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1.
Vasil Andruch Monika Telepc˘áková Ioseph S. Balogh Nikoleta Urbanová 《Mikrochimica acta》2003,142(1-2):109-113
The complex formation and extraction of chromium(VI) with 2-[2-(4-methoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium
chloride reagent was studied by means of spectrophotometry. The influence of medium acidity, the concentration of chloride
ions and dye reagent, the nature of the extractant and some other factors (time of extraction, stability of color, interference,
etc.) on the absorbance of colored extracts were studied. The optimum conditions were found to be 0.02–0.1 M H2SO4, 1.0–1.5 M NaCl, (2.0–2.5) × 10−4 M of reagent. The absorbance of the colored extracts obeys Beer’s Law in the range of 0.26–7.28 mg L−1. The procedure of Cr(VI) extraction and spectrophotometric determination was examined.
Author for correspondence. E-mail: andruch@kosice.upjs.sk
Received November 19, 2002; accepted March 10, 2003
Published online June 13, 2003 相似文献
2.
M. Madesclaire P. Coudert V. P. Zaitsev Yu. V. Zaitseva 《Chemistry of Heterocyclic Compounds》2004,40(10):1310-1314
The interaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with a series of symmetrical ketones has been studied. As a result isomeric oxazolidines are formed in a ratio of 85:15. These oxazolidines were shown to decompose readily under the action of hydrazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1518–1523, October, 2004. 相似文献
3.
M. Madesclaire V. P. Zaitsev J. V. Zaitseva S. Kh. Sharipova 《Chemistry of Heterocyclic Compounds》2007,43(10):1325-1332
A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds
was studied.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007. 相似文献
4.
K. A. Frolov V. V. Dotsenko S. G. Krivokolysko A. N. Chernega V. P. Litvinov 《Russian Chemical Bulletin》2005,54(5):1340-1342
Reduction of (E)-3-aryl-2-(4-arylthiazol-2-yl)acrylonitriles with lithium aluminum hydride in dry ether afforded (Z)-1-amino-3-aryl-2-(thiazol-2-yl)prop-1-ene derivatives in 15 to 40% yields. The structure of (Z)-1-amino-3-(2-chlorophenyl)-2-[4-(4-methylphenyl)thiazol-2-yl]prop-1-ene was confirmed by X-ray diffraction analysis.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
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Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1301–1303, May, 2005. 相似文献
5.
A. N. Chekhlov 《Journal of Structural Chemistry》2005,46(5):946-949
The crystal and molecular structure of E-3-(1,3-dimethylindol-2-yl)methylene-4-isopropylidenetetrahydrofuran-2,5-dione, C18H17NO3 (I), was investigated by XRD. The monoclinic structure of I (space group P21/c, a = 12.411(2) Å, b = 7.586(1) Å, c = 16.107(3) Å, β = 96.90(2)°, Z = 4) was solved by direct methods and refined by the full-matrix least squares in an anisotropic approximation to R = 0.044 for all 2842 independent reflections collected (CAD-4 automatic diffractometer, λCuK α). The geometric parameters of sterically strained molecule I were determined with a high accuracy. 相似文献
6.
Vera L. M. Silva Artur M. S. Silva Diana C. G. A. Pinto José A. S. Cavaleiro José Elguero 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):87-95
Abstract An efficient synthesis method for the preparation of a series of new (Z)- and (E)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles was developed. The reaction of (Z)- and (E)-3-styrylchromones with hydrazine hydrate afforded the corresponding (Z)- and (E)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles, except for nitro derivatives, where both (Z)- and (E)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations is discussed and the
stereochemistries of all products were established by NMR experiments.
Graphical abstract
相似文献
7.
Vera L. M. Silva Artur M. S. Silva Diana C. G. A. Pinto José A. S. Cavaleiro Attila Vasas Tamás Patonay 《Monatshefte für Chemie / Chemical Monthly》2008,139(11):1307-1315
Several (E)- and (Z)-3-styrylchromones were prepared by two different methodologies, the Wittig reaction of chromone-3-carboxaldehyde with benzylic ylides and the Knoevenagel condensation of chromone-3-carboxaldehyde with phenylacetic acids in the presence of potassium tert-butoxide under microwave irradiation. The Knoevenagel reaction followed by a decarboxylation offered an efficient and diastereoselective method for preparing (E)-3-styrylchromones in a shorter reaction time. It was also demonstrated that phenylacetic acid can also be substituted with
success by phenylmalonic acid. The stereochemistry of all products was assigned by NMR experiments.
Correspondence: Artur M. S. Silva, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal. 相似文献
8.
S. Belyakov M. Fleisher D. Jansone L. Leite E. Lukevics 《Chemistry of Heterocyclic Compounds》2009,45(4):417-421
Monocrystals of the trans and cis isomers of 3-cyano-4-[2-(4-methoxyphenyl)vinyl]-6,6-dimethyl-5,6-dihydro-2H-pyran have been obtained and an X-ray structural
analysis of them has been carried out. Both compounds have a molecular structure corresponding to symmetry group C1. The heterocyclic ring is in a distorted envelope conformation. The crystals of the trans isomer are rhombic and have a fir-tree type of packing. The crystal packing of the cis isomer is formed by pairs of molecules, each of which consists of only one enantiomer.
*Dedicated to deeply respected Professor Hank van der Plas in connection with his jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 535-540, April, 2009. 相似文献
9.
I. I. Ponomarev D. Yu. Razorenov D. S. Perekalin P. V. Petrovskii Z. A. Starikova 《Russian Chemical Bulletin》2007,56(1):154-159
The reaction of 2-methyl-3-(4-tolyl)-4(3H)-quinazolone with benzil produces 2-[(Z)-3-oxo-2,3-diphenylprop-1-enyl]-3-(4-tolyl)-4(3H)-quinazolone, which is readily transformed into 2-(3,3-diphenylsuccinimido)-N-(4-tolyl)benzamide on dissolution in organic water-containing solvents. The rearrangement mechanism was suggested and investigated
by the quantum chemical PM3 method.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 146–151, January, 2007. 相似文献
10.
Reactions of substituted 3-cyanopyridine-2(1H)-thiones with methyllithium gave 3-acetylpyridine-2(1H)-thiones. The best results were achieved by adding a solid-state thione to a solution of methyllithium in ether (thione:
MeLi = 1: 3). The compounds obtained and their 3-pentanoyl analogs were used to synthesize a number of fused heterocyclic
systems.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1504–1507, July, 2008. 相似文献
11.
G. Yu. Ishmuratov M. P. Yakovleva G. V. Zaripova L. P. Botsman R. R. Muslukhov G. A. Tolstikov 《Chemistry of Natural Compounds》2004,40(6):548-551
A novel synthesis of the promising optically pure chiral (4R)-4-methylpentanolide that is based on several regiospecific oxidative transformations of (4R)-2,4-dimethyl-1-(1-methylethyl)-1-cyclohexene, the product of addition of (–)-menthone and methylmagnesium iodide followed by acid dehydration, was proposed.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 451–453, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
12.
The structural transition of the l- and dl forms of poly(N-(1- hydroxymethyl)propylmethacrylamide (PHMPMA) in aqueous solution was studied by measuring the pressure dependence of the apparent scattering intensity, differential scanning calorimetry (DSC), and circular dichroism (CD). The thermodynamic implications of the results are discussed in relation to the chiral structure of the side chain, and differences in the thermal and barometric transitions. T-P diagrams of the transition showed characteristic ellipsoid features. Antagonism of the temperature and pressure effects was observed only for P(dl-HMPMA). For P(l-HMPMA), the transition temperature (T
tr) decreased with increasing pressure, and the highest T
tr was observed at atmospheric pressure (0.1 MPa). For both polymers, the highest P
trs were observed at the lowest temperatures. The l polymer showed a specific negative peak in its CD spectrum at around 220 nm in the lower temperature region and the temperature dependence was reproduced by a single-step transition, with the midpoint corresponding to the T
tr obtained from the scattering measurements. Coupled with the results from the DSC, the different behavior between the P(l-HMPMA) and P(dl-HMPMA) could be explained in terms of the chain states before and after the transition. The cooperative factors derived from the DSC measurement revealed that about 4 to 5 polymers of the present size were necessary to perform a thermal transition for P(l-HMPMA), and that P(dl-HMPMA) underwent its transition as an almost single molecular event.This revised version was published online in June 2005 with correction to the article category. 相似文献
13.
A. N. Chekhlov 《Journal of Structural Chemistry》2005,46(2):381-385
Crystal and molecular structure of 2-(o-hydroxyphenyl)-4,6-diphenylpyridine C23H17NO (I) has been studied by single crystal XRD. The structure (monoclinic, space group P21/c, a = 8.757(2) Å, b = 20.682(4) Å, c = 9.743(2) Å, β = 108.14(2)°, Z = 4) was solved by the direct method and refined anisotropically in the full-matrix approximation to R = 0.076 using all 2660 measured independent reflections (automated diffractometer CAD-4, CuKα). OH group of the molecule of I is disordered in the crystal over three positions with occupation factors 70%, 15% and 15%. The structure contains a very strong intramolecular hydrogen bond O-H?N disordered over three directions. 相似文献
14.
I. M. Aladzheva O. V. Bykhovskaya P. V. Petrovskii T. A. Mastryukova 《Russian Chemical Bulletin》2007,56(12):2456-2459
Two methods for the synthesis of N-(2-chloroethyl)glycine and-DL-alanine esters are proposed: 1) reductive amination of the C=O group of glyoxilic or pyruvic acids upon treatment with 2-chloroethylamine
and sodium cyanoborohydride in methanol and 2) alkylation of 2-chloroethylamine with α-haloalkanoic acid esters in K2CO3-MeCN two-phase system.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2372–2374, December, 2007. 相似文献
15.
M. Vorona G. Veinberg S. Belyakov M. Petrova E. Liepinsh E. Lukevics 《Chemistry of Heterocyclic Compounds》2008,44(4):486-493
By condensation of tert-butyl 3-methyl-7-oxoceph-3-em-4-carboxylate and its 3-acetoxymethyl analog with acetylmethylenetriphenylphosphorane
and 3-trimethylsilylpropyn-2-ylindenetriphenylphosphorane tert-butyl 7Z-acetylmethylene-3-methylceph-3-em-4-carboxylate and
also 7Z-and 7E-isomers of tert-butyl 3-acetoxymethyl-7-(3-trimethylsilylpropyn-2-ylidene)ceph-3-em-4-carboxylates were synthesized.
Oxidation of these compounds with 1 equivalent of meta-chloroperbenzoic acid gave their 1R-and 1S-sulfoxides, and oxidation
with 2 equivalents gave the corresponding sulfones. According to data from 1H NMR spectroscopy, the carbonyl of the β-lactam descreens proton H-9 of the alkylidene group in the 7Z-isomers more strongly
than in the 7E-isomers, shifting their signals to weaker field. Analogous shifts of the H-6 signal to weaker field was observed
in the 1R-sulfoxides in comparison with that for the 1S-sulfoxide. These results were confirmed by X-ray crystallography of
tert-butyl 7Z-acetylmethylene-3-methyl-1S-oxoceph-3-em-4-carboxylate and tert-butyl 7Z-acetylmethylene-3-methyl-1,1-dioxoceph-3-em-4-carboxy-late.
In memory of Professor A.A. Potekhin
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 618–626, April, 2008. 相似文献
16.
Hanyuan Deng 《Journal of mathematical chemistry》2008,43(1):119-133
A (n, n + 1)-graph G is a connected simple graph with n vertices and n + 1 edges. In this paper, we determine the lower bound for the Hosoya index in (n, n + 1)-graphs in terms of the order n, and characterize the (n, n + 1)-graph with the smallest Hosoya index. 相似文献
17.
Rajab Abu-El-Halawa Alaa Sarabi Mustafa M. El-Abadelah 《Monatshefte für Chemie / Chemical Monthly》2008,139(10):1251-1255
Interaction between 2,5-dichlorothiophene-3-carbonyl isothiocyanate, accessible via 2,5-dichlorothiophene-3-carbonyl chloride, and model heterocyclic amines produced the respective 2,5-dichloro-N-(substituted aminocarbonothioyl)thiophene-3-carboxamides. Upon heating, the deprotonated form of the latter underwent intramolecular
cyclization to deliver the corresponding 2-(substituted amino)-4H-thieno[3,2-e]-1,3-thiazin-4-ones. The structures of these new bicyclic derivatives and their acyclic precursors are based on microanalytical
and spectral (IR, MS, and NMR) data.
Correspondence: Rajab Abu-El-Halawa, Chemistry Department, Faculty of Science, Al al-Bayt University, Mafraq, Jordan. 相似文献
18.
A. N. Chekhlov 《Journal of Structural Chemistry》2004,45(4):724-728
The crystal structure of 1-(2-pyridiniomethyl)-2,4-bis(phenylsulfonyl)benzene bromide, (C24H20NO4S2)+. Br– (I) has been investigated by X-ray diffraction (XRD)analysis. The triclinic structure of I (space group P1, a = 7.863 , b = 8.350 , c = 9.043 , = 94.00°, = 97.81°, = 104.62°, Z = 1) was solved by direct methods and refined by full-matrix least-squares analysis in an anisotropic approximation to R = 0.048 for all 4570 reflections collected (CAD-4 automatic diffractometer, CuK
). The geometrical parameters of the organic cation were determined with a sufficient degree of accuracy. The crystal structure of I involves a very strong interionic hydrogen bond N+-HBr–.Original Russian Text Copyright © 2004 by A. N. ChekhlovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 759–763, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
19.
D. V. Shishkin E. R. Mukhamed’yarova N. Z. Baibulatova V. A. Dokichev Yu. V. Tomilov 《Chemistry of Natural Compounds》2007,43(3):293-297
Diastereomers of N-(2-(1-adamantyl)-2-hydroxyethyl)cytisine were synthesized by reduction of N-(2-(1-adamantyl)-2-oxoethyl)cytisine with NaBH4. Their structures were established using x-ray structure analysis.
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Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–247, May–June, 2007. 相似文献
20.
Ivana Bradiaková Tatiana Ďurčeková Naďa Prónayová Anton Gatial Alžbeta Krutošíková 《Chemical Papers》2009,63(5):586-591
2-[3-(Trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (I) was prepared by a three-step synthesis. Its reaction with phosphorus sulfide rendered thione II which was methylated to 2-[3-(Trifluoromethyl)phenyl]-4-methylsulfanylfuro[3,2-c]pyridine (III). 5-Methyl-2-[3-(trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (IV) was obtained by the reaction of I with methyl iodide in PTC conditions. The chlorine atom in derivate V was replaced with heterocyclic secondary amines via nucleophilic substitution and 4-substituted furopyridines VIa and VIb were thus prepared. 2-[3-(Trifluoromethyl)phenyl]furo[3,2-c]pyridine-4-carboxylic acid (VII) was obtained by hydrolysis of the corresponding carbonitrile Va. 相似文献