Grignard试剂同6,6—二烷基富烯反应的研究

烯丙基卤化镁和环戊二烯基溴化镁同６，６－二烷基富烯分别进行富烯环外双键的加成和还原反庆，生成的取代环戊二烯基负离子用（ＣｐＴｉＣｌ２）２Ｏ（Ｃｐ＝环戊二烯基）或ＴｉＣｌ４配合，合成式为Ｃｐ（Ｃ６Ｈ４－ＣＲＲ＾１－ＣＨ２Ｃｈ－ＣＨ２）ＴｉＣｌ２和（Ｃ６Ｈ４ＣＨＲＲ＾１）２ＴｉＣｌ２的化合物，对烯丙基卤化镁、环戊二烯基溴化镁同富烯的反应机理进行了探讨。     

高活性的茂基钛配合物／正丁基锂加氢催化体系的研究

考察了茂环上不同取代基及钛上阴离子配体对茂基钛配合物／正丁基锂催化体系加氢活性和稳定性的影响。在充分发挥该体系催化活性的条件下，由配合物Ｃｐ２ＴｉＣｌ２、Ｃｐ２ＴｉＦ２和Ｃｐ２Ｔｉ［ＯＣ６Ｈ３（ＣＨ３－２）Ｃｌ－４］２组成的催化体系对辛烯－１加氢的最高活性（或初活性）达到４６￣５８ｓ＾－１。     

蝶状铁硒簇合物双（μ—p—甲苯硒基）六羰基二铁双膦取代…

测得并解析了２个蝶状铁硒取代衍生物（μ－ｐ－ＭｅＣ６Ｈ４Ｓｅ）２Ｆｅ２（ＣＯ）２（Ｐｈ２ＰＣＨ２ＣＨ２ＰＰｈ２）（Ａ）和（μ－ｐ－ＭｅＣ６Ｈ４Ｓｅ）２Ｆｅ２（ＣＯ）４（ｃｉｓ－Ｐｈ２ＰＣＨ＝ＣＨＰＰＨ２）（Ｂ）的＾１Ｈ－＾１ＨＣＯＳＹ谱和＾１Ｈ－＾１５ＣＣＯＳＹ谱以及Ａ的＾１Ｈ－＾１ＨＮＯＥＳＲ谱，从而进一不确证了它们的结构。     

N-硅甲基-N-甲酰基苯胺衍生物的合成和生物活性研究

研究了醇钠存在下取代苯胺与氯甲基硅烷在二甲基甲酰胺中的反应。反应产物经元素分析、ＩＲ和１ＨＮＭＲ光谱鉴定为Ｎ－硅甲基－Ｎ－甲酰基苯胺衍生物。合成了２３种通式为ＲＲ′Ｒ″ＳｉＣＨ２Ｎ（ＣＨＯ）的新化合物,对其中１７种进行了生物活性试验。结果表明,个别化合物具有良好的杀菌活性,如ｐ－ＦＣ６Ｈ４Ｓｉ（Ｍｅ２）ＣＨ２Ｎ（ＣＨＯ）·Ｃ６Ｈ４Ｃｌ－ｐ在０．００５％即可１００％杀死芦笋茎枯病菌。     

三卤代锡钨（钼）双核化合物的制备和晶体结构

ＣｐＭ（ＣＯ）３ＳｎＰｈ３和ＣｐＭ（ｃｏ）３ｓＮｐＨ２ｘ（Ｃｐ＝Ｃ５Ｈ４ＣＨ３，Ｃ５Ｈ４ＣＯＣＨ３；Ｍ＝Ｍｏ，Ｗ；Ｘ＝Ｃｌ，Ｂｒ）与ＨＣｌ或ＨＢｒ发生取代反应，得到三氯、三溴以及混合三卤代锡钨（钼）双核化合物，并经元素分析、＾１Ｈ ＮＭＲ、ＩＲ表征。化合物Ｃｌ３ＳｎＷ（ＣＯ）３Ｃ５Ｈ４ＣＯＣＨ３的晶体属单斜晶系，空间群为Ｐ２１／ｃ，ａ＝０．７６８６（３）ｎｍ，ｂ＝１．２６２２（２）ｎｍ，ｃ＝１．６     

SO2-4/Z4O2-TiO2-SiO2固体酸催化苯乙烯选择氧化反应的研究

制备了一种ＳＯ＾２－４促进的金属氧化物固体酸ＳＯ＾２－４／ＺｒＯ２－ＴｉＯ２－ＳｉＯ２,并将其用于催化Ｃ６Ｈ５Ｃ２Ｈ３的选择氧化反应,发现该新型固体酸具有较高的活性和选择性,Ｃ６Ｈ５Ｃ２Ｈ３转化率达１０．７３％,Ｃ６Ｈ５Ｃ２Ｈ５Ｏ选择性达２０．７３％。用ＩＲ,ＸＲＤ等方法进行的表征表明,反应的选择氧化活性位可能含有Ｚｒ,Ｓｉ,Ｏ,Ｔｉ等成分。     

水杨酸烃基二甲硅基甲酯的合成及其生物活性

以三甲基氯硅烷，烃基溴化镁和水杨酸为原料，经氯化，格氏反应，亲核取代和脱氯化钠等步骤，合成了一类新型的植物生长调节剂－水杨酸烃基二甲硅基甲酯（ＣＯ２ＣＨ２Ｓｉ（Ｒ）（ＣＨ３）２，ＯＨＲ＝Ｃ２Ｈ６，Ｃ３Ｈ７，Ｃ４Ｈ９，Ｃ６Ｈ５和Ｃ６Ｈ５ＦＨ２）其结构经元素分析，ＩＲ和＾１ＨＮＭＲ证实，对四季桔的初步生物活性试验表明，有机硅基引主水杨酸分子中后，对桔桔的保花保果效果比母体化合物的更好。     

高碲酸合铜（Ⅱ,Ⅲ）配合物的合成和性质

在Ｈ６ＴｅＯ６／ＫＯＨ水溶液中以臭氧为氧化剂，将二价铜化合物氧化成三价铜化合物，并获得一个新的三价铜化合物Ｂａ４Ｋ［Ｃｕ（Ｈ２ＴｅＯ６）２］（ＯＨ）４．６Ｈ２Ｏ；描述了碱性溶液中“Ｃｕ（Ⅲ）／Ｃｕ（Ⅲ）”循环伏安图。对铜（Ⅲ）化合物，Ｎａ４Ｈ［Ｈ２ＴｅＯ６）２］．１７Ｈ２Ｏ以及相应的铜（Ⅱ）配合物的电子光谱和Ｃｕ２ｐＸＰＳ进行了研究，给出了其配位场场强参数和Ｃｕ２ＰＸＰＸ的电子结合能。由于价态升高     

四氢叶酸辅酶模型化合物的研究：I.碘化1,2—二甲基—3—芳磺酰基—△^2 …

合成了四氢叶酸辅酶甲酸态的３个模型化合物,即碘化１,２－二甲基－３芳磺酰基（芳基＝ｐ－ＣＨ３Ｃ６Ｈ４,Ｃ６Ｈ５,ｐ－ＣｌＣ６Ｈ４）－△＾２－咪唑啉,研究了其还原和水解反应。     

含杂环卡宾碳的铁羰基簇合物的结构化学研究Ⅱ.—Fe3（CO）8（：CNH（S）C（…

Ｆｅ３（ＣＯ）１２和取代２，４－二硫代乙内酰脲反应，得到新的取代物Ｆｅ３（ＣＯ）８＾－（：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ３）２ＮＨ（μ３－Ｓ２），并进行了ＩＲ，＾１ＨＮＭＲ，ＭＳ表征，测定了它的分析和晶体结构，讨论了杂环卡宾碎片：ＣＮＨＣ（Ｓ）Ｃ（ＣＨ３）２ＮＨ的取代位置，它是通过卡宾碳原子与Ｆｅ配位。     

Are amines basic or nucleophilic catalysts for oxirane ring opening by proton-donating nucleophiles?

The behavior of amines as catalysts for oxirane acidolysis and phenolysis has been studied using kinetic methods. The apparent catalytic and noncatalytic reaction rate constants have been estimated. It has been demonstrated that the noncatalytic pathway has almost no effect on the apparent reaction rate constant. In order to determine the character of the behavior of amines (bases/nucleophiles) in this reaction, their reactivity has been analyzed within the conceptions of basic and nucleophilic mechanisms of catalysis. Based on the quantitative amine structure—catalytic activity correlation, it has been shown by comparing the values of correlation coefficients (r) of equations describing mechanisms for various reaction systems that, in the reactions of oxiranes with proton donors (carboxylic acids and phenols), the catalytic activity of tertiary amines/pyridines is determined by their nucleophilicity rather than basicity.     

Nucleophilic attack by oxyanions on a phosphate monoester dianion: the positive effect of a cationic general Acid

The two negative charges on a phosphate monoester RO-PO32- at neutral pH provide a considerable electrostatic barrier toward reactions with nucleophilic reagents with a negative charge on the attacking atom. Electrostatic repulsion disappears when the hydrolysis of an aryl phosphate monoester is catalyzed by a neighboring cationic general acid. The hydrolysis of 8-dimethylammonium-1-phosphate (1) is catalyzed by oxyanions, fluoride anion, and hydroxylamines at similar rates.     

非对称氮杂环丙烷的亲核开环反应及其区域选择性

本文系统地总结了各类亲核试剂对非对称氮杂环丙烷(吖丙啶)的亲核开环反应及开环的区域选择性.氮杂环丙烷亲核开环的区域选择性是一种空间效应和电子效应平衡的结果,非芳基和非烯基取代的氮杂环丙烷的亲核开环通常发生在氮杂环丙烷取代少的碳原子上,空间效应起主导作用;而芳基和烯基取代的氮杂环丙烷的亲核开环通常发生在氮杂环丙烷芳甲位和烯丙位的碳原子上,电子效应起主导作用,烯基取代的氮杂环丙烷的亲核开环还可以发生在烯基的β-碳原子上;分子内的亲核开环反应主要受成环时环大小的控制,成环时的倾向是五元环>六元环>七元环.对于亲核试剂,一般的亲核试剂也同时受电子效应和空间效应的影响; 而亲核性强的亲核试剂通常只受空间效应的影响.容易生成稳定自由基的亲核试剂容易发生单电子转移机理的开环反应,生成相当于亲核试剂进攻氮杂环丙烷中取代多的碳原子得到的开环产物.     

Kinetics and mechanistic study of the reaction of cyclic anhydrides with substituted phenols. Structure-reactivity relationships

[reaction: see text] The kinetic of the reactions of phthalic and maleic anhydrides with different substituted phenols (Z-PhOH with Z = H, m-CH(3), p-CH(3), m-Cl, p-Cl, and m-CN) were studied in aqueous solution. Two kinetic processes well separated in time were observed. The fast one is attributed to the formation of the aryl ester in equilibrium with the anhydride and allows the determination of the rate of nucleophilic attack of the phenol on the anhydride (k(-)(A)). From the slow kinetic process, the equilibrium constant for this reaction was determined. The Bronsted-type plots for the nucleophilic attack of substituted phenols on the anhydrides were linear with slopes beta(Nuc) of 0.45 and 0.56 for phthalic and maleic anhydride, respectively. The results are consistent with a mechanism involving rate-determining nucleophilic attack and also with a concerted mechanism. The calculated effective charge on the atoms involved in the reactions and the Bronsted beta values are consistent with a mechanism involving a concerted or enforced concerted mechanism where a tetrahedral intermediate with significant lifetime is not formed along the reaction coordinate. The latter mechanism is preferred over the stepwise process.     

Concerted mechanisms of the reactions of methyl aryl carbonates with substituted phenoxide ions

The reactions of 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6-trinitrophenyl methyl carbonates (NPC, DNPC, and TNPC, respectively) with substituted phenoxide ions are subjected to a kinetic study in water at 25.0 degrees C, ionic strength 0.2 M (KCl). Production of the leaving groups (the nitro derivatives) is followed spectrophotometrically. Under excess of the phenoxide ions pseudo-first-order rate coefficients (k(obsd)) are found throughout. Plots of k(obsd) vs substituted phenoxide concentration at constant pH are linear, with the slope (k(N)) independent of pH. The Br?nsted-type plots (log k(N) vs pK(a) of the phenols) are linear with slopes beta = 0.67, 0.48, and 0.52 for the phenolysis of NPC, DNPC, and TNPC, respectively. The magnitudes of these Br?nsted slopes are consistent with a concerted mechanism. In the particular case of the phenolysis of NPC the expected hypothetical curvature center of the Br?nsted plot for a stepwise mechanism should be pK(a)(0) = 7.1 (the pK(a) of 4-nitrophenol). This curvature does not appear within the pK(a) range of the substituted phenols studied (5.3--10.3), indicating that these reactions are concerted. The phenolysis of DNPC and TNPC should also be concerted in view of the even more unstable tetrahedral intermediates that would be formed if the reactions were stepwise. The reactions of the same substrates with pyridines are stepwise, which means that substitution of a pyridine moiety in a tetrahedral intermediate by a phenoxy group destabilizes the intermediate perhaps to the point of nonexistence. The k(N) values for the title reactions are larger than those for the concerted phenolysis of the corresponding ethyl S-aryl thiolcarbonates. The k(N) values found in the present reactions are subjected to a dual regression analysis as a function of the pK(a), of both the nucleophile and leaving group, the coefficients being beta(N) = 0.5 and beta(lg) = -0.3, respectively. These coefficients are consistent with a concerted mechanism.     

Phenol Oxidation by a Nickel(III)–Fluoride Complex: Exploring the Influence of the Proton Accepting Ligand in PCET Oxidation

In order to gain insight into the influence of the H⁺-accepting terminal ligand in high-valent oxidant mediated proton coupled electron transfer (PCET) reactions, the reactivity of a high valent nickel–fluoride complex [Ni^III(F)(L)] ( 2 , L=N,N’-(2,6-dimethylphenyl)-2,6-pyridinecarboxamidate) with substituted phenols was explored. Analysis of kinetic data from these reactions (Evans–Polanyi, Hammett, and Marcus plots, and KIE measurements) and the formed products show that 2 reacted with electron rich phenols through a hydrogen atom transfer (HAT, or concerted PCET) mechanism and with electron poor phenols through a stepwise proton transfer/electron transfer (PT/ET) reaction mechanism. The analogous complexes [Ni^III(Z)(L)] (Z=Cl, OCO₂H, O₂CCH₃, ONO₂) reacted with all phenols through a HAT mechanism. We explore the reason for a change in mechanism with the highly basic fluoride ligand in 2 . Complex 2 was also found to react one to two orders of magnitude faster than the corresponding analogous [Ni^III(Z)(L)] complexes. This was ascribed to a high bond dissociation free energy value associated with H−F (135 kcal mol⁻¹), which is postulated to be the product formed from PCET oxidation by 2 and is believed to be the driving force for the reaction. Our findings show that high-valent metal–fluoride complexes represent a class of highly reactive PCET oxidants.     

Intramolecular general base catalyzed ester hydrolysis. The hydrolysis of 2-aminobenzoate esters

Rate constants have been obtained for the hydrolysis of the trifluoroethyl, phenyl, and p-nitrophenyl esters of 2-aminobenzoic acid at 50 degrees C in H(2)O. The pseudo-first-order rate constants, k(obsd), are pH independent from pH 8 to pH 4 (the pK(a) of the amine group conjugate acid). The 2-aminobenzoate esters hydrolyze with similar rate constants in the pH-independent reactions, and these water reactions are approximately 2-fold slower in D(2)O than in H(2)O. The most likely mechanism involves intramolecular general base catalysis by the neighboring amine group. The rate enhancements in the pH-independent reaction in comparison with the pH-independent hydrolysis of the corresponding para substituted esters or the benzoate esters are 50-100-fold. In comparison with the hydroxide ion catalyzed reaction, the enhancement in k(obsd) at pH 4 with the phenyl ester is 10(5)-fold. Intramolecular general base catalyzed reactions are assessed in respect to their relative advantages and disadvantages in enzyme catalysis. A general base catalyzed reaction can be more rapid at low pH than a nucleophilic reaction that has a marked dependence on pH and the leaving group.     

Transition‐Metal‐Free Catalytic Hydrodefluorination of Polyfluoroarenes by Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate

A transition‐metal‐free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion‐corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CS_NAr) process.     

Aromatic nucleophilic substitution reaction of 2,4-dinitrohalogenobenzene and ethyl α-cyano-phenylacetate benzyl anion

The aromatic nucleophilic substitution reaction of 2,4-dinitrohalogenobenzene (DNHB; halogeno =F, Cl, Br) with ethyl α-cyanophenylacetate (ECPA) benzyl anion has been studied by means of UV and IR spectrophotometry as well as gas chromatography. The rates of intermediate formation and product formation were determined respectively. In contrast with common S _N Ar reactions, the formation rate constant of the intermediates, substituted cyclohexadienates, was in the order of halogen =F>Br>Cl, whereas the rate constant of product formation was in the order F>Cl>Br, which revealed that the departure of the halogen atom was the rate-limiting step for the overall reaction in the presence of a sterically hindered nucleophile. These reactions could be catalyzed by the solvated electrons. The corresponding reaction intermediates, radical species, were detected by ESR and the reactions were proved to proceed mainly by a solvated-electron induced radical chain reaction mechanism.     

高效液相色谱研究丝素亲核基团与一氯均三嗪型活性染料反应动力学

以异丙胺、对甲酚和甲醇分别模拟蚕丝丝素的氨基、酚羟基和醇羟基,应用高效液相色谱分析一氯均三嗪型活性染料与蚕丝丝素的不同亲核基团的反应速率.结果表明:在pH=8～10、70～95 ℃的条件下,染料的酚解总反应速率远大于染料的氨解总反应速率和醇解总反应速率.其中C.I.活性红24 和C.I.活性橙2在pH=9,95 ℃条件下的酚解总速率分别约为其氨解总反应速率的8.5倍和12.5倍,为其醇解总反应速率的23倍和50倍;该两染料的酚解效率分别为47.4和96.3,氨解效率分别为4.6和6.9,醇解效率仅为1左右.通过异丙胺-对甲酚-甲醇混合溶液(1∶ 10∶ 100,V/V)模拟蚕丝与染料的反应,研究一氯均三嗪型活性染料与丝素上亲核基团的反应选择性,推断出一氯均三嗪型活性染料染蚕丝的最适宜条件为pH=8～9,温度85 ℃左右.在此条件下,酚羟基在蚕丝的一氯均三嗪型活性染料染色中起主要作用,氨基起次要作用,而醇羟基的作用甚微.