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Saulius Armalis Inga Krikŝĉiuniene Erika Kubiliene Nii-Kotey Djane Kuria Ndungu Lennart Mathiasson 《International journal of environmental analytical chemistry》2013,93(1-4):233-242
Abstract The performance of a flow-through mercury coated reticulated vitreous carbon (RVC) electrode in the potentiometric stripping analysis (PSA) of trace metals has been examined. A wall-jet glassy carbon cell was used for the comparative experiments. Experimental parameters influencing the stripping signals have been optimised in order to use the stripping analysis after the preconcentration and matrix isolation by supported liquid membrane (SLM) technique. The SLM with di-2-ethylhexyl-phosphoric acid (DEHPA) as the extractant in the membrane liquid for proton driven transport of trace metals across the membrane has been chosen. Results presented for lead determination in river water demonstrate the analytical advantages of coupled technique SLM-PSA. 相似文献
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Vytas MartynaitisRasa Steponavi?iūt? Sonata Krikštolaityt?Joana Solovjova Sven Mangelinckx Norbert De KimpeWolfgang Holzer Algirdas Ša?kus 《Tetrahedron》2011,67(21):3945-3953
1-Hydroxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones, as a new type of azaheterocyclic hydroxamic acids, have been synthesized regioselectively from 1-carbamoylmethyl- or 1-(methoxycarbonyl)methyl-2,3,3-trimethyl-3H-indolium salts by reaction with hydroxylamine in the presence of a strong base. The alkylation and reduction with sodium borohydride of these novel heterocycles have been investigated. When treated with protic acids 1-hydroxy- or 1-alkoxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones underwent ring opening of the imidazolidine to afford 1-[2-(hydroxyamino)-2-oxoethyl]-2,3,3-trimethyl-3H-indolium salts. The structural assignments are based on extensive 1H, 13C and 15N NMR spectroscopic studies and single crystal X-ray analyses. 相似文献
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Vaida Miliinait Elena Plytninkien Roberta Bakien Aurimas Bieliauskas Sonata Kriktolaityt Greta Ra
kauskien Egl Arba
iauskien Algirdas a
kus 《Molecules (Basel, Switzerland)》2021,26(18)
A simple and efficient synthetic route to the novel 3a,4-dihydro-3H,7H- and 4H,7H-pyrazolo[4′,3′:5,6]pyrano[4,3-c][1,2]oxazole ring systems from 3-(prop-2-en-1-yloxy)- or 3-(prop-2-yn-1-yloxy)-1H-pyrazole-4-carbaldehyde oximes has been developed by employing the intramolecular nitrile oxide cycloaddition (INOC) reaction as the key step. The configuration of intermediate aldoximes was unambiguously determined using NOESY experimental data and comparison of the magnitudes of 1JCH coupling constants of the iminyl moiety, which were greater by approximately 13 Hz for the predominant syn isomer. The structures of the obtained heterocyclic products were confirmed by detailed 1H, 13C and 15N NMR spectroscopic experiments and HRMS measurements. 相似文献
4.
Miglė Dagilienė Prof. Vytas Martynaitis Vilija Kriščiūnienė Dr. Sonata Krikštolaitytė Prof. Algirdas Šačkus 《ChemistryOpen》2015,4(3):363-369
A new class of chemosensors based on the 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L−1, and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials. 相似文献
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In the reaction of 4a-methyl-2,3,4,4a-tetrahydro-1H-carbazole and its 6-methyl- and 6-bromosubstituted derivatives with 2-chloroacetamide
respectively by 9-carbamoylmethyl-4a-methyl-2,3,4,4a-tetrahydro-1H-carbazolium chlorides are formed, which can be cyclized
into 5,6,7,7a-tetrahydro-1H, 4H-imidazo[2,1-k]-carbazol-2(3H)-one derivatives. Reaction of 4a-methyl-2,3,4,4a-tetrahydro-1H-carbazole
hydrochloride with acrylamide gives 8a-methyl-1,2,6,7,8,8a-hexahydro-5H-pyrimido[2,1-k]carbazol-3(4H)-one. 7a, 12-Dimethyl-3,4,4a,5,6,7,7a,12-octahydropyrido[3,2-j]carbazol-2(1H)-one
was synthesized by the reaction of 4a,9-dimethyl-2,3,4,4a-tetrahydro-9H-carbazole with acrylamide.
Department of Organic Chemistry, Kaunas University of Technology, Kaunas LT-3028, Lithuania; Published in Khimiya Geterotsiklicheskikh
Soedinenii, No. 5, pp. 645–648, May 1999. 相似文献
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Arminas Urbonavi
ius Graziana Fortunato Emilija Ambrazaityt Elena Plytninkien Aurimas Bieliauskas Vaida Miliinait Renzo Luisi Egl Arba
iauskien Sonata Kriktolaityt Algirdas a
kus 《Molecules (Basel, Switzerland)》2022,27(12)
An efficient synthetic route to construct diverse pyrazole-based chalcones from 1-phenyl-1H-pyrazol-3-ols bearing a formyl or acetyl group on the C4 position of pyrazole ring, employing a base-catalysed Claisen–Schmidt condensation reaction, is described. Isomeric chalcones were further reacted with N-hydroxy-4-toluenesulfonamide and regioselective formation of 3,5-disubstituted 1,2-oxazoles was established. The novel pyrazole-chalcones and 1,2-oxazoles were characterized by an in-depth analysis of NMR spectral data, which were obtained through a combination of standard and advanced NMR spectroscopy techniques. 相似文献
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