Acetone Cyclohexane Research Articles

The study of external growth environments on the crystal morphology of ε-HNIW by molecular dynamics simulation

Attachment energy model was adopted to research the influence of external growth environments on e-HNIW crystal morphology. The morphology of e-HNIW crystal in acetone–cyclohexane binary systems was simulated with cyclohexane mass fraction of 0.05, 0.10, 0.15 and 0.20, respectively. The influences of 0.80 acetone on e-HNIW morphology were studied in the acetone–toluene, acetone–benzene and acetone–dichloromethane binary system. Besides, the effects of the temperature and supersaturation on e-HNIW crystal morphology were also examined in the acetone–cyclohexane system. The simulation results reveal that e-HNIW crystal morphology almost maintains consistent with the increase in cyclohexane ratio. Contrarily, the variations of the anti-solvent, the temperature and the supersaturation affect e-HNIW crystal morphology dramatically. Furthermore, the influence of model dimension on the attachment energy was discussed, and a reasonable model size was obtained. The radial distribution function analysis was performed to explore the adsorption and diffusion behaviours of the solvent molecules on the e-HNIW surfaces. Overall, the simulation results can provide some guidance for the crystallization process of e-HNIW.

Design Expert-Supported Development and Validation of High-Performance Thin-Layer Chromatographic Stability-Indicating (HPTLC) Method: an Application in Quantitative Analysis of Ropinirole in the Bulk Drug and in Marketed Dosage Forms

A simple, precise and stability-indicating thin-layer chromatographic method for estimation of ropinirole HCl was developed and validated as per ICH guidelines. The mobile phase consisted of acetone–cyclohexane–6 M ammonia solution (8:5.5:0.5, v/v/v). Scanning the drug was done at 250 nm. Compact spots for ropinirole HCl were found at an Rf value of 0.51 ± 0.002. The linear regression analysis data for the calibration plots showed good linear relationship with R2 0.9976 ± 0.0011 in the working concentration range of 100–3,000 ng spot−1. The method was validated for precision, accuracy, ruggedness, robustness, specificity, recovery, limit of detection (LOD), and limit of quantitation (LOQ). The LOD and LOQ were 12.89 and 42.53 ng spot−1, respectively. The drug was subjected to degradation; the peaks of degradation products were well resolved from the standard with significantly different Rf values. Hence, this method can be used for quality control assay of ropinirole.

Influence of the dilute‐solution properties of cellulose acetate in solvent mixtures on the morphology and pervaporation performance of their membranes

AbstractThe pervaporation performance of cellulose acetate (CA) membranes prepared from acetone (AC), acetone/tetrahydrofuran (AC/THF), acetone/chloroform (AC/CF), and acetone/cyclohexane (AC/CYH) was studied for separating MeOH/MTBE (methyl tert‐butyl ether) mixture with 5 (wt) % MeOH. The dilute‐solution properties and Huggins constant (KH) of CA dissolved in AC and AC/solvent mixtures with 15 vol % of the second solvent (tetrahydrofuran, chloroform, or cyclohexane) were examined. J and α of the CA membranes were affected by the types of solvent mixtures used to prepare the casting solutions. Under the same conditions, the membrane with AC/CYH had the highest J value and the lowest α value, and it was followed by the membranes with AC/CF, AC/THF, and AC. The increasing value of J and decreasing value of α for the CA membranes from different solvent mixtures were in good agreement with the increasing value of KH of CA in corresponding solvent mixtures. Furthermore, differences in the morphology from scanning electron microscopy images of the cross sections or from atomic force microscopy photographs of the surfaces of the membranes existed, and they provided proof of the different pervaporation performances of the CA membranes prepared from AC and AC/solvent mixtures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97:1891–1898, 2005

Analysis of Phthalide, Fenobucarb and Inabenfide in Unpolished Rice Using Selective Gel Permeation Chromatography

We studied a simple cleanup method using selective gel permeation chromatography (GPC) for the analysis of phthalide, fenobucarb and inabenfide in unpolished rice. These pesticides in ground unpolished rice were extracted with acetonitrile. Acetonitrile layer was separated by salting-out with NaCl. The residue was loaded to GPC (acetone–cyclohexane, 20 : 80, v/v). After fenobucarb, inabenfide and phthalide were fractionated by GPC, the each eluant was determined by GC-NPD, HPLC and GC-ECD, respectively, without further cleanup. Average recoveries (n=5) of fenobucarb, inabenfide and phthalide from fortified rice were 98, 90 and 81% at the 0.2 μg/g level and the limit of detection was 0.01 ppm, 0.01 ppm and 0.005 ppm, respectively.

Dynamic extraction in rotating coiled columns, a new approach to direct recovery of polycyclic aromatic hydrocarbons from soils

A new approach to the direct recovery of polycyclic aromatic hydrocarbons (PAHs) from environmental solid samples has been proposed. It has been shown that rotating coiled columns (RCCs) earlier used mainly in countercurrent chromatography can be successfully applied to the fast continuous-flow extraction of PAHs from soils. A particulate solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while a mixture of organic solvents (acetone–cyclohexane, 1:1, v/v) was continuously pumped through. The separation procedure requires less than half an hour, complete automation being possible. No clean-up step is needed before the subsequent HPLC- analysis of extracts. Besides, the dynamic multistage extraction performed in the rotating column at room temperature and normal pressure may have nearly the same efficiency as accelerated batch solvent extraction repeated three times at 150 °C and 14 MPa. Contents of PAHs in extracts obtained by using both methods are in good agreement with the certified data on the PAHs concentrations in the soil samples. The use of appropriate “mild” solvents for the dynamic extraction in rotating columns may be very perspective for the simulation of naturally occurring processes and determination of environmentally-relevant forms of PAHs and other pollutants in environmental solids. A particular emphasis could be placed on time-resolved (kinetic) studies of the mobilization of toxicants in soil systems.

Simultaneous Determination of Six Triazolic Pesticide Residues in Apple and Pear Pulps by Liquid Chromatography with Ultraviolet Diode Array Detection

A method is described for the simultaneous determination of diclobutrazol, flusilazole, flutriafol, hexaconazole, paclobutrazol, and tetraconazole in apple and pear pulps used in baby food at a limit of 0.01 mg/kg. Apple and pear pulp samples are subjected to selective solid-phase microdispersion (SPMD) with SPE-ED Matrix-38 and acetone-cyclohexane, and the extracts are cleaned up on a Florisil cartridge with hexane-cyclohexane-acetone. The extracts are then analyzed by liquid chromatography with ultraviolet detection, using an octadecylsilane column with a gradient-programmed acetonitrile-water mobile phase. Recoveries were determined by spiking apple and pear pulps with the 6 pesticides under investigation at 0.1, 0.05, 0.03, and 0.01 mg/kg. Six determinations were performed at each level for each pesticide. Recoveries were > or = 70% at the 0.01 mg/kg level.

Surface and solution properties of polysiloxane–poly(methyl methacrylate) graft copolymer

AbstractA polysiloxane–poly(methyl methacrylate) (PMMA) graft copolymer was prepared by hydrosilylation reaction between a SiH containing polysiloxane and an allyl‐terminated PMMA. The obtained graft copolymer was blended with PMMA homopolymer. The addition of only 0.01 wt % of graft copolymer was sufficient to make PMMA surfaces hydrophobic. In acetone–cyclohexane mixed solvent, the graft copolymer formed a polymeric micelle by the aggregation of PMMA branches.

Ternary liquid—liquid equilibria and their representation by modified NRTL equations

Experimental liquid—liquid equilibrium data are reported for the systems acetonitrile—acetone—cyclohexane at 318.15 K and acetonitrile—methyl acetate—cyclohexane at 313.15 K. Two modified forms of the NRTL equation proposed by Renon are presented by substituting local surface fractions for local mole fractions and further by including Guggenheim's combinatorial entropy for athermal mixtures whose molecules differ in size and shape. The resultant equations involve three adjustable parameters and are extended to multicomponent systems without adding ternary (or higher) parameters. Calculated results of vapor—liquid and liquid—liquid equilibria for typical binary and ternary mixtures are presented.

Vapour—liquid equilibria of the systems acetone—benzene, benzene—cyclohexane and acetone—cyclohexane at 25°C

Vapour—liquid equilibrium data for the binary systems acetone—benzene, benzene—cyclohexane and acetone—cyclohexane have been determined experimentally at 25°C. The reduction producers based on P - x - y as well as on P - x isothermal data sets, which incorporate usual thermodynamically consistent models expressing the dependence of activity coefficients of liquid composition, have been examined for representing the reported results. Nonideal behaviour of the both phases has been taken into account. Thermodynamic consistency of the data has been shown by comparing of the experimentally obtained vapour compositions with those calculated from P - x data using the best of the examined models for activity coefficients.

An 1H n.m.r. study of complexation and self‐association processes in the ternary system: tert‐butyl alcohol–acetone–cyclohexane

AbstractThe hydroxyl proton chemical shifts of tert‐butyl alcohol, dissolved in acetone and in binary mixtures of acetone with cyclohexane, have been measured as functions of concentration at temperatures of 20, 35, 50 and 60 °C. Using both the equilibrium constant and the quasi‐lattice methods for the interpretation of experimental data, the thermodynamic parameters of self‐association and complexation have been determined, and their dependences on the solvent composition have been analysed. The chemical shifts of the hydroxyl proton obtained in the complexes and the thermodynamic parameters of complexation of tert‐butyl alcohol with acetone‐d6 proved to be the same as for the tert‐butyl alcohol–acetone system.

Densities, Excess Volumes, Surface Tensions, Viscosities, and Dielectric Constants of the Systems: Methanol–Cyclohexane, Acetone–Methanol, Acetone–Cyclohexane, and Methanol–Cyclohexane–Acetone

The density, dielectric constant, change of volume on mixing, refractive index, surface tension, and viscosity of the methanol–cyclohexane system have been investigated experimentally at temperatures ranging from 25° to 50°. The same properties of the binary systems acetone–methanol and acetone–cyclohexane, as well as of the ternary system methanol–cyclohexane–acetone were determined experimentally at 25°. The critical region of the partially miscible system methanol–cyclohexane has been investigated by determining the above physical properties at temperatures above and below the critical solution temperature. A similar investigation of the ternary system has been made, isothermally at 25°, by investigating solutions lying in the neighborhood of the plait point.The surface tension or a derived function of it, viz. the molecular surface energy, does not show a horizontal portion of the isotherm in the methanol–cyclohexane system, but the ternary system does show such a constant surface tension, probably fortuitously, all along the tangential line. The viscosity exhibits anomaly.All the systems show azeotropic behavior. The methanol–cyclohexane and acetone–cyclohexane systems show marked deviations in molar polarization from linearity and this agrees with the thermodynamic data, which indicate larger than unity values for the activity coefficients of the components' behavior (1). The viscosity isotherms of all these systems give no indication of the formation of any stable compound.

Phase Equilibria in the Systems Acetone–Methanol, Acetone–Cyclohexane, Methanol–Cyclohexane, and Acetone–Methanol–Cyclohexane

The vapor pressure and vapor composition of the methanol–cyclohexane system were investigated at temperatures ranging from 25 to 50°. The same properties of the binary systems: acetone–methanol and acetone–cyclohexane, as well as those of the ternary system: methanol–cyclohexane–acetone, were determined experimentally at 25°. The total pressures and compositions of the vapor for solutions lying close to the critical solution temperature of the binary system or close to the plait point of the ternary system are constant within the range of experimental accuracy. All these systems show azeotropic behavior. The methanol–cyclohexane system has an equimolar excess Gibbs free energy, GE, at 25° of 384.7 cal/mol, while the corresponding equimolar value of GE for the acetone–methanol system at 25° is 102.6 and for the acetone–cyclohexane system, at 25°, it is 274.5 cal/mol.