Showing papers on "Solvent published in 1985"
TL;DR: In this paper, the free energies of transfer of tetraalkylammonium halide ion pairs and dissociated ions, rates of nucleophilic substitution reactions, the contrast in solvent effects of water (HBD) and dimethyl sulfoxide (non-HBD), partition coefficients of non-hBD solutes between solvent bilayers, and family relationships between proton transfer (and non-protonic Lewis acid) basicities and corresponding β values for monomer HBA.
Abstract: Solvents have been parameterized by scales of dipolarity/polarizability π*, hydrogen-bond donor (HBD) strength α, and hydrogen-bond acceptor strength β. Linear dependence (LSER's) on these solvent parameters are used to correlate and predict a wide variety of solvent effects, as well as to provide an analysis in terms of knowledge and theoretical concepts of molecular structural effects. Some recent applications utilizing this approach are presented. Included are analyses of solvent effects on (a) the free energies of transfer of tetraalkylammonium halide ion pairs and dissociated ions, (b) rates of nucleophilic substitution reactions, (c) the contrast in solvent effects of water (HBD) and dimethyl sulfoxide (non-HBD) on the acidities of m- and p-substituted phenols, (d) partition coefficients of non-HBD solutes between solvent bilayers, and (e) family relationships between proton transfer (and non-protonic Lewis acid) basicities and corresponding β values for monomer HBA. A comprehensive summary of LSER with references is given.
514 citations
TL;DR: The microbial epoxidation of propene and 1‐butene was used to study some fundamental aspects of two‐liquid‐phase biocatalytic conversions and high activity retention was favored by a low polarity in combination with a high molecular weight.
Abstract: The microbial epoxidation of propene and 1-butene was used to study some fundamental aspects of two-liquid-phase biocatalytic conversions. Introduction of a water-immiscible organic solvent phase in a free-cell suspension gave rise to a series of undesired phenomena, e.g., inactivation by the solvent, clotting of biomass, and aggregation of cells at the liquid-liquid interface. Immobilization of the cells in hydrophilic gels, e.g., calcium alginate, prevented direct cell-organic solvent contact and the related clotting and aggregation of biomass. However, the gel entrapment did not seem to provide additional protection against the organic solvent. The influence of various organic solvents on the retention of immobilized-cell activity was related to solvent properties like the polarity (as expressed by the Hildebrand solubility parameter) and the molecular size (as expressed by the molecular weight or molar volume). High activity retention was favored by a low polarity in combination with a high molecular weight. The solubility parameter also proved useful to describe the capacity of various organic solvents for oxygen and alkene oxides. This facilitated the optimization of the solvent polarity.
248 citations
TL;DR: Elementary but general statistical‐mechanical relations are derived that relate the thermodynamic properties of the dissolution process to those of the pure solvent to conclusions drawn from qualitative arguments that these relations suggest.
Abstract: Elementary but general statistical-mechanical relations are derived that relate the thermodynamic properties of the dissolution process to those of the pure solvent. A number of conclusions are drawn from qualitative arguments that these relations suggest. These include the following: (1) The low solubility of nonpolar solutes in water arises not from the fact that water molecules can form hydrogen bonds, but rather from the fact that they are small in size. (2) The large entropy decrease attending the transfer of an inert solute from a nonaqueous solvent to water is largely due to the decrease in entropy of the nonaqueous solvent as the solvent–solvent interaction is restored on removal of the solute from it. (3) It is improper to use values of thermodynamic quantities obtained from small-molecule transfer studies for those that involve macromolecular folding and interaction.
207 citations
TL;DR: In this paper, a dependence between the acidity and basicity parameters of water/alcohol mixtures with ten organic solvents has been found, and the dependence between these parameters and E N T on B KT dependence is more complex even if these parameters are purified from nonspecific solute/solvent interactions.
200 citations
TL;DR: The thin-layer chromatographic patterns of total gangliosides obtained are clear and distinct, even when small samples with very lowganglioside concentrations are processed by this method, which is especially applicable to comparative qualitative studies of gangliosisides requiring the analysis of multiple small samples.
182 citations
TL;DR: The structure of alpha-lytic protease, a serine protease produced by the bacterium Lysobacter enzymogenes, has been refined at 1.7 A resolution and showed that basic folding pathways are maintained despite chemical changes in the hydrophobic cores.
173 citations
168 citations
Patent•
16 Apr 1985
TL;DR: A fluid extractant is a process and apparatus for using the extractant to separate an organic liquid from an aqueous mixture as mentioned in this paper, which comprises a first fluid solvent which is a gas in its near-critical or supercritical state and a cosolvent.
Abstract: A fluid extractant, and a process and apparatus for using the extractant to separate an organic liquid from an aqueous mixture. The extractant comprises a first fluid solvent which is a gas in its near-critical or supercritical state and a cosolvent. A preferred first fluid solvent is near-critical liquid carbon dioxide. Preferred cosolvents are 2-ethyl hexanol for ethanol extraction, and hexanoic acid for acetic acid extraction. Organic compounds such as monohydric alcohols, monoacids, ketones, ethers, aldehydes and esters can be recovered from dilute aqueous solutions more economically than possible by prior art processes of distillation.
153 citations
TL;DR: In vitro and in vivo evaluation of methyl tertiary butyl ether as a potential cholesterol gallstone solvent for direct instillation into the human gallbladder or bile duct concluded that further evaluation ofethyl tertiarybutyl ether for dissolution of human gall Bladder and biliary duct cholesterol stones is warranted.
129 citations
TL;DR: In this article, an analytical procedure for the determination of resin and fatty acids in pulp mill effluents is described, which involves isolation of the resin and acids from the effluent sample by solvent extraction with an equal volume of methyl tert-butyl ether under alkaline (pH 9) conditions, derivatization of the extract with diazomethane, and subsequent analysis of the methylated extracts by gas chromatography on a 25 m × 0.20 mm I.D. OV-17 fused-silica capillary column using a flame ionization detector.
113 citations
TL;DR: A two-stage cascade with cell recycling and turbidostatic cell concentration control turned out to be the best solution, the first stage of which was kept at relatively low cell and product concentrations.
Abstract: To increase the solvent productivity of the acetone-butanol fermentation, a continuous culture of Clostridium acetobytylicum with cell recycling was used. At a dry cell mass concentration of 8 g l-1 and a dilution rate of D=0.64 h-1, a solvent productivity of 5.4 g l-1 h-1 was attained. To prevent degeneration of the culture, which occurs with high concentrations of solvents (acetone, butanol and ethanol), different reactor cascades were used. A two-stage cascade with cell recycling and turbidostatic cell concentration control turned out to be the best solution, the first stage of which was kept at relatively low cell and product concentrations. A solvent productivity of 3 and 2.3 g l-1 h-1, respectively, was achieved at solvent concentrations of 12 and 15 g l-1.
TL;DR: None of the four sulfonamides yielded log-linear relationships in the ternary mixtures, and the solubility profiles did not exhibit peaks as observed for sulfisomidine in dioxane-water.
TL;DR: A retention model which predicts that the displacement of non-polar solutes from a reversed-phase chromatographic column is accompanied by the adsorption of a stoichiometric number (Z) of solvent molecules is proposed.
TL;DR: In this article, a pervaporation device has been built, which allows measurement of the selectivity of a membrane as a function of the upstream composition of the feed and the downstream total pressure of the pervaporate.
TL;DR: In this paper, the statistical mechanical study of chemically reactive fluids via the analytic solution of integral equation approximations for such fluids is extended to a consideration of solvent effects, and the results obtained near infinite dilution of the reacting solute in the inert solvent are similar in magnitude to those observed in experiments on the dissociation equilibrium of dinitrogen tetroxide.
Abstract: The statistical mechanical study of chemically reactive fluids via the analytic solution of integral equation approximations for such fluids (Cummings, P. T., and Stell, G., 1984, Molec. Phys., 51, 253; 1985, Ibid., 55, 33) is extended to a consideration of solvent effects. This is achieved by studying mixtures of molecular species some of which can undergo reaction (the solute(s)) and one of which is inert (the solvent). The results obtained near infinite dilution of the reacting solute in the inert solvent are similar in magnitude to those observed in experiments on the dissociation equilibrium of dinitrogen tetroxide.
TL;DR: By injection into rabbits of poliovirus polypeptides, obtained in high purity by chromatography in the new solvent system, monospecific antibodies were induced, the specificity of which was determined by immunoprecipitation.
TL;DR: The results indicate that the rate-determining step for protein hydrogen exchange is similar for all backbone amides and involves few water molecules.
Abstract: The rate of exchange of the labile hydrogens of lysozyme was measured by out-exchange of tritium from the protein in solution and from powder samples of varied hydration level, for pH 2, 3, 5, 7, and 10 at 25 degrees C. The dependence of exchange of powder samples on the level of hydration was the same for all pHs. Exchange increased strongly with increased hydration until reaching a rate of exchange that is constant above 0.15 g of H2O/g of protein (120 mol of H2O/mol of protein). This hydration level corresponds to coverage of less than half the protein surface with a monolayer of water. No additional hydrogen exchange was observed for protein powders with higher water content. Considered in conjunction with other lysozyme hydration data [Rupley, J. A., Gratton, E., & Careri, G. (1983) Trends Biochem. Sci. (Pers. Ed.) 8, 18-22], this observation indicates that internal protein dynamics are not strongly coupled to surface properties. The use of powder samples offers control of water activity through regulation of water vapor pressure. The dependence of the exchange rate on water activity was about fourth order. The order was pH independent and was constant from 114 to 8 mol of hydrogen remaining unexchanged/mol of lysozyme. These results indicate that the rate-determining step for protein hydrogen exchange is similar for all backbone amides and involves few water molecules. Powder samples were hydrated either by isopiestic equilibration, with a half-time for hydration of about 1 h, or by addition of solvent to rapidly reach final hydration. Samples hydrated slowly by isopiestic equilibration exhibited more exchange than was observed for samples of the same water content that had been hydrated rapidly by solvent addition. This difference can be explained by salt and pH effects on the nearly dry protein. Such effects would be expected to contribute more strongly during the isopiestic equilibration process. Solution hydrogen exchange measurements made for comparison with the powder measurements are in good agreement with published data. Rank order was proven the same for all pHs by solution pH jump experiments. The effect of ionic strength on hydrogen exchange was examined at pH 2 and pH 5 for protein solutions containing up to 1.0 M added salt. The influence of ionic strength was similar for both pHs and was complex in that the rate increased, but not monotonically, with increased ionic strength.
TL;DR: Further optimization of the PEI bonding chemistry in the preparation of HP-IEC columns for oligonucleotides and tRNA species was reported, and quaternization of the ion-exchange matrix was found to increase resolution of oligon nucleotides from 30 to 50 bases.
Patent•
25 Sep 1985
TL;DR: In this article, a raddery organopolysilsesquioxane having lower alkyl groups and alkenyl groups as the side chains and having aryl groups or hydrogen atoms bonded as side chains was presented.
Abstract: A novel raddery organopolysilsesquioxane having lower alkyl groups and alkenyl groups as the side chains and, if necessary, having aryl groups and/or hydrogen atoms bonded as the side chains can be produced by adding water to a solution of a lower-alkyltrihalogenosilane, an alkenyltrihalogenosilane, and, if necessary, an aryltrihalogenosilane and/or a trihalogenosilane in an organic solvent, and heating the resulting mixture. The aforesaid organopolysilsesquioxane can be used for forming a patterned surface-protecting layer or insulating layer for a semiconductor device, in the form of a mixture with a compound which generates crosslinking-reaction-active species upon irradiation with light or an ionizing radiation.
TL;DR: In this paper, the problem of the enhancement of the removal of a volatile impurity in a polymer film by the addition of a second solvent is analyzed, and it is shown that more than a 10-fold decrease in the devolatilization time can be achieved using a second solver and appropriate processing conditions.
Abstract: The problem of the enhancement of the removal of a volatile impurity in a polymer film by the addition of a second solvent is analyzed. The introduction of a second solvent that diffuses faster than the impurity can increase the free volume of the system and can thus facilitate removal of the volatile impurity. Solution of the ternary diffusion problem indicates the role of the properties of the second solvent and of processing conditions on the devolatilization effectiveness. It is shown that more than a 10-fold decrease in the devolatilization time can be achieved using a second solvent and appropriate processing conditions.
TL;DR: Comparisons with bulk solvent surface tension suggest the energy of cavity formation is also not a major contributor to duplex stability, and changes in stability and thermodynamic parameters with literature results for proteins suggests proteins and A7U7p interact differently with solvent.
Abstract: The thermodynamics of double-helix formation were measured spectrophotometrically for A7U7 in water at 1 M NaCl and for A7U7p in a variety of solvent mixtures and salt. Comparison of the A7U7 results with calorimetric measurements indicates duplex formation involves intermediate states. For A7U7p between 0.06 and 0.55 M Na+, dTm/d(log [Na+]) = 17.4 degrees C, similar to the value of 19.6 degrees C for poly-(A).poly(U) [Krakauer, H., & Sturtevant, J. M. (1968) Biopolymers 6, 491-512]. At 1 M NaCl, the A7U7p duplex is most stable in 100% water. For 10 mol % solutions, the order for A7U7p duplex stability is ethylene glycol greater than glycerol greater than ethanol greater than 2-propanol greater than dimethyl sulfoxide greater than 1-propanol greater than formamide greater than N,N-dimethylformamide greater than urea greater than dioxane. Comparison of changes in stability and thermodynamic parameters with literature results for proteins suggests proteins and A7U7p interact differently with solvent. The results suggest hydrophobic bonding is not a major contributor to the stability of the A7U7p duplex. Comparisons with bulk solvent surface tension suggest the energy of cavity formation is also not a major contributor to duplex stability.
TL;DR: The micellar behavior of block copolymers in selective solvents has been observed analogous to the classical surfactants in this article, where spherical polymolecular micelles have been analyzed.
TL;DR: In this article, the authors measured the critical volumes of fractions of cellulose-based polymers in dialkyl phthalate solvents over a large temperature range and compared the results with predictions of theories for the phase separation of freely jointed and worm-like chains.
Abstract: Cellulosic derivatives form an interesting range of polymer liquid crystals. They belong to a class of mesophases in which the polymer chain is stiff or semiflexible and is chemically homogeneous. The cellulose backbone, a single-stranded homopolymer of β-linked 1,4-anhydroglucose units, contains three hydroxy groups per anhydroglucose unit which provide convenient sites for substitution reactions, leading to a wide variety of cellulose ethers and esters. Many of these derivatives form cholesteric liquid-crystalline phases in suitable solvents, and some derivatives with relatively large (but non-mesogenic) side chains form both lytropic and thermotropic liquid crystals.Published observations on the phase separation of cellulose-based polymers indicate that the mesophases form at critical volume fractions of polymer ranging from 0.3 to 0.5 for high molar mass samples at room temperature. The critical volume fractions for a given polymer and solvent decrease with increasing molar mass to approach these asymptotic values. The critical volume fraction increases with temperature. The nature of the solvent is also important; highly polar or acidic solvents generally favour mesophase separation at lower critical concentrations than simple organic solvents. Furthermore, whereas heavily substituted derivatives with long flexible side-chains form mesophases easily in a wide range of solvents, the more familiar derivatives with smaller substituents seem to form mesophases with specific solvents, but not with others.We have measured the critical concentrations of fractions of (acetoxypropyl)cellulose in dialkyl phthalate solvents over a large temperature range and compared the results with predictions of theories for the phase separation of freely jointed and worm-like chains. The results indicate that chain geometry and stiffness are the major factors controlling liquid-crystalline phase formation and that anisotropic inter-chain interactions play a minor role. Thus the chemical structure of polymer and solvent govern the phase separation indirectly in these systems, primarily through effects on the chain conformation.
TL;DR: Data is presented for solute solubility parameters in solvents of variable polarity and suggestions for dealing with the chameleonic effect associated with solute-solvent interaction are given.
TL;DR: The presence or absence of the specific four-band structure in the long-wavelength region depends only on the solvent electron-pair donating capability as mentioned in this paper, and the extinction coefficient of the first satellite remains practically constant.
Abstract: — The characteristics of chlorophyll a visible absorption spectra have been analyzed in terms of empirical solvent scales of Lewis basicity (B) and acidity (E) as well as steric constants (Es) (after Koppel and Palm, 1972; Palm, 1977). The presence or absence of the specific four-band structure in the long-wavelength region depends only on the solvent electron-pair donating capability. In protic solvents the Soret band intensity is suppressed, but, in contrast, the extinction coefficient of its first satellite remains practically constant. This allows us to group spectra into four types according to the Soret-band intensity and the structure of the red-band system and assign them to chlorophyll-solvent complexes formed via 1 or 2 donor-acceptor bonds to central Mg and with and without hydrogen bond(s) to some nucleophilic center of the solute molecule.
TL;DR: The effect of solvent type on solvent-pesticide interactions was examined by interacting the fungicide captan with the solvents acetone, ethanol, methanol, hexane, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF), using growth of the fungi Pythium ultimum, Sclerotinia homeocarpa, andPestalotia sp. as a toxicity criterion as mentioned in this paper.
Abstract: The effect of solvent type on solvent-pesticide interactions was examined by interacting the fungicide captan with the solvents acetone, ethanol, methanol, hexane, dimethyl sulfoxide (DMSO), andN,N-dimethylformamide (DMF), using growth of the fungiPythium ultimum, Sclerotinia homeocarpa, andPestalotia sp. as a toxicity criterion. DMF, ethanol, and methanol were generally the most toxic solvents tested, yielding EC50 values from 0.51 to 2.29% (v/v). The least toxic solvent was hexane, with EC50 values up to 36.60% (v/v). Acetone and DMSO evidenced median toxicity, yielding EC50 values of 1.99 to 12.07% (v/v). WithP. ultimum andS. homeocarpa, captan interacted synergistically with all solvents tested except hexane, with the actual solvent concentration at which synergism occurred being dependent upon the level of captan. Hexane interacted additively with 2.5 ppm captan towardsS. homecarpa, antagonistically with 5.0 ppm captan towardsP. ultimum and synergistically with captan in all other combinations tested. WithPestalotia sp., captan interacted antagonistically with acetone, ethanol, and methanol, and synergistically with hexane, DMSO, and DMF. Captan was more toxic towardsP. ultimum when dissolved in DMSO, and less toxic in the presence of hexane and DMF. WithS. homeocarpa, captan was more toxic with ethanol and DMSO, and less toxic when dissolved in acetone, methanol, and hexane. DMSO and hexane elicited less toxicity from captan when tested towardsPestalotia sp., while acetone, ethanol, and methanol elicited the greatest toxicity.
TL;DR: Findings point to the possibility that certain mixtures of organic solvents are more damaging to membranes than the components of the mixture would indicate, and suggest that the experimental model used might help in showing mixtures that are particularly harmful.
Abstract: A simple experimental model was used to study the influence of organic solvents and solvent mixtures on the integrity of biological membranes. Radiolabelled membranes were prepared biosynthetically by growing Escherichia coli in the presence of 14C-oleic acid; the bulk of the radioactivity was incorporated into 14C-phosphatidylethanolamine, the predominant phospholipid species in E coli membranes. The radiolabelled bacteria were incubated at 37 degrees C in the presence of solvent, and the mixture filtrated through a Millipore 0.45 micron filter. This filtration retained radiolabel associated with the bacteria, and only radiolabel released as a result of solvent action was allowed through the filter. The radioactivity in the filtrate was then counted and expressed as a percentage of the total radioactivity. Results showed that aliphatic alcohols released membrane constituents in relation to their hydrocarbon chain length (1-propanol greater than 2-propanol greater than ethanol greater than methanol); the effects of aliphatic alcohols were potentiated by acetone, ethyl methyl ketone, ethylene glycol, and N,N'-dimethylformamide, and the effects of ethanol were potentiated by 1-butanol, benzyl alcohol, and ethylacetate. These findings point to the possibility that certain mixtures of organic solvents are more damaging to membranes than the components of the mixture would indicate, and suggest that the experimental model used might help in showing mixtures that are particularly harmful.
TL;DR: In this article, the authors studied the thermal conversion of 6-nitrospiropyran from a merocyanine form to a spiro form in various solvents and under high pressures.
Abstract: The thermal conversion of 6-nitrospiropyran from a merocyanine form to a spiro form was studied in various solvents and under high pressures. The rates of the thermal conversions were remarkably retarded in polar solvents, and a Kirkwood plot of the rate constants showed a large downward deviation as the solvent polarity increased. The rate constants (on a logarithmic scale) were linearly related to Kosower’s Z-values. The values of the activation volumes were positive and divided into two groups: ΔV≠≈10 cm3 mol−1 (in nonpolar solvents) and ΔV≠≈20 cm3 mol−1 (in polar solvents). These findings suggest that for the reaction in polar solvents, specific interactions are operating and that the thermal conversion proceeds via a transition state which is much less polar than the initial state.