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1.
Synthesis of diisocyanides with phenolic groups and their polymerization to helically chiral poly(quinoxaline‐2,3‐diyl)s
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Johannes Scholz Michael Reggelin 《Journal of polymer science. Part A, Polymer chemistry》2015,53(11):1320-1329
The development of synthetic routes which lead to five new diisocyanide monomers with one or two phenolic groups is described. Their polymerization behavior is studied with Pd‐ and Ni‐based initiators, as well as under microwave irradiation. The polymerizability is mainly dominated by steric effects as is concluded from experiments using different protecting groups. Chiroptical properties of these new polymers are studied by CD‐spectroscopy. After deprotection, helically chiral poly(quinoxalin‐2,3‐diyl)s are obtained which display a Brønsted function attached to a stereolabile biaryl axis whose configuration should be influenced by the chiral polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1320–1329 相似文献
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Preliminary results leading towards the total synthesis of Brefeldin A are presented. 相似文献
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Contributions to the Chemistry of Phosphorus. 203. (t-BuSi)4P3Cl3 – The First Silaphosphane with a Structure Analogous to Norcubane The reaction of t-BuSiCl3 with LiAl(PH2)4 yields the compound (t-BuSi)4P3Cl3 ( 1 ), which has been isolated in pure form. According to NMR spectroscopic investigations and an X-ray single-crystal analysis, 1 is 2,4,6,7-tetra-tert-butyl-2,4,7-trichloro-1,3,5-triphospha-2,4,6,7-tetrasilatricyclo[3.1.1.03,6]heptane and thus the first silaphosphane with a structure analogous to norcubane. The compound crystallizes monoclinically in the space group P21/n with a = 1102.1 pm, b = 1609.2 pm, c = 1612.8 pm, β = 90.90° and Z = 4. The main structural feature is a cube alternately composed of Si and P, from which one phosphorus atom has been removed. The Si atoms are each substituted by t-Bu groups, the three adjacent to the missing corner additionally by Cl atoms. 相似文献
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The Gas Complex MnAlF5 and its Influence on the Purification of AlF3 by Sublimation The gas complex MnAlF5 has been determined mass spectroscopically by the ions MnAlF5+ and MnAlF4+. The gas complex MnAlF5 is formed above 973 K by heating up mixtures of AlF3/MnF2 or AlF3 · 3 H2O endowed with Mn2+ or by heating up solid MnAlF5 too. At 1 008 K the enthalpie of dissociation is 197 kJ/mole. The equilibrium structures of the high spin molecule MnAlF5 (S = 5/2) were examined with ab initio calculations at the HF-level by comlete gradient optimizing. Two minimum structures were found on the potential energy surface. A bidentate fluorine bridged structure was found to be the most stable at the HF-level. Vibrational frequencies and thermodynamic functions of complex formation were estimated for both minimum structures. The importance of the formation of the gas complex for the separation of MnF2 and AlF3 by sublimation is discussed. 相似文献
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Orellana M Arriola P Del Río R Schrebler R Cordova R Scholz F Kahlert H 《The journal of physical chemistry. B》2005,109(32):15483-15488
During the electrochemical oxidation of Prussian blue (PB) to Prussian yellow (PY), an electrocatalytic oxygen production proceeds at the electrode when aqueous electrolyte solutions are used. The formed oxygen is scavenged by the PY, probably by absorption, and it is consumed during the electrochemical reduction of PY to PB by a heterogeneous chemical reaction of PB with oxygen to PY and hydrogen peroxide. Because of this catalytic regeneration of PY, it is impossible to determine the amount of low-spin iron by chronocoulometry using a potential program in which PB is first oxidized to PY and then the charge is measured to reduce PY to PB. The latter charge is biased by the electrocatalytic PY regeneration. 相似文献