Partition coefficients of ketones, phenols, aliphatic and aromatic acids, and esters in n-hexane/nitromethane
作者:Urszula Kotowska、Valery Isidorov
DOI:10.2478/s11532-011-0060-4
日期:2011.10.1
in sample preparation and in countercurrent and liquid-liquid chromatographic separations. Partition coefficients are widely used in toxicology, environmental, and analytical chemistry. The K hn determination procedure for the n -hexane/nitromethane system was optimized and partition coefficients for 99 ketones, esters and trimethylsilyl derivatives of phenols, aliphatic and aromaticacids were determined
液-液分配用于样品制备以及逆流和液-液色谱分离。分配系数被广泛用于毒理学,环境和分析化学中。该 ķ HN 用于确定过程 Ñ 正己烷/硝基甲烷体系进行了优化和分配系数为99酮,酯和酚的三甲基甲硅烷衍生物,测定脂族和芳族酸。对于130种化合物, 使用 K hn 与其他理化和结构参数之间的数学关系来预测 K hn 值 。
Synthesis of trimethylsilyl carboxylates by HMDS under solvent-free conditions
作者:Marjan Jereb、Janja Lakner
DOI:10.1016/j.tet.2016.08.003
日期:2016.9
carboxylic acids were transformed into their trimethylsilyl esters with HMDS in a practically completely solvent-free process, while a catalytic amount of iodine was required in some cases. The process has several advantages over the known methods: untreated reactants, air atmosphere, mild and neutral conditions, no evolution of hydrogen halide, no need of an additional base, low amount of waste, completely
The reaction of singlet oxygen with O-silylated cyclic enediols 1a,b afforded as ene products the hydroperoxy silyl enolethers 3a,b and as cleavage products the silyl esters 4a,b; the latter presumably derivedfromrearrangement of the intermediary silylperoxy ketones 2a,b.
Silyl reagents (Me3Si-X) efficiently transfer X to Ir(H)2F(PtBuP2Ph)2
作者:Alan C. Cooper、John C. Huffman、Kenneth G. Caulton
DOI:10.1016/s0020-1693(97)05851-9
日期:1998.4
Me3Si-X reagents react to completion at 25 degrees C in a short time to convert Ir(H)(2)FL2 (L = (PBu2Ph)-Bu-t) to Ir(H)(2)XL2. This involves formation of Ir-O, Ir-N, Ir-I, Ir-S and Ir-C(sp) bonds. Products include some pi(2)-X ligands such as carboxylate and acetamide, NHC(O)CH3. The acetamide is shown to be pi(2) in the solid state and in solution, but readily rearranges, by a transition state with Ir-O bond cleavage, to effect site exchange of the two inequivalent hydrides. The same synthetic approach succeeds for the more crowded metallated species and these reactions are shown to fail when F is replaced by Cl in the iridium reagent. Unsaturation at Ir is suggested to be central to the mechanism of these F/X transposition reactions. (C) 1998 Elsevier Science S.A.