共查询到20条相似文献,搜索用时 31 毫秒
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Samsonov MD Wai CM Lee SC Kulyako Y Smart NG 《Chemical communications (Cambridge, England)》2001,(18):1868-1869
Uranium dioxide can be dissolved in supercritical CO2 with a CO2-philic TBP-HNO3 complexant to form a highly soluble UO2(NO3)(2).2TBP complex; this new method of dissolving UO2 that requires no water or organic solvent may have important applications for reprocessing of spent nuclear fuels and for treatment of nuclear wastes. 相似文献
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V. N. Khrustalev L. N. Nikitin A. Yu. Vasil’kov A. R. Khokhlov 《Russian Chemical Bulletin》2006,55(3):576-578
An organometallic compound, monoacetylferrocene, was for the first time obtained as single crystals by crystallization from
supercritical carbon dioxide. This offers the possibility of utilizing supercritical media for efficient crystallization and
purification of organometallic compounds without using organic solvents.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 555–557, March, 2006. 相似文献
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超临界二氧化碳介质中有机化学反应研究 总被引:3,自引:0,他引:3
综述了本研究小组近年来在超临界二氧化碳介质中过渡金属催化的有机化学反应的研究结果,主要包括烯烃和炔烃的羰基化反应、氧化反应、自由基反应、低聚反应。 相似文献
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Fürstner A Ackermann L Beck K Hori H Koch D Langemann K Liebl M Six C Leitner W 《Journal of the American Chemical Society》2001,123(37):9000-9006
Liquid or supercritical carbon dioxide (scCO(2)) is a versatile reaction medium for ring-opening metathesis polymerization (ROMP) and ring-closing olefin metathesis (RCM) reactions using well-defined metal catalysts. The molybdenum alkylidene complex 1 and ruthenium carbenes 2 and 3 bearing PCy(3) or N-heterocyclic carbene ligands, respectively, can be used and are found to exhibit efficiency similar to that in chlorinated organic solvents. While compound 1 is readily soluble in scCO(2), complexes 2 and 3 behave like heterogeneous catalysts in this reaction medium. Importantly, however, the unique properties of scCO(2) provide significant advantages beyond simple solvent replacement. This pertains to highly convenient workup procedures both for polymeric and low molecular weight products, to catalyst immobilization, to reaction tuning by density control (RCM versus acyclic diene metathesis polymerization), and to applications of scCO(2) as a protective medium for basic amine functions. The latter phenomenon is explained by the reversible formation of the corresponding carbamic acid as evidenced by (1)H NMR data obtained in compressed CO(2). Together with its environmentally and toxicologically benign character, these unique physicochemical features sum up to a very attractive solvent profile of carbon dioxide for sustainable synthesis and production. 相似文献
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Wang J Khlobystov AN Wang W Howdle SM Poliakoff M 《Chemical communications (Cambridge, England)》2006,(15):1670-1672
A facile and efficient method has been developed for coating MWNTs with solvent resistant polymer in scCO2, which permits the selective deposition of high molecular weight fluorinated graft poly(methyl vinyl ether-alt-maleic anhydride) polymer onto MWNTs in scCO2 under 100-170 bar at 40 degrees C and forms quasi one-dimensional nanostructures with conducting cores and insulating surfaces. 相似文献
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R. G. Christensen 《Journal of separation science》1985,8(12):824-828
A two-dimensional chromatographic separation is described which makes use of the unusual properties of supercritical carbon dioxide mobile phase. This solvent has the property of giving a separation of polycyclic aromatic hydrocarbons (PAH) on amine-bonded columns similar to that given by usual normal-phase solvents, and on octadecylsilane-bonded columns similar to that given by usual reversed-phase solvents. Packed columns were used, arranged so that they could be switched in or out of the solvent flow. Polycyclic aromatic hydrocarbon mixtures isolated from coal tar were fractionated according to number of aromatic carbon atoms on an amine-bonded column, and these fractions were trapped on an octadecysilane-bonded column. They were subsequently eluted according to the polarity of the individual compounds. Separations from fractions containing 16 and 18 aromatic carbon atoms are shown. 相似文献
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Lee CK Holmes AB Al-Duri B Leeke GA Santos RC Seville JP 《Chemical communications (Cambridge, England)》2004,(22):2622-2623
The regioselectivity of dipolar cycloadditions of mesitonitrile oxide to various dipolarophiles in supercritical carbon dioxide can be tuned by changes in density, the magnesium bromide-mediated cycloaddition to pent-1-en-3-ol proceeding with higher stereoselectivity than in most conventional solvents. 相似文献
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Early TR Gordon RS Carroll MA Holmes AB Shute RE McConvey IF 《Chemical communications (Cambridge, England)》2001,(19):1966-1967
Heck and Suzuki reactions proceed in good yield in supercritical carbon dioxide in the presence of palladium acetate and tri-tert-butylphosphine with both free and polymer-tethered substrates. 相似文献
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Regeneration of cobalt-contaminated activated carbon by supercritical carbon dioxide extraction 总被引:1,自引:0,他引:1
A mixture of Di-(2-ethylhexyl) phosphoric acid (D2EPHA) and n-hexane or methanol is used as the extractant solution for extracting cobalt from activated carbon using supercritical carbon dioxide extraction technology. In this work, a semi-continuous pilot unit of SFE is employed to conduct the extraction. In order to feed the viscous extractant by HPLC pump, n-hexane or methanol is added as a diluent to reduce the viscosity of the extractant. The amount of cobalt removed along the time course of the extraction is recorded and plotted as an extraction curve. A kinetic model is also established and fit to the extraction curve, and the obtained parameters of the model are used to explain the regeneration mechanism. The effects of temperature ranged from?40 to?80?°C and the effect of the concentration of diluents on the extraction are investigated and discussed based on the established model. It is also found that the removal of cobalt ions reaches a maximum; this varies with the operational conditions and is known as maximum removal efficiency. It is presumed that the maximum removal efficiency is affected by the adsorption kinetics of the extractant and the rate of ion exchange between the extractant and metal ions on the surface of the activated carbon. After increasing the extraction temperature from?60 to?80?°C it is observed that the maximum removal efficiency is greatly increased, presumably resulting from the diminishing competitive adsorption between the extractant and diluents. The established model can help to reveal the extraction mechanism and to promote maximum removal efficiency for regenerating activated carbon without secondary pollution. 相似文献
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Supercritical carbon dioxide has been considered an appropriate alternative for extraction and purification process of cosmetics, pharmaceuticals, food supplements and natural products. Solubility information of biological compounds is essential for choosing supercritical fluid (SCF) processes. The solubility of iodopropynyl butylcarbamate (IPBC), a fungicide and anti-dandruff agent, was measured in supercritical carbon dioxide with a high pressure apparatus equipped with a variable volume view cell at 313.15, 323.15, and 333.15 K and at pressure between 80 and 35 MPa. The experimental data were correlated well with Peng–Robinson equation of state (PR EOS) and quasi-chemical nonrandom lattice fluid model. 相似文献
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Satoshi Ito Masayuki Akaki Yasutaka Shinozaki Yuuki Iwabe Masaru Furuya Marina Tobata Makoto Roppongi Takafumi Sato Naotsugu Itoh Toru Oba 《Tetrahedron letters》2017,58(13):1338-1342
Bicyclopyrroles were efficiently converted to the corresponding isoindoles by a retro Diels-Alder reaction in supercritical carbon dioxide. By adding ethylene gas as an oxygen scavenger, the isoindole yield was further improved. 相似文献
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Liquid phase hydrogenation of phenol over Pt/C catalysts was investigated under conventional conditions and supercritical carbon dioxide (scCO2). The equivalent ration of hydrogen to phenol shows a significant effect on the product selectivity. Hydrogenation of phenol in different solvents was also studied, the experimental results show that polarity of solvents influences the yield of cyclohexanone remarkably, scCO2 has the highest one. Catalytic hydrogenation of phenol in scCO2 or sub-scCO2 was emphatically researched. The result is that near the critical point of CO2 phenol has higher reaction activity than that of normal organic solvents, cyclohexanone has 47% in yield and 87% in selectivity. 相似文献
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Linda J. Gerhardt Charles W. Manke Esin Gulari 《Journal of Polymer Science.Polymer Physics》1997,35(3):523-534
Viscosity curves were measured for polydimethyl siloxane (PDMS) melts swollen with dissolved carbon dioxide at 50 and 80°C for shear rates ranging from 40 to 2300 s−1, and for carbon dioxide contents ranging from 0 to 21 wt %. The measurements were performed with a capillary extrusion rheometer modified for sealed, high-pressure operation to prevent degassing of the melt during extrusion. The concentration-dependent viscosity curves for these systems are self-similar in shape, exhibiting low-shear rate Newtonian plateau regions followed by shear-thinning “power-law” regions. Considerable reduction of viscosity is observed as the carbon dioxide content is increased. Classical viscoelastic scaling methods, employing a composition-dependent shift factor to scale both viscosity and shear rate, were used to reduce the viscosity data to a master curve at each temperature. The dependence of the shift factors on polymer chain density and free volume were investigated by comparing the shift factors for PDMS-CO2 systems to those obtained by iso-free volume dilutions of high molecular weight PDMS. This comparison suggests that the free volume added to PDMS upon swelling with dissolved carbon dioxide is the predominant mechanism for viscosity reduction in those systems. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 523–534, 1997 相似文献
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The reactions of methylenecyclopropanes (MCPs) and epoxides with alcohols and aromatic amines can be carried out in supercritical carbon dioxide (scCO2) or modified scCO2 with perfluorocarbon which offer a way to synthesize various alcohols, amino-alcohols, homoallylic ethers, and amines under an environmentally benign condition. 相似文献
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This research describes dispersion of organic pigments using supercritical fluids. With low surface tension and high diffusivity of fluids in supercritical states, aggregated particles may be effectively wetted and swelled to form the primary constituent of the dispersing solution by volume. In this paper, the conditions of temperature and pressure are used to control the density of supercritical carbon dioxide subject to PGMEA as cosolvent for dispersing organic powder in a solution. As shown from measurement with a laser scattering particle analyzer, the average diameter of phthalocyanine green 36 with the haloid structure can be significantly reduced to 93.5 nm; for aminoanthraquinone red containing and amino group (-NH(2)) and phthalocyanine blue 15:6 with symmetry benzene and inner hydrogen bond, the mean particle sizes are 178.5 and 188.7 nm, respectively, using supercritical CO(2). Additionally, the transmittance of UV light is used to confirm the dispersing performance in this study. 相似文献