Showing papers on "Solvent published in 1968"

Proton Magnetic Resonance Coordination Number Study of Al(III), Be(II), Ga(III), In(III), and Mg(II) in Water and Aqueous Solvent Mixtures

Abstract: Cation coordination number measurements of AlCl3, AlBr3, Al(ClO4)3, Al(NO3)3, BeCl2, GaCl3, GA(ClO4), InCl3, In(Cl)4)3, and Mg(ClO4)2, in water, and in aqueous acetone mixtures have been carried out by a proton magnetic resonance method. At low temperatures, solutions of these electrolytes exhibit separate proton resonance signals for bulk water, and water molecules in the first solvation shell of the cation. Integration of these signals provides a direct measure of the coordination number of the cation. The Al(III) and Ga(III) are solvated by six water molecules in all solutions, regardless of the anion present. The Be(II) is coordinated by four water molecules in water and in aqueous acetone mixtures. The In(III) and Mg(II) could only be studied in aqueous acetone mixtures, wherein they are each coordinated by six water molecules. With the possible exception of Be(II) no evidence for contact ion pairing was found.

Spectroscopic Studies of Mixed Amine Carbonyl Complexes of d6 Structure. II. Solvent Effect on the Ultraviolet and Visible Absorption Spectra of Diamine-tetracarbonyl Complexes of Chromium(0), Molybdenum(0) and Tungsten(0)

Abstract: Absorption bands, especially metal to amine charge transfer bands of bipyridyl- and phenanthroline-tetracarbonyl chromium (0), molybdenum (0) and tungsten (0) are shifted in various solvents by less than 4500 cm−1. The shift is discussed in accordance with McRae’s equation, which was derived with the point-dipole approximation. The solvents can be classified into two groups, the alcohol and the ester group. When three constants corresponding to (1) the interaction between induced dipoles of the solute and of the solvent, (2) the interaction between permanent dipole of the solute and induced dipole of the solvent, and (3) the interaction between permanent dipoles of the solute and of the solvent, are duely chosen for the two groups of solvent individually, the experimental values are satisfactorily accounted for. Short range interactions, such as hydrogen bonding can be ignored.

Beta-alkenyl substituted 8-hydroxyquinolines

Abstract: METAL VALUES, E.G., COPPER VALUES, ARE RECOVERED FROM AQUEOUS SOLUTIONS BY SOLVENT EXTRACTION WITH AN ORGANICS SOLVENT CONTAINING HYDROCARBYL-SUBSTITUTED 8-HYDROXYQUINOLINE DERIVATIVES, SUCH AS ALKYLBENZYL OR B-ALKENYL 8HYDROXYQUINOLINES.

Behaviour of tellurium(IV) chloride, bromide, and iodide in organic solvents and the structures of the species present

Abstract: Molecular weights and conductivity measurements are reported for tellurium tetrachloride, tetrabromide, and tetraiodide in several organic solvents, and far-infrared spectra are also discussed for tellurium tetrachloride. The results indicate that the tetrachloride and tetrabromide are present as associated species (approximately trimeric) in benzene and toluene. The species present when the three tetrahalides are dissolved in the other solvents can be interpreted in terms of an ionic structure [L2TeX3]+X–, where L is a molecule of solvent. The behaviour of the tetrachloride in the solid phase and in solution has been rationalised in terms of a bridged polymeric structure similar to that of solid tellurium tetrafluoride.

Excimer fluorescence - XI. Solvent-solute energy transfer

Abstract: The rate parameters of solvent-solute energy transfer and of oxygen-solvent quenching have been determined for solutions of 2, 5-diphenyloxazole in benzene, toluene, p -xylene and mesitylene. The role of excited molecules and excimers in transfer to the solute molecules is considered in terms of the Voltz relations, which include the Forster critical transfer distance, the molecular diffusion coefficients, and the solvent excitation migration coefficient. It is proposed that the migration is due to excimer formation and dissociation, and that the energy transfer occurs by a diffusion/migration-controlled collisional process. Dilution of the solvent decreases the migration, but increases the transfer distance, so that the transfer efficiency remains practically constant. The excimer formation and dissociation rate parameters in the pure alkyl benzenes are evaluated.

Food Volatiles: Gas Chromatographic Determination of Partition Coefficients in Water-Lipid Systems

Abstract: SUMMARY– The distribution of volatile solutes between two immiscible solvents can be determined by a study of the vapor pressures in the corresponding single solvent systems, since the partition coefficient is related to the Henry's constants: Kp= k2k12. Application of this principle makes possible the gas chromatographic determination of partition coefficients involving nonvolatile solvents. The method was applied to a solvent pair consisting of paraffin oil and aqueous sodium sulfate. An approximate semilogarithmic relationship exists between the partition coefficient and number of carbon atoms within each homologous series of aldehydes, ketones, alcohols and esters. Saturation with sodium sulfate increased the partial pressure of volatiles from 12 to 20 times. The partial heat of vaporization of volatiles in paraffin oil decreased with increasing temperature and was appreciably smaller than that of the pure compound at its boiling point. These observations may be utilized in quantifying food volatiles in operations involving extraction and gas stripping prior to analysis.

The structure of bis-π-cyclopentadienyldi-iron tetracarbonyl in solution

Abstract: The infrared spectrum of [π-C5H5Fe(CO2)2] is markedly solvent dependent in the 500–700, 1700–2100, and 3500–4000 cm.–1 regions. The spectra can best be explained on the assumption that there are two bridged and one non-bridged isomer present in solutions, and that their proportions vary from solvent to solvent. These suggestions also account for the dipole moment of the compound.

Some t-butylmagnesium and related complexes. Reactions between hydrides and organomagnesium compounds

Abstract: Solutions of di-t-butylmagnesium have been prepared by the dioxan precipitation method, and from them several dibutylmagnesium complexes have been obtained. These include But2Mg–dioxan, which is insoluble in toluene and soluble in ether, the bistetrahydrofuran complex which is partly dissociated in benzene, and the tetramethylethylenediamine complex. Reaction between trimethylethylenediamine and Pri2Mg and But2Mg gives (PriMgNMeC2H4NMe2)2 and (ButMgNMeC2H4NMe2)2, the latter being slightly dissociated in benzene. Pyrolysis of these compounds leads to alkane, not alkene, evolution.Reactions between diethylmagnesium and alkali-metal hydrides either do not take place or result in attack on the solvent. Butyl-lithium gives LiBunMe2Mg,OEt2 on reaction with dimethylmagnesium in ether, but pyrolysis of this gives dimethylmagnesium and lithium hydride. Exchange reactions between sodium trialkylborohydrides and some alkylmagnesium compounds result in the precipitation of magnesium hydride containing occluded alkyl groups.The solid Grignard reagent, (ButMgClOEt2)2, is dimeric in benzene, and is believed to contain chlorine bridges.

Process for making a dioxane

Abstract: Trimethylene glycol produced by hydroformylating ethylene oxide with carbon monoxide and hydrogen under pressure between about 1,000 to 15,000 psig, preferably 3,000 to 6,000, in the presence of a metallic carbonyl catalyst and at least one solvent selected from the group consisting of aliphatic ethers having four to 16 carbon atoms, e.g., isopropyl ether, and halogen-containing aromatic and aromatic hydrocarbons each having six to 24 carbon atoms, e.g., bromobenzene or toluene, wherein the ratio by volume of ethylene oxide to solvent is within a range of from about 1:8 to 1:1 at a temperature of from about 100 DEG to 130 DEG C, preferably 110 DEG to 120 DEG C, to produce hydroxyethyl hydroxy dioxane and hydrogenating said dioxane to trimethylene glycol. Hydroformylating promoters, e.g., tertiary alcohols, can be used in the reaction in order to substantially increase the conversion of ethylene oxide to trimethylene glycol. Hydrogenation is conducted with any suitable hydrogenation catalyst, e.g., Raney nickel, and best results are obtained when the pH of the aqueous hydrogenation solution is slightly acidic, e.g., a pH of 2 to 6.9 and when hydrogenation is conducted first at 90 DEG to 120 DEG C for a predetermined period and then at 150 DEG to 170 DEG C until hydrogenation is substantially complete.

A variable-temperature nuclear magnetic resonance study of complexes of borane and boron trihalides with acetone, diethyl ether, dimethyl ether, n,n-dimethylformamide, methanol, and tetrahydrofuran.

Abstract: : A proton and boron-11 chemical shift and coordination number study of complexes of diborane and the boron trihalides with dimethyl ether, diethyl ether, methanol, tetrahydrofuran, and, to a small extent, acetone and N,N-dimethylformamide has been completed. At low temperatures, separate proton resonance signals are observed for bulk solvent and solvent molecules complexed with the boron species. Coordination numbers were measured by the direct integration of the separate signals. The chemical shift separations for bulk and complexed solvent signals decreased in the order BBr3 > BCl3 > BF3 > BH3. An attempt is made to relate these separations to the coordinating abilities of the boron halides. The proton chemical shift data of the bases were correlated with some diborane 11B and 1H nuclear magnetic resonance results to obtain information concerning the species present in the ether-diborane solution. (Author)

Flash photolysis of flavins. I. Photoreduction in non-aqueous solvents.

Abstract: — The photoreduction of riboflavin, FMN, and lumiflavin in a series of hydroxylic solvents has been examined using flash photolysis. A comparison of the relative quantum yields for the photoxidation of several alcohols and esters by lumiflavin demonstrated that the hydroxyl hydrogen of the alcohol is abstracted approximately twice as readily as is the alpha hydrogen. The use of glycerol as both solvent and reductant provided direct evidence that the initial reaction proceeds by a one-electron reduction to form the flavin semi-quinone. In the case of riboflavin (and FMN) the kinetic results are consistent with an initial intramolecular hydrogen atom transfer, analogous to photobleaching in aqueous solution, followed by a reaction of the semi-quinone with the reductant which prevents degradation of the ribityl side-chain. Quenching by iodide indicates that all the reactions proceed via the flavin triplet state, as is the case in aqueous systems.

Preferential solvation of Co2+ and Ni2+ ions in mixed solvents: n.m.r. methods

Abstract: A method for the study of preferential solvation in the outer coordination spheres from paramagnetic broadening of solvent proton n.m.r. signals was proposed by Frankel, Stengle, and Langford. It is now extended to determinations of the relative concentrations of water and dioxane, dimethylformamide, or dimethylsulfoxide in the inner coordination spheres of Co2+ and Ni2+ ions in the binary solvent mixtures. The assumptions of the analysis are cross-checked by a new method based on the contact shifts experienced by protons on solvent molecules in the coordination spheres of paramagnetic ions. The second method depends upon assumptions independent of the first. Three cases are presented as tests of these n.m.r. approaches. It is clear that highly precise solvation sphere populations will be difficult to obtain but that useful and significant information can be obtained in situations to which alternative methods are almost totally inapplicable.The results indicate that dimethylsulfoxide and dimethylformamide...

Effect of solvent on single crystal formation from dilute polyethylene solution

Abstract: With fractionated linear polyethylene, single crystals were prepared isothermally from dilute solutions in various solvents asn-octane,n-hexadecane, decaline, tetralin, toluene,p-xylene and diphenyl ether, which differed in the size and the thermodynamic properties. The fold length of lamellae was plotted against the crystallization temperature. For tetralin,p-xylene and toluene systems, their observed points lay nearly on the same curve, but for other solvent systems, the relation was obviously not independent of the kind of solvent from which the single crystals were formed. To discuss the effect of solvent on single crystal formation from dilute solution, the end surface free energy of single crystal was estimated from the equation based on the kinetic theory. It was pointed out that more regularly folded single crystals may be formed with solvent having larger thermodynamic interaction parameter and larger molar volume.

Method of removing paraffin from a well with heated solvent

Abstract: A method of removing paraffin deposits from a producing well includes injecting a heated xylene bottoms solvent into the well bore at a temperature sufficiently high so that the solvent is at least 150/sup 0/F when it encounters the producing formation. The well is then pumped to remove the solvent and dissolved paraffin. The solvent includes reformed aliphatic aromatic hydrocarbons and a stabilizing catalyst additive which functions to accelerate the dissolving of paraffin deposits and to increase the capacity of the solvent to retain the paraffin in solution when the solvent is cooled to the temperature of the producing formation. (8 claims)