Synthesis of Β-Nitrostyrene in Highly Hydrophilic Ionic Liquid Media

The condensation reaction of benzaldehyde with nitromethane that resulted in the formation of β-nitrostyrene was studied in ionic liquid media - (2-hydroxyethyl)ammonium carboxylates (formates, lactates, acetates) without application of any other catalyst. The dependence of product yield on the ionic liquid cation and anion structure, the polarity of the ionic liquid and the pseudo-pH value of the reaction medium was investigated. The highest yield of the condensation reaction product - β-nitrostyrene was achieved in (2-hydroxyethyl) ammonium formate medium

Prediction of Reversed-Phase Liquid Chromatography Retention Parameters for Phenylisothiocyanate Derivatives of Amino Acids

We report our experience with highly polar and charged analyte retention parameter prediction for a reversed-phase high-performance liquid chromatographic method. The solvatic retention model has been used to predict retention of phenylisothiocyanate derivatives of 25 natural amino acids under gradient elution conditions. Retention factors have been calculated from molecular parameters of analyte structures and from the column and eluent characteristics. A step-by-step method which includes the first guess prediction of initial conditions from structural formula and fine tuning of the retention model parameters using data from successive runs can substantially save method development time

Separation of Tegafur and its Impurities by Reversed-Phase High-Perfomance Liquid Chromatography

The chromatographic behavior of tegafur and its impurities on a naphthalene Cosmosil piNAP column under reversed-phase high-performance liquid chromatography conditions was examined. A good description of the retention was achieved through the application of statistical weights to the widely used quadratic relationships between the logarithm of the retention factor (log k) and the organic solvent concentration in the mobile phase. Optimum conditions for isocratic separation of the compounds were found with acetonitrile concentration of 10-30% in the mobile phase

Characterization and Physicochemical Evaluation of Molecular Complexes Formed Between Umifenovir and Dicarboxylic Acids

The paper reports the investigation of three umifenovir molecular complexes with dicarboxylic acids, prepared to improve the bioavailability of this drug. All three molecular complexes were investigated by powder X-ray diffraction, infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. The solubility and thermal properties were determined as well. Polymorph and solvate screening of umifenovir molecular complexes were performed by recrystallization from various solvents, as well as neat and solvent-drop grinding

1,3-Dialkylimidazolium Dimethyl Phosphates – Effective Solvents and Catalysts for Condensation Reactions

We report the preparation, characterization and exploitation of 1,3-dialkylimidazolium dimethyl phosphates. Condensation reactions of benzaldehyde with ethyl cyanoacetate and with malonic acid were performed in these ionic liquids either in absence or in presence of other catalysts. The effect of ionic liquid structure on the condensation reaction rates and yields was discussed

The Behavior of Proteins on Reversed-Phase Supports During High-Performance Liquid Chromatography and Prediction of Protein Retention Time on Ymc Columns

Protein molecules present more complex analytical challenges than conventional low molecular weight pharmaceutical compounds, and thus need powerful analytical approaches for the entire pharmaceutical development and quality control process. We used high-performance liquid chromatography to investigate the reversed-phase chromatographic behavior of eleven proteins (albumin, carbonic anhydrase, cytohrome c, L-glutamic dehydrogenase, enolase, α-lactoglobulin, Lysozyme, myoglobin and ribonuclease. By using a water/organic solvent/trifluoroacetic acid system the influence of experimental parameters was examined, and chromatographic results from two C4- chain-length supports were found to be comparable. The model enables prediction of initial conditions from two experimental data points for different types of reversed-phase columns with water-acetonitrile-TFA, water-methanol-TFA, and water-2-propanol-TFA mobile phases

Recent Advances in the Synthesis and Transformations of Heterocycles Mediated by Fluoride Ion Activated Silanes

Modern methodologies that use silanes in the presence of fluoride ion for the preparation and transformation of three-, four-, five-, six-, and seven-membered heterocycles have been reviewed, covering literature from January 2010 to December 2012. Characteristic reactions in side chains of heterocyclic compounds are presented

Characterization of Humic Acids from Raised Bog Peat

Humic substances form most of the organic component of soil, peat and natural waters, but their structure and properties are very much dependent on the source. The aim of this study was to characterize humic acids from raised bog peat to evaluate the homogeneity of humic acids isolated from the bog bodies and to study peat humification impact on the properties of humic acids. Peat humic acids (HA) have an intermediate position between the living organic matter and coal organic matter, with their structure formed in a process where the relatively labile moieties (carbohydrates, amino acids, etc.) are destroyed, and thermodynamically more stable aromatic and polycyclic structures emerge. Comparatively, the studied peat HAs were at the start of this transformation process. Concentrations of carboxyl and phenolic hydroxyl groups changed depending on the source depth of peat from which HAs were isolated. The carboxylic acidity of peat HAs increased with depth of the source and the extent of peat humification

Advanced Research of the Triassic Clay from the Baltic Region

A procedure of smectite containing clay enrichment has been optimized, and the process of sedimentation has been studied. The new enrichment based method for quantitative determination of clay fraction in smectite containing sediment was developed. A new method for obtaining organoclays from enriched smectite clays has been investigated. The method is based on solid-state reaction between smectite and organic compounds, where organic molecules can be intercalated in dried clay mineral (montmorillonite) by solid-state reactions, without or with use of solvents. The enriched clay and the obtained organoclay samples were characterized with X-ray powder diffraction (PXRD).

Investigation of Radionuclide Sorption on Peat

Organic sorbents like peat can be successfully used for the purification of radioactive waste waters and are favoured by economical and technical considerations. The peat filters are also friendlier to the environment, since the manufacturing of such filters is a low emission process. This study examined the sorption of radionuclides 137Cs, 55Fe, 63Ni and 14C on peat samples. The initial radioactivity of the peat samples was studied before the experiments. Peat samples were taken from different bogs. Radionuclide solutions were prepared using deionised water and appropriate radionuclide composition from the Salaspils research reactor stock water. It was found that in all cases of peat samples, the main natural radionuclides were 210Pb, 40K and 214Bi. The artificial radionuclides 152Eu, 137Cs and 60Co were also found in the peat samples. Radionuclide sorption studies indicated that the initial radioactivity of the solution decreased in the case of radionuclides 63Ni, 14C, 55Fe and 137Cs. This confirmed that peat samples can effectively remove the radionuclides from radioactive water solutions.