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由于超临界二氧化碳(SCCO2)具有稳定、安全、不燃、清洁无毒、粘度小、扩散快、可压缩的特殊性质,所以使得超临界二氧化碳非常适合作为催化反应的绿色溶剂.除此之外,多种气体在超临界二氧化碳中的溶解度很高,这对于那些受传质阻碍和易引起安全隐患的气相反应来讲,使用SCCO2作为替代的反应溶剂具有重要的价值。值得指出的是:如果选择超临界二氧化碳作为氧化反应的溶剂,其自身不会发生反应而产生副产物,从而容易得到清洁的产物。本文主要讨论了超临界二氧化碳作为反应介质对醇、烯烃和烷烃等选择氧化反应的影响,通过与传统溶剂比较可以看出超临界二氧化碳作为氧化反应溶剂的优势,对近几年来以分子氧为氧化剂,以超临界二氧化碳为介质的催化选择氧化的反应体系作了综述,并对未来的发展提出了展望。 相似文献
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Aqueous solutions of Me2Te(OH)2 and (CH2)4Te(OH)2 readily absorb carbon dioxide giving rise to the formation of the dialkyltelluroxane carbonates (Me2TeOTeMe2CO3)n ( 1 ) and HO(CH2)4TeOTe(CH2)4CO3Te(CH2)4OH·2H2O ( 2 ·2H2O), which were characterised by 13C MAS and 125Te MAS NMR spectroscopy as well as X‐ray crystallography. The spatial arrangement of the tellurium atoms is defined by C2O2 donor sets in the primary coordination sphere and one or two secondary Te···O contacts, which involve coordination of the carbonate moieties. In turn, the different Te–O coordination modes render a lack of symmetry to the carbonate moieties, which show significantly different C–O bond lengths, an important feature when contemplating the C–O bond activation in carbonates. The structural and spectroscopic parameters of 1 and 2 are discussed in comparison with other heavy p‐block element carbonates. In solution, electrolytic dissociation of 1 and 2 takes place. 相似文献
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Pan-Feng Yuan Zhao Yang Shan-Shan Zhang Can-Ming Zhu Prof. Dr. Xiu-Long Yang Prof. Dr. Qing-Yuan Meng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(5):e202313030
Carboxylation with carbon dioxide (CO2) represents one notable methodology to produce carboxylic acids. In contrast to carbon–heteroatom bonds, carbon–carbon bond cleavage for carboxylation with CO2 is far more challenging due to their inherent and less favorable orbital directionality for interacting with transition metals. Here we report a photocatalytic protocol for the deconstructive carboxylation of alkenes with CO2 to generate carboxylic acids in the absence of transition metals. It is emphasized that our protocol provides carboxylic acids with obviously unchanged carbon numbers when terminal alkenes were used. To show the power of this strategy, a variety of pharmaceutically relevant applications including the modular synthesis of propionate nonsteroidal anti-inflammatory drugs and the late-stage carboxylation of bioactive molecule derivatives are demonstrated. 相似文献
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超临界二氧化碳体系中正八面体氧化钴颗粒的生长及其表征 总被引:1,自引:0,他引:1
研究了正八面体氧化钴颗粒在超临界二氧化碳体系中的合成过程。在密闭的不锈钢高压反应釜中,1.0 g乙酸钴和12.0 g干冰在450 ℃下,反应12 h后合成粒径大约10 μm的正八面体氧化钴颗粒。通过XRD、 XPS、TEM、 SEM以及拉曼光谱的分析,氧化钴颗粒是由八个{111}面包裹着的正八面体单晶组成。条件实验显示,超临界二氧化碳体系是正八面体氧化钴颗粒合成的充分条件。其生长机理可能是:乙酸钴在超临界二氧化碳体系中的热分解;氧化钴的结晶和定向缓慢生长。在性能方面,初步研究了正八面体氧化钴颗粒在作为锂离子电池电极材料的应用。 相似文献
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Morozovskii A. I. Solomonov A. B. Skudaev V. I. 《Russian Journal of Applied Chemistry》2001,74(4):700-701
The effect of chlorine and nitrosyl chloride impurities on the regeneration of nitrogen(IV) oxide—oxidizing agent in oxychlorination of hydrocarbons—was studied at two temperatures. An assumption is made that the process occurs by radical-chain mechanism and involves chlorine oxides. 相似文献
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Jun LIU Rui ZHANG Liang GAO Tao JIANG Zhi Min LIU Jun HE Bu Xing HAN* Guan Ying YANG Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2002,13(12)
It is known that a small change in the pressure near critical point of a fluid causes a significant change in density-dependent properties, such as the solubility parameter, viscosity, and dielectric constant1. Recently, there has been a growing interest in using supercritical fluids (SCFs) as reaction media2, 3. Homogeneous catalysts are capable of high specific activity and selectivity. But their removal from the reaction mixtures is difficult4. The application of reusable polymer-bond… 相似文献
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Catalytic Formation of Propylene Carbonate from Supercritical Carbon Dioxide/Propylene Oxide Mixture
TheuseofsupercriticalcarbondioxideasasubstitUtesolventforchemicalsynthesisisaveryattractiveareainviewofresourceutiIizationandenvironmentalproblems"'.SinceCO2,whichhasaneasilyaccessibIecriticalpointwithaTcof3l.l'CandaPcof7.3MPa,isnontoxic,nonflammableandinexpensive,itcanreplacehazardousorganicsolventandtherebyprovideavaluablepollutionpreventiontool.Assimilartoothersupercriticalfluids,SC-CO,hasgaslikediffusitivityandliquidIikedensity,andchangingpressureandtemperaturecanvaryitsphysicalpro… 相似文献
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Inga A. Ronova Lev N. Nikitin Ekaterina A. Sokolova Irina Bacosca Ion Sava Maria Bruma 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):929-936
Two series of polyheteroarylenes have been investigated with regard to their physical properties before and after swelling with supercritical carbon dioxide. The study of the dependence of glass transition temperature and free volume of polymers on their conformational rigidity showed that the process of swelling in supercritical carbon dioxide is influenced by the voluminous side groups and by the high boiling solvent N-methylpyrolidinone used for the preparation of the polymers which facilitates the formation of crosslinks or complexes with the macromolecular chains. 相似文献
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A general,green and efficient method for the synthesis of transdiiodoalkenes in CO2(sc) has been developed.Trans-diiodoalkenes were obtained stereospecifically in quantitative yields via diiodination of both electron-rich and electron-deficient alkynes in the presence of KI,Ce(SO4)2 and water in supercritical carbon dioxide [CO2(sc)]at 40℃. 相似文献
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超临界CO2在高分子合成与制备中的应用 总被引:6,自引:0,他引:6
介绍超临界二氧化碳流体作为介质在高分子合成与制备中的研究进展。文中表明,可在超临界二氧化碳中实施氟代单体的自由基溶液聚合、甲基丙烯酸甲酯的分散聚合、丙烯酸的沉淀聚合、丙烯酰胺的反相乳液聚合以及异丁基乙烯基醚的阳离子聚合等多种聚合反应,可用超临界二氧化碳溶胀聚合法制备梯度共混物。此外,超临界二氧化碳还可用于聚合物分级和聚合物微孔、微纤与微球材料的制备等,显示出超临界二氧化碳是一种对环境无污染且价廉的 相似文献
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Prof. Dr. Jing Hou Li-Li Hua Yan Huang Le-Wu Zhan Prof. Dr. Bin-Dong Li 《化学:亚洲杂志》2023,18(1):e202201092
Visible-light-mediated oxyarylation and hydroarylation of alkenes with aryl halides using formate salts as the reductant and hydrogen source under ambient conditions were developed. These protocols represent rare catalyst-free examples of the realization of such transformations. Using styrenes as substrates, oxyarylation could occur smoothly. Whereas, hydroarylation proceeds employing electron deficient alkenes. Moreover, dehalogenation proceeds successfully in the absence of alkenes. We expected that this method could provide a valuable strategy for the functionalization of aryl halides. 相似文献
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以超临界二氧化碳为介质, 进行丙烯酸与苯乙烯共聚反应, 合成出具有疏水链段结构的改性丙烯酸聚合物. 研究了压力和投料比对聚合反应的影响. 用红外光谱、紫外光谱和核磁共振谱分析其结构及组成. 采用粘度计测定其水溶液粘度随pH值的变化. 研究结果表明, 该聚合物水溶液具有明显的疏水缔合作用. 相似文献
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Joanna Shaofen Wang Dr. Chrystal N. Sheaff Dr. Byunghoon Yoon Dr. R. Shane Addleman Dr. Chien M. Wai Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(17):4458-4463
Super powers! Uranium(VI) ions can be extracted from aqueous solutions into supercritical CO2 (sc‐CO2) via an ionic liquid phase that contained tri‐n‐butyl phosphate (TBP) as a complexing agent (see figure). This process has potential applications in the nuclear industry for removing actinides from nuclear waste.
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