Volumetric Properties of the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} System at Temperatures from (283.15 to 333.15) K and Pressures from (0.1 to 35) MPa

Densities of pure 1-butyl-3-methylimidazolium methylsulfate, [C₄mim][MeSO₄], and its mixtures with methanol have been measured. Measurements were made with an accuracy of ±0.2 kg·m^?3, using a vibrating-tube densimeter, over the temperature and pressure ranges (283.15–333.15) K and (0.1–35) MPa, respectively. The experimental densities for the pure ionic liquid and alcohol have been correlated by the Tait equation. The results for the {x ₁[C₄mim][MeSO₄] + (1 ? x ₁)MeOH} system have been correlated by a van Laar equation involving parameters that are dependent on temperature and pressure. Excess volumes have been obtained directly from the experimental densities, while isobaric expansivities, isothermal compressibilities, and related excess properties were calculated from the correlation equation. Exceptionally strong pressure and temperature influences on these properties were observed.     

Chelating Polymers. II. Amino Acetic Acid Chelating Polymers Derived from Hydroxyarylamino Acetic Acids

The prototype dimeric chelating compounds 3,3′-methylenebis-[N(4-hydroxyphenyl) iminodiacetic acid] and 3,3′-methylenebis-[N(4-methoxyphenyl) iminodiacetic acid] were synthesized and characterized by composition analysis, infrared spectroscopy, and potentiometric titration data. Their chelating characteristics with Cu(II), Ni(II), Co(II), and Zn(l1) ions were established by composition analysis and comparative infrared spectroscopy.

The results suggest chelation and structures of the usual iminodiacetatometal complex type for the Ni(II), Co(II), and Zn(I1) compounds of 3,3′methylenebis-[N-(4-hydroxyphenyl) iminodiacetic acid] and for the Cu(I1, Ni(II), and Co(I1) compounds of 3,3′-methylenebis-[N-(4-methoxyphenyl) iminodiacetic acid]. The composition analysis of each of these compounds indicates 1:2:2 mole ratios of ligand to metal ion to water. Square planar structures are proposed wherein the two iminodiacetatometal chelate moieties are essentially independent of each other.

The composition analysis of the Cu(II) compound of 3,3′-methylenebis-[N-(4-hydroxyphenyl) iminodiacetic acid] indicates a 1:2:1 mole ratio of ligand to metal ion to water. Structures are proposed in which some of the carboxylate groups are bridges between two metal coordination centers.

The composition analysis of the Zn(II) compound of 3,3′-methylenebis-[N-(4-methoxyphenyl) iminodiacetic acid] indicates a 1:1 mole ratio of ligand to metal ion. A structure is proposed in which both nitrogen atoms and two of the four carboxylate groups of the dimeric ligand are coordinated to the same metal ion.

A preliminary investigation was made of oligomeric compounds analogous to the prototype dimeric compounds.     

Catalytic activity of Pd/CN systems in hydrogenation of styrene

Hydrogenation of styrene was applied as a test reaction to study the catalytic activity of Pd deposited on the surface of carbonaceous materials enriched with nitrogen (C_N). The nitrogen content in the support material was found to have a great influence on the degree of styrene conversion to ethylbenzene. In addition, the reaction was carried out in the presence of modified carbonaceous materials acting as catalysts.     

Determination of pesticides in vegetables using large-volume injection column liquid chromatography-electrospray tandem mass spectrometry

Direct injection of a large volume (900 microl) of a sample extract onto a liquid chromatographic (LC) column, LC separation and electrospray tandem mass spectrometric detection were used for the quantitative analysis of a wide polarity range of pesticides in carrots and potatoes. Rapid sample preparation involved extraction of a small amount of sample (2 g) with a small volume of organic solvent (3 ml), clean-up over a filter and dilution of the organic extract with the aqueous LC eluent. The extraction efficiency for the selected pesticides was studied using methanol, acetone and acetonitrile as solvents. Evaluation of the performance of the overall method, using extraction with acetonitrile and detection in the selected-reaction-monitoring mode, showed excellent linearity in the range of 2-100 microg/kg with limits of detection of 0.5-2 microg/kg for both types of vegetable. With relative standard deviations of the MS peak area measurements of less than 6.5% (n=8) the repeatability of the method was fully satisfactory.