Showing papers on "Solvent published in 1983"

Comparison of alternative solvents for oils extraction

Abstract: A comprehensive review of the literature about use of solvents for extraction of oilseeds is presented. Mention has been found of over 70 solvents. Currently, hexane is the major solvent in use, but recent price increases and safety, environmental and health concerns, have generated interest in alternatives. Solvents vary considerably in chemical and physical properties which affect their performance in oil extraction. The choice of solvent depends upon the primary end product desired (oil or meal). Recent research on alternative solvents has focused on ethanol, isopropanol, methylene chloride, aqueous acetone, and hexane/acetone/water mixtures.

Dispersion of the nonlinear second-order optical susceptibility of organic systems

Abstract: Dispersion experiments of the second-order nonlinear optical susceptibility are reported for two fundamentally important organic systems $p$-nitroaniline and 2-methyl-4-nitroaniline for which detailed quantum-mechanical calculations have been completed. The frequency-dependent measurements were performed by dc-induced second-harmonic generation in liquid solutions with the use of a tunable (0.2-2 \ensuremath{\mu}m) laser source by stimulated Raman scattering from hydrogen gas. Accounting for dipole-mediated interactions between the molecular sites and the surrounding solvent medium provides quite satisfactory agreement between the experimental and theoretical results, demonstrating that the origin of exceptional nonlinear optical responses of organic systems resides in special highly charge-correlated electron states.

Solvent-induced distortions and the curvature of α-helices

Abstract: The α-helix defined in 1951 by Pauling et al.1 on the basis of model building and X-ray fibre diffraction data has 3.65 residues per turn (n) achieved with planar peptides, torsion angles of φ = −48° and ψ = −57° and hydrogen bonds which are close to linear. Although X-ray analyses of proteins have confirmed the general correctness of the model for the helix, recent high resolution (1.7–1.0 A) diffraction studies have shown that the parameters described by Pauling et al.1 and later by Perutz2 and Arnott and Wonacott3 are not a good description of the α-helices in globular proteins4–7, where the mean values of φ, ψ, are usually close to −63°, −42°. Here we show that these values arise as a mean of two significantly different classes in amphipathic helices depending on whether the peptide carbonyl oxygen is hydrogen bonded to a solvent or polar side-chain atom. The hydrogen bonds made by the hydrophilic carbonyls to the NH groups within helices are longer and less linear than those involving hydrophobic carbonyls. We also show that these effects are associated with a significant curvature of helices in globular proteins. For example, the α-helix in avian pancreatic peptide (aPP) has a radius of curvature of approximately 70 A. These results are of significance in the packing of helices in fibrous and globular proteins, in the calculation of their dipole moments, solvent accessibilities and internal energies, and in the theoretical estimation of spectroscopic properties such as circular dichroism and Raman scattering.

D-Limonene based aqueous cleaning compositions

Abstract: D-Limonene-based aqueous cleaning compositions for hard and/or flexible substrates are provided wherein the normally water-immiscible d-limonene is stabilized in clear aqueous solution by the combined effect of carefully selected and proportioned surface active agents, and a coupling agent, suitably in the form of a glycol or a lower alkyl glycol ether. One or more surfactants can be employed with a glycol or glycol ether as the coupling agent. Preferred formulations contain selected anionic, nonionic, or mixed anionic-nonionic surfactants. The compositions can also contain small amounts of additives adapting the compositions to particular uses. The new cleaning compositions contain by weight, 78 to 96 parts of a d-limonene/surfactant/water mixture containing 10-60% d-limonene, 10-30% surfactant, and 20-70% water, coupling agent in the amount of 2-10 parts by weight, and 2-12 parts of additives adapting the compositions to particular uses. Because better cleaning is obtained with higher solvent levels, the d-limonene/surfactant/water mixture preferably contains 40-60% d-limonene, 10-30% surfactant, and 20-40% water.

Determination of tocopherols and sterols by capillary gas chromatography

Abstract: A method is described for simultaneously determining tocopherols and sterols in fats and oils by quantitative capillary gas chromatography. Samples containing ca. 100 mg of lipid were saponified in capped tubes with aqueous KOH by heating for 8 min at 80 C; the unsaponifiable fraction was extracted with cyclohexane, freed of solvent, derivatized to form the trimethylsilyl ethers of both tocopherols and sterols, and chromatographed on a 50 m×0.25 mm glass capillary column coated with Dexsil 400. Most of the individual tocopherols and common sterols were well separated, although interfering peaks were seen in some samples, which for better specificity should be subjected to an initial purification. For most samples, however, the simplified sample preparation, without preliminary purification, was adequate when combined with capillary gas chromatography. Recovery, method and gas liquid chromatographic precision, and applications are discussed.

High glucose-determining analytical element

Abstract: An analytical element for quantitatively determining high levels of glucose in blood is made by (a) impregnating a carrier with a first solution, having dissolved therein 4-aminoantipyrine and 3-hydroxy-2,4,6-triiodobenzoic acid or 3,5-dichloro-2-hydroxy-benzene sulfonic acid or salts thereof, a glucose oxidase and a peroxidase, and drying the carrier; and (b) applying to the carrier a second solution of a film-forming agent in a volatile solvent, and drying to remove the volatile solvent and leave a film over the dried first impregnant.

A nationwide survey on organic solvent components in various solvent products: Part 1. Homogeneous products such as thinners, degreasers and reagents.

Abstract: Organic solvent products used in the various factories were collected nationwide in Japan, and analyzed by gas chromatogarphy. Of the 1179 samples collected, 522 samples were homogeneous (including 321 thinners, 145 degreasers and 56 reagents and others), and were analyzed by means of direct injection into a FID-gas chromatograph with two FSWCOT (OV 101 and PEG 6000) capillary columns. In thinners (n=248), the average number of solvent components per sample was 4.14 when the thinners containing gasoline were excluded. Toluene was the most popular component in thinners (present in 56%) followed by ethyl acetate, methanol, xylenes, ethylbenzene, isobutyl alcohol, ethyleneglycol mono-ethylether acetate, butyl acetate and methyl isobutyl ketone. Gasoline was also detected in 23%. In degreasers (n=123), the average number of solvent components per sample was 1.64 when the degreasers containing gasoline were not taken into account. Trichloroethylene was present in 21% of degreasers followed by tetrachloroethylene, 1, 1, 1-trichloroethane, toluene, acetone, xylenes and ethyl-benzene. Gasoline was found in 14%. A small amount of 1, 4-dioxane was detected as an additive in every 1, 1, 1, -trichloroethane products. With regard to reagents and others (n=53), the avarage number of components per sample was 1.40 if samples containig gasoline were excluded, and most (73%) of reagents and others (n=41) consisted of a single component. The potent toxic solvents such as benzene, chloroform, carbon tetrachloride, 1, 2-dichloroethane, 1, 1, 2-trichloro-ethane, 1, 1, 2, 2-tetrachloroethane and carbon disulfide were only rarely found in the present homogeneous products.

Hydrophobic vitamin B12. I. Preparation and axial ligation behavior of hydrophobic vitamin B12r.

Abstract: Heptamethyl cobyrinate perchlorate, [Cob(II)ester]ClO4, was prepared in a good yield from cyanocobalamin. This hydrophobic complex is structurally comparable to the base-off form of vitamin B12r. Thermodynamic parameters (ΔG, ΔH, and ΔS) for axial ligation of [Cob(II)ester]ClO4 with various amines in dichloromethane and toluene were determined by electronic spectroscopy. The isoequilibrium temperatures obtained from plots of ΔH vs. ΔS were 194±20 and 317±20 K in dichloromethane and toluene, respectively. The equilibrium is primarily controlled by entropy at ordinary temperatures and the logK1 value varies sensitively along with the change in pKa of amine in dichloromethane, while the equilibrium values were almost invariant to the choice of amine in toluene because the measurements were carried out near the isoequilibrium temperature. The logK1 value for [Cob(II)ester]ClO4, different from the case of cobalt(II)-porphyrin complexes, depends on the nature of solvent used and undergoes wide variations. The p...

Investigation of the solvent‐evaporation effect on spin coating of thin films

Abstract: A simple empirical relationship exists between the thickness and the solvent-evaporation rate of spin-coated thin films. The thickness of a film formed from an organic solvent solution can be approximated by the relationship, where μ is the viscosity of the coating solution, ω is the rotation speed, E is the solvent-evaporation rate, λ is the latent heat of evaporation, Cp is the heat capacity of the solvent, and K0 is a constant for volatile organic solvents. A similar relationship for aqueous polymer solutions is, where RH is the relative humidity of air around the spin coater and Ka is a constant for aqueous solutions. These relationships are helpful in understanding the mechanism of thin-film formation in spin coating.

Rod-to-coil transition of a conjugated polymer in solution

Abstract: A rod-to-coil conformational transition is demonstrated for polydiacetylene, 4-butoxycarbonylmethylurethane, in solution. With use of quasielastic light scattering, a coillike structure with relatively small hydrodynamic radius is indicated for the polymer in a good solvent, CH${\mathrm{Cl}}_{3}$. As the proportion of nonsolvent (hexane) is increased, the hydrodynamic radius increases abruptly to a value consistent with the molecule being a rigid rod.

Partition coefficients of 20 polar molecules between water and trimethyldodecylammonium bromide micelles: Correlation with the water + octanol system

Abstract: The partition coefficient P between trimethyldodecylammonium bromide micelles and water of 20 nonaromatic polar molecules was determined at 29815°K by a combination of salting constant and critical micelle concentration determinations; included are amines, alcohols, ethers, esters, ketones, and some high dipole moment molecules The partition coefficients obtained for the alcohols are about one-half their value in aqueous micellar sodium dodecylsulfate solutions It is shown that for straight, branched, and cyclic amines, alcohols, esters, and ketones there is an excellent correlation between partition coefficients in the aqueous cationic micelles and in the classical octanol + water system Some ethers and halogenated alkanes do not follow this correlation; the P values in these cases in the micellar solutions are about one-third of the values predicted from the correlation The same observation can be made for halogenated alkanes in aqueous sodium dodecylsulfate solutions The behavior of simple polar solutes in the micellar systems studied resembles that found with dimyristoyl lecithin liposomes The average solubilization site of the nonaromatic solutes onto the cationic micelles may be looked upon as having the properties of a solvent such as isobutanol saturated with water

A new probe of solvent accessibility of bound photosensitizers. 1. Ruthenium(II) and osmium(II) photosensitizers in sodium lauryl sulfate micelles

Abstract: A new method of measuring solvent accessibility of photosensitizers bound to organized media is presented In particular, the solvent accessibility of a series of ruthenium(II) and osmium(II) photosensitizers bound to sodium lauryl sulfate micelles has been determined The method takes advantage of the large solvent deuterium effect on the excited-state lifetimes of these complexes The solvent accessibility of the bound complexes correlates with the hydrophobicity of the ligands The potential application of this method to a variety of other systems is mentioned

Method for solvent recovery in solvent separation of ethanol from water

Abstract: A process for the separation of ethanol from water using solvent extraction at elevated pressures is disclosed. Separation is effected by contacting aqueous ethanol with either propylene (propene), allene (propadiene), methyl acetylene (propyne), or methyl allene (1,2-butadiene). This produces two liquid layers which separate because of the difference in their densities, and are easily drawn off as separate streams. The solvent is recovered by reverse osmosis means in a liquid state. The ethanol and water remain in a liquid state and are substantially recovered.

Selective separation of heavy oil using a mixture of polar and nonpolar solvents

Abstract: A hydrocarbon feedstock may be selectively separated into its various fractions by contact with a mixture of specified polar and nonpolar solvents at a temperature so as to form a two-phase system, separating the first extract and raffinate phases so obtained, cooling the raffinate (nonpolar) phase so that three phases form, and separating the three phases. The three phases obtained consist of the polar solvent containing low molecular weight polars, the nonpolar solvent containing the saturates and aromatics, and an asphaltene-containing phase. The asphaltene-containing phase may be further washed to yield an asphalt with a higher microcarbon residue than the non-washed asphalt.

Correlation and prediction of solid-supercritical fluid phase equilibriums

Abstract: A semiempirical correlation has been developed to describe quantitatively the solubility of heavy nonpolar solids in slightly subcritical and supercritical solvents using only one temperature-independent pure component parameter for each component. The method, based partly on regular solution theory and the van der Waals equation of state, correlates available solubility data for 24 binary solid-fluid systems within an average standard deviation of 25% with ethylene, ethane, and carbon dioxide as solvents. The range of solubility correlated was 10/sup -6/ to 10/sup -2/ mole fraction, 20-80 /sup 0/C, and 80-500 bar. Pure-component parameters for solutes are presented for naphthalene, anthracene, triphenylmethane, phenanthrene, fluorene, pyrene, 2,3- and 2,6-dimethylnaphthalene, biphenyl, hexamethylbenzene, and hexachloroethane along with solvent parameters for ethylene, ethane, and carbon dioxide.

Process for the recovery of CO2 from flue gases

Abstract: A method is disclosed for recovering carbon dioxide from gases containing the same as well as oxygen and/or sulfur compounds employing aqueous 5 to 80% alkanolamine solutions Corrosion of the metals of construction and solvent degradation are minimized by the use of copper ion maintained in solution and continuous removal of ionic iron and solvent degradation products by treating the solvent or a portion of the solvent with a carbon bed, mechanical filter and/or a anion exchange resin

Solubility of hydrogen in methanol, nitrobenzene, and their mixtures experimental data and correlation

Abstract: The solublllty of hydrogen In nltrobenrene and methanol was studled In a temperature range of 25-70 OC and ai hydrogen partial pressure up to 60 atm (6060 kPa). The solublllty was also determlned In mixtures of nltrobenzene and methanol at varlous concentratlons. The values of the heat of solution of hydrogen In methanol and nltrobenzene were found to be 3.725 and 3.810 kJ/mol, respectlvely. A method to correlate the solublllty data based on thermodynamic parameters has been descrlbed for both slngle solvent and mixtures. The effect of temperature as well as the heat of solutlon can also be predlcted wlth this method.

Process for making polyetherimides

Abstract: A process for making polyetherimides involving reacting an aromatic bis(ether anhydride) with an organic diamine in an inert solvent to form a prepolymer solvent mixture, effecting solvent removal by thin-film evaporation, and heating the resulting prepolymer to a temperature above the glass transition temperature of the final polyetherimide product and less than 450° C. to form the polyetherimide.

Application and results of whole-body autoradiography in distribution studies of organic solvents.

Abstract: With the growing concern for the health hazards of occupational exposure to toxic substances attention has been focused on the organic solvents, which are associated with both deleterious nervous system effects and specific tissue injuries. Relatively little is known about the distribution of organic solvents and their metabolites in the living organism. Knowledge of the specific tissue localizations and retention of solvents and solvent metabolites is of great value in revealing and understanding the sites and mechanisms of organic solvent toxicity. Whole-body autoradiography has been modified and applied to distribution studies of benzene, toluene, m-xylene, styrene, methylene chloride, chloroform, carbon tetrachloride, trichloroethylene and carbon disulfide. The high volatility of these substances has led to the development of cryo-techniques. Whole-body autoradiographic techniques applicable to the study of volatile substances are reviewed. The localizations of nonvolatile solvent metabolites and firmly bound metabolites have also been examined. The obtained results are discussed in relation to toxic effects and evaluated by comparison with other techniques used in distribution studies of organic solvents and their metabolites.

A quasi-lattice quasi-chemical theory of preferential solvation of ions in mixed solvents

Abstract: The quasi-lattice quasi-chemical theory is used with a single fitting parameter (Z, the number of nearest neighbours) and data independent of the transfer to solvent mixtures, to describe quantitatively the standard molar Gibbs free energy of transfer of ions from a reference solvent to solvent mixtures, ΔGto (X, W → S1 + S2), as a function of the composition (mole fraction, x). The independent data include the ΔGto to the two pure solvents and the excess Gibbs free energy of mixing of these solvents. A defined preferential solvation parameter, g(x), is a convenient measure that is obtained from this treatment. The advantages of employing volume fractions, o, and g(o) rather than mole fractions, x, and g(x), are examined. The theory is applied to the transfer from water of Cl- to ethanol, of Ag+ to acetonitrile or dimethyl sulfoxide, and of NaCl to methanol, and of Na+ from acetonitrile to dimethyl sulfoxide as illustrative examples, comparing the calculated values to experimental data.

Effect of molecular weight of polymeric solvent on ion conductive behavior in poly(propylene oxide) solution of liclo4

Abstract: Effect of Molecular Weight of Polymeric Solvent on Ion Conductive Behavior in Poly(propylene oxide) Solution of LiClO 4