钾芳氧化物XC的相对反应性的温度依赖性6 ħ 4 ö - ķ +朝向4-硝基苯基(1),3-硝基苯基(2),4-氯苯基(3),和苯基(4)在二甲基甲酰胺苯甲酸酯(DMF)使用竞争反应技术进行了研究。1与4-氰基苯酚钾,2与3-溴苯酚钾,3与3-溴苯酚,4-溴苯酚和未取代的苯酚钾的反应的速率常数k X,4在25°C下用4-甲氧基钾和3-甲基苯酚钾测定。相对速率常数k X / k H(3-Me)与竞争性反应的活化参数差异(∆∆Н ≠和∆∆ S ≠)的相关分析表明存在六个等速序列。我们研究了X对每个等动力学系列的活化参数的取代基效应,并得出结论,苯甲酸芳基酯PhCO 2 C 6 H 4 Y与芳基氧化钾在DMF中的反应通过四步机理进行。大ρ 0(Y)和ρ XY1–3与带有给电子取代基的芳基氧化钾反应在25°C下获得的值是确定螺-σ-络合物形成速率的速率。1和2反应的Hammett图表现出向下的曲率
Solid-Phase Synthesis of m-Phenylene Ethynylene Heterosequence Oligomers
摘要:
Both homo- and heterosequence m-phenylene ethynylene oligomers are synthesized using a conceptually simple iterative solid-phase strategy. Oligomers are attached to Merrifield's resin through a known triazene-type linkage. The phenylene ethynylene molecular backbone is constructed through a series of palladium-mediated cross-coupling reactions. The strategy employs two types of monomers that bear orthogonal reactivity, one being a monoprotected bisethynyl arene and the other being a 3-bromo-5-iodo arene. The catalyst conditions are tailored to the requirements of each monomer type. The monoprotected bisethynyl arene is coupled to the growing chain in 2 h at room temperature using a Pd(I) dimer precatalyst ((Bu3P)-Bu-t-(Pd(mu-Cl)(mu-2-methyl allyl) Pd)(PBu3)-Bu-t) in conjunction with ZnBr2 and diisopropylamine. In alternate steps, the resin is deprotected in situ with TBAF and coupled to the 3-bromo-5-iodo arene using the iodo selective Pd(tri-2-furylphosphine) 4 catalyst in conjunction with CuI and piperidine; this reaction is also completed in 2 h at room temperature. These cross-coupling events are alternated until an oligomer of the desired length is achieved. The oligomer is then cleaved from the resin using CH2I2/I-2 at 110 degrees C and purified using preparatory GPC. Using this method, a series of homo- and heterosequence oligomers up to 12 units in length in excellent yield and purity were synthesized on the 100 mg scale. Longer oligomers were attempted; however, deletion sequences were found in oligomers longer than 12 units.
Ligand free, highly efficient synthesis of diaryl ether over copper fluorapatite as heterogeneous reusable catalyst
作者:Shafeek A.R. Mulla、Suleman M. Inamdar、Mohsinkhan Y. Pathan、Santosh S. Chavan
DOI:10.1016/j.tetlet.2012.01.124
日期:2012.4
A novel ligand-free, highlyefficient, and an inexpensive method has been developed by using ecofriendly, heterogeneous reusable copper fluorapatite (CuFAP) catalyst for the synthesis of diaryl ethers from the cross coupling reaction of the various substituted aryl halides (fluoride, chloride, bromide, and iodide) with the potassium salts of various substituted phenols in the presence of N-methyl 2-pyrrolidone
A Kinetic Study on Nucleophilic Displacement Reactions of Phenyl Y-Substituted-Phenyl Carbonates with Alkali Metal Ethoxides: Metal Ion Effect and Reaction Mechanism
作者:Ik-Hwan Um、Ji-Yoon Seo、Ji-Sun Kang、Jun-Sung An
DOI:10.1246/bcsj.20120104
日期:2012.9.15
Pseudo-first-order rate constants (kobsd) have been measured for reactions of phenyl Y-substituted-phenyl carbonates with alkalimetal ethoxides (EtOM, M = Li, Na, and K). The plot of kobsd vs. [Et...
已经测量了苯基 Y 取代苯基碳酸酯与碱金属乙醇盐(EtOM,M = Li、Na 和 K)反应的伪一级速率常数 (kobsd)。kobsd vs. [Et...
Studies of the Thiocarbonyl Compounds. I. Syntheses and Thermal Rearrangement of<i>O</i>,<i>S</i>-Diaryl Dithiocarbonates
作者:Yoshiaki Araki
DOI:10.1246/bcsj.43.252
日期:1970.1
S-diaryl dithiocarbonates with the general formula of p-X–C6H4–S–C(=S)–O–C6H4–Y-p (I) were prepared. When these substances were kept at an elevated temperature, they rearranged smoothly to S,S-diaryl dithiocarbonates of this general formula: p-X–C6H4–S–C(=O)–S–C6H4-Y-p (II). Kinetic studies showed that the rearrangement followed fairly good first-order kinetics. The rate constants in diphenyl ether at
Kinetics and Mechanism of Nucleophilic Displacement Reactions of Y-Substituted Phenyl Benzoates with Cyanide Ion
作者:Song-I Kim、Eun-Hee Kim、Ik-Hwan Um
DOI:10.5012/bkcs.2010.31.03.689
日期:2010.3.20
Discussion The kinetic study was performed spectrophotometrically. All reactions proceeded with quantitative liberation of Y-substituted phenoxide ion (and/or its conjugate acid) under pseudo-first- order conditions (i.e., the nucleophile concentration in excess over the substrate concentration). The reactions obeyed first- order kinetics and pseudo-first-order rate constants (
Y 取代苯甲酸苯酯 (1) 和苯硫代苯甲酸苯酯 (2) 与 CN 反应的二级速率常数汇总 - 在 80 mol % H 2 O/20 mol % DMSO 中,温度为 25.0 ± 0.1 o C a entry Y p K a 10 2 k CN- / M –1 s –1 12a 4-MeO 10.20 0.843 b 2.13 b 4-Me 10.19 0.783 b 1.89 c 3-CH 3 10.08 0.724 - d H 9.95 1.02 b 2.75 e 4-Cl 9.38 2.32 - f 3-COMe 9.19 3.59 b - g 3-Cl 9.02 4.19 - h 3-CHO 8.98 3.93 - i 4-COOEt 8.50 6.07 - j 3-NO 2 8.35 14.1 b 18.0 k 4-COMe 8.05 7.68 b 7.88 l 4-CN 7
Synthesis, Characterization, and Biologic Activity of New Acyl Hydrazides and 1,3,4-Oxadiazole Derivatives
Starting from isoniazid and carboxylic acids as precursors, thirteen new hydrazides and 1,3,4-oxadiazoles of 2-(4-substituted-phenoxymethyl)-benzoic acids were synthesized and characterized by appropriate means. Their biological properties were evaluated in terms of apoptosis, cell cycle blocking, and drug metabolism gene expression on HCT-8 and HT-29 cell lines. In vitro antimicrobial tests were performed