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991.
A facile procedure for the synthesis of 3-(2'-amino-3'-cyano-4'-arylpyrid-6'-yl) coumarins are being reported starting from 3-acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carded out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR,1H NMR,and mass spectral data. 相似文献
992.
N. Ilayaraja 《Journal of fluorine chemistry》2009,130(7):656-661
The electrochemical perfluorination of benzoyl chloride, p-substituted benzoyl chlorides and cyclo-hexane carboxylic acid chloride in anhydrous hydrogen fluoride (AHF) medium on nickel electrode is reported. Experimental conditions suppressing polymeric film formation on the electrode are optimized. Addition of 1 wt.% dimethyl sulfide based on the volume of AHF in the initial stage of electrochemical fluorination and maintenance of the reactant and intermediate concentrations below a critical level ensured electrochemical fluorination of all the reactants without fouling of the electrode surface. Presence of p-substituents in the benzene ring improved the selectivity of alicyclic perfluoro carboxylic acid. GC/MS and 19F NMR data for the major perfluorinated products are reported. 相似文献
993.
Cui‐Hua Zhao Dr. Eri Sakuda Dr. Atsushi Wakamiya Dr. Shigehiro Yamaguchi Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10603-10612
A series of 2,5‐bis(dimesitylboryl)‐1,4‐bis(arylethynyl)benzenes 1 – 6 that contain various p‐substituents on the terminal benzene rings, including NPh2 ( 1 ), OMe ( 2 ), Me ( 3 ), H ( 4 ), CF3 ( 5 ), and CN ( 6 ) groups, were synthesized, and the effects of the p‐substituents on the absorption and fluorescence properties were investigated both in solution and in the solid state. Linear relationships were obtained not only between the Hammett σp+ constants of the p‐substituents and the absorption and fluorescence maxima, quantum yields, and excited‐state dynamics parameters in solution, but also between the σp+ constants and the fluorescence quantum yields in the solid state. An important finding extracted from these results is that the suppressed fluorescence quenching in the solid state is a common feature for the present laterally boryl‐substituted π‐conjugated skeletons. Hence, the diborylphenylene can serve as a useful core unit to develop highly emissive organic solids. In fact, most of the derivatives showed more intense emission in the solid state than in solution. In addition to these studies, the titration experiment of 1 by the addition of nBu4NF was conducted, which showed the stepwise bindings of two fluoride ions with high association constants as well as a drastic change in the fluorescence spectra, while constantly maintaining high quantum yields (0.61–0.76), irrespective of the binding modes. This result also demonstrated the potential utility of the present molecules as an efficient fluorescent fluoride ion sensor. 相似文献
994.
Effect of substituents in phenol and aniline nucleophiles on activation parameters in SNAr reactions
Vladislav M. Vlasov 《Journal of Physical Organic Chemistry》2009,22(8):756-760
Changes of activation parameters, ΔH≠ and ΔS≠, with σ constants of substituents in the phenol and aniline nucleophiles for their SNAr reactions in various solvents give the δΔH≠ and δΔS≠ reaction constants which are linearly related. The dependence obtained, δΔH≠ versus δΔS≠, allow estimation of the contribution of changes of the internal enthalpy, δΔH≠int, to the enthalpy reaction constant, δΔH≠, which give a linear dependence on the Hammett reaction constants, ρ. The results obtained show that the substituent effects on the charge development in the transition state (TS) are governed by the magnitude of δΔH≠int. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
995.
The use of PPh3/Br2/AgNO3 provides a new reagent system for the novel and highly chemoselective nitration of aromatic amines under mild reaction conditions. 相似文献
996.
The second-order rate constants at three different temperatures have been determined for nucleophilic substitution reactions
of ethyl bromoacetate with various substituted aliphatic carboxylate ions (XCH2COO−) in 90% acetone-10% water (v/v) mixture and the activation parameters have been evaluated. The rate data have been analysed
in terms of electronic and steric effects by using various single and multi-parameterequations. Analysis of the results shows
that localized and steric effects are more important than the delocalized effect. The regression coefficient of the inductive
component is negative indicating that inductively electron-releasing substituents accelerate the reaction and electron-withdrawing
substituents retard it. The steric component corresponds to the reaction being subject to steric acceleration by the substituents.
The per cent steric effect has been calculated. The Br?nsted type correlation is fair, and theβ
N value has been determined. 相似文献
997.
A series of novel triphenylamine-containing aromatic poly(amine-amide)s were prepared from the dicarboxylic acid, N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine-amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195-280 °C). These polymers exhibited strong UV-Vis absorption bands at 330-346 nm and their photoluminescence showed maximum bands around 516-535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide)s prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73-0.78 V and 1.12-1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine-amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms. 相似文献
998.
Toshinobu Korenaga 《Journal of fluorine chemistry》2003,122(2):201-205
Presence of an unique atom-to-face alcoholic oxygen atom?π interaction between a pentafluorophenyl group and alcoholic oxygen (O?π) has been demonstrated by X-ray analysis of the novel chiral amino alcohol instead of the well-known interaction between usual aromatic ring and alcoholic hydrogen atom (OH?π). 相似文献
999.
Summary Two modes of capillary electrophoresis (CE), capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography
(MEKC), were investigated for the separation of 12 aromatic sulphonate compounds. In CZE, although the voltage applied, the
buffer concentration and the pH were optimized for effective separation of the compounds studied, under the best conditions
four of the five amino compounds coeluted, as did naphthalene-1-sulphonic acid and naphthalene-2-sulphonic acid. In MEKC,
sodium dodecyl sulphate (SDS) and Brij 35 were chosen as the anionic and nonionic surfactants and the effect of the concentration
of micelles was examined. The effect of adding methanol as the organic modifier was also investigated with each of these micellar
systems. All the analytes, including the isomers, were completely separated by use of MEKC with Brij 35 but when SDS was used
only 11 compounds were separated because two amino compounds coeluted. 相似文献
1000.
Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalline behaviour has been characterized by differentialscanning calorimetry (DSC) and optical polarizing microscopy. Structural broadening bysubstitution of methoxy group in 2, 2" positions of the mesogenic core produce polymers withlower transition temperatures. Polymers synthesized from ortho and meta substituted phenylenediamine did not form a liquid crystal phase. 相似文献