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1.
A simple, rapid and reproducible HPLC method was developed and validated for the simultaneous determination of olmesartan
(OLM) medoxomil and hydrochlorothiazide (HCT) in combined tablets. Chromatography was carried out on a 4.6 mm I.D × 200 mm,
5 μm cyano column with methanol–10 mM phosphoric acid containing 0.1% triethylamine (pH 2.5, 50:50 v/v) at a flow rate of 1.0 mL min−1 and UV detector was set at 260 nm. Valsartan (VAL) was used as internal standard (IS). A linear response was observed in the
range of 0.2–6 μg mL−1 (r
2 = 0.9998) for OLM and 0.1–4 μg mL−1 (r
2 = 0.9999) for HCT, respectively. The method showed good recoveries (99.56% for OLM and 99.48% for HCT) and the relative standard
deviation (RSD) values for intra- and inter-day precision were 0.70–1.59 and 0.80–2.00% for OLM and 1.20–1.37 and 1.63–1.93%
for HCT, respectively. The developed method was applied successfully for quality control assay of OLM and HCT in combined
tablets and in vitro dissolution studies. 相似文献
2.
Kamaluddin Abdur-Rashid Tara P. Dasgupta John Burgess 《Transition Metal Chemistry》2005,30(8):948-956
Solubilities in t-BuOH–, i-PrOH–, and EtOH–H2O mixtures at 298.2 K are reported for a number of salts of mono- and bi-nuclear cobalt(III) complexes. From these solubilities
and published single ion transfer chemical potentials, on the TATB (Ph4As +≡ BPh4-) assumption, transfer chemical potentials have been derived for most of these cobalt(III) complexes. The results and trends
are discussed in relation to those for other ions and complexes. Effects of ligand nature for transfer to t-BuOH–H2O mixtures are detailed and, for a selection of complexes, trends for transfer of a given complex to t-BuOH–, i-PrOH–, EtOH– , and MeOH– H2O mixtures are compared. 相似文献
3.
Summary Direct chiral-phase HPLC methods have been developed for the determination of flurbiprofen and its major metabolites, namely
4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen, in biological fluids using a derivatized amylose chiral stationary
phase (CSP; Chiral-pak AD). Quantification of all three analytes, both free and conjugated, in urine was carried out following
liquid-liquid extraction using tandem ultraviolet (UV) and fluorescence detection. Determination of flurbiprofen and the 4′-hydroxy-metabolite
in plasma utilized the same CSP but required modification in the mobile phase composition and sole use of fluorescence detection.
The urine assay was linear (r>0.998) between 0.05–10 μg mL−1, 0.1–20 μg mL−1 and 0.01–2 μg mL−1 for the enantiomers of flurbiprofen, 4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen respectively. The plasma
assay was linear (r>0.997) between 0.1–6 μg mL−1 and 0.01–0.6 μg mL−1 for the enantiomers of flurbiprofen and 4′-hydroxyflurbiprofen respectively. Both assays, typically yielded within- and between-day
imprecision and accuracy values less than 10% for the enantiomers of the different analytes. Initial volunteer studies suggest
that the disposition of flurbiprofen displays modest enantioselectivity in humans. 相似文献
4.
The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by
electron diffraction at 130∘C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface
has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified.
Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations
resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ
energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data
to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter
values (ra in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers
are r(C–C) = 1.507(5), r(C–C)ring, av = 1.397(3), r(C–S)av = 1.814(4), r(C–N) = 1.495(4), r(N–O)av = 1.223(3), ∠(C–C–C)ring = 116.0–122.5, ∠ C6–C4–C7 = 118.2(4), ∠ C–C–S = 113.6(6), ∠ C–S–C = 98.5(12), ∠ N–C–C4 = 121.9(3), ∠(O–N–C)av = 116.8(3), ∠ O–N–O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the
rotation about C–N bond, φC−N, were found to be 30.5–36.5∘ for different conformers. As to internal rotation about C–C and C–S bonds, values of φC−C = 68–118∘ and φC−S = 66–71∘ were obtained for the three most stable conformers with gauche orientation with respect to these bonds.
Some conclusions of this work were presented in a short communication in Russ. J. Phys. Chem. 2005, 79, 1701. 相似文献
5.
Z. Fengqi G. Hongxu L. Yang H. Rongzu C. Pei G. Sheng-li Y. Xu-wu S. Qizhen 《Journal of Thermal Analysis and Calorimetry》2006,85(3):791-794
The constant-volume combustion energies of
the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine
(4HDNPPb), ΔU
c
(2HDNPPb(s) and 4HDNPP(s)),
were determined as –4441.92±2.43 and –4515.74±1.92
kJ mol–1 , respectively, at 298.15 K. Their
standard enthalpies of combustion, Δc
m
H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K), and standard enthalpies of formation,
Δr
m H θ(2HDNPPb(s) and 4HDNPPb(s),
298.15 K) were as –4425.81±2.43, –4499.63±1.92 kJ
mol–1 and –870.43±2.76, –796.65±2.32
kJ mol–1 , respectively. As two combustion
catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the
pressure exponent of RDX–CMDB propellant. 相似文献
6.
G. Pavlović V. Tralić-Kulenović M. Vinković D. Vikić-Topić I. Matanović Z. Popović 《Structural chemistry》2006,17(3):275-285
The supramolecular synthon of amide group in the primary and secondary amides is well recognized to be infinite chains of the C(4) type formed by the intermolecular hydrogen bond of the type N–HO=C. On the other hand, there is a lack of structural data for the thioamides. Three compounds belonging to the class of N-aryl-fura-mides (N-(4-bromophenyl)-5-bromo-2-furancarboxamide, N-(4-chlorophenyl)-5-bromo-2-furancarboxamide) and to the class of N-aryl-thiofuramide (N-(4-methoxyphenyl)-2-furanthiocarboxamide) are prepared and characterized by the NMR spectroscopy in solution; molecular and crystal structures in the solid state have been determined by X-ray single crystal diffractometry and the structures in the gas phase by DFT and AM1 calculations. The investigation is carried out in order to establish supramolecular amide and thioamide synthons of hydrogen bonding patterns in these crystal structures. The geometry of the N–HO=C and the N–HS=C type of hydrogen bonds are compared due to the possibility of the N–H amide group to form intramolecular hydrogen bond with the furan oxygen atom, thus, commonly, leading to the three-center hydrogen bond pattern. The competition between the S=C proton acceptor of thioamides and the other proton acceptors (such as methoxy group) for the amide N–H proton donor group has been investigated. In that context, the above-mentioned compounds are correlated with the others of this class, structurally determined, so far. 相似文献
7.
The monomer 4-methylcoumarylacrylate (4-MCA) was synthesized from 7-hydroxy-4-methylcoumarin and characterized by conventional
methods. Homo and copolymers of 4-methylcoumarylacrylate and styrene were synthesized with different feed ratios using N,N-dimethylformamide (DMF) as a solvent and 2,2′-azobisisobutyronitrile as an initiator at 70°C.The resulting polymers were
characterized by infrared spectroscopy. Copolymer compositions were determined by nuclear magnetic resonance spectroscopy.
The monomer reactivity ratios were determined by applying the conventional linearization method of Fineman–Ross and Kelen–Tudos.
The reactivity ratios values of 4-methylcoumarylacrylate and styrene obtained from F–R plot are 1.36 and 0.62, respectively,
and from K–T plot 1.24 and 0.58, respectively. 相似文献
8.
T. V. Tyumkina I. F. Nuriev L. M. Khalilov V. R. Akhmetova U. M. Dzhemilev 《Chemistry of Natural Compounds》2009,45(1):61-65
The structure of a new compound was determined using PMR and 13C NMR spectroscopy (HHCOSY, HSBC, HMBC, ROESY) as 2-[3′-methoxy,4-O-β-D-galactopyranos-1-yl)benzyl]-3-(3″,4″-dimethoxybenzyl)-4hydroxybutyric acid, which was isolated for the first time from
seeds of Scotch thistle Onopordum acanthium L.
*For No. XII, see [1].
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 53–55, January–February, 2009. 相似文献
9.
A method for the simultaneous determination of N-methyl-2-pyrrolidone (NMP) and its metabolites 5-hydroxyl-N-pyrrolidone (5HNMP), N-methylsuccinimide (MSI) and 2-hydroxy-N-methylsuccinimide (2HMSI) in plasma and urine has been developed. Samples were purified by SPE using an ASPEC XL4. Analysis
was performed using LC–MS equipped with an APCI interface. The analysis provided linear responses in the range of 0.125–12 μg
mL−1 for all of the analytes and up to 150 μg mL−1 for 5HNMP and 2HMSI. The within day precision was in the range of 0.9–19.1% for plasma samples and 1.9–10.4% for urine samples
whereas the between day precisions were 4.5–11.9% and 1.2–17.5%, respectively. The method was deemed to be suitable for monitoring
the levels of NMP and its metabolites in the plasma and urine of occupationally exposed persons. 相似文献
10.
Manuel J. S. Monte Luís M. N. B. F. Santos José M. S. Fonseca Carlos A. D. Sousa 《Journal of Thermal Analysis and Calorimetry》2010,100(2):465-474
The vapour pressures of six para-substituted benzoic acids were measured using the Knudsen effusion method within the pressure range (0.1–1 Pa) in the following
temperature intervals: 4-hydroxybenzoic acid (365.09–387.28) K; 4-cyanobenzoic acid (355.14–373.28) K; 4-(methylamino)benzoic
acid (359.12–381.29) K; 4-(dimethylamino)benzoic acid (369.29–391.01) K; 4-(acetylamino)benzoic acid (423.10–443.12) K; 4-acetoxybenzoic
acid (351.28–373.27) K. From the temperature dependence of the vapour pressure, the standard molar enthalpy, entropy and Gibbs
energy of sublimation, at the temperature 298.15 K, were derived for each of the studied compounds using estimated values
of the heat capacity differences between the gaseous and the crystalline phases. Equations for estimating the vapour pressure
of para substituted benzoic acids at the temperature of 298.15 K are proposed. 相似文献
11.
Bikshandarkoil R. Srinivasan Christian Näther Sunder N. Dhuri Wolfgang Bensch 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):397-411
Summary. Four new organic ammonium tetrathiotungstates (N–Me–enH2)[WS4] (1), (N,N′-dm-1,3-pnH2)[WS4] (2), (1,4-bnH2)[WS4] (3), and (mipaH)2[WS4] (4), (N–Me–enH2 = N-methylethylenediammonium, N,N′-dm-1,3-pnH2 = N,N′-dimethyl-1,3-propanediammonium, 1,4-bnH2 = 1,4-butanediammonium, and mipaH = monoisopropylammonium) were synthesized by the base promoted cation exchange reaction and characterized by elemental analysis,
infrared, Raman, UV-Vis and 1H NMR spectroscopy as well as single crystal X-ray crystallography. The structures of 1–4 consist of [WS4]2− tetrahedra which are linked to the organic ammonium cations via N–H⋯S hydrogen bonding. The strength and number of the S⋯H
interactions affect the W–S bond lengths as evidenced by distinct short and long W–S bonds. The IR spectra exhibit splitting
of the W–S vibrations, which can be attributed to the distortion of the [WS4]2− tetrahedron. From a comparative study of several known tetrathiotungstates it is observed that a difference of more than
0.033 ? between the longest and shortest W–S bonds in a tetrathiotungstate will result in the splitting of the asymmetric
stretching vibration of the W–S bond. 相似文献
12.
A simple, sensitive and accurate spectrophotometric method for the determination of sulphonamides (sulphamethoxazole (SMZ),
sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX), sulphametrole (SMR), and sulphadimidine sodium (SDD)) has been developed.
The charge-transfer reactions between sulphonamides as n-electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone
(chloranilic acid, p-CLA) as π-acceptors resulting in highly coloured complexes were studied. Experimental conditions for these CT reactions were carefully
optimised. Beer’s law is valid over the concentration ranges from 4–280 μg mL−1, 4–260 μg mL−1, 4–200 μg mL−1, and 4–200 μg mL−1 of SMZ, SGD, SQX, and SDD using DDQ reagent, respectively. While the calibration curves are linear in the concentration ranges
from 4–180 μg mL−1, 4–80 μg mL−1, 4–60 μg mL−1, 4–180 μg mL−1, and 4–60 μg mL−1 of SMZ, SGD, SQX, SMR, and SDD, respectively, using TCNQ reagent and from 4–380 μg mL−1 and 4–300 μg mL−1 of SQX and SDD, respectively, using p-CLA reagent, respectively. Different analytical parameters, namely molar absorptivity
(ε), standard deviation, relative standard deviation, correlation coefficient, limit of detection, and limit of quantification,
were calculated. The results obtained by the proposed methods are in good agreement with those obtained by the official method
as indicated by the percent recovery values. 相似文献
13.
A novel polymer-forming diimide–diacid, 5,5′-bis[4-(4-trimellitimido phenoxy)phenyl]-hexahydro-4,7-methanoindan (II), was prepared by the condensation reaction of 5,5′-bis[4-(4-aminophenoxy)phenyl]-hexahydro-4,7-methanoindan with trimellitic
anhydride. A series of novel aromatic poly(amide–imide)s (PAIs) containing polycyclic cardo groups was prepared by the direct
polycondensation of II with various aromatic diamines using phosphorylation techniques. The polymers had inherent viscosities between 0.71 and 0.96 dl/g.
The polymers were soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide, and could be cast from their DMAc solutions into transparent, flexible, and tough films, except for III
a
. These films had yield strengths of 85–114 MPa, tensile strengths of 77–102 MPa, an elongation at break of 8–17%, and initial
moduli of 2.0–2.7 GPa. Wide-angle X-ray diffraction revealed that the polymers are amorphous. The glass-transition temperatures
of the polymers were in the range 242–312 °C. All the PAIs exhibited no appreciable decomposition below 430 °C, and their
10%-weight-loss temperatures were in the range 484–507 °C in nitrogen and 494–515 °C in air.
Received: 26 January 1999 Accepted in revised form: 11 May 1999 相似文献
14.
Bikshandarkoil R. Srinivasan Christian N?ther Sunder N. Dhuri Wolfgang Bensch 《Monatshefte für Chemie / Chemical Monthly》2006,121(2):397-411
Four new organic ammonium tetrathiotungstates (N–Me–enH2)[WS4] (1), (N,N′-dm-1,3-pnH2)[WS4] (2), (1,4-bnH2)[WS4] (3), and (mipaH)2[WS4] (4), (N–Me–enH2 = N-methylethylenediammonium, N,N′-dm-1,3-pnH2 = N,N′-dimethyl-1,3-propanediammonium, 1,4-bnH2 = 1,4-butanediammonium, and mipaH = monoisopropylammonium) were synthesized by the base promoted cation exchange reaction and characterized by elemental analysis,
infrared, Raman, UV-Vis and 1H NMR spectroscopy as well as single crystal X-ray crystallography. The structures of 1–4 consist of [WS4]2− tetrahedra which are linked to the organic ammonium cations via N–H⋯S hydrogen bonding. The strength and number of the S⋯H
interactions affect the W–S bond lengths as evidenced by distinct short and long W–S bonds. The IR spectra exhibit splitting
of the W–S vibrations, which can be attributed to the distortion of the [WS4]2− tetrahedron. From a comparative study of several known tetrathiotungstates it is observed that a difference of more than
0.033 ? between the longest and shortest W–S bonds in a tetrathiotungstate will result in the splitting of the asymmetric
stretching vibration of the W–S bond. 相似文献
15.
The current state and prospects of development of the chemistry of isomeric thienopyridines (synthesis, chemical transformations,
and biological activities) are analyzed. Particular attention is given to studies published in the last 10–15 years.
Dedicated to Academician V. I. Minkin on the occasion of his 70th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 847–885, April, 2005. 相似文献
16.
Ar and Kr matrix effect on the geometry and Cl–H stretching (ν
s
(Cl–H)) and librational (ν
l
(Cl–H)) frequencies of the hydrogen-bonded complex Cl–H···NH3 are simulated within the framework of polarizable continuum model with integral equation formalism (IEF-PCM) at B3LYP and
MP2 levels of theory with the basis set 6-311++G(2df,2pd). Within the framework of B3LYP and IEF-PCM, the simulated gas phase,
Ar, and Kr matrix ν
s
(Cl–H) of the complex are 2140, 1684, and 1550 cm−1, respectively, which deviate from the experimental values (~2200, 1371, and 1218 cm−1) by −60, 313, and 332 cm−1. Within the framework of MP2 and IEF-PCM, the gas phase, Ar, and Kr matrix ν
s
(Cl–H) are calculated as 2366, 2037, and 1957 cm−1 by the harmonic approximation, and as 2177, 1876, and 1665 cm−1 by the full-dimensional anharmonic correction. The matrix effect modeling is of greater importance than the anharmonic correction
in accounting for the large experimental gas phase to Ar or Kr matrix shift of the ν
s
(Cl–H) (−829 or −982 cm−1). Our calculations do not support the assignment of the 733.8 and 736.9 cm−1 bands to the Ar and Kr matrix ν
l
(Cl–H). 相似文献
17.
B. V. Paponov O. V. Shishkin S. V. Shishkina R. I. Zubatyuk A. L. Kalyuzhny V. I. Musatov 《Russian Chemical Bulletin》2008,57(3):622-631
6-Aroyl-7-arylindolo[3,4-jk]phenanthridin-5(4H)-ones (2a–i) were synthesized by heating 3-(2-aryl-2-oxoethylidene)-2,3-dihydroindol-2-ones (1a–i) in DMF. Compounds 2a–i are formed via the dimerization of two molecules of unsaturated ketones 1a–i proceeding as the [2+4] cycloaddition through the formation of intermediate spiro adducts. The further Pfitzinger rearrangement,
decarboxylation, and heteroaromatization afford compounds 2a–i. The structures of the reaction products were established by spectroscopic methods and X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 609–618, March, 2008. 相似文献
18.
Summary The separation ofm-, p-, o- xylenes andm-, p- ethyltoluenes was studied on a packed column with 2,5% of 4-[(4-chlorobenzyl)oxy]-4′-cyanoazobenzene (CBOCA) on Chromosorb
W HP 100–120 mesh. The synthesis and study of the mesomorphic behaviour of CBOCA are presented. Temperature range for the
separation ofm-, p-, o- xylenes (in this order of elution) is 125–85°C, at cooling. The best separation was achieved at about 90°C. The separation
temperature domain ofm-ethyltoluene fromp- ethyltoluene is 160–85°C. 相似文献
19.
Liviu V. Costea Vasile N. Bercean Valentin Badea Klaus Gerdes Ulrich Jordis 《Monatshefte für Chemie / Chemical Monthly》2006,8(2):737-744
1H-3-Methyl-4-ethoxycarbonyl-5-(benzylidenehydrazino)pyrazoles are key intermediates in obtaining various heterocyclic systems
including pyrazolotriazoles. We present the voltammetric behavior of these compounds in nonaqueous media, with the following
para substituents grafted on the benzene ring: –N(CH3)2, –OH, –OCH3, –F, –Cl, –CF3, –NO2, as well as of the novel compounds with –Br, –I, and –SCH3 in the para position, in order to elucidate the influence of the various substituents on the mechanism of anodic oxidation. 相似文献
20.
Liviu V. Costea Vasile N. Bercean Valentin Badea Klaus Gerdes Ulrich Jordis 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):737-744
Summary. 1H-3-Methyl-4-ethoxycarbonyl-5-(benzylidenehydrazino)pyrazoles are key intermediates in obtaining various heterocyclic systems
including pyrazolotriazoles. We present the voltammetric behavior of these compounds in nonaqueous media, with the following
para substituents grafted on the benzene ring: –N(CH3)2, –OH, –OCH3, –F, –Cl, –CF3, –NO2, as well as of the novel compounds with –Br, –I, and –SCH3 in the para position, in order to elucidate the influence of the various substituents on the mechanism of anodic oxidation. 相似文献