Nanocrystalline TiO2–HClO4 as a new, efficient and recyclable catalyst for the chemoselective trimethylsilylation of alcohols, phenols and deprotection of silyl ethers
摘要:
TiO2-HCIO4, as a new solid acid, was found to be an efficient catalyst for the chemoselective trimethylsilylation of alcohols and phenols. Deprotection of the resulting trimethylsilylethers was achieved using the same catalyst in methanol solvent. The synthesized catalyst was characterized by FT-IR, SEM, TEM, BET and XRD analyses. Our novel synthetic method has the advantages of high yields, short reaction times, low cost and recyclability of the catalyst, simplicity and easy work-up compared to the conventional methods reported in the literature. (C) 2011 Elsevier B.V. All rights reserved.
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 。
Multicyclic Poly(ether sulfone)s of Phloroglucinol Forming Branched and Cross-Linked Architectures
作者:Hans R. Kricheldorf、Detlev Fritsch、Lali Vakhtangishvili、Gert Schwarz
DOI:10.1021/ma021569i
日期:2003.6.1
of linear oligomers due to numerous side reactions. In contrast, polycondensations of silylated phloroglucinol under similar conditions were not plagued by such side reactions but involved various cyclization reactions with high efficiency. The MALDI−TOF mass spectra revealed the formation of various cyclic, bicyclic, and multicyclic species of complex structure up to 12 000 Da. Therefore, cross-linking
钾2 CO 3DMSO中的间苯三酚和4,4'-二氟二苯砜(DFDPS)促进的缩聚反应会由于许多副反应而生成线性低聚物的混合物。相反,在类似条件下甲硅烷基间苯三酚的缩聚反应不会受到此类副反应的困扰,但会涉及各种高效的环化反应。MALDI-TOF质谱揭示了高达12 000 Da的各种复杂结构的环状,双环和多环物种的形成。因此,仅当添加大量过量(+ 30mol%)的DFDPS时才发生交联。所得的支链和交联聚合物主要由环状结构单元组成。由于环化程度高,试图通过将侧基OH基团与磺内酯烷基化引入磺酸基团仅产生了中等程度的取代。
Influence of fluorination on CO<sub>2</sub> adsorption in materials derived from fluorinated covalent triazine framework precursors
作者:Zhenzhen Yang、Song Wang、Zihao Zhang、Wei Guo、Kecheng Jie、Mohamed I. Hashim、Ognjen Š. Miljanić、De-en Jiang、Ilja Popovs、Sheng Dai
DOI:10.1039/c9ta02573a
日期:——
Give me more fluorines: introduction of fluorine in the structure of Covalent Triazine Frameworks can improve their CO2 adsorption. Materials with optimal fluorine content and narrow nanopore distribution are promising CO2 scavengers.
Surpassing Robeson Upper Limit for CO2/N2 Separation with Fluorinated Carbon Molecular Sieve Membranes
作者:Zhenzhen Yang、Wei Guo、Shannon Mark Mahurin、Song Wang、Hao Chen、Long Cheng、Kecheng Jie、Harry M. Meyer、De-en Jiang、Gongping Liu、Wanqin Jin、Ilja Popovs、Sheng Dai
DOI:10.1016/j.chempr.2019.12.006
日期:2020.3
triazine units, fluorine, and ether groups, these carbon molecular sieve membranes obtained after pyrolysis exhibit intrinsic ultra-micropores, high surface areas and excellent thermalstability under air. Excellent CO2 permeability and CO2 to N2 selectivity surpassing the Robeson upper bound are achieved. Our general design and synthesis protocol allow an easy access to fluorinated porous membranes, thus
Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
作者:Nader Ghaffari Khaligh
DOI:10.1016/j.molcata.2011.08.021
日期:2011.10
New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, H-1 NMR and C-13 NMR studies. All the products were extensively characterized by H-1 NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification. (C) 2011 Elsevier B.V. All rights reserved.