3. Zur Verfolgung von Ionenreaktionen wurden konduktometrische Titrationen ausgeführt. ZnCl2 und AlCl3 geben 2 Chloridionen, BCl3, TiCl4, SnCl4 und PCl5 je 1 Chloridion an die Akzeptoren FeCl3 oder SbCl5, ab. In Gegenwart von polaren Chloriden nehmen BCl3, AlCl3, FeCl3, PCl5 und SbCl5 je 1 Chloridion, ZnCl2, TiCl4 und SnCl4 je nach Angebot 1 oder 2 Chloridionen auf. Sowohl die Chlorometallate, als auch die Chloroniumverbindungen sind im gleichen Ausmaß wie Et4NCl ionisiert.Mit 4 Abbildungen2. Mitt.:M. Baaz, V. Gutmann, M. Y. A. Talaat undT. S. West, Mh. Chem.92, 150 (1961).Herrn Prof. Dr.L. F. Audrieth zum 60. Geburtstag gewidmet. 相似文献
942.
T. Paryjczak J. M. Farbotko K. W. Jówiak 《Reaction Kinetics and Catalysis Letters》1982,20(1-2):227-231
Temperature-programmed reduction and oxidation of bimetallic catalysts Pd–Ni/Al2O3 seem to indicate phase segregation of palladium and nickel oxides and alloying of palladium and nickel in the process of reduction of oxidized catalysts.
- Pd–Ni/Al2O3 , .相似文献
943.
The removal of excess reagent extracted into an organic phase in the solvent extraction of a metal complex anion with a quaternary ammonium ion is discussed. With a given chelating ligand (HO—R—SO3H), the order of extractability is HO—R—SO3- > M(OR—SO3)n- > X- > -O—R—SO3- when an anion such as nitrate or halide is added. If suitable amounts of the anion are added, only the excess of reagent can be removed. The principle is applied to the extraction with zephiramine of the cobalt complex anion formed with 2-nitroso-1-naphthol-4-sulfonic acid. Micro amounts of cobalt in pure nickel salts were determined spectrophotometrically. 相似文献
944.
T P Davis C W Gehrke C W Gehrke T D Cunningham K C Kuo K O Gerhardt H D Johnson C H Williams 《Journal of chromatography. A》1979,162(3):293-310
A remarkably sensitive, simple and selective reversed-phase high-performance liquid chromatographic (HPLC) method has been developed, allowing, for the first time, the direct measurement of histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin and tyramine in a single sample of plasma (2 ml), tissue (0.2 g), or urine. The biogenic amines were modified by pre-column derivatization with o-phthalaldehyde which stabilizes the molecules, aids in extraction, and improves HPLC detection at the nanogram level. To minimize losses during the sampling procedure a careful collection procedure was designed. We developed a simple sample cleanup in which the samples were thawed, neutralized with KOH, immediately derivatized, extracted into ethyl acetate (EtOAc) and then chromatographed by HPLC. The derivatives were stable in EtOAc for more then 24 h. Interfering amino acids were removed from the EtOAc by partitioning twice with Na2HPO4 buffer (pH 10.0). Complete separation was achieved in ca. 60--90 min on a muBondapak phenyl column using a stepwise gradient of acetonitrile and/or methanol-phosphate buffer (pH 5.1). A variable wavelength fluorometer with a 5-microliter flow-cell was used (excitation 340 nm; emission 480 nm). Linearity ranged from 200 pg to 50 ng onto the column. Precision (R.S.D.) for retention times was 1% and for derivatization and injection 2.5%. Recoveries of the seven biogenic amines from plasma spiked with 25 ng/ml averaged 70%, with a relative standard deviation of 6%. Separation studies were also done using a muBondapak C18 column. The effects of various eluents are presented. Gas-liquid chromatography was also investigated but lacked the sensitivity achieved by HPLC. The HPLC method is used routinely for the determination of biogenic amines in plasma from pigs with malignant hyperthemia and thermally stressed bovine. Significant differences in levels of biogenic amines were noted between stressed and non-stressed animals. Data on rat brain tissue samples were compared with the trihydroxyindole method and canine heart tissue was analyzed for ventricular norepinephrine and dopamine. Application of the method to urine from normal persons and a patient with a brain tumor has been demonstrated. 相似文献
945.
T. M. Gorrie S. Kalyana Raman H. K. Rouette Heinrich Zollinger 《Helvetica chimica acta》1973,56(1):175-195
An NMR. investigation of the state of formaldehyde in acidic solutions has been carried out. Solutions of DCl/D2O/CD3COOD containing two sources of formaldehyde, i.e. paraformaldehyde (I) and trioxane (II), were used for this purpose. In systems I and II the effect of various D2O/CD3COOD ratios, at a constant DCl concentration, was studied, while for II the effect of changing DCl concentration was also investigated. The results show that in aqueous solution, formaldehyde exists primarily as the monomeric and linear oligomeric forms of methylene glycol. Reducing the amount of D2O (at constant DCl concentration), while increasing the CD3COOD content, results in an increase in the polymeric species and in trioxane. In addition, substitution of water by acetic acid results in systems that are catalytically more active than aqueous solutions of the same hydrochloric acid concentration. Along with the usual polymer-monomer equilibria which exist in such solutions, side reactions of methylene glycol with the hydrochloric acid present also occur to a small extent, e.g. acetylation, substitution of OH by Cl and the Cannizzaro reaction. It is suggested that these findings will result in a better understanding of the formaldehyde crosslinking reactions in cotton cellulose. 相似文献
946.
Conclusions The partial hydrolysis of the pectin ofPanax ginseng C. A. Mey gives a polygalacturonide which has a linear carbohydrate chain consisting of residues of D-galacturonic acid in the pyranose form linked by -(1 4)-bonds.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 4, pp. 201–203, 1969 相似文献
947.
Mechanism for polymerization of ε-caprolactam in the presence of both sodium and aluminum caprolactamate was investigated at 171°C. The role of Al(Cap)3 as an initiator was revealed. The apparent rate constant of propagation reaction decreased with the increase in the concentration of Al(Cap)3, as the two different metal salts interact even at 171°C. The activation energy of the overall polymerization reaction with this catalyst system was estimated to be 41.18 kcal/mole. 相似文献
948.
The percutaneous absorption of ketoprofen (KPF) from gel patches containing d-limonene and ethanol was investigated in rats. Plasma levels of KPF varied with the kind of polymers which constitute the gel patch, and the highest level was observed when the copolymer of ethylacrylate (EA) and diethyleneglycolmethacrylate (DEGMA) was used as a vehicle. The amount of KPF permeating through the rat skin from the gel patch was well correlated with that of ethanol. Permeations were enhanced with increase in the amount of d-limonene distributed from the vehicle to the skin tissue. The amount of d-limonene accumulated in the skin varied greatly with the kind of polymers; the highest accumulation was observed with the EA-DEGMA copolymer, and decreased with increasing affinity of d-limonene to the polymers. The reason EA-DEGMA copolymer showed the highest percutaneous absorption of KPF from gel patches containing d-limonene may be the hydrophilic nature of this polymer which showed the lowest affinity to d-limonene. 相似文献
949.
A. I. Nekhaev B. I. Kolobkov M. T. Toshev Kh. B. Dustov G. G. Aleksandrov 《Russian Chemical Bulletin》1991,40(4):827-830
Reaction of excess styrene with Fe3(CO)12 and sulfur (60°C, 15 h, Ar, S/Fe3(CO)12 0.6 g-atom/mole) gave Fe2(CO)6S2, Fe3(CO)9S2, Fe2(CO)6(S2CO), Fe2(CO)6S2(PhCHCH2), PhCHCH2S4, and a novel binuclear complex Fe2(CO)6(S2CH2S), whose structure was analyzed by x-ray crystallography. The crystals are monoclinic, a=7.764(3), b=13.205(4), c=6.628(6) Å, =98.97(3)°. V=671.2(7) Å3, Z=2, space group P21/m. The bond lengths are Fe-Fe 2.520(2), Fe-S 2.236(2), S-S 2.078(4), C-S 1.825(12), Fe-CO 1.784(8), and CO 1.148(9) Å.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 930–934, April, 1991. 相似文献
950.
Zusammenfassung Aus Fichten- und Buchen-Kunstfaserzellstoffen wurden -und -Cellulosen präparativ hergestellt und diese polymeranalog nitriert. Die entstandenen Nitrate wurden durch Behandeln mit Aceton in einen löslichen und unlöslichen Teil getrennt, die gewichtsmäßig bestimmt wurden. Die acetonlöslichen Nitratanteile wurden aus den Acetonlösungen durch steigende Wasserzusätze fraktioniert gefällt und die Fraktionen gewichtsmäßig bestimmt; weiters wurden die reduzierten Viskositäten der Fraktionen bestimmt. Während die Stickstoffgehalte der acetonlöslichen Nitratanteile etwa jenen von Cellulosenitraten entsprechen, betragen die Stickstoffwerte der acetonunlöslichen nur etwa die Hälfte bis ein Drittel davon. In den acetonlöslichen Anteilen liegen im wesentlichen Hexosane vor. Die höchsten Fraktionen der -Cellulosen enthalten Anteile bis annähernd etwa DP 200. Im Gegensatz dazu bestehen die acetonunlöslichen Nitratanteile von - und -Cellulosen hauptsächlich aus Mischungen von Nitraten von Pentosanen und Polyuronsäuren. Die Acetonlöslichkeit von Nitraten laugenlöslicher Anteile aus Kunstfaserzellstoffen gibt demnach orientierende Hinweise auf die chemische Zusammensetzung dieser Anteile.Herrn Prof. Dr.A. Wacek zum 60. Geburtstag gewidmet.Die vorliegenden Untersuchungen wurden bereits in den Jahren 1952 und 1953 durchgeführt. 相似文献