排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
2.
The reaction of fluorobenzene with urotropine in trifluoroacetic acid (TFAA) at high pressures and temperatures affords predominantly fluorobenzaldehydes andN-(fluorophenylmethyl)trifluoroacetamides. The yields of these products depend considerably on the reaction conditions. The rates of their formation have the maximum values at the momemt of the phase transition (PT) of TFAA. A new efficient cyclic (dynamic) regime is proposed for the synthesis at high pressures. The regime involves periodically occurring PT of the solvent. The change in the relative rate of product formation with the degree of fluorobenzene conversion is wave-like.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 319–323, February, 1995. 相似文献
3.
2,4-二硝基氟苯柱前衍生高效液相色谱法测定18种氨基酸 总被引:15,自引:0,他引:15
建立了测定18种氨基酸的高效液相色谱方法。以Hypersil ODS-c_(18)柱(100mm×4.6mm i.d.,5μm)为色谱柱,2,4-二硝基氟苯为衍生化试剂,梯度洗脱。流动相A:0.05mol/L乙酸钠缓冲溶液(pH=6.5,含10mL/LN,N-二甲基甲酰胺),流动相B:乙腈-水(体积比为1:1)。所测氨基酸组分的浓度在0.2~3.0mg/L范围内与峰面积之间具有良好的线性关系,回收率为90.4%~101.0%,检出限为0.120~1.225mg/L,测定结果的相时标准偏差为1.05%~5.93%。 相似文献
4.
V. D. Yumatov A. V. Okotrub G. G. Furin N. F. Salakhutdinov 《Russian Chemical Bulletin》1997,46(8):1389-1395
The electronic structure of fluorobenzene was investigated by X-ray emission spectroscopy (using the F−Kα- and C−Kα-spectra)
and quantum-chemical MNDO calculations. Molecular orbitals of fluorobenzene were compared with those of benzene and hydrogen
fluoride. The Pπ−pπ-interaction between the phenyl ring and the fluorine atom in the fluorobenzene molecule is weak for both the outer and inner
π levels.
For Part 2, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1454–1460, August, 1997. 相似文献
5.
Zotti LA Teobaldi G Palotás K Ji W Gao HJ Hofer WA 《Journal of computational chemistry》2008,29(10):1589-1595
We modelled the adsorption of benzene, fluorobenzene and meta-di-fluorobenzene on Cu(110) by Density Functional Theory. We found that the adsorption configuration depends on the coverage. At high coverage, benzene assumes a tilted position, while at low coverage a horizontal slightly distorted geometry is favoured. Functionalizing the benzene ring with one or two fluorine atoms weakens the bonding to the surface. A rotation is induced, which decreases the distance of the fluorine atom from the surface. STM simulations reveal that details about both, benzene adsorption geometry and fluorine position, can be only detected at short tip-surface distances. 相似文献
6.
Toxicity (-lgEC50) Measurement of the Fluorobenzene Derivants against Vibrio Qinghaiensis (Q67) and Their 2D,3D-QSAR Study 总被引:1,自引:1,他引:0
Toxicities (-lgEC50) of 16 fluorobenzene derivants against vibrio qinghaiensis (Q67) were measured systematically,and their quantum chemistry parameters were calculated at the B3LYP/6-311G** level. Based on the experimental toxicity data and quantum chemistry parameters,2D-QSAR model was proposed,which was validated by variance inflation factors (VIF),t-value and cross-validation method. At the mean time,comparative molecular force field (CoMFA) based on molecular simulation was used to investigate the toxicity of fluorobenzene derivants. Furthermore,the intoxicating mechanism of fluorobenzene derivants was discussed. To our interest,2D-QSAR and CoMFA models exhibit good prediction ability,with which the toxicity of similar compounds can be predicted. Finally,toxicities (-lgEC50) of 12 fluorobenzene derivants against vibrio qinghaiensis (Q67) were predicted with these models. 相似文献
7.
Pedro Bernal Sherril D. Christian Edwin E. Tucker 《Journal of solution chemistry》1986,15(11):947-956
An automated vapor pressure apparatus has been used to obtain measurements of the vapor pressure of aqueous solutions of fluorobenzene at temperatures of 15, 25, 35, and 45°C, and in the concentration range 0 to 0.011M. The results have been interpreted to infer the dimerization constant of fluorobenzene in very dilute aqueous solutions, equivalent to the second virial coefficient of interaction between fluorobenzene molecules. The hydrophobic association of fluorobenzene molecules is thermodynamically quite similar to that of benzene at comparable temperatures and concentrations. A dimerization constant of fluorobenzene of 0.56 M–1 at 30°C and an endothermic enthalpy of association equal to 3.9 kcal-mol–1 are calculated from the measurements. 相似文献
8.
9.
Johannes Ermert Thomas Ludwig René Gail Heinz H. Coenen 《Journal of organometallic chemistry》2007,692(19):4084-4092
Based on the recent availability of no-carrier-added (n.c.a.) 1-bromo-4-[18F]fluorobenzene with high radiochemical yield, the 4-[18F]fluorophenyl compounds of lithium, sodium and magnesium can now also effectively be prepared. Thus, [18F]fluoroarene reagents with a nucleophilic reaction centre are available and suitable among others for the formation of [18F]fluorophenyl compounds with electron donating substituents in the radiosynthesis of 18F-labelled complex organic structures. For these arylation reactions, however, the presence of macroscopic amounts of a haloarene as co-reactant is necessary with all n.c.a. [18F]fluorophenyl metallics. The 18F-fluoroarylation was verified for examples of aryl-carbon, -silicon, -sulphur, and -nitrogen bond formation with radiochemical yields of 20-25% related to the starting radioactivity of [18F]fluoride. 相似文献
10.
Pedro J. Bernal Sherril D. Christian Edwin E. Tucker 《Journal of solution chemistry》1986,15(12):1031-1040
Vapor pressure measurements have been made on dilute aqueous solutions of benzene-benzyl alcohol (BZOH), benzene-phenethyl alcohol (PEOH), and fluorobenzene-BZOH at 15, 25, 35, and 45°C. The benzene results have been interpreted with a mass action model which attributes deviations from ideality to the formation of benzene dimers and heterodimers with BZOH and PEOH. The benzene heterodimers form endothermically at 25°C with large and negative heat capacity changes. The dimerization constant for the benzene-BZOH dimer reaches a maximum of 0.57 M–1 at about 37°C, while the benzene-PEOH dimer reaches a maximum of 0.60 M–1 around 30°C. The fluorobenzene results have been interpreted with a mass action model which, in addition to fluorobenzene dimers and heterodimers, includes the formation of a fluorobenzene-BZOH trimer. Thermodynamic properties for these aggregates are reported and compared with results obtained in previous studies. 相似文献