Methanol System Research Articles

Kinetics of Carbon Dioxide (CO2) with DiethylenetriamineinNon-aqueous Solvents Using Stopped-flow Technique

In this work, the reaction kinetics of carbon dioxide (CO2) with diethylenetriamine (DETA)in methanol and ethanol systems were measured using the stopped flow technique over a temperature range of 293-313K in terms of pseudo first-order rate constant (k0). Concentration in the range of 10 to 50mol/m3 for diethylenetriamine were studied. The experimental data show that the pseudo first-order rate constants (k0) increase with the increase of both amine concentration and temperature. The zwitterion mechanism and the termolecular mechanism were used to representthe data for DETAinmethanol and ethanol systems with excllent ADDs of 3.5%, 2.4%, respectively. In comparison with EDA and AEEA in terms of k2, DETA exhibits a better reaction kinetics performance for capturingCO2. Those results will be useful in finding an efficient method for the removal of CO2 from industrial gases.

Synthesis, structural, spectroscopic, anti-cancer and molecular docking studies on novel 2-[(Anthracene-9-ylmethylene)amino]-2-methylpropane-1,3-diol using XRD, FTIR, NMR, UV–Vis spectra and DFT

The novel titled compound 2-[(Anthracene-9-ylmethylene)amino]-2-methylpropane-1,3-diol (AMD) has been synthesized by slow evaporation technique from mixed solvent system of methanol with anthracene-9-carbaldehyde and 2-amino-2-methylpropane-1,3-diol. The synthesized molecule AMD was characterized experimentally by single crystal XRD, FTIR, NMR and UV–Vis spectra and density functional theory (DFT) computations. The structure of the crystal has been determined as orthorhombic system with space group P 21 21 21 and the cell parameters are obtained using XRD data. The optimized ground state geometry of the molecule is determined by evaluating torsional potentials as a function of angle of free rotation around CC bonds of functional groups by DFT method employing B3LYP functional with 6–311++G(d,p) basis set. All the fundamental vibrations of the molecule are assigned unambiguously using potential energy distribution (PED) obtained in the DFT computations. The rms error between the observed and scaled frequencies is 6.20 cm−1. The values of dipole moment, polarizability and hyperpolarizability are evaluated to study the NLO behavior of the molecule. The HOMO-LUMO energies and thermodynamic parameters are also determined. The molecular electrostatic surface potential (MESP) is mapped to obtain the charge density distribution. The 1H and 13C NMR chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV–visible spectrum of the compound is also recorded in the region 200–800 nm to know the type of electronic transitions involved. The anti-cancer activity of AMD is determined against human breast cancer cell line MCF-7 and human prostate cancer cell line PC-3 and correlated the results with study of molecular docking against pharmacological protein IDO-1 receptor.

Extract of olive fruit fly males (Diptera: Tephritidae) attract virgin females

Research conducted during the past three decades suggests that in contrast to most other tephritid fruit flies, in which sexual pheromones are produced by males, the olive fruit fly Bactrocera oleae (Rossi) relies for its sexual communication on a pheromone that is produced by females. However, our present study suggests that virgin, mature females are attracted to male odors. In olfactometer assays extracts of male bodies obtained with a two-solvent system of methanol and dichloromethane were highly attractive to virgin females. This was observed during the last two hours of the photophase, when males are sexually active, but not during the first hours of the photophase, or when mated females were tested. Extracts of male bodies obtained with diethyl ether were also attractive to virgin females, albeit not as strongly as the two-solvent extracts. These results strongly indicate that males of the olive fruit fly elicit attraction to virgin females based on olfactory stimuli. The importance of these findings for understanding the sexual behavior of the olive fruit fly is discussed.

Development of an ultra-fast liquid chromatography-tandem mass spectrometry method for simultaneous determination of seven flavonoids in rat plasma: Application to a comparative pharmacokinetic investigation of Ginkgo biloba extract and single pure ginkgo flavonoids after oral administration.

For deeper pharmacokinetic investigation and further curative application of ginkgo flavonoids, a delicate, efficient and precise UFLC-MS/MS technique for synchronous quantitation of seven flavonoids, apigenin, luteolin, naringenin, quercetin, diosmetin, kaempferol and isorhamnetin in rat plasma has been established. After mixing with the internal standard (IS) linarin, bio-samples were pretreated via ethyl acetate for liquid-liquid extraction, then isolated at 0.2ml/min flow rate on a Venusil MP C18 chromatographic column (100mm×2.1mm, 3μm) by means of gradient elution. 0.1% formic acid-water and methanol system was used as the mobile phase. Mass spectrometric inspection was conducted on a 4000Q UFLC-MS/MS system with turbo ion spray source in patterns of negative ion and multiple reaction-monitoring (MRM). All calibration curves proved favorable linearity (R2≥0.9918) in linear ranges. Intra-day and inter-day precisions didn't exceed 14.0% for all the analytes, and the accuracy was within 6.9%. Extraction recoveries of analytes and IS were less than ±15.0% of nominal concentrations. This method has been under thorough and firm verification for a comparative pharmacokinetic research after gavage between Ginkgo biloba extract and single pure ginkgo flavonoids. The results demonstrated that there're evident pharmacokinetic discrepancies, and possible structural influences were innovatively proposed. Generally, substitution with 3-hydroxylation, a double bond in ring C, ring B methoxylation often confer longer onset period. The existence of ring B catechol group gives rise to faster clearance.

Quantitative analysis of eight polyacetylenes derived from Bupleuri Radix by ultra-performance liquid chromatography coupled with photodiode array detector

To establish quantitative methods for determination of polyacetylenes in Bupleuri Radix, an ultra-performance liquid chromatography method coupled with photodiode array detector (UPLC-PDA) was developed. The analysis was performed on a Waters BEH C₁₈ column (2.1 mm×100 mm, 1.7 μm) using a gradient system of methanol and water. The flow rate was 0.3 mL•min⁻¹ and the detection wavelength was 315 nm. Eight polyacetylenes were prepared using traditional extraction and isolation method, of which compounds 7 and 8 were two new polyacetylenes. All calibration curves showed good linearity (r>0.999 0) within the concentration range. Both the intra- and inter-day precisions for eight analytes were less than 1.9%, respectively, with the mean recovery at the range of 93.21%-108.4%. Meanwhile, 17 bupleurum samples were examined with this process. The results showed a variety either the chemotaxonomic or content of polyacetylenes. The method indicated good linearity, limit of detection and quantification, precision, accuracy and recovery. The developed method allows quantitative assessment and quality control of polyacetylenes, and might be a good alternative according to detection levels in polyacetylenes from Bupleurum Radix.

Quantification of a Novel Photosensitizer of Chlorin e6-C15-Monomethyl Ester in Beagle Dog Plasma Using HPLC: Application to Pharmacokinetic Studies.

Chlorin e6-C15-monomethyl ester (CMME) is a novel photosensitizer, which is synthetized from the degradation products of silkworm excrement. Preclinical studies on the promising photosensitizer CMME are necessary to determine its therapeutic efficacy and druglikeness. A high-performance liquid chromatography with UV detection (HPLC–UV) method was established for the determination of CMME in beagle dog plasma. The sample preparation involved a protein-precipitation method with acetonitrile after the addition of tanshinone IIA as an internal standard (IS). CMME and the IS were separated on a Diamonsil C18 (2) column (100 mm × 4.6 mm, 5 μm) with a isocratic system of methanol–water containing 20 mM ammonium acetate with 0.3% glacial acetic acid (85:15, v/v). The flow rate was 1.0 mL/min with UV detection using a wavelength of 400 nm. The method was sensitive enough with a lower limit of quantitation (LLOQ) of 0.05 μg/mL and had a good linearity (r2 > 0.999) over the linear range of 0.05–5.00 μg/mL. The intra-day and inter-day accuracies ranged from 98.5% to 102.8% and precisions (RSD) were within 6.8%. The validated method was successfully applied to the pharmacokinetic study of CMME after intravenous administration of single and multiple doses in beagle dogs.

High-Throughput Determination of Sodium Danshensu in Beagle Dogs by the LCMS/MS Method, Employing Liquid-Liquid Extraction Based on 96-Well Format Plates.

Sodium Danshensu (sodium d-(+)-β-(3,4-dihydroxyphenyl) lactate), one of the water-soluble ingredients in Salvia miltiorrhiza, exhibits potent relaxation of the coronary artery and anticoagulation effection. A high-throughput, rapid, and sensitive method combining liquid chromatography with electrospray ionization tandem mass spectrometry to determine the sodium danshensu in beagle dog plasma was developed and validated, using gallic acid as an internal standard (IS). Acidified plasma samples were extracted using 96-well liquid-liquid extraction, and were eluted on a CNW Athena C18 column (3 μm, 2.1 × 100 mm) by using a gradient mobile phase system of methanol and water (containing 0.2% formic acid). The mass spectrometric detection was achieved using negative ion electrospray ionization mode and monitoring the precursor→production combinations of m/z 197→135 for sodium danshensu and 169→125 for IS, in multiple reaction monitoring modes. Good linearity was achieved, and the linear range was 10–1000 ng/mL (R2 > 0.996) with a quantification limit of 10 ng/mL for sodium danshensu in beagle dog plasma. The intra- and inter-day precision (RSD) ranged from 2.1% to 9.0%. The accuracy (RE) was between −8.6% and 5.7% at all quality control levels. The validated method was successfully applied to the pharmacokinetics study of sodium danshensu in beagle dog plasma after intravenous injection and oral administration of sodium danshensu.

Unique solvatochromism of cyanine/saponite hybrid systems

The present study is primarily focused on the investigation of spectral properties of cationic cyanine dye (1,1′-diethyl-4, 4′-carbocyanine iodide, denoted as “NK5”) adsorbed into the structure of synthetic clay mineral (Sumecton SA, denoted as “SUM”) as a host matrix. The hybrid systems were investigated by means of absorption and fluorescence spectroscopy. Beside the solvent effect, the influence of dye/saponite ratio on the formation of specific dye species was studied in detail. It was found that used solvents have greatly affected the spectral properties of prepared hybrids. The NK5/saponite systems in ethanol and methanol were dominated by isolated dye cations. In the NK5/saponite systems in acetone and acetonitrile, the formation of higher aggregates was significantly suppressed. Moreover, the fluorescence spectra showed evidence of the formation of highly fluorescent J-aggregates. Finally, the fluorescence quantum yields of the NK5/saponite systems in various solvents were calculated. It was found that polar protic solvents as ethanol and methanol could stabilize the hybrid cyanine/saponite system with higher quantum yields as in case of used aprotic solvents.

A simple, sensitive HPLC-DAD method for simultaneous determination of carotenoids, chlorophylls and α-tocopherol in leafy vegetables

Leafy vegetables are the important components of our diet and are the source of several beneficial phytochemicals. A sensitive, simple analytical method is therefore required to precisely measure the phytochemical composition. A validated reversed phase high performance liquid chromatography with diode array detection (HPLC-DAD) method was developed to determine simultaneously carotenoids, chlorophylls and α-tocopherol composition of six leafy vegetables (B. compestris, B. rapa, B. juncea, M. neglecta, and two spinach varieties). Carotenoids were extracted and efficiently separated using a tertiary mobile gradient system of methanol–water, water and MTBE in 40 min on a reversed phase C18 column. The method was simple, precise, accurate and highly reproducible. Twelve carotenoids namely lutein and its three isomers, β-carotene-5,6-epoxide, neoxanthin, violaxanthin, two cis-isomers of zeaxanthin, 8-apo-carotenal, all-trans-β-carotene and its 13-cis-isomer; one fatty acid ester (β-cryptoxanthin ester); α-tocopherol and chlorophyll a & b were quantified in vegetable leaves. α-Tocopherol, neoxanthin, violaxanthin, lutein, 8-apo-carotenal, chlorophyll a and all-trans-β-carotene were present in higher amounts. Significant variations in the major compounds were observed in the selected vegetables. It was concluded that the developed method was highly sensitive, accurate and can be used to analyze carotenoids, chlorophylls and α-tocopherol simultaneously in leafy vegetables as well as in other plant leaves.

Isothermal Vapor–Liquid Equilibrium Data for the Toluene + Methanol + N-Butylpyridinium Bromide System

Salt effect on vapor–liquid equilibrium (VLE) for the toluene + methanol + N-butylpyridinium bromide system at 318.15 K and different salt concentrations (0.300, 0.700, 1.000, 1.200, and 1.500 mol·kg–1) has been determined by headspace gas chromatography. The azeotrope mixture of the toluene + methanol system can be broken by using N-butylpyridinium bromide. The experimental VLE data were correlated well with an electrolyte nonrandom two-liquid model.

Enhancing silymarin fractionation using the conductor-like screening model for real solvents

A significant hurdle for discovery of plant-derived products is the numerous trial-and-error experiments required to develop an effective purification strategy. To overcome the experimental burden, a quantum mechanics-based molecular modeling approach – known as the COnductor-like Screening Model for Real Solvents (COSMO-RS) – was used to predict a suitable two-phase solvent system to purify six silymarins from an aqueous mixture. Silymarins, a class of flavonolignans found in milk thistle (Silybum marianum L.), are well suited for assessing the use of a molecular modeling approach to predict partitioning in a countercurrent chromatography (CCC) separation because they are well characterized and previous studies report low purity fractionation in liquid–liquid solvent systems. They also present an opportunity to evaluate the use of COSMO-RS in predicting the partitioning of structurally similar isomeric compounds that are present together in an aqueous solution upon extraction from their native source. The COSMO-RS model results predicted the partition coefficients in: three traditional ARIZONA solvent systems (composed of heptane, ethyl acetate, methanol, and water), nine additional variations of this quaternary solvent system, and two chloroform, methanol, and water solvent systems. Predicted results were concise but not accurate when compared to experimental results determined by the shake flask method. The 1:4:3:5 n-heptane:ethyl acetate:methanol:water (v/v/v/v) system was identified to be an improvement on the 1:4:3:4 system previously reported. The present study verified the ability of COSMO-RS to hone in on one or two solvent systems that will yield the best fractionation using CCC.

Effect of composition and temperature variations on thermophysical properties of binary and ternary mixtures of 1-ethyl-3-methylimidazolium ethylsulfate with 1-butanol and/or methanol

The thermophysical properties, densities, ρ, speeds of sound, u and dynamic viscosities, η of pure ionic liquid, 1-ethyl-3-methylimidazolium ethylsulfate, ([EMIM][ES]), and solvents 1-butanol, methanol and of their binary and ternary mixtures have been measured experimentally at a temperature range from (298.15–323.15) K, with an interval of 5 K and at pressure 0.1 MPa by using Anton Paar vibrating tube density and sound velocity meter DSA 5000M and Lovis microviscometer 2000M. The excess molar volumes, VE, isentropic compressibilities, κs, molar isentropic compressibilities, Кs,m, excess molar isentropic compressibility, Кs,mE, and viscosity deviations Δη have been calculated using the experimental ρ, u and η data at the same temperature range and pressure for [EMIM][ES] + 1-butanol/methanol binary systems and the VE, κs, excess isentropic compressibility, κsE and Δη for ternary [EMIM][ES] + 1-butanol + methanol system. The VE, κsE, Кs,mE and Δη data for the studied binary/ternary systems have been fitted to Redlich-Kister equation. The variations in VE,κsE, Кs,mE and Δη values with changes in composition and temperature have been discussed in terms of hydrogen bonding, ion–dipole interactions and structural effects on mixing of ILs and solvents.

Disorder of the dimeric TCNQ-TCNQ unit in the crystal structure of [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane).

Crystallization from an aqueous methanol system composed of Ni(NO3)2, 2,2'-bipyridine (bpy) and LiTCNQ (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane) in a 1:3:2 molar ratio yielded single crystals of bis-[tris-(2,2'-bi-pyridine-κ2N,N')nickel(II)] bis-(7,7,8,8-tetra-cyano-quinodi-methane radical anion) bi[7,7,8,8-tetra-cyano-quino-dimethanide] hexa-hydrate, [Ni(C10H8N2)3]2(C24H8N8)(C12H4N4)2·6H2O or [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O. The crystal structure comprises [Ni(bpy)3]2+ complex cations, two centrosymmetric crystallographically independent TCNQ ·- anion radicals with π-stacked exo groups, and an additional dimeric TCNQ-TCNQ unit which comprises 75.3 (9)% of a σ-dimerized (TCNQ-TCNQ)2- dianion and 24.7 (9)% of two TCNQ·- anion radicals with tightly π-stacked exo groups. The title complex represents the first example of an NiII complex containing a σ-dimerized (TCNQ-TCNQ)2- dianion. Disordered solvent water mol-ecules present in the crystal structure participate in hydrogen-bonding inter-actions.

Synthesis, spectral, magnetic, and thermal properties of Ge(IV) tetrachlorocobaltates complexes with 2-hydroxyarylaldehydes pyridinoyl(aminobenzoyl) hydrazones

The interaction in the GeCl4–nicotinoyl(isonicotinoyl, 2-, or 4-aminobenzoyl) hydrazone of 2-hydroxybenz(2-hydroxy-1-naphth)aldehyde (H2L)–CoCl2–methanol systems has resulted in the formation of [Ge(L·H)2][CoCl4]·nCH3OH complexes with germanium chelates [Ge(L·H)2]2+ protonated at the exo chelate nitrogen atom (NPy or NH2) as the cation. The type of electrolytic dissociation and character of thermolysis of the complexes have been revealed. Spectral, thermal, and magnetic properties of the complexes have been studied.

Isobaric Vapor–Liquid Equilibrium for Two Binary Systems (Methanol + Dibutyl Carbonate) and (n-Butanol + Dibutyl Carbonate) at p = 40.0, 70.0, and 100.0 kPa

The isobaric vapor–liquid equilibrium (VLE) data for the two binary systems of (methanol + dibutyl carbonate) and (n-butanol + dibutyl carbonate) were measured with a modified Rose equilibrium still under pressures of 40.0, 70.0, and 100.0 kPa in this work. The thermodynamic consistency tests of the experimental VLE data were performed according to the methods of the Herington area test and Van Ness point test. All of the experimental isobaric VLE data were well-correlated using nonrandom two-liquid (NRTL), Wilson, and Margules activity coefficient models. The results showed that the average absolute deviations of the vapor-phase mole fraction (AADy) between the calculated and the experimental values were less than 0.01 and the maximum absolute average deviations of the boiling temperature (AADT) was 0.13 K. Consequently, the calculation values showed good agreements with the experimental data measured for the two binary systems in this study.

Separation of methanol + dimethyl carbonate azeotropic mixture using ionic liquids as entrainers

Isobaric vapor-liquid equilibrium (VLE) data of methanol + dimethyl carbonate, methanol + dimethyl carbonate + 1-Ethyl-3-Methylimidazolium Bromide ([EMIM][Br]) and methanol + dimethyl carbonate + 1-Butyl-3-Methylimidazolium Chloride ([BMIM][Cl]) were measured by a modified Othmer still at 101.3 kPa. The two investigated ionic liquids produced significant effects on the separation of the methanol and dimethyl carbonate azeotropic system. The relative volatility of dimethyl carbonate to methanol was enhanced with the addition of ionic liquid. The two ionic liquids could both eliminate the azeotropic point as their concentration increased to a certain value, but [BMIM][Cl] showed a greater separation effect on methanol and dimethyl carbonate azeotropic system than [EMIM][Br]. Furthermore, the measured data were well correlated with the nonrandom two-liquid (NRTL) model.

Optical Sensing of Fluoride Through a Self-Organized Fluorescent Ensemble of Quinizarin-Al(III) Complex.

A one-pot, cost-effective system for sensing fluoride ions using quinizarin as a novel chromophore is reported. Quinizarin complexes with Al(III) to form a self-organized turn-on fluorescence system in methanol. In the presence of fluoride ions, this system undergoes a subsequent ligand swap reaction with the fluoride ion and consequently the fluorescence turns off, delivering a sensitive route for the estimation of fluoride. This domino effect presents a sensitive and selective reaction system for the detection of fluoride ions in the concentration range 0.5-15 ppm. The study was performed using spectrophotometric and spectrofluorimetric techniques. Various analytical parameters such as pH, equilibration time, ambient temperature, and applicability of the method have been reported along with the study of the associated interfering ions.

Non-catalytic preparation of biodiesel in supercritical methanol system

ABSTRACTBiodiesel was prepared with microalgae oil under supercritical methanol condition. The calorific value, chemical composition, molecular structure, and fuel behaviors of the as-prepared biodiesel were characterized by several means. All the results show that most fuel performances of the product oil resemble those of the fossil diesel except for the low-temperature performance. The product oil has long molecular chains and many unsaturated double-bond structures. In this meaning, the biodiesel is suitable to be mixed with fossil diesel or to be added to pour point depressant for industrial application.

Volumetric, compressibility and viscosity studies of binary mixtures of [EMIM][NTf2] with ethylacetate/methanol at (298.15–323.15) K

Densities, speeds of sound and viscosities of pure and binary mixtures 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([EMIM][NTf2])+ethyl acetate/methanol have been measured experimentally over the entire composition range and at six temperatures from 298.15K to 323.15K, at pressure 0.1MPa using Anton Paar Density and Sound velocity meter DSA 5000M and, Lovis microviscometer 2000M. From these experimental data, the excess molar volumes (VE), viscosity deviations (∆η) and isentropic compressibility deviations (∆κs) have been evaluated. The VE values are negative for [EMIM][NTf2]+ethyl acetate system upto x1=0.90 and positive above this x1 value at all temperatures of study. However, the VE values are negative for [EMIM][NTf2]+methanol system at entire mole fraction range and at all temperatures. The VE values in both studied systems decrease with increase in temperature. The ∆η and ∆κs are found to be negative over the entire range of mole fraction and decrease with increasing temperature in both binary systems. The computed data of VE, ∆η and ∆κs have been correlated with Redlich-Kister polynomial equation. The measured and computed data have been interpreted in terms of ion-dipole, ion-ion and dipole-dipole interactions and structural effects between like and unlike molecules upon mixing. The experimental data of VE have also been used to examine the applicability of Prigogine–Flory–Patterson (PFP) theory in predicting the VE of the binary mixtures. The minimum and maximum percent deviations of experimental and calculated by PFP VE values are 0.017 and 3.01 for [EMIM][NTf2]+ethyl acetate and 1.19 and 2.10 for [EMIM][NTf2]+methanol systems, respectively.

Tamoxifen citrate-loaded poly(d,l) lactic acid nanoparticles: Evaluation for their anticancer activity in vitro and in vivo

The optimization of tamoxifen citrate entrapment and its release from biodegradable poly(d,l) lactic acid nanoparticles are prepared by modified spontaneous emulsification solvent diffusion method. Since the addition of tamoxifen citrate induces the formation of drug crystals from nanoparticle suspension the influence of several parameters on tamoxifen citrate encapsulation was investigated. In vitro studies for cytotoxicity, DNA ladder, and the expression of Bcl-2-Bax expression were also investigated for MCF-7 and MDA-MB-231 cells after the addition of tamoxifen citrate alone and tamoxifen citrate-poly(d,l) lactic acid-nanoparticles (encapsulated tamoxifen citrate). From results, it was noticed that the size and zeta potential of the drug loaded nanoparticles were not differed much in their physicochemical properties from drug free counterparts. The drug-loaded and drug-free nanoparticles exhibited size of in between 271.4 and 282.7 nm and zeta potential of -34 to -27.4 mV, respectively. There was significant increase in drug incorporation in the particles noticed in dichloromethane + methanol system in comparison to acetone + methanol and ethyl acetate + methanol systems. The drug was partly released from the nanoparticles after 48 h of incubation at 37℃. From Fourier transform infrared spectroscopy and differential scanning calorimetry data demonstrated drug-polymer characteristics within the nanoparticles and unincorporated drug that appeared in the form of crystals from polarized microscopic study. MCF-7 and MDA-MB-231 cells were more sensitive to tamoxifen citrate-poly(d,l) lactic acid-nanoparticles than tamoxifen citrate alone. DNA ladder and the expression of Bax to Bcl-2 ratio were much higher in tamoxifen citrate encapsulated in nanoparticles than that in tamoxifen citrate alone. These results demonstrated the feasibility of encapsulation of tamoxifen citrate and its enhanced efficiency in vitro and in vivo studies.