Methanol Water Mixed Solvent Research Articles

Reduction of hexaazacyclophane complexes of Co(II) and Cu(II) by z.rad;CH 2OH and esol−; A pulse radiolysis study

The reactions of CH 2OH and e sol − with hexaazacyclophane complexes of Co(II) and Cu(II) in methanol and or methanol-water mixed solvents were investigated by pulse radiolysis. The primary products from the reduction of the macrocyclic complexes were assigned a radical nature by comparing their optical spectra with those of related Co(I) and Cu(I) species. Such metal-ligand radical products undergo disproportionations. The product of the disproportionation was assigned as a Co(III)-hydride complex. Although a similar hydride could be produced in the disproportionation of the Cu(II)-ligand radical, the optical spectrum of the product is in accordance with the hydrogenation of a double bond in the ligand. Interception of the metal-ligand radical intermediates with CO 2 resulted in the formation of adducts.

Raman and IR study on the H 2O - CH 3OH mixed solvent at 25°C using fourier deconvolution technique

The intermolecular interactions in water-methanol mixed solvent have been investigated by Raman and infrared studies of the C-H and C-O stretching bands. The Fourier deconvolution method in combination with curve fitting is used to resolve the structure of the overtone of the C-H deformation vibration 2δ s in the Raman spectrum and the C-O band in the infrared spectrum. The changes in the intensities of the Fermi resonance doublet in the C-H stretching region of the Raman spectra and in the structure of the C-O infrared band are explained in terms of the hydrogen bonding interactions between methanol/methanol and methanol/water molecules.

Thermodynamics of the sodium bromide-methanol-water and sodium bromide-ethanol-water two ternary systems by the measurements of electromotive force at 298. 15K

Abstract Electromotive force measurements of the following cells ; are carried out. The molal concentration m of NaBr in methanol-water mixed solvents changes from 0. 01m to 3.0m and those in ethanol—water mixed solvents from 0. 01m to 5.0m. The weight percent of methanol or ethanol in the mixed solvent w equals 0, 10, 20, 40, 60, 80, 90 and 100 respectively. Calculations of standard cell potential of each conditions are made by using the extended Debye—Huckel equation and the Pitzer equation. The calculation results of standard potentials of both of the two equations are in good agreement with each other. The ionic association effect of NaBr in the mixed solvent are investigated by the Pitzer—Simonson equation extended to ion pairing.

Determination of Henry's constants of organic compounds of low volatility: methylanilines in methanol-water

A flow-through gas-liquid equilibration method is described for the determination of the Henry's constants of organic compounds of low volatility. This method was applied to the determination of the Henry's consits of aniline, 4-methyniline, 3,4-dimethyniline, and 2,4,5-trimethylaniline as a function of composition of the methanol-water mixed solvent. The logarithms of the Henry's constants of methylanilines vary quadratically with the volume fraction of methanol

Thermodynamic Studies on the Complexation Reactions of Copper(II) Complex of o2n2-Donor Macrocycle with Halide and Pseudohalide Ions

Complexation reactions of 5,6,7,8,9,10,16,17-octahydrodibenzo[e, m][1, 4]dioxa-[8, 11]diazacyclotetradecine-copper(II) complex with halide and pseudohalide ions have been studied at 25.0° in three water-methanol mixed solvents by spectro-photometric method. It is found that the equilibrium constants increases in the order of 50 vol.% CH3OH<75 vol.% CH3OH<95 vol.% CH3OH for solvents and I-<Br−<CI−<SCN−, N−3 for anions.

Formation and Catalytic Functionality of Synthetic Polymer-Noble Metal Colloid

Abstract Colloidal dispersions of noble metals in synthetic polymers are prepared by reduction with alcohol. Reflux of a solution of rhodium(III) chloride and poly(vinyl alcohol) (PVA) in a methanol-water mixed solvent under argon or air for 4 hr gives a homogeneous solution of colloidal dispersion of rhodium (Rh-PVA-MeOH/H2O). The particle size of metallic rhodium is distributed n a narrow range of 30-70 Å, and the average diameter is 40 A. The formation of colloidal rhodium proceeds through three steps: coordination of poly(vinyl alcohol) to rhodium(III) ion, reduction with methanol to form small particles (8 Å in diameter), and growth of the small particle to large particle (40 Å in diameter). Polyvinylpyrrolidone (PVP) and poly(methyl vinyl ether) (PMVE) can be used in place of poly(vinyl alcohol) and result in colloidal dispersions, respectively, similar to Rh-PVA-MeOH/H2O. Colloidal dispersions in nonaqueous solvent can be prepared by using ethanol instead of methanol-water (Rh-PVP-EtOH) and by using methanol instead of methanol-water, with addition of small amount of methanol solution of sodium hydroxide (Rh-PVP-MeOH/NaOH). The average diameters of rhodium particles in Rh-PVP-EtOH and Rh-PVP-MeOH/NaOH are 22 and 9 Å, respectively. The colloidal dispersions of palladium, silver, osmium, iridium, platinum, and gold in aqueous or nonaqueous solvent are prepared by using polyvinylpyrrolidone. The colloidal dispersions are very stable even under air for 20 days. Those of rhodium, palladium, and platinum are effective catalysts for hydrogenation of olefins at 30°C under an atmospheric hydrogen pressure. The colloidal dispersion of palladium catalyzes highly selective hydrogenation of diene and dienoate to monoene and monoenoate, respectively.

Conductance of Some High Valence Type Electrolytes in Mixed Solvents. I. Conductance of Tris(1,10-phenanthroline)iron(II) Sulfate and Chloride in Water-Methanol Mixtures at 25 °C

Abstract The conductance of tris(1,10-phenanthroline)iron(II) sulfate, Fe(phen)3SO4, and chloride, Fe(phen)3Cl2, has been measured in water-methanol mixed solvent at 25 °C. The data of the sulfate could be explained by means of the Fuoss-Onsager equation (1957) and the Fuoss-Onsager-Skinner equation (1965) on the assumption that the salt is completely dissociated in the entire composition range of the solvent system. Application of the Fuoss-Hsia equation which contains a c3⁄2 term gave association constants increasing from a value of KA=40 in water to KA=3900 in methanol. The logKA vs. 1/D plot is in good agreement with ion association theoreies. The limiting equivalent conductance of Fe(phen)32+ ion was estimated to be 34.3 in water and 62.3 in methanol.

Dissociation constants of the ampholyte glycine in 50 mass % methanol-water from 5 to 55°C, with related thermodynamic quantities

The two thermodynamic dissociation constants of glycine at 11 temperatures from 5 to 55°C in 50 mass % methanol-water mixed solvent have been determined from precise emf measurements with hydrogen-silver bromide electrodes in cells without liquid junction. The first acidic dissociation constant (K 1)for the process HG+⇌H++G± is expressed as a function ofT(oK) by the equation pK 1 = 2043.5/T − 9.6504 + 0.019308T. At 25°C, pK 1is 2.961 in the mixed solvent, as compared with 2.350 in water, with ΔH°=1497 cal-mole−1, ΔG°=4038 cal-mole−1, ΔS°=−8.52 cal-°K−1-mole−1, and ΔC p o =−53 cal-°K−1-mole−1. The second acidic dissociation constant (K 2)for the process G±⇌H++G− over the temperature range studied is given by the equation pK 2 = 3627.1/T − 7.2371 + 0.015587T. At 25°C, pK 2is 9.578 in MeOH−H2O as compared with 9.780 in water, whereas ΔH° is 10,257 cal-mole−1, ΔG° is 13,063 cal-mole−1, ΔS° is −9.41 cal-°K−1-mole−1, and ΔC p o is −43 cal-°K−1-mole−1. The protonated glycine becomes weaker in 50 mass % methanol-water, whereas the second dissociation process becomes stronger despite the lower dielectric constant of the mixed solvent (ω=56.3 at 25°C).

ChemInform Abstract: SOLVENT EFFECT OF METHANOL ON THE RATE OF FORMATION REACTION OF MONOCHLOROIRON(III) COMPLEX IN AQUEOUS SOLUTION

AbstractDie Geschwindigkeitskonstanten für die Bildung des F eC12 ‐Komplexes aus F e(III) 5 und Cl′werden in Wasser‐Methanol‐Lösungsmittelgemischen gemessen.

Solvent Effect of Methanol on the Rate of Formation Reaction of Monochloroiron(III) Complex in Aqueous Solution

Abstract The rate constants of the formation reaction of FeCl2+ complex from Fe(III) and Cl− ion were measured in water-methanol mixed solvents by use of a stopped-flow spectrophotometer. The apparent rate constant k is dependent upon the acid concentration of the medium, indicating that the reaction can proceed through two parallel paths, Fe3++Cl− (k1) and Fe(OH)2++Cl− (kH). Both k1 and kH increase with the increase in the mole fraction of methanol in the medium, xM. Since kH is much larger and is consequently much more accurately determined than k1 considerations were mainly made on the nature of kH. According to the dependence of kH on the dielectric constant of the medium, it was found that the activation free energy of the Fe(OH)2++Cl− reaction consists of the electrical and non-electrical parts and that the dimension of the activated complex corresponds approximately to the distance of the outer-sphere approach between the reacting species. These facts are therefore in favor of an outer-sphere mechanism in the anation reactions of iron (III) by simple anions.

Catalytic action of metallic salts in autoxidation and polymerization: 11. Polymerization of methacrylic acid esters with sodium hexanitrocobaltate in methanol-water

The polymerization of a series of methacrylic acid esters (methyl, ethyl, isopropyl and n-butyl) with sodium hexanitrocobaltate, Na 3[Co(NO 2) 6] was carried out in a methanol-water mixed solvent. The homogeneity of the polymerization system was dependent on the composition of the mixed solvent and greatly affected the rate of the polymerization. A maximum rate was obtained at approximately equimolar fractions of methanol and water in the polymerization of methyl methacrylate. The effect of bulkiness of ester groups on the polymerizability of each monomer was indistinguishable in the mixed solvent system. Kinetic study of the polymerization of methyl methacrylate in a mixed solvent of about an equimolar fraction of methanol and water gave the following polymerization equation: R p = k[l] 1 2 [ M] 2 , and an apparent activation energy of 10.6 kcal/mol. The copolymerization of methyl methacrylate and styrene with the initiator suggested that polymerization proceeded via a radical mechanism. The possibility of a certain interaction between initiator, solvent and monomer in the initial stage of the polymerization is discussed on the basis of the kinetic data, properties of oligomers of methyl methacrylate, spectroscopic and other data.

SOLUBILITY OF ETHYLENE-VINYLALCOHOL COPOLYMERS

In order to obtain the basic information of wet and dry spinnings of Ethylene-vinylalcohol copolymers (EVA), their solubility was investigated in many solvents and mixed solvents.The following results were obtained:1. Solubility of various EVA were closely related to solubility parameter (δ) of solvents and were, especially, interpreted with polar component (δp) and hydrogen-bonding component (δh) of the solubility parameter.2. Proton donating solvents such as m-Cresol, Phenol, Ethylene chlorohydrin and Dimethyl sulfoxide showed good solubility to EVA.3. Low vinylalcohol content EVA tended to dissolve in Benzene-Methanol mixed solvents, while high vinylalcohol EVA tended to dissolve in Methanol-Water mixed solvents.4. In case of EVA (vinylalcohol 73.4mol%) in n-Propanol/Water (8/2 vol. ratio), both lower and upper critical solution temperatures (LCST and UCST) were observed.

Reversed-phase chromatography of some aromatic hydrocarbons : Structure-retention relationships

The chromatographic behaviour of some aromatic hydrocarbons has been studied on columns of Zipax Permaphase ODS in water—methanol mixed solvents. The increase in retention with the number of aromatic rings in a molecule is noted. A simple relation between k′ (measure of retention) and empirical formulae for unsubstituted polynuclear aromatic hydrocarbons is suggested. The substitution of alkyl side chains on to an aromatic nucleus causes a further increase in retention. Comparisons show that aliphatic carbon atoms are more effective at increasing retention than their aromatic counterparts. Chromatographic retention of alkylbenzenes can be related to the number of carbon atoms in the aliphatic chain. These relationships together with that linking mobile phase composition to retention might be used to give an approximate idea of the k′ value of an aromatic hydrocarbon given its structure. The carbon content of unsubstituted polynuclear aromatic hydrocarbons could be estimated from their positions in these reversed-phase chromatograms. Furthermore, given the identity of the aromatic nucleus of an aralkyl hydrocarbon, the extent of aliphatic substitution could also be estimated. Such structural assignments can be reinforced by spectroscopic examination of the separated fractions.

Induced solvolysis of halochromium(III) and azidochromium(III) ions and the spontaneous solvolysis of iodochromium(III) ion in water-methanol mixed solvents

Induced solvolysis of halochromium(III) and azidochromium(III) ions and the spontaneous solvolysis of iodochromium(III) ion in water-methanol mixed solvents

The Effects of Concentration, Temperature and Solvent Composition on Partial Molar Volumes of Cetyltrimethylammonium Bromide in Methanol-Water mixed Solvent Media

The author Ajay Bhattarai was changed to Ajaya Bhattarai and the author Kumar Chatterjee was changed to Sujeet Kumar ChatterjeePrecise measurements on the density of cetyltrimethylammonium bromide solutions in pure water and in methanol(1) + water (2) mixed solvent media containing 0.10, 0.20 and 0.30 volume fractions of methanol at 308.15, 318.15 and 323.15 K are carried out to calculate the partial molar volumes. The concentrations are varied from 0.3 - 1.0 x 10-1 mol.l-1. The results showed almost constant on the partial molar volumes with increasing surfactant concentration. Also, the partial molar volumes are found to increase with increasing temperature over the entire concentration range investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. Keywords: Mixed solvent; Cetyltrimethylammonium bromide; Surfactan; Partial molarDOI: 10.3126/jncs.v24i0.2383 Journal of Nepal Chemical Society, Vol. 24, 2009 Page: 24-30

Effects of Concentration, Temperature and Solvent Composition on the Partial Molar Volumes of Sodium Polystyrenesulphonate in Methanol -Water Solvent Media

Precise measurements on the density of sodium polystyrenesulphonate solutions in methanol-water mixed solvent media containing 8, 16, and 25 weight per cent of methanol at 308.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used is 1, and the concentrations are varied from 1×10-2 to 3.8 ×10-2 monomol.l-2. The results showed a slight increase on (V0) were determined. the partial molar volumes with increasing polyelectrolyte concentration. The partial molar volumes of the polyelectrolyte at infinite dilution, (effects of the temperature and solvent composition on the partial molar volumes are also investigated.Keywords: Sodium polystyrenesulphonate, polyion, partial molar volume.DOI: 10.3126/jncs.v23i0.2100Journal of Nepal Chemical Society, Vol. 23, 2008/2009 Page: 82-88

Electrical Conductivity of a Semidilute Polyelectrolyte in Mixed Solvent Media

The electrical conductivity of solutions of sodium salt of polystyrenesulfonate in methanol-water mixed solvent media containing 8, 16, 25, and 34 weight per cent of methanol at 308.15, 313.15, 318.15 and 323.15 K was studied earlier. In that report, an attempt was made to interprete the results using the Manning Counterion Condensation Theory. Unfortunately, a major deviation of the theoretical prediction from the experimental results was noticed and the possible reasons for this discrepancy have been discussed. In this communication, the experimental conductivity have been analyzed on the basis of a new model for semi-dilute polyelectrolyte conductivity which takes into electrical conductivity of semidilute solutions of polyelectrolytes without added salt has been recently described by Colby et al. (1997) using the scaling description proposed by Dobrynin et al. (1995) for the configuration of a polyelectrolyte chain in semi-dilute solution. The predictions are found to be compared favorably well with the observed conductivity over the whole range of concentrations investigated. Key Words: conductivity; counterion; condensation; semi-dilute; Manning theory DOI: 10.3126/njst.v9i0.3182 Nepal Journal of Science and Technology 9 (2008) 163-170