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Open access

S. Pavlovica, A. Gaidule and A. Zicmanis

Abstract

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

Open access

L. Anteina, A. Gaidule and A. Zicmanis

Abstract

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

Open access

E. Ausekle, A. Priksane and A. Zicmanis

Cyclodehydration of Diols in Acidic Ionic Liquids

In the presence of sulfonic acid group functionalized Bronsted-acidic ionic liquids, cyclodehydration of 1,2-ethanediol and 1,4-butanediol is investigated. The role of structure and catalytic activity of ionic liquids on the formation of cyclic ethers: 1,4-dioxane and tetrahydrofuran - is determined.

Open access

A. Podjava, P. Mekšs and A. Zicmanis

Liquid Chromatography - Mass Spectrometry of Zwitterionic Liquids

We have implemented full mass spectrometric assay of several 3-(1-alkyl-2-methylimidazolio)propanesulfonates, which are known as zwitterionic liquids (ZILs). Hydrophilic interaction liquid chromatography (HILIC) column and different mobile phases in both isocratic and gradient elution conditions were used for separation of the compounds present in these samples. The structures of the impurities have been confirmed by LC-MS/MS experiments. In addition, fragmentation pathways of ZILs were studied for different collision energies (0-50 eV) in positive electrospray ionization (ESI) mode under collision-induced dissociation conditions. Several new routes of fragmentation are briefly discussed. These include possible rearrangements and imidazolium ring expansions, which hypothetically proceed through carbocationic intermediates in the gas phase. Currently these processes are studied in a more detailed fashion.

Open access

A. Robalds, M. Klavins and A. Zicmanis

Peat as Sorbent for Cu2+ and Cr3+ Ions

Heavy metals as trace elements can often be found in industrial waste waters, and their discharge to the environment is a significant threat due to their acute toxicity to the aquatic and terrestrial life. The common methods used for removal of toxic metals and trace elements from the municipal and industrial waste waters are based on their adsorption onto insoluble compounds - sorbents. Synthetic sorbents usually are quite expensive; therefore, as a prospective approach to the metal removal, the use of a natural sorbent - peat - was tested. Peat as sorbent was proved to have a relatively high sorption capacity in respect to the studied metal ions, it can be used batchwise and in a dynamic regime and is a relatively robust and reliable sorbent regarding pH, the ionic strength, and the amounts of sorbed metal.

Open access

M. Klavins, L. Ansone and A. Zicmanis

Behaviour of Nanomaterials in the Environment: A Study of Interaction between Humic Acids and Fullerene C60

Interaction between buckminsterfullerene and humic substances of different origin was investigated using fluorescence spectrometry as function of concentration of humic substances, pH and ionic strength. Binding constants of humic substances and buckminsterfullerene were calculated. It can be suggested that the complexation was driven by hydrophobic interaction depending on properties of the interacting compounds. Hydrophobic interaction model was indicated by linear Stern-Volmer plot, and high Kd values characterized interaction between buckminsterfullerene and humic acids. The results of this study support the development of understanding of fate of nanomaterials in environment as well as development of analytical techniques for nanomaterials in water and wastewater treatment approaches.

Open access

A. Zicmanis, S. Pavlovica, E. Gzibovska, P. Mekss and M. Klavins

2-Hydroxyethylammonium Carboxylates - Highly Biodegradable and Slightly Toxic Ionic Liquids

Highly hydrophilic ionic liquids easily form in reactions between 2-hydroxyethyl amines and carboxylic acids. They have low toxicity and high biodegradability, serve both as reaction solvents and catalysts in condensation reactions, and they may be reused several times without any purification.

Open access

S. Pavlovica, E. Gzibovska, A. Zicmanis, P. Mekss and M. Klavins

Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester

Hantzsch ester synthesis was investigated using (2-hydroxyethyl)-ammonium carboxylates, polar and hydrophilic ionic liquids possessing low toxicity and high biodegradability. The reaction rates and yields of the products in ionic liquids were greater than those in common organic solvents. The relationship between the structure of the ionic liquid used and the structure of the heterocyclic compound was investigated.

Open access

A. Podjava, P. Mekss, A. Zicmanis and S. Krasnov

Gas-phase chemical properties of several (1-methylimidazol-3-io)-alkane-1-carboxylates (alkane=ethane, propane and butane) have been investigated in this study. These substances are synthesized using classical transformations and analyzed in positive ionization mode using collision-induced dissociation (0-50 eV). These experiments were carried out in both deuterated and undeuterated solvent media. The data obtained in this study show, that carboxylate group weakly influences fragmentation of zwitterionic imidazolium carboxylates in positive electrospray mode. On the other hand, these compounds exert a tendency to form various adducts with sodium and potassium ions and to participate in hydrogen/deuterium exchange in the gas phase.