Cux+催化的N-芳基化反应研究进展

N-芳基胺和N-芳基含氮杂环化合物广泛应用于生化、药物、光电转化材料。对Cux+催化的N-芳基化反应研究进展进行了综述,指出研发高效、通用、价廉易得的配体是Cux+催化N-芳基化反应的发展方向。     

合成芳基硼酸及其酯的研究进展

综述了近年来芳基硼酸及其酯的合成研究进展,介绍了各种合成方法的优缺点及其应用前景。     

芳基硼酸在有机合成中的应用

芳基硼酸作为一种重要的中间体,在有机合成中的应用相当广泛。Suzuki偶联反应是合成联芳基结构最有效的方法之一,近年许多用于芳基硼酸与各种卤代芳烃偶合的催化剂相继被开发。芳基硼酸与苯酚在Cu(OAc)2和NEt3存在时用于合成二芳基醚,与胺的偶联是合成C-N键的有效方法,与,α-β不饱和体系的1,4-共轭加成反应广泛用于β-取代羰基化合物的合成。反应采用相对无毒而又廉价的普通试剂,反应条件温和,产率高,立体选择性好。综述了芳基硼酸在联芳基合成、二芳基醚合成、芳香胺合成和催化加成反应中的应用。     

废芳基硼酸类化合物的回收利用

为了提高芳基硼酸化合物的收率,减少芳基硼酸制备过程中含硼酸副产物对环境的污染,开发出了芳基硼酸化合物的脱硼酸技术,以4’-乙基-4-苯基-2-氟苯硼酸(Ⅰ)脱除硼酸基团为例,在碱性条件下,于60~68℃反应,得到了(Ⅰ)的初始原料4’-乙基-4-苯基-2-氟苯,收率87%。并对4’-乙基-4-苯基-2-氟苯的结构进行了质谱确认,对芳基硼酸化合物脱硼酸的机理给出了推测,利用此技术可以回收有用原材料,减少芳基硼酸生产中的废物排放量。     

无配体铜催化氮杂环化合物的N-芳基化反应

为建立经济,高效,环保的含氮杂环化合物的N-芳基化反应体系,考察了不同取代的芳烃卤化物与氮杂环芳香化合物在无配体下使用廉价易得的铜盐为催化剂,1,4-二氧六环为溶剂的N-芳基化反应。实验结果表明,该反应体系在以廉价的氧化亚铜为催化剂,回流状态下含氮杂环化合物与卤代芳烃顺利反应生成C-N偶联产物,得到优良的产率。     

二芳基碘(钅翁)盐参与的芳基化反应研究进展

综述了近年来二芳基碘钅翁盐在有机合成中促进芳基化反应的最新进展,着重介绍了羰基化合物的芳基化反应、C-H芳基化反应、C-杂芳基化反应以及串联环化反应。     

超声条件下单取代芳基硼酸的合成研究

在超声条件下,以碘为催化剂,利用硼酸酯与卤代芳烃、金属镁粉合成了4种单取代芳基硼酸.确定了反应的最佳工艺条件:在碘的催化作用下,超声波功率170 W,反应温度46℃,反应时间30min,产物收率79%～86%.研究表明,随着硼酸酯取代基空间结构的增大,收率也会提高.产品经1HNMR、IR进行了确认.     

芳香酰氯和芳基硼酸的Suzuki-Miyaura偶联反应研究进展

芳香酰氯具有较高的反应活性,易于和芳基硼酸反应生成工业上应用广泛的芳基酮。概述了应用各种钯催化剂,在条件温和、低毒的情况下进行芳香酰氯和芳基硼酸的Suzuki-Miyaura偶联反应,并就各类反应的优点进行了详细阐述。     

硝基咪唑N-羟烷基化的研究

N-羟烷基化反应是制备塞克硝唑 ,奥硝唑等硝基咪唑类药物的关键步骤。通过对此过程的不同方法进行了对比 ,提出一条以环硫酸酯为 N-羟基化试剂 ,并以塞克硝唑为例进行了合成。此路线产率较高 ,操作方便 ,易于工业化生产。     

1-芳基取代咪唑盐及固相1-芳基取代咪唑的Suzuki反应性能研究

测试了合成的一系列1-芳基取代咪唑盐及固相1-芳基取代咪唑催化的suzuki反应。     

聚乙二醇对聚乳酸纤维性能的改善

采用在双螺杆中熔融共混,以不同相对分子质量聚乙二醇(PEG)作为增塑剂,对聚乳酸(PLA)进行增塑改性,并把改性后的PLA进行熔融纺丝。用扫描电子显微镜(SEM)、熔体流动速率仪(MFR)、单纤维电子强力仪(EYST)和差示扫描量热仪(DSC)对改性PLA纤维进行表征。讨论了不同相对分子质量的PEG对PLA纤维性能的影响,发现随着PEG含量的增加,改性PLA的流动性增加。当PEG质量分数≤8%时,随着PEG含量的增加,改性PLA纤维强度增加,断裂伸长率增加,玻璃化转变温度(Tg)和熔点(Tm)下降。PLA与PEG组分间表现出较好的相容性。PEG200改性的PLA纤维综合效果最好。     

乙二醇铝催化酯化法合成聚丁二酸乙二醇酯

聚丁二酸乙二醇酯(PES)具有优异的力学性能和生物降解性能,在可生物降解塑料领域具有广泛的应用前景。以乙二醇铝为催化剂,催化丁二酸和乙二醇直接酯化缩聚合成了高分子量聚丁二酸乙二醇酯(PES)。采用FT-IR和1H-NMR对催化剂和合成聚合物的结构进行了表征,系统分析了催化剂浓度、聚合反应温度和时间对聚合反应的影响。经常压酯交换后获得的预聚体,在240℃条件下,缩聚4 h后,合成PES的特性黏数[η]可达到0.684 dL/g,重均分子量Mw和数均分子量Mn分别可以达到78632和47945,相对分子质量分布系数PDI值为1.64。乙二醇铝体系中获得的PES聚合物分子量与商业锑系和钛系催化体系中合成聚合物分子量相当,具有广泛工业化应用前景。     

不同PEG含量对PLA/PEG共混物结晶动力学的影响

采用溶液共混法制备了一系列不同配比的聚乳酸(PLA)/聚乙二醇(PEG)共混物。通过偏光显微镜(POM)、扫描电镜(SEM)和差式扫描量热仪(DSC)研究了不同PEG含量的PLA/PEG共混物在不同结晶温度下,聚乳酸的晶体形貌、球晶生长速率及热力学性能。研究发现,PEG能够显著提高聚乳酸球晶的生长速率。当PEG含量为60%时,PLA/PEG共混物中聚乳酸球晶的生长速率最快,达到23.6μm/min,比纯聚乳酸的最快球晶生长速率(0.5μm/min)高47倍。但是,当PEG含量高于60%时,聚乳酸球晶的生长速率有所降低。同时,PLA/PEG共混物中聚乳酸球晶速率随结晶温度变化的取向,均向低温移动。另外,PLA/PEG共混物中聚乳酸球晶呈现环状花纹。DSC测试结果表明,随着PEG含量的增加,PLA/PEG共混物的玻璃化转变温度明显降低。     

聚乙二醇中共轭烯炔化合物的合成

发展了一种在聚乙二醇介质中末端炔烃与缺电子炔烃选择性生成共轭烯炔化合物的方法。在三苯基膦氯化钯(2mol%)、溴化亚铜(4mol%)、PEG-400(1.0g)和氮气的作用下,1mmol末端炔烃与0.5mmol缺电子炔烃可以顺利地发生交叉偶联反应选择性生成相应的共轭烯炔化合物,该反应产率较高,对环境友好,且催化体系可以适当地重复使用。     

Biodegradable polymer blends of poly(lactic acid) and poly(ethylene glycol)

Poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were melt-blended and extruded into films in the PLA/PEG ratios of 100/0, 90/10, 70/30, 50/50, and 30/70. It was concluded from the differential scanning calorimetry and dynamic mechanical analysis results that PLA/PEG blends range from miscible to partially miscible, depending on the concentration. Below 50% PEG content the PEG plasticized the PLA, yielding higher elongations and lower modulus values. Above 50% PEG content the blend morphology was driven by the increasing crystallinity of PEG, resulting in an increase in modulus and a corresponding decrease in elongation at break. The tensile strength was found to decrease in a linear fashion with increasing PEG content. Results obtained from enzymatic degradation show that the weight loss for all of the blends was significantly greater than that for the pure PLA. When the PEG content was 30% or lower, weight loss was found to be primarily due to enzymatic degradation of the PLA. Above 30% PEG content, the weight loss was found to be mainly due to the dissolution of PEG. During hydrolytic degradation, for PLA/PEG blends up to 30% PEG, weight loss occurs as a combination of degradation of PLA and dissolution of PEG. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1495–1505, 1997     

Properties of Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline Conductive Films: The Effect of Poly(ethylene glycol) Diglycidyl Ether

The effect of polyaniline and poly(ethylene glycol) diglycidyl ether on tensile properties, morphology, thermal degradation, and electrical conductivity of poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films was studied. The poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films were prepared using a solution casting technique at room temperature until a homogeneous solution was produced. Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline/poly(ethylene glycol) diglycidyl ether conductive films exhibit higher electrical properties, tensile strength, modulus of elasticity but lower final decomposition temperature than poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films. Scanning electron microscopy morphology showed that the polyaniline more widely dispersed in the poly(vinyl chloride)/poly(ethylene oxide) blends with the addition of poly(ethylene glycol) diglycidyl ether as surface modifier.     

Biodegradability of poly(ethylene terephthalate) copolymers with poly(ethylene glycol)s and poly(tetramethylene glycol)

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T_m), cold crystallization and glass transition (T_g) decreased with the copolymerization. T_m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T_g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.     

Dynamics of Poly(ethylene glycol)-Tethered, pH Responsive Networks

Smart biomaterials composed of pH responsive polymers, poly((meth)acrylic acid), were synthesized using a precipitation polymerization technique. The microparticles were grafted with poly(ethylene glycol) (PEG) chains that are capable of complexing with the hydroxyl groups of the polyacid and interpenetrating into the mucus gel layer upon entry into the small intestine. Upon introduction of an alkaline solution, these materials imbibe a significant amount of water and create a highly viscous suspension. These materials have the necessary physicochemical properties to serve as mucoadhesive controlled release drug carriers for the oral delivery of drugs.     

Poly(ethylene glycol) electrolyte gels prepared by condensation reaction

Poly(ethylene glycol) electrolyte gels were prepared by condensation reaction in the presence of tetraethoxysilane. Differential scanning calorimetry and X‐ray diffraction spectroscopy were used to investigate the thermal transition behavior and crystalline structure of polymer gels prepared. Both formation of crosslinks and incorporation of salts or plasticizers reduced the development of crystalline structure of poly(ethylene glycol)s. Cyclic voltammetric and ion‐conducting behaviors of polymer gels were analyzed using potentiostat and impedance spectroscopy, and those were also considerably affected by the crosslinking density of polymers and the concentration of electrolyte salt or plasticizers incorporated. Poly(ethylene glycol) gels possessing certain levels of electrolyte salt and plasticizer were expected to have applications of solid electrolytes for lithium polymer secondary batteries. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 948–956, 2002