Supercritical ethylene carbonate

During the 1940s, a large amount of solubility data was obtained by Francis (6, 7), who carried out measurements on hundreds of binary and ternary systems with liquid carbon dioxide just below its critical point. Francis (6, 7) found that liquid carbon dioxide is also an excellent solvent for organic materials and that many of the compounds studied were completely miscible. In 1955, Todd and Elgin (8) reported on phase equilibrium studies with supercritical ethylene and a number of... 

In the patent of the Krupp company [60], ground paprika and oleoresin may be used as the raw material in the SFE process. The solvent can be supercritical fluid carbon dioxide, ethane, ethylene, or a mixture of the last two. As modifiers ethanol, acetone, water, and mixtures of these solvents were proposed. 

Using this technique, the spectra of thiophene (b.p. 84 °C) dissolved in supercritical ethylene and carbon disulfide was obtained. Because of the intrinsic insensitivity of the sulfur nucleus, 2 x 10 transients were acquired for these spectra, which resulted in signal-to-noise ratios of 4 1. The line widths obtained at 60°C and 200bar were approximately 200 Hz for thiophene in ethylene which correspond to narrowing factors of 7, when compared to the literature values <1985J(F2)63> for the line widths of the neat liquids at ambient conditions. 

The similarity in P-x behavior near the UCEP for naphthalene-ethylene and biphenyl-carbon dioxide suggests that the location of the UCEP can be estimated solely from solubility data. Hence, it is possible to assume (incorrectly) that the solubility data of both the naphthalene-ethylene and the biphenyl-carbon dioxide systems represent solid solubilities in a supercritical fluid solvent. Notice, however, that the P-x behavior for these systems is very different at pressures greater than their respective UCEP pressures. At 55°C and at pressures greater than 465 bar, the solubility of biphenyl in supercritical carbon dioxide decreases dramatically for a small increase in pressure at 50°C and at pressures greater than 175 bar, the solubility of naphthalene in supercritical ethylene increases for a small increase in pressure until at higher pressures the solubility eventually reaches a limiting value. Obviously these two systems are not as similar as we initially conjectured. How can we explain these experimental observations ... 

CTFE dissolves in a number of gases, e.g., carbon dioxide, ethylene, and the chlorofluorocarbons. In this instance, ethylene is arbitrarily chosen. The polymer is easily fractionated by supercritical ethylene at a temperature level of 90°C and a pressure range from 124 to 330 bar. Although eight fractions are obtained (see table 9.30), these fractions do not represent the results of an... 

This silane polymer was found to be virtually insoluble in carbon dioxide at pressure and temperature levels up to 552 bar (8,000 psia) and 120°C, respectively. Additionally, it was difficult to solubilize in supercritical ethylene and ethane at the same conditions. Supercritical propane proved to be a better solvent, and the extraction of the low molecular weight oligomers was accomplished at conditions of 483 bar (7,000 psia) and 120°C. 

This patent predates, both in filing and in issue, the big Zosel patent described first in this pendix. There are many anecdotal stories, perhaps some apocryphal, that have circulate about the aluminum alkyl work carried out at the Max Planck Institut fur Kohlenforschung in Mulheim (Ruhr), Germany. It was found during the aluminum alkyl synthesis studies that supercritical ethylene could separate aluminum trialkyls and olefins by carbon number. 

Polycarbonates and cyclic carbonates are obtained by the well-known and well-studied reactions of CO2 and oxiranes (Scheme 7). These reactions have also been successfully performed in supercritical mixtures. [28] It turned out, however, that the industrial production of ethylene carbonate (similar to propylene carbonate) in a liquid (product) phase (190-200 °C, total pressure 80 bar) is more economical for capacities of 4000 t per year and installation when it is run nearly stoichio-metrically. [44] In the cases of substituted or polycyclic oxiranes, solvents are usually added and 1 to 40 bar of CO2 are introduced, depending on the catalyst employed. [28] However, the development of a CO2-soluble Zn catalyst formed the polycarbonate from... 

In Table 1.1, the critical properties of some compounds which are commonly used as supercritical fluids are shown. Of these, carbon dioxide and water are the most frequently used in a wide range of applications. The production of polyethylene in supercritical propane is described in a loop reactor [13]. Supercritical ethylene and propylene are also apphed, where they usually act both as a solvent and as the reacting monomer. In the field of polymer processing, the Dow Chemical Company has developed a process in which carbon dioxide is used to replace chlorofluorocarbon as the blowing agent in the manufacture of polystyrene foam sheet [14, 15]. 

Lu X-B, Feng X-J, He R (2002) Catalytic formatimi of ethylene carbonate from supercritical carbon dioxide/ethylene oxide mixture with tetradentale Schiff-base complexes as catalyst Appl Catal A 234 25-34... 

Lu, X.-B. Feng, X.-J. He, R. Catalytic Formation of Ethylene Carbonate from Supercritical Carbon Dioxide/Ethylene Oxide Mixture with Tetradentate Schiff-base Complexes as Catalyst. Appl. Catal. A Gen. 2002,234,25-33. 

Carbon dioxide and water are the most commonly used SCFs because they are cheap, nontoxic, nonflammable and environmentally benign. Carbon dioxide has a more accessible critical point (Table 6.13) than water and therefore requires less complex technical apparatus. Water is also a suitable solvent at temperatures below its critical temperature (superheated water). Other fluids used frequently under supercritical conditions are propane, ethane and ethylene. 

This industrial process remains essentially unchanged from the 1950s [25], Here, a free-radical initiator is added to the ethylene monomer at supercritical conditions (276 MPa and 200-300 °C). The polyethylene remains in the supercritical solution until the pressure is lowered to around 5 MPa, whereupon it precipitates. A range of other monomers can be copolymerized, including carbon monoxide to give polyketones, as shown in Scheme 10.19 [26],... 

Bach, E. Cleve, E. Schiittken, J. Schollmeyer, E. Rucker, J.W. Correlation of solubility data of azo disperse dyes with the dye uptake of poly(ethylene terephthalate) fibres in supercritical carbon dioxide. Color. Technol. 2001, 117, 13-18. 

The hard-sphere expansion (HSE) theory is incorporated in the Kirkwood-Buff fluctuation integral to predict solubilities of solids in supercritical carbon dioxide and ethylene (Kwon and Mansoori, 1993). 

Among potentially interesting solvents for enzymatic catalysis, carbon dioxide is the most widely nsed snpercritical fluid. However, there is a growing interest in using other supercritical fluids (e.g., ethylene, fluoroform, ethane, sulfur hexafluoride, and near-critical propane) (Kamat et al., 1995b). 

Enzymes can express activity in supercritical and near-supercritical fluids, such as carbon dioxide, freons (CHF3), hydrocarbons (ethane, ethylene, propane) or inorganic compounds (SFe, N2O). The choice of supercritical fluids is often... 

Selective oxidation of ethylene to acetaldehyde was carried out over carbon-supported Pd and Pt membrane catalysts.1322 The concept of supported liquid-phase catalysis was also successfully applied in the Wacker oxidation.1323 The Wacker reaction can be performed in alcohol-supercritical C02.1324 C02 as cosolvent accelerates reaction rates and remarkably affects the selectivity towards methyl ketone in the presence of an alcohol. 

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