三苯基硅自由基的电子自旋共振研究

有机硅自由基的电子自旋共振(ESR)的研究一直十分活跃,Bock等已做了大量工作。然而,对于三苯基硅自由基的ESR研究报道却甚少。采用X射线辐照单晶生成的三苯基硅自由基的ESR谱并未获得理想的超精细结构谱,而采用三苯基硅烷与二苯甲酮热反应仅获得Ph_2COSiPh_3自由基的ESR谱。本文报道在氯仿溶液中,用无水三氯化铝与三苯基硅醇或三苯基硅烷在室温下反应,获得三苯基硅烷正离子自由基(Ph_3Si~+)ESR的研究结果,并进行计算机模拟。     

含吡啶基取代多苯基芳基有机硅化合物的合成

2,4,5-三苯基,3-吡啶基环戊二烯酮(4), 分别与烯丙基三乙氧基硅烷及乙烯基三乙氧基硅烷发生Diels-Alder反应, 生成2,4,5-三苯基 3-吡啶基苄基三乙氧基硅烷(5),2,4,5-三苯基 3-吡啶基苯基三乙氧基硅烷(6),1,3,4-三苯基 2-吡啶基苯(7)和1,3,4-三苯基 2-吡啶基二环[2.2.1]-2-烯-7-酮(8). 它们的产率分别为75%, 41%, 10%和10%.     

含吡啶基取代多苯基芳基有机硅化合物的合成

2,4,5-三苯基、3-吡啶基环戊二烯酮(4),分别与烯丙基三乙氧基硅烷及乙烯基三乙氧基硅烷发生Diels-Alder反应,生成2,4,5-三苯基3-吡啶基苄基三乙氧基硅烷(5)、2,4,5-三苯基3-吡啶基苯基三乙氧基硅烷(6)、1,3,4-三苯基2-吡啶基苯(7)和1,3,4-三苯基2-吡啶基二环[2.2.1]-2-烯-7-酮(8)。它们的产率分别为75％、41％、10％和10％。     

聚有机硅氧烷的研究——Ⅰ.三甲基羥基硅烷与三苯基羥基硅烷的共縮合反应

以当量的三甲基羥基硅烷与三苯基羥基硅烷混合而溶于二氧六环,在100°加热一小时半,用0.05N氫氧化鈉为催化剂时,得到90％的共縮合物三甲基三苯基二硅氧烷;用1N盐酸,得到70％的共縮合物。三甲基氯(或乙氧基)硅烷与三苯基氯(或乙氧基)硅烷在酸性介貭中共水解共縮合反应也能得到同样結果。試驗証明,在酸性介貭中反应是先由三甲基羥基硅烷自縮聚以生成六甲基二硅氧烷,后者再与三苯基羥基硅烷反应,生成三甲基三苯基二硅氧烷。在碱性介貭中三甲基羥基硅烷和三苯基羥基硅烷直接共縮聚。文中报告三苯基羥基硅烷与六甲基二硅氧烷或三甲基羥基硅烷的反应速度,以及三甲基三苯基二硅氧烷的重排反应速度的結果。文中尚討論Eaborn对共縮合反应所作的結論。     

三苯基锡化合物与牛血清白蛋白作用光谱

三苯基锡化合物与牛血清白蛋白作用光谱;三苯基一氯化锡(TPTCl); 牛血清白蛋白(BSA); 光谱     

三苯基锡芳氧乙酸酯的合成和表征

三苯基锡芳氧乙酸酯的合成和表征刘宝殿，包明，张景萍（东北师范大学化学系、东北师范大学分析测试中心，长春，１３００２４）关键词芳氧乙酸，三苯基锡芳氧乙酸酯，合成，生物活性三苯基醋酸锡和三苯基氢氧化锡是防治甜菜褐斑病的有效药剂［１］．芳氧乙酸及其酯也具有...     

四氯化碳的辐射分解机理

用三苯基锑作为氯气的吸收剂,研究了⁶⁰Coγ射线对四氯化碳、三苯基锑-空气-四氯化碳体系的辐射效应.     

含氟酰基胂叶德的合成及其裂解反应

作者曾报道三氟乙酰基亚甲基三苯基胂 和双(三氟乙酰基)亚甲基三苯基胂的合成, 发现这二种含氟胂叶立德非常 稳定, 难于和醛酮反应。通过对三氟乙酰基亚甲基三苯基胂晶体结构的测定。证实了其稳定性。本文将上述方法扩展, 用来合成多氟酰基胂叶立德和双(多氟酰基)胂叶立德。     

卟啉化合物研究(Ⅸ)——聚5-邻丙烯酰胺苯基-10,15,20-三苯基卟啉及其钴配合物的合成

将丙烯酰氯和5-邻氨基苯基-10,15,20-三苯基卟啉(Ⅰ)相连合成了5-邻丙烯酰胺苯基-10,15,20-三苯基卟啉(Ⅱ)。在引发剂作用下,Ⅱ进一步聚合,生成聚5-邻丙烯酰胺苯基-10,15,20-三苯基卟啉(Ⅲ),同时还合成了单体和聚合物的钴配合物。通过元素分析、核磁共振谱、红外光谱和可见吸收光谱对单体和聚合物的结构进行了鉴定。     

含氟酰基胂叶德的合成及其裂解反应

作者曾报道三氟乙酰基亚甲基三苯基胂 和双(三氟乙酰基)亚甲基三苯基胂的合成, 发现这二种含氟胂叶立德非常 稳定, 难于和醛酮反应。通过对三氟乙酰基亚甲基三苯基胂晶体结构的测定。证实了其稳定性。本文将上述方法扩展, 用来合成多氟酰基胂叶立德和双(多氟酰基)胂叶立德。     

Reactions of methylated cyclopropanes and olefins with chloroplatinic acid. I. Diacylation and pyrylium ion formation

In contrast to cyclopropane itself, simple methyl-substituted cyclopropanes do not produce platinum insertion products upon reaction with chloroplatinic acid in acetic anhydride. Instead, the major products are aromatic heterocyclic cations, the pyrylium ions, which are formed as the result of diacylation of the cyclopropane ring and subsequent dehydration and ring closure to the aromatic heterocycle. Similar products are formed from the diacylation of certain olefins in the presence of chloroplatinic acid in anhydride solvents. The combination of solvent and substrate variations has led to a proposed mechanism for these reactions which demonstrates the essential and unique mole of platinum. In particular, the specific pyrylium ions produced are formed as a consequence of initial activation of the least-substituted cyclopropane ring bond by insertion of platinum, followed by acylation of platinum-bonded carbon, proton loss to a β,γ-unsaturated carbonyl, a second acylation, and, finally, ring closure.     

Liquid-phase fluorination of aromatic compounds by elemental fluorine

The fluorination of aromatic compounds (benzene, toluene, phenol and benzoic acid) by elemental fluorine diluted with nitrogen has been investigated in various solvents (Freon 11, chloroform, methanol, trifluoroacetic acid, 2,2,2-trifluoroethanol, water) in order to define the influence of the experimental conditions on the reaction. Experiments have been carried out by varying the temperature, the substrate concentration in solution, the molar ratio of fluorine to substrate, and the concentration of fluorine in the fluorine/nitrogen mixture. In all cases, the effects on the yield of fluorinated products were studied. Monofluorinated compounds were mainly found in the reaction mixture, the isomers formed being in accord with the mechanism for electrophilic substitution. The highest yield of monofluorinated products was obtained with polar solvents and the following order was found: CFCl₃ < CHCl₃ < CH₃OH < CF₃CH₂OH < CF₃COOH. Interesting results were also found using particular additives (for instance, KOH or C₄F₉SO₃Na in methanol) or water as the solvent. A direct relationship was observed between the yield of monofluorinated compounds and the molar ratio of fluorine to substrate, which has to be less than one in order to obtain high yields. In contrast, low selectivity, expressed as the yield ratio of ortho to para (or meta) isomers, was found.     

Electrostriction, ion solvation, and solvent release on ion pairing

The theoretical mean molar electrostriction volume of electrolytic solvents, DeltaVel(solvent), was calculated from their properties: the relative pressure derivatives of the density (the compressibility) and permittivity and their second pressure derivatives. The molar electrostriction caused by ions at infinite dilution was taken as the differences of their standard partial molar volumes in the solution and their intrinsic volumes: DeltaVel(ion) = Vinfinity(ion) - Vin(ion). The ratio ninfinity = DeltaVel(ion)/DeltaVel(solvent) then represents the solvation number of the ion in the solvent at infinite dilution. Similarly, from the molar volume change on ion pair formation, DeltaVip, the ratio Deltanip = DeltaVip/DeltaVel(solvent) represents the number of solvent molecules released thereby. These values were tabulated for those solvents, ions, and ion pairs for which the relevant information could be found, the extension to nonaqueous solvents not having been attempted previously.     

Spectroscopic studies on 2,3,4,5-tetraphenylpyrylium salts with and without silver (I)-bridged structures

Two novel phenylated pyrylium compounds, silver (I)-bridged 2,3,4,5-tetraphenylpyrylium perchlorate (P1) and its silver (I)-free pyrylium ligand (P2) were prepared from 1,2,3,4-tetraphenylcyclopentadiene to examine their spectroscopic behaviors. The UV/vis absorption and fluorescent emission spectra of P1 and P2, measured in three solvents (acetonitrile, dichloromethane and toluene), reveal that the photophysical behaviors are closely related to silver (I) fragment, and strongly dependent on solvent polarity. In polar acetonitrile, P1 displays longer absorption wavelength and much lower fluorescent emission intensity than P2, although they exhibit much similarity in shape. In contrast, in nonpolar toluene, while P2 shows an apparent absorption band at 338 nm, P1 displays a tail-like line without absorption band observed. All the spectra obtained indicate a better coplanarity and a stronger intra-molecular charge transfer in P1 due to the effect of silver (I) fragment. Additionally, the 1H NMR spectra of P1 and P2, which were recorded under the same conditions, indicate that the silver (I) fragment reinforces pyrylium ring's capacity to localize the formal positive charge within the heterocyclic ring.     

meso-四(4-磺酸基苯基)卟啉与银(Ⅰ)高灵敏显色反应的研究与应用

本文提出以meso-四(4-磺酸基苯基)卟啉(TPPS_4)为显色剂和CTMAB、β-CD为辅助配合剂,在酸性条件下灵敏度最高的测定痕量银的分光光度新体系。实验发现在此显色反应进行完全后,以适量H_2SO_4溶液(2+3)酸化,将过量的显色剂转化为质子化H_4P~(2+)形体,其最大吸收波长红移,而配合物稳定且最大吸收峰不变,增大了对比度(Δλ=66nm);同时提高了方法的灵敏度和选择性,表观摩尔吸光系数ε=5.21×10~5L/mol·cm。应用本法于相纸、定影废液和矿石等试样中银的测定,与AAS法结果一致。     

Synthesis of Vitamin E Succinate from Candida rugosa Lipase in Organic Medium

A screening of commercially available lipases for the synthesis of vitamin E succinate showed that lipase from Candida rugosa presented the highest yield. The synthesis of vitamin E succinate in organic solvents with different lgP values ranging from -1.3 to 3.5 was investigated. Of particular interest was that dimethyl sulfoxide (DMSO) with the lowest lgP exhibited the highest yield among all the organic solvents used. It suggests that lgP is incapable of satisfactorily predicting the biocompatibility of organic solvents due to the complexity of enzymatic reaction with hydrophilic and hydrophobic substrates in organic solvent. Effects of different operating conditions, such as molar ratio of substrate, enzyme concentration, reaction temperature, mass transfer, and reaction time were also studied. Under the optimum conditions of 10 g/L enzyme, a stirring rate of 100 r/min, a substrate molar ratio of 5:1 at 55℃ for 18 h, a satisfactory yield(46.95%) was obtained. The developed method has a potential to be used for efficient enzymatic production of vitamin E succinate.     

Acylation of Quercetin with a Novel Thermophilic Esterase as Biocatalyst

The regioselective acylation of quercetin catalyzed by a novel thermophilic esterase(APE1547)from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents.The effects of acyl don...     

Etude de la reactivite de l'ion azoture vis a vis de cations heterocycliques-II: Inhibition de la formation d'azides covalents par un complexe pyrylium-azoture constituant un “cul de sac” reactionnel. approche theorique

The reactivity of pyrylium ions with azide is discussed on a theoretical basis (EHMO calculations). As long as pyrylium ring is hindered, the most favorable approach of the reactants corresponds to a reaction coordinate yielding azidopyrans. On the other hand, when the ring approach is free, the system can reach a geometry allowing the formation of a stable complex. The latter is favoured by exchange, coulombic and charge transfer interactions and constitutes a dead-end reaction, quenching the formation of azidopyrans.     

A practical and efficient green synthesis of β-aminophosphoryl compounds via the aza-Michael reaction in water

Biphasic systems room temperature imidazolium ionic liquid (RTIL)/water or water as a solvent significantly accelerate the addition of amines to vinylphosphoryl compounds hence opening green and effective synthesis of β-aminophosphoryl compounds in excellent yields over short reaction times. The application of water, being the cheapest and most non-toxic solvent, without any catalyst or co-solvent, is more advantageous as it provides a simple isolation procedure for products having high purity (> 95% according to the NMR data) via simple freeze-drying and does not require extraction with organic solvents. The solubility of the starting phosphorus substrate in water does not play crucial role in the reaction as it was demonstrated using water insoluble diphenylvinylphosphine oxide. In contrast to typical procedures, using a reactant ratio (vinylphosphoryl compound: amine) of 2:1 readily resulted in double phosphorylation of primary amines, including polyamines, in water.     

Solvent effect on regioselectivity of epoxide ring opening in styrene oxide by O- and N-nucleophiles in neutral and basic media

The results of ring opening in styrene oxide by alcohols, amines, amino alcohols, and diamines were generalized. On low polarizing ability of the solvent, the main direction of the process is the formation of normal α-substituted products. The solvent effect on regioselectivity of the reaction was studied for N,N-diethylethylenediamine. The ratio of products correlates well with the value of dielectric constant for mixed aqueous-organic solvents and with the parameters of polarity E _T and AN for neat solvents.