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31.
Klaus Anders Norbert Roth Arnold Frohn 《Particle & Particle Systems Characterization》1996,13(2):125-129
Rainbow refractometry allows the determination of the refractive indices of droplets if a homogeneous refractive index can be assumed throughout the whole droplet. The influence of gradients on the angular position of the rainbow was examined for refractive index distributions with constant gradients and for distributions as they occur during cooling, heating and burning of droplets. Geometrical optics were used to determine rainbow positions. For a given value of refractive index at the surface, the rainbow position is in many cases a measure for the gradient itself. It was found that information obtained for constant gradients can often be used in cases with more complex distributions, which are found, for instance, for droplets undergoing heat-transfer processes. Significant errors may be obtained only for a very short initial phase of the process. Experimental results obtained with monosized droplet streams, which confirm theoretical predictions of the influence of gradients on the rainbow position, are presented. 相似文献
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The oxidation of C6F5I by oxidizers containing positive chlorine was investigated with the intention to prepare pentafluorophenyliodine (III) compounds: C6F5IX2, where X are halides or oxoderivatives. Using ClF, ClOCF3, Cl2/AlCl3 or Cl2O as oxidizers C6F5 IF2, C6F5 I Cl2 and C6F5I (OCl)2 - all thermally unstable - could be prepared and characterized.In contrast to these compounds the perfluoroaromatic carboxylates: C6F5I [O(O)C RF]2 are crystalline solids thermally stable up to 200 °C. Single crystal investigations show T-coordinated iodine with significant secondary bonding between iodine and the keto oxygens. C6F5 IO-formed by hydrolysis of C6F5IX2 - changes if stored at RT forming (C6F5)2I IO3.(C6F5)2I+ - formation is also observed when C6F5 IO is heated in inert (C6F5I, C6H6, CCl4 …), protic (H2O, CH3OH, …) and strong acidic (FSO3H …) dilution medium.C6F5IO reacts with acids, acid anhydrides and acid halides as could be shown by the preparation of C6F5 ICl2 and C6F5 ICl (NO3).Starting with C6F5 IX2 different preparative ways for (C6F5)2 I+ - compounds were successful. Principly (C6F5)2 IX - compounds decompose thermally forming C6F5I + C6F5X.C6F5 IX4 - compounds can be obtained from C6F5 IF4 which is the specific displacement product of IF5 with Si (C6F5)4. By nucleophilic displacement it is possible to prepare C6F5 IF2O, C6F5 IO2, C6F5 IO (OAcF)2 and C6F5 I [OC(CH3)2 C(CH3)2O]2,wich are all white, thermally stable solids.For the fluorine-ligand-exchange we used silycompounds as reagents. If the ligand is oxidable by C6F5 I(V) a stepwise reduction via C6F5I(III) to C6F5I could be shown by NMR-measurements. 相似文献
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The new type of alkenylxenon(II) salts [CF2=CXXe] [BF4] (X = H, Cl, CF3) was prepared by reacting the corresponding alkenyldifluoroboranes CF2=CXBF2 with XeF2 in 1, 1, 1, 3, 3‐pentafluoropropane (PFP) at —60 °C. The alkenylxenon(II) salts were characterised by multinuclear NMR spectroscopy. The influence of the substituent X at C‐1 on the stability of alkenylxenon(II) salts is discussed. Additionally the preparation of the potassium alkenyltrifluoroborate salts K [CF2=CXBF3] and their transformation into the boranes CF2=CXBF2 by fluoride abstraction in PFP is reported. 相似文献
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The oxidation of perfluoroquinoline with nitric acid (98%) yields perfluoropyridine-2.3-dicarboxylic acid (V) besides 2.3.4.6.7-pentafluoro-5.8-dioxo-5.8-dihydro-quinoline (IV) and 3.4.5.6.7.8-Hexafluoro-2-oxo-1.2-dihydro-quinoline (VIa). 相似文献
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