Trennung der Platinelemente unter Anwendung von Ionenaustauschern

Zusammenfassung Untersuchungen der Chloro-, Hydroxo- und Nitritokomplexe der Elemente Rhodium, Palladium, Iridium und Platin an Anionenund Kationenaustauschern ergaben, daß das Verhalten der Komplexe weitgehend von Struktur der Ankergruppe, Beladungsform und Vernetzungsgrad der Austauscher abhängt. Aufbauend auf den Ergebnissen von Einzelversuchen wurde eine Reihe von Zwei- und Dreistofftrennungen erarbeitet.Die vorliegende Arbeit wurde im Anorganisch-Chemischen Institut der Technischen Universität Berlin durchgeführt. Wir danken dem Direktor des Institutes, Herrn Prof. Dr. G. Jander, für Unterstützung und Diskussion, und der Gesellschaft der Freunde der Technischen Universität, der ERP-Verwaltung sowie der Firma Heraeus, Hanau, für die Bereitstellung von Mitteln und Material.     

Silicon‐modified surfactants and wetting: III. The spreading behaviour of equimolar mixtures of nonionic trisiloxane surfactants on a low‐energy solid surface

The spreading behaviour of binary and ternary equimolar mixtures of siloxane surfactants of general formula [(CH₃)₃SiO]₂CH₃Si(CH₂)₃ (OCH₂CH₂) _nOCH₃, n = 3–9, has been investigated. The mixtures show a pronounced temperature dependence on the initial spreading rate. Mixtures imitating the average oligoethylene glycol chain length n = 5 are the fastest spreaders at 15 °C. At 23 °C and 40 °C these mixtures spread fastest sucking n = 6 and n = 8, respectively. For a given average chain length an increasing length difference between the components of the binary mixtures reduces the initial spreading rate. Nevertheless, substantial differences between the phase transition temperature T_c from the lamellar phase (L_α) into the two‐phase state (2Φ) and the actual spreading temperature are tolerated. A clear relation between phase transition temperature T_c and initial spreading rate does not exist. Copyright © 1999 John Wiley & Sons, Ltd.     

Silicon‐modified surfactants and wetting: II. Temperature‐dependent spreading behaviour of oligoethylene glycol derivatives of heptamethyltrisiloxane

The temperature‐dependent spreading performance of defined trisiloxane surfactants of the general formula [(CH₃)₃SiO]₂CH₃Si‐­(CH₂)₃(OCH₂CH₂)_3–9OCH₃ and Silwet L77 on a trimethylsilylated silicon‐wafer surface has been investigated. At 6 °C the tetraethylene glycol derivative showed the highest initial spreading rate. At 40 °C the octaethylene glycol derivative was the fastest spreader. It is shown that spreading behaviour and phase behaviour are closely related. The highest initial spreading rates were found for solutions in the two‐phase state (2Φ) closely above the liquid–liquid insolubility boundary. Copyright © 1999 John Wiley & Sons, Ltd.     

Anionic ring‐opening polymerization of propylene oxide in the presence of phosphonium catalysts

Anionic ring‐opening polymerization of propylene oxide in the presence of potassium alcoholate initiator was accelerated by addition of the bulky phosphonium salt tetrakis[cyclohexyl(methyl)amino]phosphonium‐tetrafluoroborate. Dipropylene glycol (DPG) was partially deprotonated (5%) and used as an initiator for the polymerization performed at 100 °C at normal pressure. The delocalization of the positive charge over five atoms promoted the formation of a separated ion pair, thus enhancing nucleophilicity and reactivity. Compared with those of polyaminophosphazenes and tetrabutylphosphonium cation, the average propagation rates increased in the order of Bu₄P⁺, K⁺, P, P, and ^tBuP₄H⁺. DP_n for the polymers was in the range of 20–64. Characterization of poly(propylene oxide)s by means of ¹H NMR, size exclusion chromatography (SEC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) showed low polydispersities (M_w/M_n) without any byproducts or impurities. The M_w/M_n obtained was 1.03–1.09 (MALDI‐TOF‐MS) and 1.11–1.15 (SEC), respectively. Values calculated from titration of the hydroxyl groups showed good agreement. Determination of the total degree of unsaturation in the range of 13–60 mmol/kg indicated larger amounts with increasing polymerization rates. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 864–873, 2002; DOI 10.1002/pola.10163     

Silicon‐modified surfactants and wetting: I. Synthesis of the single components of Silwet L77 and their spreading performance on a low‐energy solid surface

Defined surfactants of general formula [(CH₃)₃SiO]₂CH₃Si(CH₂)₃(OCH₂CH₂)_3–9OCH₃, have been synthesized from the corresponding oligoethylene glycol monoallyl monomethyl ethers via hydrosilylation. The concentration‐dependent spreading performance on hydrophobized silicon wafers has been investigated and compared with that of Silwet L77. For the hexaethylene glycol derivative the highest initial spreading velocities and largest spreading areas were found. Since Silwet L77 spreads faster than all the other derivatives under investigation, a synergistic effect of different compounds is unlikely. Minor differences were found for handshaken and sonicated solutions. Copyright © 1999 John Wiley & Sons, Ltd.     

乙烯氧气法氧氯化反应中铜催化剂的研究

用微分固定床和沸腾床反应器考查了在乙烯氧气法氧氯化制二氯乙烷反应中,浸渍法制备的铜催化剂的反应活性及其应用的可能性,并与共沉淀法制备的铜催化剂进行了比较。用x射线衍射分析,程序升温还原和乙烯脉冲反应探讨了乙烯氧氯化催化剂的活性相结构与反应机理。