首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
Chloroquine sulphate, like the phosphate, is an antimalarial formulation widely used in the tropics. The stability of such formulations is therefore of interest in the combat against malaria. A DSC study has been made of the effects of exposure to the sun, heat and UV radiation on the stability of chloroquine sulphate, similarly as performed earlier for chloroquine phosphate. When freshly recrystallized from a water-acetone mixture, chloroquine sulphate exhibits two endothermic peaks, at 169.4° and 204.7°, for the expulsion of crystal water (one molecule) and for the melting process, respectively. The exposure of chloroquine sulphate to the sun, heat and UV radiation leads to splitting of the peak for melting.
Zusammenfassung Chloroquine-Sulfat ist ebenso wie das entsprechende Phosphatderivat ein in den Tropen weitverbreitet angewandtes Antimalaria-Präparat. Die Stabilität dieses Präparates hat damit Bedeutung für die Malariabekämpfung. Die vorliegende Arbeit ist eine Erweiterung einer Untersuchung über den Effekt der Einwirkung.von Sonne, Hitze und UV-Strahlen auf die Stabilität von Chloroquine-Phosphat auf Chloroquine-Sulfat. Aus Wasser-Aceton-Mischungen frisch kristallisiertes Chloroquine-Sulfat zeigt zwei endotherme Peaks bei 169,4 und 204,7 °C, die durch Abgabe von Kristallwasser (ein Molekül) bzw. durch den Schmelzvorgang bedingt sind. Wird Chloroquine-Sulfat der Sonne, Wärme oder UV-Licht ausgesetzt, so wird der dem Schmelzvorgang zuzuscheibende Peak aufgespalten.

, -, , . . , . , , 169,4 204,7°, , , . , .
  相似文献   

2.
Oxidation rates and k2/k6 ratios are given for some acids from propionic to lauric. The k2/k6 ratio is shown to be influenced by the electrostatic effect of the solvent. A linear dependence between the isodielectric values of k2/k6 and the number of methylene groups in the acid molecules is described.
k2/k6 . k2/k6 k2/k6 .
  相似文献   

3.
Magnesia aerogel activated by hydrogen spillover at 430 °C or at 200 °C becomes a catalyst for the hydrogenation of ethylene. This catalytic activity, observed already at 50 °C, is further enhanced by a treatment in oxygen at 430 °C.
, 430 200°C, . 50°C 430°C.
  相似文献   

4.
Spray decomposition of solutions is an uncommon but very promising technique for the preparation of multicomponent solid systems with welldefined structure. The experimental arrangement is described and a summary of the systems prepared until now is given. These are MgO–ZnO, CaO, CdO, Al2O3. Fe2O3 solid solutions and CdO. CdSO4 and Al2O3. Al2(SO4)3 systems.
, , . : MgO·ZnO, CaO·CdO,. Al2O3·Fe2O3 CdO·CdSO4 Al2O3·Al2 (SO4)3.
  相似文献   

5.
Supported Ni-Pd/SiO2 catalysts of different Ni and Pd composition were studied in n-butane hydrogenolysis. The reaction rate, selectivity towards methane, ethane and propane were determined. On the basis of these data the relationship between the size and composition of the active center and the possibility of surface segregation of one of the components is discussed.
Ni-Pd/SiO2 Ni Pd -. , . .
  相似文献   

6.
Several new supported K2Cr2O7 reagents are used in the oxidation of secondary alcohols. The influence of the number of active sites and the nature of solid support on the yield is discussed. The influence of the structure of alcohol on the yield of ketone is analyzed.
K2Cr2O7 . . .
  相似文献   

7.
    
Zusammenfassung Mit Hilfe einer Kombination aus drei dünnschichtchromatographischen Anordnungen wurden Trennungen von Hydroxydicarbonsäuren, von Diund Tricarbonsäuren des Citratcyclus und einigen anderen Dicarbonsäuren pflanzlichen Ursprungs durchgeführt. Als Schichtmaterial fand Polyamid Woelm DC Verwendung. Mischungen aus Diisopropyläther-Petroläther-Kohlenstofftetrachlorid-Ameisensäure-Wasser (50202081), Acetonitril-Ameisensäure-n-propylester-Essigsäure-n-propylester-Ameisensäure (45451010) und Amylalkohol-Kohlenstofftetrachlorid-Ameisensäure (403015) dienten als Fließmittel. Eine Behandlung mit Jodsäure, durch die einige der untersuchten Säuren zerstört oder in charakteristischer Weise verändert wurden, bot in Verbindung mit der rein chromatographischen Arbeitsweise zusätzliche Differenzierungsmöglichkeiten.
Summary Separations of hydroxydicarboxylic acids, of di- and tricarboxylic acids from the citrate cycle, as well as of several other dicarboxylic acids of plant origin, were carried out by means of a combination of three thin-layer chromatographic systems. Polyamide Woelm DC was used as the film material. Mixtures of diisopropyl ether-petroleum ether-carbontetrachloride-formic acid-water (50202081), acetonitrile-n-propyl formate-n-propyl acetate-formic acid (45451010), and amyl alcohol-carbon tetrachloride-formic acid (453015) were used as eluents. Treatment with iodic acid, which decomposed or altered the characteristics of some of the tested acids, offered additional differentiation possibilities when combined with the purely chromatographic technique.


IV. Mitteilung: Knappe, E., u. I. Rohdewald: diese Z. 210, 183 (1965).  相似文献   

8.
Comments are given on the paper Alternative Interpretation of Infrared Spectra of the Zeolite NaHY+Butene-1 System of Forster and Seelemann /2/. Our previous paper /1/ was partly revised but the usefulness of comprehensive studies by infrared and temperature-programmed desorption methods has been emphasized.
: NaHY+-1. [2]. [1] , - .
  相似文献   

9.
The standard thermodynamic properties of M(OH)2 (M=Mn, Ni and Cd) solid phases have been retrieved using a graphical approach based on the already reportedP vs. T curves obtained from hydrothermal studies of MO-H2O systems. This approach avoids the use of heat capacity effects. The values retrieved by this modified approach are in good agreement with the calorimetric values.
Zusammenfassung Basierend auf unlängst beschriebenen, aus hydrothermischen Untersuchungen von MO-H2O Systemen gewonnenenp-T Kurven wurden mittels einer graphischen Näherung die thermodynamischen Standardeigenschaften von M(OH)2 Festphasen (M=Mn, Ni und Cd) bestimmt. Dieses Verfahren umgeht den Gebrauch von Wärmekapazitätseffekten. Die durch dieses modifizierte Verfahren erhaltenen Werte stehen in guter Übereinstimmung mit den kalorimetrischen Werten.

- , O-H2O, M(OH)2, M=, . . .


The authors express their grateful thanks to Prof. V. Venkatachalapathy, Director of the Minerological Institute, for his encouragement during the course of this work.  相似文献   

10.
The paper deals with the relationship between the crystal and molecular structures of CuSO4.5 H2O, CuSO4.3 H2O and CuSO4.H2O on the one hand, and the stoichiometries of their thermal decompositions on the other. With the use of methods of X ray powder diffractograms, i.r. and electronic spectra, evidence is provided that the intermediates of the thermal decomposition of CuSO4.5 H2O have the same crystal and molecular structures as CuSO4.3 H2O and CuSO4.H2O prepared by other procedures. It is also shown that at temperatures near that of the thermal decomposition, certain, not further identified structural changes take place in CuSO4.5 H2O.
Zusammenfassung Es wird einerseits der Zusammenhang der Kristall- und Molekularstruktur von CuSO4 · 5H2O, CuSO4 · 3H2O und CuSO4 · H2O behandelt und andererseits die Stöchiometrie ihrer thermischen Zersetzung. Mit der Auswertung der Röntgen-Pulverdiffraktogramme, der IR- und Elektronenspektren wurde der Beweis erbacht, da\ die Zwischen-produkte der thermischen Zersetzung von CuSO4 · 5H2O dieselben Kristall- und Molekül-strukturen besitzen, wie auf anderen Wegen hergestelltes CuSO4 · 3H2O bzw. CuSO4 · H2O. Ferner wurde gezeigt, da\ bei Temperaturen in der NÄhe der thermischen Zersetzungstemperatur gewisse, jedoch noch nicht identifizierte StrukturÄnderungen in dem CuSO4 · 5H2O stattfinden.

Résumé L'article examine la corrélation entre les structures cristallines et moléculaires de CuSO4.5 H2O, CuSO4.3 H2O et CuSO4.H2O d'une part et la stoechiométrie de leur décomposition thermique de l'autre. En se servant des méthodes des diffraction des rayons X sur poudre et des spectres infra-rouges et électroniques on montre que les produits intermédiaires de la décomposition thermique de CuSO4.5 H2O ont les mÊmes structures cristallines et moléculaires que celles de CuSO4.3 H2O et de CuSO4.H2O préparées par d'autres procédés. On montre également qu'à des températures proches de celle de la décomposition thermique de CuSO4. 5H2O des changements structuraux non encore identifiés ont lieu.

uSO4 · 52, uSO4 · 2 uSO4 · 2, — . , , , uSO4 · 52 uSO4 · 2 uSO4 · 2, . , , uSO4, · 52 , .
  相似文献   

11.
    
A higher activity of Na–X than Na–Y in CH3SH+SO2 reaction at 343 was observed. The increase of the copper content in the samples causes an increase of their activity. Water, sulfur, dimethyl disulfide, dimethyl trisulfide and sometimes dimethyl sulfide are registered as reaction products. (CH3)2S3 is formed as a result of the reaction between sulfur and (CH3)2S2.
, Na–X , Na–Y CH3SH+SO2 343 . . , , , , . (CH3)2S2 (CH3)2S3.
  相似文献   

12.
Hexadiene formation from 2-propanol was investigated in view of acid-base properties of Ca–P–O catalysts with the Ca/P atomic ratio varying from 1.5 to 5.0. The catalytic activity in hexadiene formation increased up to a maximum at Ca/P=2.0, having almost the same amount of weak acidic sites as weak basic sites, and decreased with futher increase in Ca/P ratio.
2- - Ca–P–O Ca/P, 1,5 5,0. , Ca/P=2, , Ca/P.
  相似文献   

13.
The products of selective oxidation are shown to be formed via a stepwise mechanism with participation of surface allylic complexes. A successive transformation of -allyl to -allyl and further to acrolein is possible. The products of complete oxidation may be formed through surface carbonate-carboxylate complexes via either a stepwise mechanism involving the catalyst's oxygen, or a concerted mechanism with the participation of molecular oxygen.
, . - -, . - , .
  相似文献   

14.
The hydrogen sorption of carbon-supported platinum catalysts, studied by the potentiodynamic method, differs significantly from that of unsupported platinum. The difference depends on the preparation method and on the nature of the support. Possible explanations are suggested as (i) some kind of interaction between metal and support atoms during impregnation, (ii) high dispersity (amorphous structure) and (iii) hydrogen spillover onto the carbon support.
Pt/C, . . (I) , (II) ( ), (III) .
  相似文献   

15.
With increasing the lead content both CO and hydrogen sorption drop considerably. The influence of lead can be observed starting from a concentration of 0.5%. This may indicate that the surface is enriched in lead atoms.
CO, H2. , 0,5%. .
  相似文献   

16.
The paper deals with the thermal properties of complex compounds of the general formula CuL2(NCX)2 (whereL=bipy or phen,X=S or Se). The phenanthroline complexes exhibit a higher thermal stability than those with bipyridine. For the latter complexes thermal decomposition begins with the release of bipyridine molecules, while for the phenanthroline complexes redox reactions of pseudohalogenide ligands with Cu(II) take place. The redox reactions start at a lower temperature for the selenocyanate complexes than for the thiocyanate complexes.
Zusammenfassung Vorliegende Arbeit behandelt die thermischen Eigenschaften von Komplexverbindungen der allgemeinen Formel CuL2(NCX)2 (mitL=Bipyridin oder Phenanthrolin undX=S oder Se). Die Phenanthrolinkomplexe zeigen eine grössere thermische Stabilität als die Bipyridinkomplexe. Die thermiscne Zersetzung letzterer beginnt mit der Abgabe von Bipyridinmolekülen, während bei den Phenanthrolinkomplexen Redoxreaktionen von Pseudohalogenidliganden·mit Cu(II) stattfinden. Diese Redoxreaktionen beginnen bei den Selenozyanatkomplexen bei niedrigeren Temperaturen als bei den Thiozyanatkomplexen.

CuL2(NCX)2, L= , X= . . , — . - , .
  相似文献   

17.
Chemical oscillatory behavior in the uncatalyzed bromate oxidation of hydroquinone and nitrophenols is reported. The reaction is strongly inhibited by stirring. Effect of one-electron redox couples (EZ catalysts) on the system is described.
. . - ( EZ) .
  相似文献   

18.
The presence of CO2 on TiO2 affects the process of oxygen photo-adsorption depending on the hydroxylation state of the surface. In dehydroxylated samples CO2 blocks the formation of O 3 and O 2 . On H2O2/TiO2 samples pretreated in the range of 150–200°C it leads to CO2–O 2 species.
, Cu(II). . .
  相似文献   

19.
Yields of n-C4H10 have been measured from the flow pyrolysis of C2H4 at 897 (±7) K. From 77 to 720 Torr the order of n-C4H10 formation was found to be 2.0±0.3 The rate constant for the reaction, was estimated to be 2.4(±0.6)×10–4l mol–1s–1.
-C4H10 C2H4 897 (±7) . -C4H10 77 720 2.0±0.3. 2C2H4C2H3+C2H5 2,4 (±0,6)×10–4 –1–1.
  相似文献   

20.
Pt/sol and Pt/support catalysts with 6–15 Å Pt particles have been established to be low active in the hydrogenation of propargyl alcohol, butyn-l-ol-3 and dimethylethynylcarbinol. The specific catalytic activity significantly rises with increasing dPt above 15 Å and after the thermal treatment of highly dispersed catalysts in a hydrogen flow.
, -30 -- 6–15 Å , -1, -3 . dPt>15 Å .
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号