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The ring opening and oligomerisation reactions of an epoxide and an episulfide on aluminosilicates in the liquid phase

100%

Fási A., Pálinkó I., Gömöry Á., Kiricsi I.

Open Chemistry

2005

vol. 3

issue 2

230-244

The ring opening reactions of propylene oxide (methyloxirane) or ethylene sulfide )thiirane) were studied in the liquid phase over HZSM-5, HY-FAU or AlMCM-41 at 363 K or 423 K and under 1 or 20 bar pressure in a batch reactor. The proportion of these routes were identified: (i) single C−O scission providing non-cyclic products, (ii) double C−O cleavage leading to the loss of the heteroatom, (iii) oligomerisation resulting in cyclic dimers and the trimer of thiirane and a non-cyclic dimer of methyloxirane. The reaction pathway depended on the conditions and the solid acids used. Findings are compared to those in the gas phase over the same solid acids. Transformation mechanisms are also suggested.

Mimicking catalase and catecholase enzymes by copper(II)-containing complexes

76%

Szilágyi I., Horváth L., Labádi I., Hernadi K., Pálinkó I., Kiss T.

Open Chemistry

2006

vol. 4

issue 1

118-134

An imidazolate-bridged copper(II)-zinc(II) complex (Cu(II)-diethylenetriamino-μ-imidazolato-Zn(II)-tris(2-aminoethyl)amine perchlorate (denoted as “Cu,Zn complex”) and a simple copper(II) complex (Cu(II)-tris(2-aminoethyl) amine chloride (“Cu-tren”) were prepared and immobilised on silica gel (by hydrogen or covalent bonds) and montmorillonite (by ion exchange). The immobilised substances were characterised by FT-IR spectroscopy and their thermal characteristics were also studied. The obtained materials were tested in two probe reactions: catalytic oxidation of 3,5-di-tert-butyl catechol (DTBC) (catecholase activity) and the decomposition of hydrogen peroxide (catalase activity). It was found that the catecholase activity of the Cu,Zn complex increased considerably upon immobilization on silica gel via hydrogen bonds and intercalation by ion exchange among the layers of montmorillonite. The imidazolate-bridged copper(II)-zinc(II) complex and its immobilised versions were inactive in hydrogen peroxide decomposition. The Cu(II)-tris(2-aminoethyl)amine chloride complex displayed good catalase activity; however, immobilisation could not improve it.

The solubility of Ca(OH)2 in extremely concentrated NaOH solutions at 25°C

76%

Pallagi A., Tasi Á., Gácsi A., Csáti M., Pálinkó I., Peintler G., Sipos P.

Open Chemistry

2012

vol. 10

issue 2

332-337

The solubility of Ca(OH)2 in aqueous NaOH solutions up to 12.50 M at 25°C has been determined. The solubility data obtained for NaOH concentrations lower than 3 M was compared with those published in the literature. The solubility of Ca(OH)2 steadily decreases with the increasing NaOH concentration. The solubility data obtained at a constant ionic strength (I = 1 M Na(Cl,OH)) enabled the determination of the conditional solubility product of Ca(OH)2(s) (lgLCa(OH)2 = − 4.10 ± 0.02). Formation of the hydroxo complex CaOH+(aq) was invoked to describe the variation of [Ca2+]T with [OH−]T. Its conditional stability constant was found to be lgKCaOH+ = 0.97 ± 0.02. The experimental protocol employed was proven to be suitable for accurate solubility determinations in rapidly equilibrating systems comprising of highly concentrated, alkaline solutions and containing analytes in the ppm range. [...]

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3 Open Chemistry

1 2012

1 2006

1 2005

3 Pálinkó I.

1 Csáti M.

1 Fási A.

1 Gácsi A.

1 Gömöry Á.

1 Hernadi K.

1 Horváth L.

1 Kiricsi I.

1 Kiss T.

1 Labádi I.

1 Pallagi A.

1 Peintler G.

1 Sipos P.

1 Szilágyi I.

1 Tasi Á.

Search results

The ring opening and oligomerisation reactions of an epoxide and an episulfide on aluminosilicates in the liquid phase

Mimicking catalase and catecholase enzymes by copper(II)-containing complexes

The solubility of Ca(OH)2 in extremely concentrated NaOH solutions at 25°C