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911.
A. D. Karavaev G. S. Parshin V. P. Kazakov 《Reaction Kinetics and Catalysis Letters》1986,30(2):237-244
Abnormal fluctuations of chemiluminescence intensities have been observed in the CH2(COOH)2–BrO3–Ru(bipy)
3
2+,3+
system, when catalyst concentrations are insufficient for stable self-oscillations to be generated. Amplitude distribution of these fluctuations (reaction noise) are of the bell shape, which is typical for the normal Gaussian distribution. Their nature is similar to the large-scale fluctuations that are the nuclei for dissipative structures.
CH2(COOH)2–BrO 3 – –Ru(bipy) 3 2+,3+ , . ( ) , . , , .相似文献
912.
Summary Pb, Tl, Bi and Sb yield well defined polarograms in 1 M ethylenediamine in presence of 3% mannitol, with half-wave potentials at – 0.71 V, – 0.51 V, – 0.60 V and – 1.10 V, respectively. Only Pb and Tl develop maxima which can be suppressed by 0.02% gelatin. Presence of mannitol prevents the precipitation of Pb, Bi, and Sb in the alkaline solution. Simultaneous determinations of Pb/Tl, Bi/Sb, and Pb/Sb can be carried out.
Polarographische Bestimmung von Pb, Tl, Bi und Sb in Äthylendiamin in Gegenwart von Mannit
Zusammenfassung Gut ausgebildete Polarogramme kann man von diesen Elementen in 1 M Äthylendiamin in Gegenwart von 3% Mannit erhalten. Die Halbstufenpotentiale liegen bei – 0,71 V (Pb), – 0,51 V (Tl), – 0,60 V (Bi) und – 1,10 V (Sb). Maxima, die im Falle von Pb und Tl gebildet werden, können durch 0,02% Gelatine unterdrückt werden. Durch Mannit wird die Fällung von Pb, Bi, und Sb in der alkalischen Lösung verhindert. Simultanbestimmungen von Pb/Tl, Bi/Sb und Pb/Sb sind möglich.
Our sincere thanks are due to Dr. G. B. Singh, Professor and Head, Department of Chemistry, B.H.U. for providing the necessary facilities. 相似文献
913.
A. K. Karimdzhanov A. I. Ismailov Z. S. Abdullaev Sh. Yu. Islambekov F. G. Kamaev A. S. Sadykov 《Chemistry of Natural Compounds》1977,12(2):211-214
Summary A new phenolic compound — gossyvertin — has been isolated from the stems of a cotton plant infected with fungusVerticillium dahliae Kleb.; the structure 8-formyl-1,7-dihydroxy-5-isopropyl-2-methoxy-3-methylnaphthalene has been proposed for gossyvertin.Division of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 238–242, March–April, 1976. 相似文献
914.
The reaction of di-p-tolyltelluride with ferric, cupric and mercuric chloride, performed in glacial acetic acid, effects the reduction of the metallic salts giving rise to di-p-tolyltellurium dichloride. In toluene solution only the ferric chloride was reduced and the anhydride of di-p-tolyltellurium hydroxychloride formed, due to the hydrolysis of the tellurium dichloride. The reaction of the mentioned telluride and benzoyl chloride gave rise to a mixture of the dichloride and the dibenzoate. The mechanism of this reaction is discussed. 相似文献
915.
S. K. Tobia Y. A. Gawargious M. F. El-Shahat 《Fresenius' Journal of Analytical Chemistry》1973,265(1):23-24
Summary Simple and accurate methods are described for the microdetermination of arsenate and arsenite ions using 12- and 14-fold amplification reactions. The arsenate method is based upon reaction with calcium iodate and iodometric titration of the liberated iodate, whereas the arsenite method depends upon reaction with iodine and oxidation of the resulting iodide with bromine. This is followed by iodometric titration of the iodate in addition to the arsenate present in solution. The overall recovery amounts to 99.51 and 99.63% for arsenate and arsenite respectively.
Mikrobestimmung von Arsenat- und Arsenitionen mit Hilfe einer Vervielfachungsreaktion mit Jodat bzw. Jod
Zusammenfassung Ein einfaches und genaues Verfahren mit 12- bzw. 14facher Vervielfachung wird beschrieben. Die Arsenatbestimmung beruht auf der Reaktion mit Calciumjodat und jodometrischer Titration des freigesetzten Jodats, die Arsenitbestimmung auf der Reaktion mit Jod, Oxydation des erhaltenen Jodids mit Brom und jodometrischer Titration des gebildeten Jodats zusammen mit dem aus dem Arsenit entstandenen Arsenat. 99,51 bzw. 99,63% von eingesetztem Arsenat bzw. Arsenit konnten wiedergefunden werden.相似文献
916.
Quantitative IR solution data in carbon tetrachloride and chloroform are recorded for the CO and OH regions of 31 chromones. In the 1580–1700 cm−1 region, 5-hydroxychromones show three main maxima, the two of highest frequency, at 1663 ± 3 cm−1 and 1630 ± 5 cm−1 in CCl4 (1661 ± 2 cm−1 and 1627 ± 5 cm−1 in CHCl3), being sufficiently intense as to possess high CO character. Typically, 5-alkoxychromones exhibit two intense maxima in this region, 1663 ± 3 cm−1 and 1613 ± 7 cm−1 in CCl4 (1657 ± 2 cm−1 and 1608 ± 12 cm−1 in CHCl3). Diagnostically useful changes in contour and principal peak positions can be seen for substituted and annellated 5-hydroxychromones. In the 2500–3650 cm−1 region, the stretching frequencies of OH groups at the most commonly encountered positions (C-5, C-7, and 2-CH2OH) in natural chromones, are identified. 相似文献
917.
Summary It has been found that in alkaline triethanolamine medium the complex of bivalent manganese is oxidised by hexacyanoferrate(III), hydrogen peroxide or lead dioxide to the red-coloured complex of MnIV, which can be titrated potentiometrically with ferrous salt solution (MnIV MnIII and MnIII MnII). The stability of this complex has been studied in dependence on the oxidant employed, and it has been found that lead dioxide is best suited for this oxidation process. Similarly the oxidation of the complex CoII CoIII has been studied in the same medium, and conditions have been found for the reductometric determination of the CoIII complex formed.The possibilities for determining manganese in the presence of cobalt and of other accompanying elements are discussed. The results obtained have been applied to the determination of manganese in ores and alloys.
Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday. 相似文献
Zusammenfassung Bei Untersuchungen zum Oxydations-Reduktions-Verhalten von Mangan und Kobalt in alkalischer Triäthanolaminlösung wurde gefunden, daß der MnII-Komplex durch Hexacyanoferrat(III), Wasserstoffperoxid oder Bleidioxid zum rotgefärbten MnIV-Komplex oxydiert wird, der potentiometrisch mit, FeII-Lösung titriert werden kann (MnIV MnIII; MnIII MnII). Die Stabilität des Komplexes wurde in Abhängigkeit von der Art des Oxydationsmittels geprüft und Bleidioxid als am günstigsten gefunden. Analog wurden auch die Oxydation des CoII- zum CoIII-Komplex untersucht und Bedingungen zur reduktometrischen Bestimmung des letzteren ausgearbeitet. Die Möglichkeiten zur Manganbestimmung in Gegenwart von Kobalt sowie anderen Begleitelementen werden diskutiert, und als praktische Anwendung wird die Manganbestimmung in Erzen und Legierungen beschrieben.
Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday. 相似文献
918.
A. A. Nishanov B. Tashkhodzhaev I. M. Usupova M. N. Sultankhodzhaev 《Chemistry of Natural Compounds》1993,28(5):466-469
The known alkaloid lepenine and the new diterpene alkaloid akirine have been isolated from the epigeal part ofAconitum kirinense Nakai. To establish the structure of akirine, its spectral characteristics have been studied and an x-ray structural analysis has been made. It is 1,8-dihydroxy-16-methoxy-9,14-methylenedioxy-3,4-epoxy-N-ethylaconitane — the first diterpene alkaloid with a lycoctonine skeleton containing a 9,14-methylenedioxy group and a -oriented substituent at C14.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 534–538, September–October, 1992. 相似文献
919.
Highly porous nanocomposites of zirconium dioxide and silicate are synthesised in an aqueous system from an inorganic salt of zirconium; the nanacomposites, with tailorable pore structures, exhibit superior performance as catalyst supports. 相似文献
920.
Kinetic studies of the reduction of Hg(II) salts in aqueous acidic solutions by SO2 in mild conditions have revealed that SO2 quantitatively reduces Hg(II) to metal in the examined HClO4 concentration range (2–8M–1).
Hg(II) . , HClO4 (2–8 .–1) SO2 Hg(II) .相似文献