2-芳氧基-5-苯基-1,3,4-噁二唑类化合物的合成

本文通过芳氧基负离子在2—甲磺酰基—苯基—1,3,4—噁二唑环2—位上的亲核取代反应制得9个新的2—芳氧基—5—苯基—l,3,4—噁二唑衍生物。所有化合物的结构经元素分析,IR,~1H NMR和MS确认。初步抗菌实验表明这些化合物具有一定的抑制枯草芽孢杆菌繁殖的活性。 2,5—二取代l,3,4—噁二唑衍生物具有广泛的生物活性,如抗菌,抗黄球菌,除草杀棉花牙虫等。Madhavan等曾通过芳胺在2— 甲磺酰基—5—芳基1,3,4—噁二唑环上的亲核取代反应,制得了2—芳氨基—5—芳基—l,3,4—噁二唑衍生物,我们也曾通过酰肼等亲核试剂在2—甲磺酰基—5—(3,4,5—三甲氧基苯基)—1,3,4—噁二唑环上的亲核取代反应,得到了2—取代酰肼基—5—(3,4,5—三甲氧基苯基)—l,3,4—噁二唑衍生物。在此基础上,我们拟通过Aro在2—甲磺酰基     

含1,3,4-噁二唑环PPV齐聚物的合成及发光特性研究

含有1,3,4-噁二唑结构单元的PPV齐聚物是一类具有良好电子传输功能的发光材料。通过Wittig—Homer反应合成了2,5-二{4-[2-(取代苯基)乙烯基]苯基}-1,3,4-噁二唑(1)。1的化学结构经元素分析和光谱分析确认,其分析数据表明1分子结构中的C=C双键均为反式结构。苯环上的取代基对1的UV—Vis吸收光谱和PL荧光光谱有显著影响。     

2-苯基苯并噁唑的光解反应

聚对苯撑苯并二噁唑(PBO)纤维对光较为敏感,在紫外光照射下会发生降解.本文研究了该纤维的单体2-苯基苯并噁唑(PO)的初级光化学反应机理.当PO分子吸收一个光子而跃迁到第一激发态后,克服25.59kJ·mol-1能垒而越过过渡态,此时噁唑环打开,且两个苯环形成大约90°的二面角而得到产物,该产物可进一步与空气中的水发生次级反应.计算结果表明在第一激发态上噁唑开环反应很容易,但在基态势能面并没有发现噁唑的开环路径.分子中的原子(AIM)的计算结果与上述分析过程相吻合.     

2,5-二[4-(2-芳基乙烯基)苯基]噁二唑的合成及发光特征

二乙烯联苯及其衍生物是一种可发射蓝光的小分子空穴型有机发光材料, 通过Wittig-Horner反应, 将电子传输型噁二唑环“嵌入”其中, 设计合成了6个2,5-二[4-(2-芳基乙烯基)苯基]-1,3,4-噁二唑化合物. 经光谱分析和元素分析等方法确认了它们的化学结构. IR和UV-vis分析数据表明标题化合物分子结构中的C＝C双键均为反式结构特征. 研究结果表明: 2,5-二[4-(2-对二甲氨基苯基乙烯基)苯基]-1,3,4-噁二唑具有良好的蓝色发光性能; 取代基对标题化合物的UV-vis吸收光谱和发光特性的影响显着.     

含氮亲核试剂在2-甲磺酰基-5-(3,4,5-三甲氧基苯基)-1,3,4-噁二唑环上取代反应的研究

2,5—二取代—l,3,4—噁二唑化合物具有消炎,抗菌,调节植物生长,杀虫门等广泛的生物活性。作者曾研究了取代胺在2—甲磺酰基—5—(2—苯基—4—喹啉基)—1,3,4—噁二唑化合物环2—位上的亲核加成消去反应,制得了一系列新的2—取代基—5—(2—苯基—4—喹啉基)—1,3,4—噁二唑衍生物,并发现它们具有一定的抗菌活性。在此基础上,我们又研究了含氮亲核试剂在 2—甲磺酰基—5—(3,4,5—三甲氧基苯基)—1,3,4,—噁二唑环2—位上的亲核加成消去反应,制得一系列新的2—取代基—5—(3,4,5—三甲氧基苯基)—1,3,4—噁二唑衍生物。作者用3,4,5—三甲氧基苯甲酰肼在KOH催化下与CS_2反应得到2—巯基—5—(3,4,5—三甲氧基苯基)—l,3,4—噁二唑1,1在NaOH溶液中与Me_2S0_4作用得到2—甲硫醚—5—(3,4,5—三甲氧基苯基)—1,3,4—噁二唑2,2在冰醋酸水溶     

水相中“一锅法”合成1-[(5-甲基异噁唑-3-氨基)-(苯基)]甲基-2-萘酚

在硫酸钠的存在下,以环境友好的水为溶剂,将苯甲醛、2-萘酚和5-甲基-3-氨基异噁唑通过"一锅法"制备得到了收率为92%的1-[(5-甲基异噁唑-3-氨基)-(苯基)]甲基-2-萘酚,并经过~1H NMR、~(13)C NMR和元素分析进行了表征.同时,对目标产物产率的影响因素进行了考察,得到了优化的合成条件.     

1-[3′-(4"-甲氧基苯基)-5′-甲基异噁唑-4′-甲酰基]-4-芳基氨基硫脲及其衍生物的合成

以3,5-二取代异噁唑-4-甲酰肼为基本原料制备关键中间体1-(3-对甲氧基苯基-5-甲基异噁唑-4-基)-4-芳基氨基硫脲(3a～3c);3在不同条件下经关环反应制得含有3,5-二取代异噁唑的2-芳氨基噻二唑(4a～4c),2-芳氨基噁二唑(5a～5c)和3-[3′-(4"-甲氧基苯基)-5′-甲基-异噁唑4′-基)-4-芳基-1,2,4-三唑-5-硫酮(6a～6c);6与碘甲(乙)烷反应合成了4-芳基-5-[3′-(4″-甲氧基苯基)-5′-甲基异噁唑-4′-基]-3-甲(乙)硫基-1,2,4-三唑(7a～8c),其结构经1H NMR,IR,MS和元素分析表征,其中4,5,7和8未见文献报道.     

醋酸铜促进的酰胺-噁唑啉化合物与芳基硫醇的C—H键双硫代化反应研究

以酰胺-噁唑啉为辅助基团,在廉价的醋酸铜促进下,实现了酰胺衍生物C(sp2)—H键与芳基硫醇S—H键的脱氢偶联反应;以中等到优秀的产率(最高可达90%)简单高效地合成了一系列双硫化的酰胺衍生物.值得一提的是,底物范围并不局限于各种取代苯基酰胺化合物,吡啶基酰胺化合物也可以兼容.该反应的特点是:金属廉价、底物范围广、反应条件温和、无需外加配体、空气作为氧化剂、区域选择性好(仅酰胺基团邻位的C—H键发生反应,而噁唑啉基团邻位的C—H键不发生反应);此外,克级规模的反应表明了其在合成中的实用性.     

抗紫外老化聚对苯撑苯并二噁唑(PBO)纤维的制备与表征

通过化学添加2,5-二羟基对苯二甲酸(DHTA)共聚,以及添加金红石型纳米TiO2物理共混的方法,制备了聚对苯撑苯并二噁唑(PBO)的抗紫外改性纤维.考察了纤维的力学性能、特性粘度及表面形貌在紫外老化过程中的变化,并结合PBO纤维紫外加速老化后的红外分析,对PBO纤维的光老化机理进行了初步研究.结果表明,本实验所制备的DHPBO纤维以及DHPBO/n-TiO2纤维的抗紫外老化能力明显高于PBO纤维,并且金红石型纳米TiO2对PBO的抗紫外改性效果要优于有机紫外吸收剂(2,2'-(1,2-乙烷二基)双(4,1-亚苯基)双苯并噁唑).     

1-[3’-(4″-甲氧基苯基)-5’-甲基异噁唑-4’-甲酰基]-4-芳基氨基硫脲及其衍生物的合成

以3,5-二取代异噁唑-4-甲酰肼为基本原料制备关键中间体1-(3-对甲氧基苯基-5-甲基异噁唑-4-基)-4-芳基氨基硫脲(3a～3c);3在不同条件下经关环反应制得含有3,5-二取代异噁唑的2-芳氨基噻二唑(4a～4c),2-芳氨基噁二唑(5a～5c)和3-[3’-(4″-甲氧基苯基)-5’-甲基-异噁唑-4’-基)-4-芳基-1,2,4-三唑-5-硫酮(6a～6c);6与碘甲(乙)烷反应合成了4-芳基-5-[3’-(4″-甲氧基苯基)-5’-甲基异噁唑-4’-基]-3-甲(乙)硫基-1,2,4-三唑(7a～8c),其结构经1H NMR,IR,MS和元素分析表征,其中4,5,7和8未见文献报道。     

Interfacial strength and mechanisms of silicone resin composites reinforced with 2 different polyhedral oligomeric silsesquioxanes/carbon fiber hybrids

Grafting nanoscale reinforcement onto macrolevel carbon fiber (CF) surface is an efficient approach to improve interfacial strength and properties of composites. In the research, 2 different polyhedral oligomeric silsesquioxanes (POSS)/CF hybrids have been prepared by a facile 2‐step method. Carbon fiber was grafted with aniline groups by aryl diazonium reaction using water as the reaction medium, and then separately functionalized with glycidyllsobutyl POSS (EP0418) or glycidyl POSS (EP0409) by the chemical bonding. Characterization of fiber surface structures before and after modification confirmed the covalent bonding nature between both kinds of POSS and CF. Atomic force microscopy images showed the uniform distributions of EP0418 or EP0409 modified on the fiber surface and the similar enhanced degree of surface roughness (89.3 and 88.7 nm). Dynamic contact angle tests showed that EP0409‐grafted CF (CF‐g‐EP0409) had lower contact angles and higher surface free energy than those of EP0418‐grafted CF (CF‐g‐EP0418). Interfacial strength and hydrothermal aging resistance of composites enhanced significantly after POSS modification, especially for CF‐g‐EP0409 composites. Interfacial reinforcing mechanisms of composites reinforced with 2 different POSS/CF hybrids have also been analyzed and compared.     

Effects of surface synergy for the dispersion of short carbon fibers sized by adipic acid modified epoxy resin potassium

The carbon fiber (CF) surface plays a critical role in the performance of CF composite materials. Adipic acid modified epoxy resin potassium (AAEK) prepared with epoxy resin and adipic acid, and KOH was employed as the CF sizing agent. Then, series of surface properties of AAEK‐treated carbon fiber (CF‐AAEK) including surface charge, morphology, and groups were characterized by using Faraday cup, friction coefficient gauge, atomic force microscopy, X‐ray photoelectron spectroscopy, and thermogravimetry. The results indicated that the dispersion coefficient of CF‐AAEK was increased by 1.72 times and there were synergistic effects for the dispersion of short CFs during the sizing treatment process with AAEK. In addition, the flexural strength of treated short CF composite proved to increase by 168%, which evaluated that the better CF dispersion in the matrix was a critical factor for the mechanical property improvement of short CF‐AAEK/epoxy resin composites.     

Improving the interfacial property of carbon fibre/epoxy resin composites by grafting amine-capped cross-linked poly-itaconic acid

To improve the interfacial properties of carbon fibre-reinforced polymer composites, a surface treatment was used to cap cross-linked poly-itaconic acid onto carbon fibres via in-situ polymerization after itaconic acid grafting. The chemical composition of the modified carbon fiber (CF) surface was characterized by X-ray photoelectron spectral and Fourier-transform infrared spectroscopy. Scanning electron microscopy and atomic force microscopy images showed that the poly-itaconic acid protective sheath was uniformly capped onto the CF surface and that the surface roughness was obviously enhanced. Chemical bonds also played a key role in the interfacial enhancement. The results showed that the interfacial shear strength of the composites with poly-itaconic acid on the carbon fibres (72.2 MPa) was significantly increased by 89.5% compared with that of the composites with pristine CF (38.1 MPa). Moreover, the poly-itaconic acid sheath promoted a slight increase in mono-fibre tensile strength. In addition, the interfacial mechanisms were also discussed. Meanwhile, the mechanical property of the functionalized CF/epoxy resin composites was also significantly improved.     

羧基化含氟聚芳醚的合成及涂层性能

以四烯丙基联苯二酚(TABP)、 双酚A和十氟联苯为原料, 通过室温缩聚制得含氟聚芳醚(FPAEs), 再将其与3-巯基丙酸进行加成, 制得羧基化含氟聚芳醚(CFPAEs). 通过改变TABP的投料量来调节产物的羧基含量. 以N-甲基吡咯烷酮(NMP)为溶剂, 将CFPAE涂层喷涂在马口铁上. 研究发现, CFPAE涂层具有优异的热稳定性和机械强度, 羧基的引入可显著提高含氟聚芳醚涂层的附着力. 当羧基含量为0.265 mmol/g时, 涂层的黏附力等级为0级, 铅笔硬度为6H, 不引起涂层破坏的最小轴棒直径为0.5 mm, 水接触角为103.9°. 此外, CFPAE涂层还具有优异的耐酸、 耐盐、 抗紫外老化和防腐蚀等性能. 研究结果表明, 羧基化是拓展含氟聚芳醚在特种氟碳涂料上应用的一种有效途径.     

New and efficient syntheses of alpha-iodo-alpha,alpha-difluoro- and beta-iodo-alpha,alpha,beta,beta-tetrafluorocarboxylic acid derivatives as useful building blocks for making functional fluoro compounds

Perfluoroolefins reacted with I-Cl and ClSO(3)H under mild conditions to give R(F)CFICF(2)OSO(2)Cl, which could be readily converted into various alpha-iodo-perfluorocarboxylic acid derivatives or telomerized with tetrafluoroethylene to I(CF(2)CF(2))(n)()OSO(2)Cl. Ring-opening reaction of perfluoroalkoxypentafluorocyclopropane with iodine at 240 degrees C produced ICF(2)CF(2)COF, which was quenched by alcohol, water, or NH(3) to give beta-iodo-alpha,alpha,beta,beta-tetrafluorocarboxylic acid derivatives. These functional fluorinated iodides can be used as building blocks for making selectively fluorinated compounds.     

Photolysis of a fluorinated polymer film by vacuum ultraviolet radiation

We studied the photolysis of a fluoroethylene–fluoropropylene copolymer (FEP) film by vacuum ultraviolet (VUV) radiation from a resonance Xe lamp at a wavelength of 147 nm and air pressures of 0.05 and 2.5 Torr. The chemical changes in the FEP surface layer were investigated by Fourier-transform infrared spectroscopy with attenuated total reflection attachment and X-ray photoelectron spectroscopy. Double bonds were found to be the main product in the case of VUV treatment at 0.05 Torr, while photo-oxidation of FEP occurred predominantly by VUV treatment at 2.5 Torr under formation of the —CF₂C(O)F group. This oxygen-containing group was more effectively formed in the FEP surface layer by VUV photo-oxidation than by conventional surface oxidation techniques such as treatments by plasma and corona discharge and ozone. Storage of the VUV-treated polymers in air at 50% relative humidity resulted in hydrolysis of —CF₂C(O)F to the —CF₂COOH group. Substantial improvement of the film wettability was noticed after VUV photo-oxidation. These findings suggest that VUV irradiation provides a high potential for surface modification of fluorinated polymers which are known to be particularly resistant against functionalization by conventional surface modification techniques such as plasma treatment. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2215–2222, 1998     

Environmentally benign processes for making useful fluorocarbons: nickel- or copper(I) iodide-catalyzed reaction of highly fluorinated epoxides with halogens in the absence of solvent and thermal addition of CF2I2 to olefins

Highly fluorinated epoxides react with halogens in the presence of nickel powder or CuI at elevated temperatures to provide a useful and general synthesis of dihalodifluoromethanes (CF(2)X(2)) and fluoroacyl fluorides (R(F)COF) in the absence of solvent. At 185 degrees C, hexafluoropropylene oxide and halogens produce CF(2)X(2) (X = I, Br) in 68-90% isolated yields, along with small amounts of X(CF(2))(n)()X, (n = 2, 3). With interhalogens I-X (X = Cl, Br), a mixture of CF(2)I(2), CF(2)XI, and CF(2)X(2) was obtained. The fluorinated epoxides substituted with perfluorophenyl, fluorosulfonyl, and chlorofluoroalkyl groups also react cleanly with iodine to give CF(2)I(2) and the corresponding fluorinated acyl fluorides in good yields. The reaction probably involves an oxidative addition of fluorinated epoxides into metal surfaces to form an oxametallacycle, followed by rapid decomposition to difluorocarbene-metal surfaces, which alters the reactivity of the difluorocarbene carbon from electrophilic to nucleophilic. The increase of nucleophilicity of difluorocarbene facilitates the reaction with electrophilic halogens. CF(2)I(2) reacted with olefins thermally to give 1,3-diiodofluoropropane derivatives. Both fluorinated and nonfluorinated alkenes gave good yields of the adducts. Reaction with ethylene, propylene, perfluoroalkylethylene, vinylidene fluoride, and trifluoroethylene provided the corresponding adducts in 58-86% yields. With tetrafluoroethylene, a 1:1 adduct was predominantly formed along with small amounts of higher homologues. In contrast to perfluoroalkyl iodides, CF(2)I(2) also readily adds to perfluorovinyl ethers to give 1,3-diiodoperfluoro ethers.     

Does alpha-fluorination affect the structural trans-influence and kinetic trans-effect of an alkyl ligand? Molecular structures of Pd(TMEDA)(CH(3))(R(F)) and a kinetic study of the trans to cis isomerization of Pt(TMEDA)(CH(3))(2)I(R(F)) [R(F) = CF(2)CF(3), CFHCF(3), CH(2)CF(3)

Reaction of Pd(TMEDA)(CH(3))(2) [TMEDA = tetramethylethylenediamine] with fluoroalkyl iodides R(F)I affords a series of square planar Pd(II) complexes Pd(TMEDA)(CH(3))(R(F)) [R(F) = CF(2)CF(3) (9), CFHCF(3) (10), CH(2)CF(3) (11)], presumably by oxidative addition followed by reductive elimination of CH(3)I. The solid-state structures of each compound have been determined by single crystal X-ray diffraction studies, allowing the effect of increasing alpha-fluorination on the structural trans-influence of alkyl ligands to be examined. In these compounds there is no significant difference observed in the trans-influence of the three fluorinated alkyl ligands toward the trans-N atom, although a significant cis-influence on the neighboring methyl ligand is apparent. Oxidative addition of the same series of fluoroalkyl ligands to the corresponding Pt(TMEDA)(CH(3))(2) affords octahedral Pt(IV) complexes trans-Pt(TMEDA)(CH(3))(2)(R(F))I [R(F) = CF(2)CF(3) (12), CFHCF(3) (13), CH(2)CF(3) (14)] as the kinetic products. In each case, subsequent isomerization to the corresponding all cis-isomers is observed; in the case of 13, the stereocenter at the alpha-carbon results in two diastereomeric cis-isomers, which are formed at different rates. The molecular structures of 13 and its more stable all cis-isomer 16b have been crystallographically determined. Kinetic studies of the trans-cis isomerization reactions show the mechanism to involve a polar transition state, presumably involving iodide dissociation, followed by rearrangement of the cation, and iodide recombination. High dielectric solvents increase the rate, but solvent coordinating ability has no effect. Dissolved salts (LiI, LiOTf) show normal accelerative salt effects, with no inhibition in the case of added iodide, consistent with the formation of an intimate ion pair intermediate. The kinetic parameters show that the trans-effects of fluoroalkyl ligands in these compounds follow the order expected from the relative sigma-donor properties of the ligands, with CF(2)CF(3) < CFHCF(3) < CH(2)CF(3).     

A unique reaction pathway of fluorine-substituted ethyl groups on Cu(111): successive alpha,alpha-fluoride elimination

Fluorine-substituted ethyl groups on Cu(111) were generated by thermal scission of the C-I bond in the adsorbed C2F5I. Temperature-programmed reaction spectrometry observed a novel pathway resulting in the evolution of C4F6 above 400 K. Among the various isomers, this product was identified as hexafluro-2-butyne. Although abstraction of two fluorine atoms from the starting Cu-CF2CF3 was required, Cu-CCF3 (trifluoroethylidyne) was favored over Cu-CF=CF2 (trifluorovinyl) as the intermediate because this ethyl-ethylidyne-butyne pathway was suppressed on a Cu(100) surface devoid of the key threefold hollow binding sites for ethylidyne. Once formed, perfluoroethylidyne readily coupled to afford a tightly surface-bound hexafluoro-2-butyne up to 400 K. Therefore, the C-F bonds adjacent to the metal were found to be more susceptible to the bond activation, leading the chemisorbed perfluoroethyl to eliminate two F atoms successively from the alpha-carbon. This preference for alpha-elimination rather than beta-elimination (the most favorable route in hydrocarbons) may be quite general for metal surface-mediated reactions involving fluorinated alkyl groups.     

Study on the enhancement of the interface performance between CF and polyimide by triethylamine grafting nano-TiO2 particles

The TiO₂ is grafted by triethylamine and is introduced on the surface of the carbon fiber, which improves the wettability and activity of the carbon fiber surface and at the same time strengthens the carbon fiber/polyimide composite. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the triethylamine grafting successfully on TiO₂. Scanning electron microscope (SEM) results show that when the trimethylamine concentration is 1.0%, a uniform coating is formed on the surface of the carbon fiber. The interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) were increased by 32% and 69%, respectively.