Solvent Mixtures Of Methanol Research Articles

Solubility of Tris(hydroxymethyl)aminomethane in Methanol + 1-Propanol Mixtures at Various Temperatures

Solubility of tris(hydroxymethyl)aminomethane (TRIS) in various mass fractions of binary solvent mixtures of methanol and 1-propanol [at (293.2, 298.2, 303.2, 308.2, and 313.2) K] was measured and mathematically represented using the Jouyban-Acree model. The correlated mole fraction solubilities are in good agreement with the corresponding experimental values with an overall mean percentage deviation of 1.7%. Densities of saturated solutions of TRIS in pure methanol and 1-propanol at various temperatures were measured and employed to predict the density of saturated solutions of TRIS in their binary solvent mixtures.

Origin of Solubility Behavior of Polar π-Conjugated Crystals in Mixed Solvent Systems

We investigate the origins of solubility behavior of polar π-conjugated crystals in mixed solvent systems and the influence of nonpolar aromatic solvents on solubility and crystal growth characteristics. In solvent mixtures of polar nonaromatic methanol and nonpolar aromatic toluene (or o-xylene), solubility of three analogous polar crystals, consisting of a π-conjugated phenyltriene bridge between electron donor and acceptor groups, shows a maximum at the midpoint of composition. The maximal solubility mole fraction in such mixed solvent systems can be as high as 67 times as that in a single solvent. For comparison, a mixed solvent system consisting of only polar nonaromatic solvents (methanol and acetonitrile) is also examined. Main intermolecular interactions between the solute and solvent molecules in mixed solvent systems, related to the solubility behavior, are experimentally provided by the UV–vis absorption spectroscopy and 1H NMR measurements. In the presence of aromatic solvents, additional strong interactions between the solvent and π-conjugated solute molecules, such as face-to-face and edge-to-face π–π interactions including π···HO–Ar hydrogen bonds are clearly observed. The aromatic characteristics of solvents also importantly influence the morphology and polymorphism of single crystals grown by solution crystal-growth methods.

Determination of pharmaceutical compounds in sewage sludge using a standard addition method approach

An analytical method for the simultaneous determination of eight pharmaceutical compounds in biosolids from urban wastewater treatment plants (WWTPs) was developed and validated. The compounds evaluated were non-steroidal anti-inflammatory drugs (naproxen, diclofenac, and ibuprofen), lipid regulators (clofibric acid), and antibiotics (sulfathiazole, sulfapyridine, sulfamethazine, and sulfamethoxazole). Ultrasound assisted extraction with a water–methanol solvent mixture (1:1, v:v) was performed and the compounds were then determined by liquid chromatography coupled with tandem mass spectrometry. The design of the method was based on the application of the standard addition calibration methodology to reduce matrix interferences. Validation procedures were conducted with rabbit excrements as blank samples. Recoveries of the target analytes ranged from 76 to 131% in spiked samples at 50, 200 or 1000 ng g−1 dry weight (dw). The relative standard deviations were in the range of 5–15% and the method detection limits ranged from 2 to 12 ng g−1dw. The method was applied to monitor pharmaceutical concentrations in biosolids from different WWTPs over an eight-month period (May to December 2011). Diclofenac, sulfapyridine and ibuprofen were detected in most of the samples whereas sulfamethazine and ibuprofen were the pharmaceuticals found in the highest concentrations (>200 ng g−1 dw on average).

About intermolecular interactions in binary and ternary solutions of some azo-benzene derivatives

The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (ADi, i=1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet–Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute–solvent molecular pairs were obtained analyzing the ternary solutions of ADi, i=1, 2, 3 compounds in solvent mixture Methanol (M)+n-Hexane (H).

Solubilities of 1,1′-[1,2-Ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] Dihexafluorophosphate in Water, Methanol, Ethanol, Dimethylformamide, Dimethyl Sulfoxide, and (Acetone + Water) Binary Solvent Mixtures

The chemical structure of a new gemini dicationic imidazolium ionic liquid, 1,1′-[1,2-ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] dihexafluorophosphate ([C6O2(mim)2][PF6]2), was established by 1HNMR. The thermal stability of [C6O2(mim)2][PF6]2 was studied with differential scanning calorimetry and thermogravimetric analyses. With the use of the analytical stirred-flask method at atmospheric pressure, the solubilities of [C6O2(mim)2][PF6]2 in water, methanol, ethanol, dimethylformamide, dimethyl sulfoxide, and (acetone + water) binary solvent mixtures were measured from (283.00 to 323.00) K. The experimental data was correlated with the modified Apelblat equation.

Determination and correlation of solubility of spironolactone form II in pure solvents and binary solvent mixtures

The solubility data of spironolactone form II in six pure solvents and binary solvent mixtures of ethyl acetate and methanol were measured over the temperature range from (278.85 to 317.75)K by using a dynamic method under atmospheric pressure. The results show that the solubility of spironolactone form II in pure solvents increases with increasing temperature while the solubility in binary solvent mixtures increases with the increasing of the fraction of ethyl acetate. This phenomenon is well explained by using relative dielectric constants of the solvents. The solubility data of spironolactone form II in pure solvents were well correlated by the modified Apelblat equation, the Wilson model and the NRTL model while the solubility of spironolactone form II in binary solvent mixtures were correlated by the modified Apelblat equation and the CNIBS/R-K model. Furthermore, the thermodynamic properties of the dissolution process of spironolactone form II were also determined by using the van’t Hoff equation.

Solubility Determination of Tris(hydroxymethyl)aminomethane in Water + Methanol Mixtures at Various Temperatures Using a Laser Monitoring Technique

The solubility of tris(hydroxymethyl)aminomethane (TRIS) in various mass fractions of water + methanol solvent mixtures at (293.2, 298.2, 303.2, 308.2, and 313.2) K was measured using a laser monitoring technique. The generated data were mathematically represented using the Jouyban–Acree model. The back-calculated mole fraction solubilities are in good agreement with the corresponding experimental values as documented by an overall mean percentage deviation of 3.2 %.

Construction of a novel guest biomimetic glutathione peroxidase with solvent-dependent catalytic behavior by incorporating the active center into adamantyl molecule

A novel guest biomimetic glutathione peroxidase (3,3'-tellurobis(propane-3,1-diyl) diadamantanecarboxylate, denoted as ADA-Te-ADA) was synthesized. ADA-Te-ADA functioned to overcome the disadvantages in the construction of building block for giant supramolecular biomimetic enzyme. To reveal the catalytic property of hydrophobic ADA-Te-ADA, the catalytic mechanism was investigated using PBS (phosphate buffer (pH 7.0. 50 mM))/methanol solvent mixture as assay solution. Itindicated that ADA-Te-ADA exhibited typical enzyme catalytic behavior by saturation kinetics measurement. Importantly, ADA-Te-ADA exhibited the typical solvent-dependent catalytic behavior. And the highest catalytic rate 4.29 µM x min-1 was obtained when the volume ratio of PBs: methanol was 5 : 5. Especially, the catalytic rates obtained based on various substrates proved that ADA-Te-ADA slightly displayed special substrate selectivity, which was the ideal catalytic characterization of building block for giant supramolecular biomimetic enzyme. The successfully synthesis of ADA-Te-ADA might highlight for the understanding of the catalytic mechanism of hydrophobic guest biomimetic glutathione peroxidase. And it also might provide the basement for the construction of giant supramolecular biomimetic enzyme.

Synthesis of poly(2-hydroxyethyl methacrylate) end-capped with asymmetric functional groups via atom transfer radical polymerization

Poly(2-hydroxyethyl methacrylate) (PHEMA) end-capped with living chloride and alkyne groups was synthesized via ATRP of HEMA using CuCl/CuCl2/2,2′-bipyridine as a catalyst in a solvent mixture of methanol and 2-butanone. The effects of parameters including the initiator, solvent, temperature and initial monomer to initiator ratios on polymerization were studied in terms of polymerization kinetics, the degree of polymerization (DP) and molar mass dispersity (Đ) of the resulting PHEMA polymer. ATRP of HEMA using propargyl 2-bromoisobutyrate (PBiB) as an initiator was poorly controlled, but those using 3-(trimethylsilyl)propargyl 2-bromoisobutyrate (TMSPBiB) and 3-(triisopropysilyl)propargyl 2-bromoisobutyrate (TiPSPBiB) as initiators were well-controlled. Moreover, the apparent propagation rate constant for ATRP of HEMA using the TMSPBiB initiator was higher than that using the TiPSPBiB initiator. The solvent mixture of methanol–2-butanone at different compositions greatly affected the polymerization controllability. A high molecular weight PHEMA sample with a DP of 1000 and a Đ of 1.34 was obtained under appropriate conditions. The poly(2-hydroxyethyl methacrylate)-block-poly(butyl acrylate) (PHEMA-b-PBA) diblock copolymer was prepared through ATRP of BA using (CH3)3Si–CC–PHEMA–Cl as a macroinitiator. The methoxyl polyethylene glycol-block-poly(2-hydroxyethyl methacrylate) (MPEG-b-PHEMA) diblock copolymer was prepared by click reaction between MPEG-N3 and HCC–PHEMA–Cl. These two reactions demonstrated the reactivity of the asymmetric functional groups end-capping the PHEMA, and further provided modular examples for the synthesis of a novel well-defined (co)polymer with complex architectures.

Synthesis and spectroscopic exploration of carboxylic acid derivatives of 6-hydroxy-1-keto-1,2,3,4-tetrahydrocarbazole: Hydrogen bond sensitive fluorescent probes

Two new fluorescent carboxylic acid derivatives having 6-hydroxy-1-keto-1,2,3,4-tetrahydrocarbazole moiety, 2-(1-oxo-2,3,4,9-tetrahydro-1H-carbazol-6-yloxy)acetic acid [OTHCA] and 2-(7-methoxy-1-oxo-2,3,4,9-tetrahydro-1H-carbazol-6-yloxy)acetic acid [MOTHCA] were synthesized by Japp–Klingemann reaction followed by Fischer indole cyclization. Extensive spectroscopic investigation has been carried out on the compounds in sixteen different aprotic and protic solvents as well as in binary solvent mixtures using absorption, steady-state and time-resolved fluorescence techniques. Fluorescence maxima of the compounds have shifted consistently to longer wavelength in mediums of higher polarity and hydrogen bonding ability. Dipole moment change of the molecules upon photoexcitation has been calculated using Lippert–Mataga theory of solvatochromic shifts. Kamlet–Taft solvatochromic comparison method has been used to determine the dependence of spectral shifts upon empirical solvent parameters. Formation of intermolecular hydrogen bonding of both OTHCA and MOTHCA with protic solvents has been proved by comparing their spectral responses in toluene–acetonitrile and toluene–methanol solvent mixtures.

Solubility of puerarin in the binary system of methanol and acetic acid solvent mixtures

The solubility of puerarin in methanol and acetic acid solvent mixtures was measured by a static analytical method at temperatures ranging from (293.15 to 333.15)K. The mass fraction of acetic acid in the solvent mixtures (w3) ranges from 0 to 0.6. The Apelblat equation was applied for correlating the experimental solubility data, and subsequently used to derive the apparent molar enthalpy, Gibbs energy, and entropy of dissolution of puerarin in methanol+acetic acid binary mixtures.

Picosecond Spectral Relaxation of Curcumin Excited State in a Binary Solvent Mixture of Toluene and Methanol

Picosecond spectral relaxation of the excited state of curcumin in a binary solvent mixture of toluene and MeOH (or MeOH-d4) is reported with an instrument time resolution of ∼40 ps. With increasing mole fraction of MeOH (MeOH-d4) the fluorescence intensity and lifetime of curcumin increase to a maximum at a MeOH (MeOH-d4) mole fraction of 0.14 (0.40) and then decrease. In addition, fluorescence decays taken at the red edge of the emission spectrum started to show measurable rise times (170 to 30 ps), the magnitude of which decreased gradually with increasing alcohol mole fraction. This is attributed to the modulation of the nonradiative rates associated with the excited-state intermolecular H(D) bonding between the pigment and the polar protic solvent. As a consequence, the solvation times in the binary mixture were observed to slow down considerably (20-40 times) at certain solvent compositions compared to neat MeOH. The fact that three Gaussian components are needed to adequately represent the steady-state emission spectra and two isosbestic points are observed in the time-resolved area normalized emission (TRANE) spectra of the pigment suggests the existence of at least three species in the excited state. The observed results are rationalized with a scheme where ground state of the pigment exists in free and H-bonded (intermolecular) state. Optical excitation results in a mixture of these species in the excited state and the observed spectral relaxation correspond to the conversion of these two species in to a third species where dipolar solvation and intermolecular H-bonding have been optimized.

Salting-Out Induced Aggregation for Selective Separation of Vanadyl-oxide Tetraphenyl-porphyrin from Heavy Oil

This work presents a technique for separating vanadyl-oxide tetraphenyl-porphyrin, VOTPP, from heavy oil. This technique involves sequential separation of heavy oil and VOTPP from a solvent mixture of (4:1) volume ratio tetrahydrofuran, THF, and methanol upon stepwise addition of 1.0 M aqueous NaCl solution. Nevertheless, the salting-out of VOTPP from the solvent mixture was not NaCl specific, and many electrolytic solutions produced the same effect. The leftover concentration of heavy oil and VOTPP was determined using UV–vis spectroscopy following the Beer–Lambert law. Two bands were targeted, one at 549 nm and another at 700 nm. Both bands were assigned for heavy oil, and one, α band, at 549 nm was assigned for VOTPP. Accordingly, the leftover concentration of VOTPP was back calculated once the concentration of heavy oil was obtained from the absorbance measurement at 700 nm. Optimum separation required lower volume percent of NaCl at lower heavy oil concentration, and 10 vol % NaCl provided the best window for separation at 100 ppm heavy oil, while 20 vol % was needed for 1000 and 2000 ppm heavy oil.

Biocatalytic activity of methyl-modified microperoxidase-11 in transformation of nickel- and vanadium-porphyrins

► Application of peroxidases as useful biocatalysts in green chemistry has been proved. ► Microperoxidase-11 (MP-11) was chemically modified to methylated MP-11 (mMP-11). ► We examined porphyrin transformation activity of MP-11 and its methylated derivative. ► mMP-11 showed higher activity against porphyrins in organic solvents than native MP-11. ► mMP-11 also exhibited a good degradation potential in the presence of 35% kerosene. Microperoxidase-11 (also known as MP-11) was chemically modified by boron trifluoride–methanol reagent to obtain methylated MP-11 (mMP-11). Porphyrin transformation capability of mMP-11 in a ternary solvent system was investigated by spectroscopic and kinetic techniques and compared with those of native MP-11. Methyl-modified MP-11 showed higher porphyrin transformation efficiency for synthetic nickel- and vanadium-porphyrins than native MP-11. Upon the chemical modification, the initial rates of porphyrin transformation in a solvent mixture of methylene chloride, methanol and water (up to 5%, v/v) were increased by 60.0-, 4.1-, 7.0- and 1.13-fold for VTPP (V-tetraphenyl porphyrin), VOEP (V-octaethyl porphyrin), NiTPP (Ni-tetraphenyl porphyrin) and NiOEP (Ni-octaethyl porphyrin), respectively. Modified MP-11 also exhibited a good degradation potential in the presence of kerosene (a crude oil fraction). In an organic solvent mixture containing kerosene (35%, v/v), mMp-11 in compared to unmodified MP-11 showed 46.0-, 2.1-, 14.1- and 3.1-times higher activity for VTPP, VOEP, NiTPP and NiOEP, respectively. Experimental data showed that concentration and type of organic hydroperoxides, temperature, and pH of the added water play significant roles on the porphyrin degradation.

Optimisation of CGO suspensions for inkjet-printed SOFC electrolytes

Abstract A detailed procedure for the preparation of gadolinium doped (10 mol%) cerium (IV) oxide (CGO) suspension for inkjet printing is described in this paper. The optimisation of inkjet printing parameters for the deposition of solid oxide fuel cell electrolytes was also performed using a custom-built drop visualisation system. Additionally, the uniformity of the deposited drop relics on porous substrates was evaluated. The ink used in this study was an evaporative type comprising a solvent mixture of terpineol and methanol, ethyl cellulose and CGO powder. Successful printing of regular drops was achieved after printing optimisation. It has been demonstrated that inkjet printing is a promising technique for high quality membrane fabrication for applications including solid oxide fuel cells. The ink formulation and optimisation procedure would also be applicable for other ceramic ink development.

New Spectrophotometric Method for the Determination of Bosentan - An Anti-Hypertensive Agent in Pharmaceutical Dosage Forms

A new, simple and sensitive spectrophotometric method in ultraviolet region has been developed for the determination of Bosentan in bulk and in pharmaceutical formulations. Bosentan exhibits absorption maxima at 273 nm with apparent molar absorptivity of 1.3293×104L/mol.cm in methanol and octane 1-sulfonic acid solvent mixture. Beer's law was found to be obeyed in the concentration range of 0.1-100 μg/mL. The method was validated as per the ICH guidelines.

Facile Synthesis of Colloidal CuO Nanocrystals for Light‐Harvesting Applications

CuO is an earth‐abundant, nontoxic, and low band‐gap material; hence it is an attractive candidate for application in solar cells. In this paper, a synthesis of CuO nanocrystals by a facile alcohothermal route is reported. The nanocrystals are dispersible in a solvent mixture of methanol and chloroform, thus enabling the processing of CuO by solution. A bilayer solar cell comprising of CuO nanocrystals and phenyl‐C61‐butyric acid methyl ester (PCBM) achieved a power conversion efficiency of 0.04%, indicating the potential of this material for light‐harvesting applications.

Determination of water content in Brazilian honeybee-collected pollen by Karl Fischer titration

This paper assesses the performance of a chemical method based on the Karl Fischer titration to determine the water content in samples of dehydrated honeybee-collected pollen. The following analysis parameters were investigated: extraction temperature, particle size, reaction time, and weight of a dried pollen sample. After optimization, the method was used to determine the water content of 154 samples of dried honeybee-collected pollen from different geographical regions of Brazil. The Karl Fischer titration method, performed using a solvent mixture of methanol and n-octanol (1:1 v/v) at 50 °C on pollen particles 600 μm in size produced the best results. Mean values for water content of the 154 samples of dried honeybee-collected pollen from 12 Brazilian regions ranged from 3% to 9%.

Solubility of disodium 5′-guanylate heptahydrate in aqueous methanol mixtures

The solubility of disodium 5′-guanylate heptahydrate (5′-GMPNa2) in binary aqueous methanol solvent mixtures with the temperature ranging from 278.15 to 323.15K was measured by a dynamic method with a laser monitoring observation technique. The solubility data were correlated with the Combined Nearly Ideal Binary Solvent/Redlich–Kister (CNIBS/R–K) model and the modified Jouyban–Acree model, respectively. For the ten groups of data studied, the CNIBS/R–K model was found to provide a more accurate mathematical representation of the experimental data, while the modified Jouyban–Acree model containing provisions for correlating both the solvent composition and temperature.

Hierarchical Self‐Assembly of Surfactant‐Encapsulated and Organically Grafted Polyoxometalate Complexes

A series of surfactant-encapsulated and organically grafted polyoxometalates (SEOPs) were prepared through a co-precipitation procedure. Through a rational selection of the molecular components in the structure of the complex, SEOP complexes self-assemble into ordered aggregates with two different hierarchical self-assembled structures in an organic solvent mixture of dichloromethane and methanol in different volume ratios. FTIR, (1)H NMR, and X-ray photoelectron spectroscopy were used to characterize the self-assembly process and the involved driving forces. In a weakly polar solvent, SEOPs aggregated into fibers with a lamellar structure. When the solvent polarity was increased, SEOPs formed ribbonlike aggregates with a tetragonal structure. The change of the hierarchical self-assembled structure was deduced in regard to the arrangement of alkyl chains, electrostatic interactions, and hydrogen bonding between the pyridyl groups and terminal oxygen atoms of the polyoxometalates. The ribbonlike aggregates exhibit birefringence due to the ordered arrangement of SEOPs in the microstructure.