Organic liquids environment

A complete set of intermolecular potential functions has been developed for use in computer simulations of proteins in their native environment. Parameters have been reported for 25 peptide residues as well as the common neutral and charged terminal groups. The potential functions have the simple Coulomb plus Lennard-Jones form and are compatible with the widely used models for water, TIP4P, TIP3P and SPC. The parameters were obtained and tested primarily in conjunction with Monte Carlo statistical mechanics simulations of 36 pure organic liquids and numerous aqueous solutions of organic ions representative of subunits in the side chains and backbones of proteins... 

As described above, the application of classical liquid- liquid extractions often results in extreme flow ratios. To avoid this, a completely symmetrical system has been developed at Akzo Nobel in the early 1990s [64, 65]. In this system, a supported liquid-membrane separates two miscible chiral liquids containing opposite chiral selectors (Fig. 5-13). When the two liquids flow countercurrently, any desired degree of separation can be achieved. As a result of the system being symmetrical, the racemic mixture to be separated must be added in the middle. Due to the fact that enantioselectivity usually is more pronounced in a nonaqueous environment, organic liquids are used as the chiral liquids and the membrane liquid is aqueous. In this case the chiral selector molecules are lipophilic in order to avoid transport across the liquid membrane. 

Nature of the environment This is usually water, an aqueous solution or a two- (or more) component system in which water is one component. Inhibitors are, however, sometimes required for non-aqueous liquid systems. These include pure organic liquids (Al in chlorinated hydrocarbons) various oils and greases and liquid metals (Mg, Zr and Ti have been added to liquid Bi to prevent mild steel corrosion by the latter ). An unusual case of inhibition is the addition of NO to N2O4 to prevent the stress-corrosion cracking of Ti-6A1-4V fuel tanks when the N2O4 is pressurised... 

Interfaces between two different media provide a place for conversion of energy and materials. Heterogeneous catalysts and photocatalysts act in vapor or liquid environments. Selective conversion and transport of materials occurs at membranes of biological tissues in water. Electron transport across solid/solid interfaces determines the efficiency of dye-sensitized solar cells or organic electroluminescence devices. There is hence an increasing need to apply molecular science to buried interfaces. 

Thus, room-temperature ionic liquids have the potential to provide environmentally friendly solvents for the chemical and pharmaceutical industries. The ionic liquid environment is very different from normal polar and nonpolar organic solvents both the thermodynamics and the kinetics of chemical reactions are different, and so the outcome of a reaction may also be different. Organic reactions that have been successfully studied in ionic liquids include Friedel-Crafts, Diels-Alder,Heck catalysis, chlorination, enzyme catalysis,polymeriz-... 

Demond, A.H. and Lindner, A.S. Estimation of interfacial tension between organic liquids and water. Environ. Sci. Technol, 27(12) 2318-2331, 1993. 

Gerstl Z, Galin T, Yaron B (1994) Mass flow of volatile organic liquid mixture in sods. J Environ Qual 23 487 93... 

Yaron B, Dror I, Graber E, Jarsjo J, Fine P, Gerstl Z (1998) Behavior of volatile organic liquid mixtures in the soil environment. In Rubin H, Narkis N, Carberry J (eds) Soil and aquifer pollution. Springer, Berlin... 

Although the vomeronasal system is specialized to detect stimuli in a liquid environment, it probably is not functional in utero, at least in mice. Fluorescent microspheres were not taken up by the vomeronasal organ as the access canal is not open yet in utero. In rats, by contrast, the canal is open before birth and the microspheres can be taken up. The olfactory epithelium of the main olfactory system plays a greater role prenatally, as evidenced by the uptake of radiolabeled 2-deoxyglucose (Coppola and Coltrane 1994). Fetal mice respond to amyl acetate and isovaleric acid delivered into the nasal cavity through a tiny cannula (Coppola, 2001). In both rats and mice, the main olfactory system, and not the vomeronasal system, appears to mediate prenatal olfaction (Coppola, 2001). 

Feilberg, A., and T. Nielsen, Model Systems to Simulate Photochemistry in the Organic Liquid Phase of Combustion Aerosols, presented at the 6th FECS Conference on Chemistry and the Environment, Atmospheric Chemistry and Air Pollution, University of Copenhagen, Copenhagen, Denmark, August 26-28, 1998. 

These coatings are also employed as solid lubricants in engine components. Refractory materials such as MoS2 and WSe2 are lamellar compounds and provide very effective solid-state lubrication in spacecraft bearings and components used in radiation environments where conventional organic liquid lubricants are not stable (see Lubrication and lubricants). 

When water-immiscible liquids are used, three quite different classes of inactivation mechanism must be distinguished. First, in some cases inactivation is related to removal of water from the molecular environment of the enzyme rather than any direct effect of the solvent itself. A second possibility is that individual molecules of the organic species dissolved in an aqueous phase around the enzyme may interact with it. Third, contact of the enzyme molecules with the bulk organic liquid at the phase interface may be involved. There is evidence that in many cases interfacial effects provide the dominant mechanism. 

While this ice forms at the surface, the organisms that require a liquid environment are happily swimming below the ice in liquid water at a warm 4°C, as Figure 8.12 illustrates. 

Matrix Considerations Non-volatile and thermally fragile molecular samples are dissolved in a liquid matrix for introduction into the spectrometer to perform FABMS measurements. The properties generally Imposed upon the matrix include ability to dissolve samples and possession of low vapor pressure to extend life time in the vacuum environment. Sample life time should be several minutes to be able to optimize the spectral signal and make several spectral runs. Many organic liquids that satisfy these requirements have been used to obtain FAB data by several investigators (7, 31, 32). Two of the more often used matrices are glycerol and thioglycerol In addition, a liquid metal matrix was used to float the sample to obtain FABMS spectra (33). 

Demond, A. H Lindner, A. S. Estimation of Interfacial Tension Between Organic Liquids and Water, Environ. Sci. Technol, 1993, 27, 2318-2331. 

Zimmerman, J. B. Kibbey, T. C. G. Cowell, M. A. Hayes, K. F. "Partitioning of Ethoxylated Nonionic Surfactants into Nonaqueous-Phase Organic Liquids Influence on Solubilization Behavior," Environ. Sci. Technol, 1999,33, 169-176. 

Chiou, C.T., Kile, D.E., Malcolm, R.L. (1988) Sorption of vapors of some organic liquids on soil humic acid and its relation to partitioning of organic compounds in soil organic matter. Environ. Sci. Technol. 22, 298-303. 

Heldebrant DJ, Yonker CR, Jessop PG et al (2008) Organic liquid C02 capture agents with high gravimetric C02 capacity. Energy Environ Sci 1(4) 487 193... 

General rules for the occurrence of stress corrosion cannot be given, since the phenomenon is very specific for certain combinations of polymer and environment, and is also dependent on the processing conditions in manufacturing the article (such as the occurrence of cooling stresses and orientations). When plastics are used in articles which are subjected to mechanical stress, such as pipes, crates, bottles, screw-caps, etc., the risk of stress corrosion in the presence of fat, soap or organic liquids, should always be taken into account. Proper choice of material and dimensions can minimize the occurrence of crack formation. 

As discussed below, ionic liquids often behave comparably to conventional polar organic solvents [6, 8, 10]. But the physics underlying solvation are entirely different. As noted above, ILs are characterized by considerable structural and dynamic inhomogeneity, and even simple concepts, such as the dipole moment, cannot be productively applied. We are therefore in the unusual position of needing to explain how an exotic microscopic environment produces conventional macroscopic behavior. To this end, we will review empirical characterizations of the ionic liquid environment, and then turn our attention to the underlying physics of solute-solvent interactions. 

In previous sections of this chapter, as well as in chapter 6, we have discussed several reasons why liquid water is so critical for life. To briefly review the salient points (1) Water is essential for driving the formation of the three-dimensional structures of macromolecules. These structures, on which macromolecular function depends, are encoded in a latent form in the linear primary structures of proteins and nucleic acids, but can be manifested only when liquid water is present to foster hydrophobic interactions. (2) The assembly of bilayer membranes from lipids and proteins likewise is driven in large measure by hydrophobic effects. (3) Water in the liquid state is a requirement for most types of transport of materials between organism and environment and between compartments within the organism. (4) Lastly, the... 

The facility with which metal complexes bring about reactions 8.16 and 8.17 depends on several factors, one of the important ones being the half-cell potential (E°) of the M"+/M(n+1)+ couple. It should be remembered, however, that most E° values for metal ions have been measured in an aqueous environment. On complexation and in an organic liquid these values are expected to change substantially. The initial hydroperoxide required for metal-catalyzed decomposition, reactions 8.16 and 8.17, is normally present in trace quantities in most hydrocarbons. 

An important difference between the radiation chemistry of water and of organic liquids is that the concept of the spur (a reasonably well-defined volume in which the formation of the reactive species occurs along the track of the ionizing particle) becomes hazy. The radicals formed in water tend to recombine rather than react with the environment immediately after formation. The volume in which recombination is likely defines the spur. The radical products of irradiated organic liquids, however, are more likely to interact with their immediate environment than to undergo recombination. This is evidenced by the low molecular yields of hydrogen from irradiated organic systems. 

The dispersion energy is the universal attractive glue that leads to the formation of condensed phases. It is additive at second order in perturbation theory, and the form of the three-body term that arises at third order (the tripledipole dispersion term) is also well known from perturbation theory. This Axilrod-Teller term " was the only addition to the pair potential for argon that was required to quantitatively account for its solid and liquid state properties. This may be grounds for optimism that other nonadditive dispersion terms are negligible. Whether this can be extended to less symmetrical organic molecules and their typical crystalline and liquid environments has not yet been established however. 

Solvent Organic liquid, such as ether Aqueous environment in cells... 

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