Abstract  IPA COPYRIGHT: ASHP A study of the effects of water dilution on reactivity and structure of aluminum hydroxide gel is presented. Loss of reactivity is directly related to the degree of dilution. It is hypothesized that dilution with water causes a change in the equilibrium between stabilizing ions incorporated in the gel structure and ions in solution. As stabilizing ions leave the gel structure to reestablish the equilibrium, a loss of reactivity is observed until a new equilibrium is established.

Abstract  A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO(3)H. BET measurements of the catalyst showed the surface area to be 340 m(2) g(-1) with the average pore volume of 0.24 mL g(-1) and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Bronsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.

Abstract  NMR and XRD data are reported for several new forms of finasteride, including the results of complete structure determinations for three solvates. Form III of finasteride, hitherto only mentioned in the patent literature, and a new anhydrous form designated Form X, have been found in mixtures of polymorphs and their (13)C NMR chemical shifts obtained. The results demonstrate that the crystallographic asymmetric units contain three molecules and one molecule, respectively. Attempts to reproduce "Form H1", as described in a patent, resulted in a new IPA solvate hydrate. The previously-reported acetic acid, dioxane, and ethyl acetate solvates have been further characterised, and new THF and diethyl ether solvates prepared and characterised. The crystal structures of the dioxane, IPA, and THF solvates have been determined by single-crystal X-ray diffraction. All the solvates (except the acetic acid case) are found to be hemihydrates, to have a finasteride: solvent molar ratio of 2:1 and to have a common structure. The solvate molecules are highly disordered and sited in channels in the structure. The powder XRD patterns are characteristic of the common structure. These solvates may be distinguished by the characteristic CPMAS (13)C signals from the solvent molecules, but the resonances of the host finasteride structures differ only marginally, and powder XRD patterns are almost indistinguishable. Magic-angle spinning (MAS) proton spectra give sharp lines for the solvent peaks, confirming their high degree of mobility. This is further shown in one case by direct polarisation (13)C spectra. Mobility of the tert-butyl group is also implied. Thermal characteristics have been studied and TGA used (in conjunction with solution-state proton NMR) to estimate molar ratios.

Abstract  Organic Solvent Nanofiltration (OSN) is an emerging membrane separation process with the potential to replace traditional separation techniques. Its advantages include lower energy consumption than alternatives such as distillation, easy up scaling and flexibility. However, manufacturing OSN membranes involves a number of stages contributing towards the discharge of hazardous chemicals as waste. Thus the environmental advantages of employing OSN are to some extent cancelled out by the waste released during OSN membrane production. This paper describes a process for the preparation of polyimide integrally skinned asymmetric OSN membranes with adjustable molecular weight cut off (MWCO). Previously reported methods for producing polyimide based OSN membranes are modified in the presented work without compromising the performance of the membranes. The toxic solvents used to form polymer dope solution, i.e. dimethylformamide (DMF)/1,4-dioxane are replaced by an environmentally friendly dimethyl sulfoxide (DMSO)/acetone solvent system. In order to further diminish the environmental impact, isopropanol was successfully replaced with water in the crosslinking step. Scanning electron microscope images revealed that membranes with spongy matrix without macrovoids were obtained regardless the DMSO/acetone ratio.

Abstract  The kinetics of urease-catalyzed urea hydrolysis has been studied in mixtures of water with organic solvents (DMF, DMSO, ethanol, isopropanol, or dioxane), in detergent-free microemulsions (hexane-isopropanol-water), and inverted micelles formed by anionic, cationic, or nonionic detergents (Aerosol(R)-OT, cetyltrimethylammonium bromide, and Triton X-100, respectively), including mixed inverted micelles (Aerosol(R)-OT plus Triton X-100). The kinetic parameters of the reaction (k(cat) and K-m) and the parameter ratios were determined for all the systems of urease-catalyzed urea hydrolysis in nonaqueous media. The value of k (cat)/K-m obtained for the enzyme incorporated into the mixed micelles was maximal, suggesting that under the conditions mimicking the natural environment of urease its operation is most effective. Practical recommendations on the choice of organism solvents which ensure optimal conditions for urease-catalyzed urea hydrolysis are provided as well.

Abstract  The proton ligand constants of 4-chloro and 4-amino picolinic acid N-oxide and the formation constants of corresponding binary chelates of Cu(II) and Ni(II) have been measured at 30-degrees-C and 0.1 M ionic strength in varying percentages of dioxane-water, acetone-water, ethanol-water and isopropanol-water. The results are discussed with reference to the change in dielectric constants of water in the presence of organic solvent, change in the structuredness of water, change in hydrogen bonding ability of the organic solvent in water, solvent basicity and proton solvation by organic solvent. The values have been compared with aqueous and mixed aqueous systems of picolinic acid N-oxide and 4-methoxy picolinic acid N- oxide.

Abstract  The photophysical behavior of 3-pyrazolyl-2-pyrazoline derivative (PZ), a newly synthesized biologically active compound has been studied in micellar solutions of anionic sodium dodecyl sulfate (SDS), cationic cetyl trimethylammonium bromide (CTAB) and nonionic p- tert-octylphenoxy polyoxyethanol (Triton X-100, TX-100) micelle using steady state and time-resolved fluorescence spectroscopy technique. Influence of the micelles on the photophysics of PZ has also been investigated using different approaches. The location of the fluorophore PZ in the micelle has been identified by cetyl pyridinium chloride (CpCl) induced fluorescence quenching and micropolarity surrounding that fluorophore in micellar solution. The effect of urea on the steady state fluorescence and relaxation dynamics of the micelle bound probe has also been observed. The results have been interpreted in terms of the model that urea displaces water molecules from the micellar interface and the consequent destabilization leads to the expulsion of the probe molecules from the interfacial region. An attempt has been made to determine probe sensing microviscosities for these micellar microenvironments in the light of average reorientation times of the probe PZ.

Abstract  Vapor-liquid equilibria were measured for dilute aqueous solutions of formic acid, acetic acid, pyridine, aniline, isobutyl alcohol, isoamyl alcohol, n-butyl acetate, dimethyl phthalate, diethyl phthalate and dioxane, respectively, at various pH, temps and concns of sodium chloride. The substances chosen are very important raw materials or intermediates in chemical industry and are widely used. Phthalates are used as plasticizers and leach, in small amounts, into water from plastics. Recently in Japan, phthalates are being recognized as a new polluting material in sea water and river water. The vapor-liquid equilibria were severely affected by the pH of the solution, not only for the electrolytes (such as formic acid and pyridine), but also for esters. This is probably due to the effect of pH on the degree of the dissociation to electrolytes and on the hydrolysis of esters. The phase equilibria of some organic materials which are less soluble in water (such as phthalates and higher alcohols) were greatly affected by the salting-out effect of salinity. If the feed sea water to distillation plants is contaminated by volatile organic materials, some of them concentrate in the distilled water. Therefore, attention must be given to the properties of volatile, polluting materials n sea water when the product water from desalination processes is for human consumption.

Abstract  A heated purge-trap-desorb (H-PTD) analysis method for polar, water soluble volatile organic analytes was developed and tested. The research goal was to obtain analysis sensitivities for the target analytes comparable to those achieved presently for non-polar analytes using the room temperature PTD approach of EPA SW-846 Method 5030 while at the same time not deviating significantly from the type of apparatus currently in use for Method 5030. Thirty-three polar, water soluble analytes from Appendix VIII and the Michigan list were included in the scope of work. Eight analytes proved to be amenable to the developed method: acrolein, methyl ethyl ketone, methylacrylonitrile, acrylonitrile, acetonitrile, propionitrile, 1,4-dioxane and isobutanol. The gas chromatography-mass spectrometry (GC-MS) method detection limits for the analytes ranged from 2 to 9 micrograms/L and were about 5-fold higher than would be obtainable with more optimized chromatography. Three alcohols, propargyl alcohol, 2-chloroethanol and 1,3-dichloro-2-propanol could not be recovered to any degree by H-PTD even using 80% saturation of the sample with salts and dramatically increased purge gas volumes. One analyte, 3-chloroproprionitrile, could not be recovered from the trap desorption step, even though it was shown to be only slightly hydrolytically unstable. The other 21 analytes had plausible chemical reasons for the absence of any H-PTD recovery for them: nine were nitrogen bases, six were hydrolytically unstable, two were mercaptans and four had very low volatility and/or very high water solubility. The absolute H-PTD recoveries obtained ranged from about 80% for analytes such as acrylonitrile and methylacrylonitrile to about 30% for 1 ,4-dioxane. The developed method employs a standard 5-ml purge vessel with an integral, very small volume water cooled condenser and the same all-Tenax trap as specified in Method 5030 for use in Method 8030. Commercially available PTD apparatus can be used without modification except to accommodate the 90 C water bath used to heat the purged sample. (Author 's abstract)

Abstract  Adsorption, thermal decomposition, and photoreactions of ethylene oxide (EO) on powdered TiO2 have been studied by Fourier-transformed infrared spectroscopy. Most of the adsorbed EO molecules at the saturated coverage on 35 degrees C TiO2 remain intact. As the temperature is increased (>= 100 degrees C), the surface EO molecules dissociate into ethylene glycol-like species (-OCH2CH2OH or -OCH2CH2O-) by ring rupture and crotonaldehyde (CH3CH = CHCHO) possibly via acetaldehyde from EO isomerization. The ring-opening process is enhanced in the presence of coadsorbed H2O molecules. EO with the highly strained three-membered ring is thermally more reactive than 1,4-dioxane on TiO2. EO molecules adsorbed on TiO2 readily undergo photodegradation in O-2, forming surface H2O, CO2, HCO3, CO3, and HCOO. The,comparative studies of O-16(2) and O-18(2) indicate that both O-2 and lattice oxygen take part in the EO photodecomposition. The reaction pathways involving the two oxygen species are discussed.

Abstract  The purpose of the present work was to find optimum conditions of headspace gas chromatography (HS-GC) determination of residual solvents which usually appear in pharmaceutical products. Two groups of solvents were taken into account in the present examination. Group I consisted of isopropanol, n-propanol, isobutanol, n-butanol and 1,4-dioxane and group II included cyclohexane, n-hexane and n-heptane. The members of the groups were selected in previous investigations in which experimental design and chemometric methods were applied. Four factors were taken into consideration in optimization which describe HS conditions: sample volume, equilibration time, equilibrium temperature and NaCl concentration in a sample. The relative GC peak area served as an optimization criterion which was considered separately for each analyte. Sequential variable size simplex optimization strategy was used and the progress of optimization was traced and visualized in various ways simultaneously. The optimum HS conditions appeared different for the groups of solvents tested, which proves that influence of experimental conditions (factors) depends on analyte properties. The optimization resulted in significant signal increase (from seven to fifteen times).

Abstract  Using data available in the Products Register at the Swedish National Chemical Inspectorate, an analysis was undertaken of the occurrence and turnover of glycol ethers in Sweden between 1986 and 1993. The most commonly used glycol ethers during 1991 and 1992 were propylene-glycol-monomethyl-ether (107982), ethylene-glycol-monobutyl-ether (111762), diethylene-glycol-monobutyl-ether (112345), and dipropylene-glycol-monomethyl-ether (20324327). Also used to a large extent were diethylene-glycol-monobutyl-ether-acetate (124174) (DEGBEA), diethylene-glycol-monoethyl-ether-acetate (112152), diethylene-glycol-monomethyl-ether (111773), and diethylene-glycol-monoethyl-ether (111900). The use of ethylene-glycol-monoethyl-ether (110805) and ethylene-glycol-monoethyl-ether-acetate (111159) decreased markedly from 1992 to 1993 while the use of all the other glycol ethers increased. The authors suggest that the marked increase in the use of ethylene-glycol-monomethyl-ether (109864) between 1992 and 1993 warrants further study.

Abstract  The retention of several bi- and trifunctional model solutes using different adsorbents, Florisil and silica, and different binary eluent systems containing isopropanol, dioxane or tetrahydrofuran as modifiers in n-heptane was investigated by high- performance liquid chromatography. The retention parameters are presented as log k'-log k' relationships obtained for solutes in different chromatographic systems. The selectivity of the systems investigated and the influence of modifiers on the adsorptive properties of the adsorbents are discussed.

Abstract  This paper describes a block silver impregnation technique for the CNS. The procedure, which is quite simple, yields highly consistent and reproducible results. After fixation during 6-10 days in 10% saline formaldehyde, 4 mm thick blocks of brain are treated with chromic anhydride and sodium potassium tartrate solution for 4 days. After this period the specimens are rinsed in 0.75% silver nitrate solution to which 8-10 drops of pyridine per 100 ml of solution have been added. This is followed by impregnation for 4 days at 37 degrees C in silver nitrate-pyridine solution identical to that used in the previous rinsing step. The impregnated blocks are reduced during 20-26 h in 1% pyrogallol to which 6 ml commercial formaldehyde per 100 ml of solution have been added, followed by dehydration in dioxan and paraffin embedding. Sections no thicker than 30 microns are then cut for histological study. This fundamentally neurofibrillar method reveals: neuronal somata and their processes; synaptic structures; fibre bundles; and cell nuclei and nucleoli.

Abstract  The stability and activity of the low redox potential Melanocarpus albomyces laccase (MaL) in various aqueous organic (acetone, ethanol, propylene glycol, diethylene glycol monomethyl ether) solvent systems was studied spectrophotometrically using 2,6-dimethoxyphenol (2,6-DMP) as substrate. In addition, reactivity of the enzyme with two lignans; matairesinol (MR) and 7-hydroxymatairesinol (HMR), was examined by oxygen consumption measurements in the most potential aqueous organic solvent systems. Polymerization of the lignans by MaL was verified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). Polymerization of the higher molecular weight lignin model compound, dehydrogenation polymers (DHPs), was studied by SEC. The solubilities of industrial softwood and hardwood kraft lignins were evaluated as parameters for investigation of enzymatic modification in aqueous organic solvent systems. The functioning of MaL in different aqueous organic media was excellent. Propylene glycol and diethylene glycol monomethyl ether were better solvents than ethanol or acetone in enzymatic oxidations. Even though they were the best solvents for enzyme oxidation, ethanol and propylene glycol were selected for further tests because of their different physicochemical properties. The results obtained in this study for the use of laccase-catalysed reactions in organic solvents to improve the efficiency of lignin oxidation may be exploited in several applications and areas in which the solubility of the reactants or products is a limiting factor. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  The water permeability (hydraulic conductivity; Lp) of turgid, intact internodes of Chara corallina decreased exponentially as the concentration of osmolytes applied in the medium increased. Membranes were permeable to osmolytes and therefore they could be applied on both sides of the plasma membrane at concentrations of up to 2.0 m (5.0 MPa of osmotic pressure). Organic solutes of different molecular size (molecular weight, MW) and reflection coefficients (sigma(s)) were used [heavy water HDO, MW: 19, sigma(s): 0.004; acetone, MW: 58, sigma(s): 0.15; dimethyl formamide (DMF), MW: 73, sigma(s): 0.76; ethylene glycol monomethyl ether (EGMME), MW: 76, sigma(s): 0.59; diethylene glycol monomethyl ether (DEGMME), MW: 120, sigma(s): 0.78 and triethylene glycol monoethyl ether (TEGMEE), MW: 178, sigma(s): 0.80]. The larger the molecular size of the osmolyte, the more efficient it was in reducing cell Lp at a given concentration. The residual cell Lp decreased with increasing size of osmolytes. The findings are in agreement with a cohesion/tension model of the osmotic dehydration of water channels (aquaporins; AQPs), which predicts both reversible exponential dehydration curves and the dependence on the size of osmolytes which are more or less excluded from AQPs (Ye, Wiera T Steudle, Journal of Experimental Botany 55, 449-461, 2004). In the presence of big osmolytes, dehydration curves were best described by the sum of two exponentials (as predicted from the theory in the presence of two different types of AQPs with differing pore diameters and volumes). AQPs with big diameters could not be closed in the presence of osmolytes of small molecular size, even at very high concentrations. The cohesion/tension theory allowed pore volumes of AQPs to be evaluated, which was 2.3 +/- 0.2 nm(3) for the narrow pore and between 5.5 +/- 0.8 and 6.1 +/- 0.8 nm(3) for the wider pores. The existence of different types of pores was also evident from differences in the residual Lp. Alternatively, pore volumes were estimated from ratios between osmotic (P-f) and diffusional (P-d) water flow, yielding the number of water molecules (N) in the pores. N-values ranged between 35 and 60, which referred to volumes of 0.51 and 0.88 nm(3)/pore. Values of pore volumes obtained by either method were bigger than those reported in the literature for other AQPs. Absolute values of pore volumes and differences obtained by the two methods are discussed in terms of an inclusion of mouth parts of AQPs during osmotic dehydration. It is concluded that the mouth part contributed to the absolute values of pore volumes depending on the size of osmolytes. However, this can not explain the finding of the existence of two different types or groups of AQPs in the plasma membrane of Chara.

Abstract  The protonation constant values of 12 new triazole derivatives have been determined by potentiometric and spectrophotometric methods. Potentiometric and spectrophotometric methods were used in ethanol %50 - water %50, dioxan %50 - water %50 and methanol %50 - water %50 mixtures at 25 degrees C with an ionic strength of 0.10 M. The calculation of the stoichiometric protonation constants was carried out using a PKAS computer program. In spectrophotometric method, the electronic absorption spectra of these triazole derivatives at various pH values at 200-400 nm intervals were recorded. The calibration of the electrode system was done potentiometrically by Gran's method. Data were calculated using the linearization method with Henderson-Hasselbach equation. The obtained results are in good accordance with potentiometric values. In addition, these triazole derivatives were studied in non-aqueous media (isopropyl alcohol, t-butyl alcohol, N,N-dimethyl formamide and acetonitrile) by potentiometric method according to half neutralization method. The half neutralization potential values and the corresponding pKa values were determined for all cases. The effect of solvents composition on the stoichiometric protonation constants are discussed.

Abstract  Lipase from Burkholderia cepacia (lipase BC) and lipase B from Candida antarctica (CALB) show an increase of the transesterification activity in toluene (up to 2.4- and 1.7-fold, respectively), when lyophilized with 18-crown-6. Nevertheless, the increase was observed only for low (less than 100) 18-crown-6/lipase molar ratio, while at higher ratios, the activity decreased for both enzymes to values lower than those obtained in the absence of the additive. In 1,4-dioxane, the activation is lower for lipase BC (1.7-fold) and for CALB (1.5-fold). Concerning enantioselectivity, tested in the kinetic resolution of 6-methyl-5-hepten-2-ol, only in the case of CALB, an effect of the additive (the E value varied from about 120 to 280) was observed. In water, 4% (w/w) of 18-crown-6 caused a loss of activity in the hydrolysis of p-nitrophenyl laurate of about 88 and 99.75%, compared to that observed in the absence of the crown ether for CALB and lipase BC, respectively. These data and the conformational analysis of both lipases, carried out by FT/IR spectroscopy indicate that the enzyme inactivation in water and in organic solvents at 18-crown-6/lipase molar ratios, higher than 100 might be due to conformational changes caused by the additive. Instead, at molar ratios lower than 100, 18-crown-6 might increase the activity - particularly, in toluene - thanks to the fact that in its presence, the enzyme has an hydrogen bonds pattern, more similar to that in water. This suggests that the additive would be able to provide the enzyme with more water.

Abstract  1,4-Dioxane is a probable human carcinogen, and an important emerging water contaminant. In this study, the biodegradation of dioxane by 20 bacterial isolates was evaluated, and 13 were found to be capable of transforming dioxane. Dioxane served as a growth substrate for Pseudonocardia dioxanivorans CB1190 and Pseudonocardia benzenivorans B5, with yields of 0.09 g protein g dioxane(-1) and 0.03 g protein g dioxane(-1), respectively. Cometabolic transformation of dioxane was observed for monooxygenase-expressing strains that were induced with methane, propane, tetrahydrofuran, or toluene including Methylosinus trichosporium OB3b, Mycobacterium vaccae JOB5, Pseudonocardia K1, Pseudomonas mendocina KR1, Ralstonia pickettii PKO1, Burkholderia cepacia G4, and Rhodococcus RR1. Product toxicity resulted in incomplete dioxane degradation for many of the cometabolic reactions. Brief exposure to acetylene, a known monooxygenase inhibitor, prevented oxidation of dioxane in all cases, supporting the hypothesis that monooxygenase enzymes participated in the transformation of dioxane by these strains. Further, Escherichia coli TG1/pBS(Kan) containing recombinant plasmids derived from the toluene-2- and toluene-4-monooxygenases of G4, KR1 and PKO1 were also capable of cometabolic dioxane transformation. Dioxane oxidation rates measured at 50 mg/L ranged from 0.01 to 0.19 mg hr(-1) mg protein(-1) for the metabolic processes, 0.1-0.38 mg hr(-1) mg protein(-1) for cometabolism by the monooxygenase-induced strains, and 0.17-0.60 mg hr(-1) mg protein(-1) for the recombinant strains. Dioxane was not degraded by M. trichosporium OB3b expressing particulate methane monooxygenase, Pseudomonas putida mt-2 expressing a toluene side-chain monooxygenase, and PseudomonasJS150 and Pseudomonas putida F1 expressing toluene-2,3-dioxygenases. This is the first study to definitively show the role of monooxygenases in dioxane degradation using several independent lines of evidence and to describe the kinetics of metabolic and cometabolic dioxane degradation.

Abstract  The goal of this study was to characterise the surface properties of completely degradable composite, polylactic acid and calcium phosphate glass, scaffolds. The composite scaffolds are made by solvent casting or phase-separation, using chloroform and dioxane as a solvent respectively. The surface properties were measured on composite films which were made using the same procedure as for the three-dimensional (3D) scaffolds without the pore-creating step. The surface morphology, roughness, wettability and protein adsorption capacity of the films was measured before and after sterilisation with ethylene oxide. The results reveal the influence of solvent type, glass weight content and sterilisation on the wettability, surface energy and protein adsorption capacity of the materials. The addition of glass particles increase the hydrophylicity, roughness and protein adsorption capacity of the surface. This effect, however, depends on the extent of the coating of the glass particles by the polymer film, which is much higher for dioxane films than for chloroform films. This information can be used to interpret and understand the biological behaviour of the 3D scaffolds made of this composite materials.

Abstract  Palladium-catalyzed cascade C-H alkenylation and arylation provides convenient access to polycyclic aromatic compounds. Treatment of 3-bromoaniline derivatives bearing a bromocinnamyl group on the nitrogen atom with a catalytic amount of [Pd(OAc)(2)] and PCy(3)·HBF(4) in the presence of Cs(2)CO(3) in dioxane affords naphthalene-fused indole derivatives in good yields. This double cyclization reaction is also applicable to heterocyclic substrates, giving fused indoles containing a heteroaromatic ring such as dibenzofuran, dibenzothiophene, carbazole, indole, or benzofuran through heterocyclic C-H arylation. When using a 2,6-unsubstituted aniline derivative, the first C-H arylation preferentially proceeds at the more hindered position of the aniline ring.

Abstract  A new one-pot synthesis of 9-(pyridin-2-yl)-9H-carbazoles through the simultaneous C-H activation and palladium(II)-catalyzed cross-coupling of N-phenylpyridin-2-amines with potassium aryltrifluoroborates is presented. Silver acetate and 1,4-dioxane proved to be the best oxidant and solvent, respectively. The product yields fluctuated from modest to excellent and the reaction showed sufficient functional group tolerance. p-Benzoquinone served as an important ligand for the transmetalation and reductive elimination steps in the catalytic process. The kinetic isotope effects (k(H)/k(D)) for the first and second C-H activation/C-C or C-N formation steps were measured as 2.14 and 1.18, respectively. Finally, a rational catalytic mechanism is presented based on all experimental evidence.

Abstract  New solvent systems--dioxane--isopropanol--water--ammonium (4:2:4:1) and dioxane--water--ammonium (6:4:1)--for rapid qualitative and quantitative estimation of nucleosides, nucleoside-5'-mono-, di- and triphosphates by thin layer chromatography is Silufol UV-254 are proposed. The Rf values for 40 ribo- and deoxyribonucleotides of these systems are given.

Abstract  A column containing a chemically bonded phase, MicroPak-NH2, was used to seperate six components of a chloramphenicol-intermediate mixture. Two-component eluents comprising a non-hydrogen-bonding apolar solvent (cyclohexane) and a polar hydrogen-bonding solvent (dioxan, tetrahydrofuran or isopropanol) were tested. A correlation was found to exist between the values of the capacity factor (k') and the Hildebrand parameter (delta). Three-component eluents comprising cyclohexane and one of the binary mixtures dioxan-isopropanol or tetrahydrofuran-isopropanol were also studied. Optimum separation conditions with respect to analysis time, degree of resolution and detection limit were established. The system was successfully used to analyse production samples.

Abstract  Using a customized capillary gas-liquid chromatography column, Henry's constants and activity coefficients at infinite dilution are reported for benzene, toluene, ethyl acetate, 1,4-dioxane, 1,2-dimethoxyethane, acetonitrile, nitromethane, tetrahydrofuran, chloroform, methanol, ethanol, and 1-propanol in ionic liquids 1-butyl, 3-methylimidazolium hydrogen sulfate [BMIM][HSO4] and 1-methyl, 3-trimethylsilylmethylimidazolium [SiMIM][Cl] chloride from 313 to 413 K. These acidic ionic liquids may provide suitable media for acid-catalyzed chemical reactions. (C) 2012 Elsevier Ltd. All rights reserved.