共查询到20条相似文献,搜索用时 203 毫秒
1.
I. V. Ukrainets A. A. Tkach L. V. Sidorenko O. V. Gorokhova 《Chemistry of Heterocyclic Compounds》2006,42(10):1301-1307
1-R-4-Hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid anilides have been prepared. It has been shown experimentally that
these compounds are brominated by molecular bromine in glacial acetic acid at position 4 of the anilide fragment. The antitubercular
properties of the compounds synthesized are discussed.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1508–1516, October, 2006. 相似文献
2.
Jinzhang Gao Jing Liu Jie Ren Xiuli Niu Yingying Zhang Wu Yang 《Central European Journal of Chemistry》2009,7(3):298-302
This paper described the determination of p-nitroaniline in a double organic substrate oscillating system of tartrate-acetone-Mn2+-KBrO3-H2SO4. Under the optimum conditions, temperature was chosen as a control parameter to design the bifurcation point and proposed
a convenient method for determination of p-nitroaniline. Results showed that the system consisting of 3.5 mL 0.06 mol L−1 tartrate, 4.0 mL 0.7 mol L−1 H2SO4, 1.5 mL 1.5×10−4 mol L−1 MnSO4, 4.0 mL 0.4 mol L−1 acetone and 7.0 mL 0.05 mol L−1 KBrO3 was very sensitive to the surrounding at 33.5°C. A good linear relationship between the potential difference and the negative
logarithm concentration of p-nitroaniline was obtained to be in the range of 2.50×10−7∼3.75×10−5 mol L−1 with a lower detection limit of 2.50×10−8 mol L−1.
相似文献
3.
Characterization of ganoderma spore lipid by stable carbon isotope analysis: implications for authentication 总被引:2,自引:0,他引:2
Liu X Xu SP Wang JH Yuan JP Guo LX Li X Huang XN 《Analytical and bioanalytical chemistry》2007,388(3):723-731
The ratios of stable carbon isotopes (13C/12C) of ganoderma fruiting body, ganoderma spore, ganoderma spore lipid (GSL) and individual fatty acids in GSL were determined
by gas chromatography–stable isotope ratio mass spectrometry and elemental analysis–stable isotope ratio mass spectrometry.
These values fall into a range from −26.9 to −23.3‰, suggesting that the cut log as the Ganoderma-cultivated substrate in Fujian, China, may belong to C3 plants. Eighteen fatty acids were identified and their abundances
measured by gas chromatography–mass spectrometry in the six GSL samples with C16:0, C18:0, C18:1 and C18:2 as major constituents, and C16:1 is evidently enriched compared with the other edible vegetable oils. On the basis of the compositions of fatty acids and
stable carbon isotopes in GSL, we have developed a novel method to detect the adulteration of GSL products with cheaper edible
vegetable oils. An example of ideal blending between GSL and C4 or C3 vegetable oil is further provided to expound the discrimination
procedures and corresponding sensitive indicators. Simultaneously, the carbon isotope fractionation in the biosynthesis of
individual fatty acids was observed, revealing that the formation of C18:0 from C16:0 in ganodema spores had no conspicuous 13C enrichment of +0.4‰ for Ganoderma sinensis spore and +0.1‰ for G. lucidum spore; the desaturation of C18:0 to C18:1 resulted in a distinct 13C depletion of −1.4‰ for G. sinensis spore and −0.9‰ for G. lucidum spore; and the next desaturation from C18:1 to C18:2 displayed no evident 13C fractionation of −0.1‰ for G. sinensis spore and −0.2‰ for G. lucidum spore.
Figure
Ganoderma lucidum has been widely used in traditional Chinese medicines. Ganoderma spore lipid (GSL) extracted from the spores of G. lucidum has been approved as a health food supplement. However, because of rarity, GSL has become a target for adulteration with
cheaper vegetable oils. 相似文献
4.
A systematic study on the structural characteristics of the 2-pyranone ring containing molecules with bromine, nitrile, and
amide substituents at the C-3 position in the ring is conducted in the electronic ground (S
0) state by DFT calculations using the B3LYP/6-311++G** method. The geometrical structure of the bromine substituted compound,
which shows potent hepatoprotective activity, is studied both in the ground (S
0) and first excited singlet (S
1) states using RHF/6-311++G** and CIS/6-311++G** methods respectively. The molecules are found to exist in two isomeric forms
gauche and trans that have the enthalpy difference of less than 3.32 kcal/mol; the latter is the preferred orientation in the gaseous phase.
The S
1 state is a 1(π,π*) state that arises π-electron transfer from the region of a double bond in the pyranone ring to the region of the internuclear
bond connecting the 2-pyranone and benzene rings. A complete vibrational analysis is conducted for the 3-bromo-6-(4-chlorophenyl)-4-thiomethyl-2H-pyran-2-one
molecule based on the experimental infrared spectra in the 50–4000 cm−1 region and DFT/6- 311++G** computations of vibrational frequencies for the gauche and trans isomeric forms. Spectral assignments based on the potential energy distribution along the internal coordinates confirm the
nonplanar structure of the molecule. 相似文献
5.
Yu. N. Belokoń Yu. N. Bubnov T. D. Churkina A. A. Chesnokov K. A. Kochetkov N. Yu. Kuznetsov V. N. Khrustalev N. I. Raevskii 《Russian Chemical Bulletin》1997,46(5):982-989
The stereochemistry of addition of Br2 toE-andZ-(R)-N-cinnamoyl-4-phenyloxazolidin-2-ones was studied. It was established that both theE-andZ-isomers give only two out of four possible diastereoisomers in the presence of Lewis acids (BPr3 or AlBr3). The absolute configurations of the diastereoisomers [(2S', 3R') and (2R', 3S') of the side chain] were established by X-ray structural analysis. The stereochemistry observed is a consequence of the stepwise
bromination and the absence of bridging bromine atoms along the reaction coordinate. In the case of theZ-isomer, the diastereoselectivity of the reaction was high, whereas it is low in the case of theE-isomer. It was suggested that at the first stage of addition of Br2 at the C=C bond, the attack of the Br+ cation occurs at the α position, and the second stage of transfer of Br− occurs with the participation of boron or aluminum complexes in the intermediate state of the bromination reaction. This
hypothesis as well as the results of calculations of the initial conformations of the substrates provide an explanation of
the regularities observed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1022–1028, May, 1997. 相似文献
6.
D. G. Kim 《Chemistry of Heterocyclic Compounds》2008,44(11):1355-1358
Bromination of 2-vinylthioquinoline and cis-2-styrylthioquinoline with molecular bromine leads to the formation of 2-bromo(3-phenyl)-2,3-dihydrothiazolo[3,2-a]quinolinium
bromides, and of 2-allyl-thioquinoline to a mixture of 2-and 3-bromomethyl-2,3-dihydrothiazolo[3,2-a]quinolinium bromides.
Iodine reacts with allylthioquinoline with the formation of 3-iodomethyl-2,3-dihydrothiazolo-[3,2-a]quinolinium triiodide.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1664–1668, November, 2008. 相似文献
7.
2-(2-Furyl)-1-methyl-1H-acenaphtho[9,10-d]imidazole was obtained by the condensation of 9,1-acenaphthenequinone with furfural
in the presence of ammonium acetate followed by N-methylation of the obtained 2-(2-furyl)-1H-acenaphtho[9,10-d]imidazole with
methyl iodide in N-methylpyrrolid-2-one in the presence of potassium hydroxide. It was established that its electrophilic
substitution in an acidic medium only takes place at position 2 of the furan ring while in a neutral medium both position
2 and position 7 of the aromatic part of the molecule undergo electrophilic attack.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 191–196, February, 2006. 相似文献
8.
A series of novel 3‐((4‐(t‐butyl)‐2‐(2‐benzylidenehydrazinyl)thiazol‐5‐yl)methyl)quinolin‐2(1H)‐ones ( 7a – 7z ) were designed, synthesized and evaluated for their ability of inhibiting neuraminidase (NA) of in?uenza H1N1 virus. Some compounds displayed moderate influenza NA inhibitory activity. Compound 7l with the scaffold of 2‐(2‐(2‐methoxybenzylidene)hydrazinyl)thiazole was the best one, exhibiting moderate NA inhibitory activity with IC50 of 44.66 µmol/L. Structure‐activity relationship showed that compounds with methoxy or hydroxy groups at the ortho position, fluorine and nitro groups at the meta position and chlorine and bromine groups at the para position of phenyl ring were more active. Docking study indicated that compound 7l has important interactions with some key residues (including Asp151, Glu119, Arg292, Tyr406, and Asn347) and binds to 430‐cavity adjacent to NA active site. 相似文献
9.
Katsu T Tsunamoto Y Hanioka N Komagoe K Masuda K Narimatsu S 《Analytical and bioanalytical chemistry》2007,387(6):2057-2064
S,S,S-Tris(2-ethylhexyl) phosphorotrithioate proved to be an effective solvent mediator for constructing a mexiletine-sensitive
membrane electrode in combination with an ion-exchanger, sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate.
Among a series of phosphorus compounds containing phosphoryl (P=O) groups, this solvent mediator showed the highest sensitivity
to mexiletine in phosphate-buffered physiological saline containing 0.15 mol L−1 NaCl and 0.01 mol L−1 NaH2PO4/Na2HPO4 (pH 7.4), giving a detection limit of 2 × 10−6 mol L−1 with a slope of 58.8 mV decade−1. This is the best reported detection limit of any mexiletine-sensitive electrode developed to date. Owing to its high selectivity
toward inorganic cations, the electrode was used to determine the level of mexiletine in saliva, the monitoring of which is
quite effective for controlling the dose of this drug noninvasively. The mexiletine concentrations determined with the mexiletine-sensitive
electrode compared favorably with those determined by high-performance liquid chromatography. 相似文献
10.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
11.
I. V. Ukrainets N. L. Bereznyakova O. V. Gorokhova A. V. Turov 《Chemistry of Heterocyclic Compounds》2007,43(11):1426-1433
The bromination of 3-allyl-4-hydroxy-2-oxo-1,2-dihydroquinoline by molecular bromine is accompanied by the closure of a five
membered furan ring and gives the corresponding 2-bromomethyl-3,9-dihydro-2H-furo[2,3-b]quinolin-4-one.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1677–1686, November, 2007. 相似文献
12.
R. Berkecz I. Ilisz A. Ivanov-Sztojkov I. Szatmári F. Fülöp D. W. Armstrong A. Péter 《Chromatographia》2007,65(5-6):337-341
The enantiomers of 1-(α-aminobenzyl)-2-naphthol and 2-(α-aminobenzyl)-1-naphthol analogs were separated isothermally on a 3,5-dimethylphenylcarbamoylated β-cyclodextrin-based chiral stationary phase (Cyclobond DMP), with an n-hexane/alcohol modifier as mobile phase. Optimization of the separation was achieved by variation of combinations of the
polar mobile phase additives ethanol and methanol. The nature and position of the α-aminobenzyl substituent of the 1- and 2-naphthol analogs influenced the retention and the selectivity. 相似文献
13.
The reactions of 2-trichloromethylchromones with trimethylenediamine in ethanol at room temperature afford 2-(2-hydroxyaroylmethylene)hexahydropyrimidines.
Under analogous conditions, 2-methylchromone gives a mixture ofN,N′-trimethylenebis[3-amino-1-(2′-hydroxyphenyl)-2-buten-1-one] andN,N′-trimethylenebis(imine) of 2-hydroxyacetophenone.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2140–2143, November, 1999. 相似文献
14.
The reactions of 1-amino-2-phenylethynyl-and 2-acylethynyl-1-amino-9,10-anthraquinones with HNO2 in a mixture of dioxane and a mineral acid at 20 °C were studied. Under these conditions, 2-alkynyl-1-amino-9,10-anthraquinones,
irrespective of the structure of the C=CR substituent, are cyclized into 3-substituted 1H-naphtho[2,3-glindazole-6,11-diones. The nature of the acetylenic group in the initial compound and the choice of the mineral
acid determine the structure of the substitutent in position 3 of the product (1,1-dichloroalkyl or acyl) but have no effect
on the regiospecificity of cyclization.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 110–114, January, 1997. 相似文献
15.
I. V. Ukrainets N. L. Bereznyakova O. V. Gorokhova A. V. Turov S. V. Shishkina 《Chemistry of Heterocyclic Compounds》2007,43(8):1001-1007
The hydrogenation of the benzene part of the molecule in N-allyl-substituted 4-hydroxy-2-quinolinones does not affect the
nature of their bromination by molecular bromine and gives 2-bromomethyl-5-oxo-1,2,6,7,8,9-hexahydro-5H-oxazolo[3,2-a]quinolines.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1180–1188, August, 2007. 相似文献
16.
T. M. Ugurchieva A. V. Lozanova M. V. Zlokazov V. V. Veselovsky 《Russian Chemical Bulletin》2007,56(8):1544-1549
trans-Stereoselective electrophilic cyclization of (2R*,SS*)-N, N-diisopropyl-2-phenylsulfinylpent-4-enamide under the action of bromine afforded (3R*,5S*, SS*)-N-(5-bromomethyl-3-phenylsulfinyltetrahydrofuran-2-ylidene)-N,N-diisopropylammonium bromide. Its transformations under the conditions of hydrolysis, dehydrobromination, and hydride reduction
were studied.
Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1485–1490, August, 2007. 相似文献
17.
A. N. Kost L. G. Yudin V. A. Budylin N. G. Yaryshev 《Chemistry of Heterocyclic Compounds》1966,1(4):426-427
In bromination of indoles, the bromine atom will most probably enter at position 2 or 3. For example, indole and 2-methylindole [1] brominate at position 3, while some 3-substituted indoles [2] brominate at position 2. In the case of 2, 3-dimethylindole it was shown [3], that bromine does not enter the benzene ring, as would have been expected, but adds to the active 2, 3 (double) bond of the indole. 相似文献
18.
CeO2 nanoparticles approximately 12 nm in size were synthesized and subsequently characterized by XRD, TEM and UV-vis spectroscopy.
Then, a gold electrode modified with CeO2 nanoparticles was constructed and characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).
The modified electrode demonstrated strong catalytic effects with high stability towards electrochemical oxidation of rutin.
The anodic peak currents (measured by differential pulse voltammetry) increased linearly with the concentration of rutin in
the range of 5.0 × 10−7–5.0 × 10−4 mol · L−1. The detection limit (S/N = 3) was 2.0 × 10−7 mol · L−1. The relative standard deviation (RSD) of 8 successive scans was 3.7% for 5.0 × 10−6 mol · L−1 rutin. The method showed excellent sensitivity and stability, and the determination of rutin in tablets was satisfactory. 相似文献
19.
E. B. Melnikova M. M. Elchaninov A. A. Milov B. S. Lukyanov 《Chemistry of Heterocyclic Compounds》2008,44(9):1070-1076
The electrophilic reactions (nitration, bromination, hydroxymethylation, formylation, acylation) and radical substitution
reactions (nitration, arylation) of 2-(2-furyl)benzothiazole have been studied. It was found that all of the reactions occur
at position 5 of the furan ring. Only nitration in PPA gave the 5',6-dinitro derivative. Quantum-chemical calculation data
for the electron density distribution in the neutral and protonated 2-(2-furyl)benzothiazole molecules are given.
Dedicated to Boris Aleksandrovich Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1331–1338, September, 2008. 相似文献
20.
Hg stable isotope analysis by the double-spike method 总被引:2,自引:0,他引:2
Recent publications suggest great potential for analysis of Hg stable isotope abundances to elucidate sources and/or chemical
processes that control the environmental impact of mercury. We have developed a new MC-ICP-MS method for analysis of mercury
isotope ratios using the double-spike approach, in which a solution containing enriched 196Hg and 204Hg is mixed with samples and provides a means to correct for instrumental mass bias and most isotopic fractionation that may
occur during sample preparation and introduction into the instrument. Large amounts of isotopic fractionation induced by sample
preparation and introduction into the instrument (e.g., by batch reactors) are corrected for. This may greatly enhance various
Hg pre-concentration methods by correcting for minor fractionation that may occur during preparation and removing the need
to demonstrate 100% recovery. Current precision, when ratios are normalized to the daily average, is 0.06‰, 0.06‰, 0.05‰,
and 0.05‰ (2σ) for 202Hg/198Hg, 201Hg/198Hg, 200Hg/198Hg, and 199Hg/198Hg, respectively. This is slightly better than previously published methods. Additionally, this precision was attained despite
the presence of large amounts of other Hg isotopes (e.g., 5.0% atom percent 198Hg) in the spike solution; substantially better precision could be achieved if purer 196Hg were used. 相似文献