乙烯系单体自由基聚合的阻聚效应 ⅩⅢ.1,3,5-三苯甲(月替)与取代硝基苯混合物对甲基丙烯酸甲酯聚合的影响

研究1,3,5-三苯甲(月替)(TFH)与一些4-取代硝基苯(4SNB)和4-取代-1,3-二硝基苯(4SDNB)的混合物对偶氮二异丁腈引发的甲基丙烯酸甲酯(MMA)自由基聚合的影响。结果表明,TFH-4SNB配方对MMA聚合的阻聚功效与4SNB中取代基的电子效应有关。吸电子取代基能延长诱导期,提高阻聚能力。推电子基则降低聚合诱导期。对于TFH-4SDNB配方,聚合诱导期依赖于取代基的空间位阻:取代基的原子半径增大,聚合诱导期降低。     

用四氨基铝酞菁共振光散射技术测定纳克级核酸

痕量核酸对四氨基铝酞菁的共振散射光产生增强作用,且增强程度与核酸浓度之间有良好的线性关系.据此建立了测定核酸的高灵敏共振散射光增强分析方法.在pH=6.0、最大散射波长400nm处,测定小牛胸腺DNA(CTDNA)、鲑鱼精子DNA(SMDNA)和酵母RNA(YeastRNA)的线性范围分别是0～250ng/mL,0～200ng/mL和0～400ng/mL,检测限分别为1.4ng/mL,1.4ng/mL和2.7ng/mL.该法简单,灵敏度高,用于实际样品中核酸含量的测定,所得结果与紫外吸收法一致.     

Derivatives of sym-Triazines. 6. Some Special Features of the Addition of Substituted Acetylenes to Triazine Monoazides

The special features of the interaction of 2-azido-4-R-6-R'-sym-triazines with some acetylenic compounds have been investigated. A series of new derivatives of sym-triazine linked at position 2 with a 1,2,3-triazole ring has been synthesized.     

相转移催化合成酯基取代酞菁铜及其光导性能

酞菁配合物的大π键共轭体系使其具有独特的物理化学性能．但酞菁的难溶性,限制了其进一步的研究和应用．Baker等首次制备了可溶性酞菁单分子膜,并将其应用到光电池中;随后,已有大量的相关研究报道．作为常见的可溶性酞菁衍生物,酯基取代酞菁由于含酯基的前体物质高温分解而不能采用直接缩合的方法,     

Free radical copolymerization of methyl substituted stilbenes with maleic anhydride

Stilbene-maleic anhydride is a well-known donor-acceptor comonomer pair which undergoes free radical copolymerization to form an alternating copolymer. A series of methyl substituted stilbenes were synthesized and copolymerized with maleic anhydride. A conversion versus time study was undertaken to understand the methyl substituent effect on copolymerization rates. Methyl substituents on the phenyl ring of stilbene can change the reactivity of stilbene by changing the resonance stability of the propagating radical and steric hindrance in the propagation step and thereby change the copolymerization rate. Methyl substituted stilbene-maleic anhydride copolymers were determined by quantitative ¹³C 1D NMR to be alternating copolymers. Size exclusion chromatography (SEC) measurements showed that the weight-average molecular weights of these copolymers varied from 3000 to over 1,000,000 g/mol. Interchain aggregation was observed in poly((E)-4-methylstilbene-alt-maleic anhydride) by dynamic light scattering (DLS). The SEC trace for poly((E)-4-methylstilbene-alt-maleic anhydride) exhibited bimodal peaks. No glass transition temperature or crystalline melting temperature was observed between 0 °C and 250 °C by differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) showed that these polymers have 5% weight loss around 290 °C.     

Synthesis and Characterization of Poly(chiral methylpropargyl ester)s Carrying Azobenzene Moieties

Novel chiral methylpropargyl esters bearing azobenzene groups, namely, 4‐[4′‐(benzyloxy)phenylazophenyl]‐ carbonyl‐(S)‐1‐methylpropargyl ester ( e ), 4‐[4′‐(n‐butyloxy)phenylazophenyl]carbonyl‐(S)‐1‐methylpropargyl ester ( f ), 4‐[4′‐(n‐hexyloxy)phenylazophenyl]carbonyl‐(S)‐1‐methylpropargyl ester ( g ), and 4‐[4′‐(n‐octyloxy)phenylazo‐ phenyl]carbonyl‐(S)‐1‐methylpropargyl ester ( h ) were synthesized and polymerized with Rh⁺(nbd)[η⁶‐C₆H₅B^?‐ (C₆H₅)₃] (nbd=norbornadiene) catalyst to give the corresponding polymers with moderate molecular weights (M_n=8.4×10³–15.7×10³) in good yields (76%? –?91%). The structures of polymers were illustrated by IR and NMR spectroscopies. Polymers were soluble in comment organic solvents including toluene, CHCl₃ CH₂Cl₂, THF, and DMSO, while insoluble in diethyl ether, n‐hexane and methanol. Large optical rotations of polymer solutions demonstrated that all the polymers take a helical structure with a predominantly one‐handed screw sense in organic solvents.     

一类含氟多取代苯酚的合成及其核磁共振研究

一类含六个碳的长链叶立德通过分子内维蒂希反应可生成含氟多取代苯酚. 通过对中间产物及最终成环产物的¹H NMR和¹³C NMR的分析,讨论了其化学位移及J-偶合特征. 同时研究了整个反应可能的历程和机理.     

取代芳烃对月芽藻、大鼠等毒性的构效关系研究

提出了新的原子生物活性值(αi)并由其建构自相关拓扑指数(^mL)．^oL和L分别与取代芳烃对月芽藻、发光菌慢性毒性关联，其相关系数分别为0．9315和0．9439；对酵母菌、发光菌、大鼠的急性毒性的相关系数依次为0．9482，0．9064和0．9762．     

N′-(取代嘧啶-2-基)-N-菊酰硫脲的合成与生物活性研究

采用活性基团拼接法, 将第一菊酸构型中的最高活性组分(＋)-反式菊酸以及二氯菊酸引入到含取代嘧啶环的酰基硫脲结构中, 合成了5个未见文献报道的N′-(取代嘧啶-2-基)-N-(＋)-反式菊酰硫脲衍生物(3a～3e)和3个均未见文献报道的N′-(取代嘧啶-2-基)-N-二氯菊酰硫脲(3f～3h), 结构经元素分析、IR和¹H NMR得到确证. 初步的生物活性测试结果表明: 大部分化合物具有较好的杀菌活性, 有的化合物兼具除草和杀菌活性, 有的化合物兼具杀虫和杀菌活性.     

Ethene homopolymerization and copolymerization with 1‐hexene for all methyl‐substituted (RnC5H5−n)2ZrCL2/MAO catalytic systems: Effects of split methyl substitution

Ethene homopolymerization and copolymerization with 1‐hexene were catalyzed by methyl‐substituted cyclopentadienyl (Cp) zirconium dichlorides, (R_n C₅H_5−n)₂ZrCl₂ (R_n = H, Me, 1,2‐Me₂, 1,3‐Me₂, 1,2,3‐Me₃, 1,2,4‐Me₃, Me₄, or Me₅), and methylaluminoxane. The polymers were characterized with Fourier transform infrared, nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry techniques. Generally, an increasing number of methyl substituents on the Cp ligand results in lower 1‐hexene incorporation in the copolymer. The two catalysts with split methyl substitution (R_n = 1,3‐Me₂ and R_n = 1,2,4‐Me₃) show a higher comonomer response than their disubstituted and trisubstituted counterparts (R_n = 1,2‐Me₂ and R_n = 1,2,3‐Me₃). They even incorporate more 1‐hexene than R_n = H and R_n = Me. These findings are qualitatively in agreement with the results of a theoretical study based on density functional calculations. The presence of comonomer does not influence the termination reactions after the insertion of ethene. There is more frequent termination after each hexene insertion with increasing comonomer incorporation except for the two catalysts with split methyl substituents. The termination probability per inserted comonomer is highest for the less substituted catalysts. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3161–3172, 2000