- Synthesis, protolytic equilibria, and antimicrobial action of nifuroxazide analogs
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The present paper reports on the synthesis of four hydrazones derived from 5-nitro-2-furfural, 5-nitro-2-thiophenal, isoniazid, 2,4- and 3,4-dihydroxy-N′-methylenebenzohydrazide. The acid-base dissociation constants of these compounds were determined in an aqueous solution. The protolytic equilibria-related ability of hydrazones to “sense” anions in dimethyl sulfoxide-containing water of different concentrations is studied using spectrophotometry, NMR spectroscopy, and quantum chemistry methods. The antimicrobial action of the hydrazones was tested and compared with that of the known drug nifuroxazide.
- Gamov,Kiselev,Murekhina,Zavalishin,Aleksandriiskii,Kosterin, D.Yu.
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- Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime-Zn System
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Reaction of 2-hydroxyimino-4,4-dimethyl-3-oxo-pentanenitrile (common abbreviation HPiCO, pivaloyl-cyanoxime) with zinc sulfate in an aqueous solution results in the formation of the two new complexes: [Zn(PiCO){H(PiCO)2}(H2O)] (I) and tetranuclear Zn complex [Zn4(μ3-OH)2(PiCO)6 (H2O)4] (II). Both complexes were characterized by elemental analysis, IR- and UV-visible spectra, DSC/TGA studies, and X-ray analysis. In complex II, the PiCO- cyanoxime anion adopts three bidentate binding modes: O-monodentate, chelating (κ2), and bridging (2) coordinations. Also, the ligand represents the mixture of two diasteromers (cis-anti and cis-syn) that form five- and six-membered chelate rings with Zn atoms and cocrystallize in one unit cell at population of 0.57-0.43. There are two crystallographically different Zn-centers in the ASU, and two μ3-bridging hydroxo-groups arrange via inversion center the formation of an elegant tetranuclear complex. Each Zn atom has a molecule of coordinated water and is in the distorted octahedral environment. Because of the structural flexibility and multidentate propensity of the pivaloyl-cyanoxime, complex II may act as a structural model of naturally occurring Zn-containing enzymes. Indeed, compound I exhibits an efficient catalytic performance for transesterification reaction of various esters in ethanol under mild reaction conditions. Therefore, obtained results allow assignment of observed activity as green catalysis.
- Opalade, Adedamola A.,Karmakar, Anirban,Rúbio,Pombeiro, Armando J. L.,Gerasimchuk, Nikolay
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p. 13962 - 13974
(2017/11/24)
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- Novel chemoselective de-esterification of esters of polyacetoxy aromatic acids by lipases
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Candida cylindracea lipase (CCL) and porcine pancreatic lipase (PPL) have been used for deacetylation of peracetates of methyl and ethyl esters of six different polyphenolic acids in organic solvents. Exclusive de-esterification of the ester groups derived from the phenolic hydroxy and aliphatic acid over the ester group of the aromatic acid and aliphatic alcohol has been achieved affording the corresponding esters of phenolic acids in as high yields as 90-97%. The results have been corroborated with the mechanism of lipase action.
- Parmar, Virinder S.,Kumar, Ajay,Bicht, Kirpal S.,Mukherjee, Shubhasish,Prasad, Ashok K.,Sharma, Sunil K.,Wengel, Jesper,Olsen, Carl E.
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p. 2163 - 2176
(2007/10/03)
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