Showing papers on "Solvent published in 1973"

Process for preparing microcapsules

Abstract: Microcapsules are made by dissolving or dispersing a core substance in a solution of a wall material dissolved in a solvent having a dielectric constant of about 10 or less and poorly miscible with a polyhydric alcohol, then emulsifying in fine droplets this dispersion or solution into the polyhydric alcohol and finally removing the solvent through evaporation.

Method for making polyetherimides and products produced thereby

Abstract: A method is provided for making polyetherimides involving the reaction of aromatic bis(ether anhydride)s and organic diamines in the presence of a phenolic solvent. The resulting polyetherimide-phenolic solvent mixture can be employed as a wire coating enamel.

Preparation of microcapsules

Abstract: Microcapsules are made by (a.) dispersing or dissolving a core substance in a film-forming polymer solution, (b.) emulsifying in fine droplets the resulting dispersion or solution in a vehicle which is poorly miscible with the solvent of the polymer solution and which doesn't dissolve said polymer to prepare an emulsion, and (c.) adding to the emulsion a non-solvent for the polymer wherein the non-solvent is miscible with the solvent, poorly miscible with the vehicle, and does not dissolve the polymer, whereby the solvent is removed by being absorbed by non-solvent emulsion droplets to precipitate the polymer film around the core substance.

Preparation of asymmetric polymer membranes

Abstract: A method is disclosed for the preparation (by the utilization of a proper solvent system) of dry asymmetric membranes comprising a porous layer of interconnected crystals of polymer material. Membranes of many polymer materials may be optionally prepared either with or without a dense surface layer as one face thereof. In either case the porous layer is structured with graded porosity. A three-component casting solution is prepared containing the polymer, a first good volatile solvent for the polymer and (relative to the first solvent) a poor less-volatile solvent for the polymer, which is miscible with the good solvent. A membrane is cast at room temperature, allowed to desolvate at room temperature for a short time and is then immersed in a precipitating agent, that is miscible with both the aforementioned solvents but is a non-solvent for the polymer. The membrane is then permitted to dry.

Process for the manufacture of multi-component substances

Abstract: Glassy, crystalline, or glassy crystalline oxidic multi-component substances, which are produced without going through a molten phase. An alkali or alkaline earth metal compound and at least one other metal compound, both dissolved in an organic solvent, are reacted in the solvent, the solvent is evaporated to form a precipitate, and the precipitate is heated to form the multi-component substance. The compositions are applied as coatings to substrates, e.g., glasses. Application can be by dipping the substrates in the solutions.

A simple molecular model for adsorption chromatography. VII. Relationship between the RM value and the composition for phenols in systems of the type (cyclohexane+polar solvent)/silica

Abstract: The effect of the composition of binary developing solvents on RM values of phenols with one, two or three hydroxyl groups was investigated. In most cases linear RM vs. (log XS) relationship were obtained for wide composition ranges (XS — mole fraction of polar solvent; diluting solvent: cyclohexane), the slope of the lines being related to the molecular mechanism of adsorption. The slopes of some derivatives of quinoline, aniline and phenols are compared and the effects of the molecular structure of the solute and the eluen strength of solvent are discussed. The experimental data for phenols are interpreted in terms of competitive solvation in the mobile phase by electron donor solvents; practical rules concerning optimization of TLC systems for the analysis of the compounds investigated are formulated.

Ionic entropies of transfer from water to nonaqueous solvents

Abstract: Heats of solution of 1:1 electrolytes in acetonitrile have been determined, and enthalpies of transfer of the electrolytes from water to acetonitrile thus calculated. Free energies of transfer of a number of electrolytes from water to nonaqueous solvents have also been determined. Together with previous data, these measurements yield entropies of transfer of electrolytes from water to N-methylformamide (NMF), methanol, ethanol, dimethyl sulphoxide (DMSO), acetonitrile, NN-dimethylformamide (DMF) and acetone; single-ion entropies of transfer from water to these solvents are tabulated for up to 11 cations and 5 anions. It is shown that ΔS°t(M++ X–) is relatively independent of M+ and of X– if M+ is Na+, K+, Rb+, and Cs+ and if X– is Cl–, Br–, I–, and ClO–4. For transfers to or from water and methanol, this constancy of ΔS°t(M++ X–) is not maintained if M+ is R4N+, Ph4As+, and Ph4P+ and if X– is Ph4B–.“Absolute” single-ion entropies of transfer have been obtained, and a treatment is given that enables these single-ion values to be reproduced accurately, and further single-ion values to be predicted, for transfers from water to NMF, methanol, ethanol, DMSO, acetonitrile, DMF, acetone, formamide and liquid ammonia. For these solvents (other than water and methanol) only one adjustable parameter per solvent is required. It is also shown that the so-called “iceberg effect” for solution of organic ions is very large in water, small in methanol, and non-existent in NMF, ethanol, acetonitrile, DMF, acetone and (possibly) DMSO.

Electrochemical cells having an electrolytic solution comprising a covalent inorganic oxyhalide solvent

Abstract: Electrochemical cells having an oxidizable active anode material, a solid metallic cathode current collector, and an electrolytic solution between and in contact with the anode and the cathode current collector, the electrolytic solution comprising a liquid covalent inorganic oxyhalide or thiohalide solvent and a solute dissolved therein, the inorganic solvent being the sole oxidant material and sole solvent material in the cell. The cathode comprises a solid, non-consumable, electrically conducting, inert current collector upon the surface of which the inorganic solvent is electrochemically reduced, whereby the inorganic solvent in conjunction with the oxidizable anode serves as a source of electrical energy during operation of the cell.

Very polarisable hydrogen bonds in solutions of bases having infra-red absorption continua

Abstract: As in aqueous base solutions (BH⋯B)–(where B is CH3O–) hydrogen bonds form in alcohol solutions of CH3OK and KOH. A continuous i.r. absorption shows that a double minimum potential well is present in these hydrogen bonds and that their polarisability is extremely large. Based on the experimental results presented here and on previously developed theories the following are discussed: (1) the fluctuation of the H7O–3 group; (2) the transition of the anomalous defect proton conductivity (Grotthus mechanism) to the normal hydrodynamic mechanism with increasing concentration; (3) the processes occurring during dissociation of a base. Furthermore, the i.r. spectra of solutions of pyrrole in alcohol and of imidazole and hydroxypyridine both in water and alcohol are plotted as a function of their deprotonation by CH3OK or KOH. In addition to the symmetrical (BH⋯B)– hydrogen bonds between alcohol molecules, strongly polarisable (NH⋯N)– hydrogen bonds between pyrrole molecules and polarisable (NH⋯O)– bonds between pyrrole and alcohol are also found in the pyrrole solutions. Strongly polarisable (NH⋯N)– hydrogen bonds form in the imidazole solutions at deprotonation degrees of up to 50 %. Unsymmetrical polarisable (NH⋯O)– hydrogen bonds with the solvent molecules at degrees of deprotonation > 50 % and symmetrical (BH⋯B)– hydrogen bonds between the solvent molecules at degrees of deprotonation > 80 % are found. This is shown by the variation in the plots of the absorbance of the continuum against % deprotonation. Finally, the formation of polarisable hydrogen bonds on deprotonation of the 2-hydroxypyridine is discussed.

Influence of isopropanol-water solvent mixtures on the conformation of poly-L-lysine.

Abstract: The helix–coil transition of poly-L-lysine (PLL) in water–isopropanol solvent mixtures has been investigated at room temperature by circular dichroism measurements. Within the range of 70%–80% isopropanol concentration (by volume), the polymer undergoes a sharp transition, characterized by the formation of a fully charged α-helical structure. On the basis of some experimental evidence the role of the organic component in solution appears more complicated than that of strengthening the intramolecular hydrogen bonds in the polymer. By analogy with the distribution of the components of alcohol–water mixtures in simple ionic systems, it is thought that only an high co-solvent concentration brings about an extensive and possible cooperative depletion of the clusters of firmly-bound water molecules in the domain of the polylelectrolyte, favoring the transition to the α-helical structure. On the other hand, CD spectral patterns show that the addition of NaCl in the alcohol-rich–water mixtures of charged poly-L-lysine gives rise to a transition from the α-helical to a β-structures conversion obeys a first-order rate law at all times, with a rate constant dependent on solvent composition and ionic strength. In these conditions, the rate of the process is close to that found for the thermally induced α–β transition. Higher polymer concentration and/or ionic strength cause a phase separation of β-PLL, suggesting that in this case interchain reactions (where hydrogen bonding should play the major role) predominate. Titration experiments on charged α-helical poly-L-lysine in 85% or 90% isopropanol mixtures confirm the occurrence of a conformational transition, which takes place within a degree of dissociation α of 0.2–0.75. The transition is accompanied by a visible turbidity, which increases as the titration proceeds. Implications of the solvent distribution around the macroion on the observed conformational phenomena are also discussed.

Nucleic acid-solvent interactions: temperature dependence of the heat of solution of thymine in water and ethanol.

Abstract: The heats of solution of thymine in water and ethanol have been determined calorimetrically as a function of temperature. These data, along with solubility data, have been used to calculate the thermodynamic quantities (ΔGt, ΔHt, ΔSt and ΔCp,t) associated with the transfer of thymine from ethanol to water. Since ΔSt = −2 cal/mole deg and ΔCp,t = 0, it has been concluded that hydrophobic bonding does not play an important role in the thermocynamic stability of nucleic acids. However, large heat capacities of solution of thymine are observed in both solvents (ΔC°p2 = 45 ± 4 cal/mole deg). This is explained in terms of temperature variation in the degree of solvent–solute hydrogen bonding. It is our proposal that the components of macromolecules (i.e., nucleic acid bases and amino acids) do not make all possible hydrogen bonds with the solvent in the vicinity of room temperature. Thus the thermodynamic contribution of hydrogen bonding to the stability of macromolecules in aqueous solution must be reassessed.

Method for removing sulfur and nitrogen in petroleum oils

Abstract: A method for the removal of sulfur and nitrogen components from petroleum oils is disclosed. The unwanted sulfur and nitrogen is oxidized to the extent that the resultant compounds exhibit preferential solubility characteristics in some solvent with respect to the oil. The oxidation step involves reacting the sulfur and nitrogen compounds present with an oxide of nitrogen. In particular instances, pretreatment of the oil to remove active groups which cause undesirable side reactions or removal of low sulfur fractions prior to the oxidation step will increase the efficiency of the process. The oil containing the oxidized forms of sulfur and nitrogen is then mixed with a selective solvent, which is immiscible in the oil and in which the sulfur and nitrogen compounds will dissolve. Methanol is the presently preferred solvent. Separation of the oil from the methanoloxidized compound solution may be effected in a gravity separator. The oxidant gas may be regenerated by the addition of oxygen and recirculated. The oxidized sulfur and nitrogen compounds may be decomposed in a hydrolysis reaction with a dilute base to separate inorganic sulfate and sulfite, and nitrate and nitrite compounds from the hydrocarbon parts of the compounds.

Nuclear magnetic resonance studies of preferential solvation. Part 2.—Thermodynamic treatment and application to methanol + water solvents

Abstract: From a detailed consideration of the thermodynamics of preferential solvation of ions in a binary solvent mixture, making reasonable assumptions about the variation of chemical potential of the variously solvated ions with solvent composition, it is shown how the variation of the free energy of transfer of a salt from water to mixed aqueous solvents derived from e.m.f. measurements can be related to spectroscopic information.

Effect of alcohols and neutral salt on the thermal stability of soluble and precipitated acid-soluble collagen

Abstract: The effects of mono- and poly-hydric alcohols in the presence of KCl on the intrinsic stability of collagen molecules in dilute acid solution were compared with corresponding solvent and salt effects on the increased stability of the aggregated molecules in salt-precipitated fibrils. Salt addition decreased solubility and increased the thermal stability of fibrils, but progressively decreased the stability of collagen molecules in solution. In contrast, the alcohols enhanced solubility and decreased fibril stability, the effects increasing with solvent hydrocarbon chain length and with decreasing hydroxyl/methylene-group ratio. Molar destabilization of dissolved collagen by alcohols was lower than for fibrils, and at low salt concentration, both ethylene glycol and glycerol were structural stabilizers. Electron-micrograph studies indicated that salt-precipitated fibrils tended to adopt the native aggregation mode, and qualitatively similar solvent effects were observed in insoluble collagens. Implications of the experimental findings are discussed in terms of a model in which electrostatic and apolar interactions mainly govern the excess of stability in collagen fibrils whereas intrinsic stability of single molecules is a function of polar interactions and polypeptide-chain rigidity.

The Cobalt Carbonyl-catalyzed Hydroesterification of Butadiene with Carbon Monoxide and Methanol

Abstract: The cobalt carbonyl-catalyzed hydromethoxycarbonylation of butadiene is studied The reaction proceeds in the presence of a pyridine base to give methyl 3-pentenoate Isoquinoline is found to be a better solvent for the production of methyl 3-pentenoate than pyridine, not only because the yield of the ester is somewhat higher in the presence of isoquinoline than in the presence of pyridine, but also because it is far less volatile than pyridine, so that the product can be easily separated from the solvent and the catalyst by distillation Also, the hydromethoxycarbonylation of methyl 3-pentenoate under somewhat different conditions is found to give a good yield of dimethyl adipate The hydroformylation of methyl 3-pentenoate is studied as well The effect of such a solvent as THF, benzene, and acetonitrile in increasing the selectivity to methyl 5-formylpentanoate is found to increase in this order: acetonitrile

Direct and sensitized photolysis of dimethyl sulphoxide in solution

Abstract: Excitation (2537 A 112 kcal/mole) of dimethyl suiphoxide (DMSO) in solution leads to singlet excited DMSO (E5 = 105 kcal/mole) that undergoes three primary reactions: fragmentation to methyl and methanesuiphinyl radicals, a bimolecular disproportionation reaction to dimethyl sulphone and dimethyl sulphide by a reaction with a ground state DMSO molecule at higher DMSO concentrations, and deactivation to DMSO ground state molecules. The triplet state of DMSO (ET = 83 ± 3 kcal/mole), if formed at all, appears to be chemically inert. At relatively dilute DMSO solutions, the fragmentation (D = 53 kcal/mole) occurs with a quantum yield of 0.14 which is independent of the nature of the solvent (acetonitrile, alcohols, water), of the viscosity of the solvents as well as of the pH of the solvents. No H/D and 160/180 exchanges take place thermally or photochemically under the reaction conditions applied. In acetonitrile, the radicals formed in the primary reactions abstract hydrogen atoms from the solvent; in water, electron transfer from methanesulphinyl radical to methyl radical proceeds thereby producing solvated ions, whereas both these reactions occur in alcohols depending upon the alcohols' ability to stabilize such ions. Methanesulphinyl radicals are able to undergo various reactions: they abstract hydrogen from acetonitrile and alcohols, they dimerize in neat DMSO, they transfer an electron to methyl radicals in water, and they add to an aromatic system such as benzene. Methyl radicals, however, were found to undergo exclusively hydrogen abstraction except in water where they accept an electron from the methanesulphinyl radical. DMSO proved itself as a very poor hydrogen donor. Only during photolysis of neat DMSO was the appearance of 'dimsyl' radicals, CH3SOCH2, apparent; their major reaction under these conditions is fragmentation to formaldehyde and methanesuiphenyl radicals. A qualitative as well as a quantitative analysis of all the products formed in neat DMSO and in various solvents has been made; the reaction sequences that ar assumed to follow the primary processes can quantitatively account for all the products observed such as methane, methanesulphonic acid, dimethyl disuiphide, dimethyl suiphide, and methyl methanethiolsuiphonate. Photolysis of DMSO can be sensitized by benzene and toluene whereas p-cymene, tetralin, mesitylene, acetone, and benzophenone are incapable of doing so. Fluorescence quenching of benzene by DMSO and the inefficiency of cyclohexene to quench the benzene-sensitized photolysis of DMSO show that singlet—singlet energy transfer and decomposition of the singlet excited DMSO take place. The kinetics of the methane formation (methanesuiphinyl Present address: Institut fur Organische Chemie der Universitat Munchen, 8000 Munchen 2, Karlstrasse 23, Germany.

Multiple solvent miscible flooding technique for use in petroleum formation over-laying and in contact with water saturated porous formations

Abstract: A petroleum recovery method employing a mixed solvent for use in formation in contact with and over-laying a substantially water saturated porous formation which is prone to bottom water coning. The mixed solvent density is less than the density of water and greater than the density of the formation petroleum, and has a boiling point less than the boiling point of the formation petroleum. The solvent is injected into the formation near the petroleum-water interface and the mixture comprising solvent and petroleum is recovered from production wells. The solvent may be separated from the produced petroleum-solvent mixture by distillation and recondensation for reinjection into the formation.

Field crystallization of anodic films on tantalum

Abstract: The radial growth rate of crystalline areas during the anodization of tantalum is found to be related to the nature and concentration of both the solute and the solvent and also to the pH of the electrolyte. In general, the use of high solute concentrations or the addition of certain organic solvents produces reduced growth rates in aqueous electrolytes.

Apparatus for producing polyamide esters

Abstract: This invention relates to an improved apparatus for producing polyamide esters at a given reaction location by providing a substantially anhydrous solvent, an aromatic tetracarboxylic dianhydride which is added in excess of its solubility rate within the organic solvent and immediately following is added a quantity of aromatic diamine to produce a polyamide ester precursor which has a greater solubility rate within the organic solvent than the dianhydride; an irreversible formation of aromatic anhydride precipitates is thereby prevented. The reaction mass is continuously monitored for viscosity and temperature, and the viscosity of the reaction mass approaches the order of 1,000,000 centipoises. After formation of the polyamide precursor ester, the precursor is then treated with additional aromatic diamine to form a polymer of controlled imidization, molecular weight and molecular distribution, which may thereafter be treated with ammonium hydroxide and other material to render the product water soluble and therefore storable and more advantageous to use.

Displacement of organic liquid films from solid surfaces by non aqueous systems

Abstract: A non-aqueous liquid surface-active composition for displacing aqueous or ganic liquid films from solid surfaces. The composition contains fluorinated polyethers having the formula CF.sub.3 CF.sub.2 CF.sub.2 [OCF(CF.sub.3)CF.sub.2 ].sub.n OCHFCF.sub.3 and may include a fluoro-alcohol, or a fluoro-acid a fluorinated diester solute and/or a fluorinated benzene solvent, fully fluorinated bromo- and chloro-alkane solvent or a perfluoroalkane solvent.