13－臂星形文化聚苯乙烯的某些溶液性质

本文对合成的四个不同分子量的１３－臂星形聚苯乙烯试样，用ＧＰＣ－粘度计联用装置对之进行了测定．用良溶剂中的粘度数据，通过一定的线性外推，得到了它们在θ条件下的ｇθ’因子对良溶剂中的ｇ’因子和ｇθ’因子之间存在的差异以及ｇθ’因子与ｇθ因子间关系式中ε的选值问题进行了详细的实验验证和讨论，并与前文［７］所得４－臂和７－臂星形支化聚苯乙烯试样的结果进行了比较．     

13－臂星形文化聚苯乙烯的某些溶液性质

本文对合成的四个不同分子量的１３－臂星形聚苯乙烯试样，用ＧＰＣ－粘度计联用装置对之进行了测定，用良溶液剂中的粘度数据，通过一定的线性外推，得到它们在θ条件下的ｇθ因子（＝＜η＞ｂ，θ／＜η＞ｌ，θ）。良溶剂中的ｇ’因子（＝＜η＞ｂ／＜η＞ｌ）和ｇθ因子之间存在的差异以及ｇθ因子与ｇθ因子（＝Ｓｂ＾２，θ／Ｓｌ＾２，θ）间关系式ｇθ’＝ｇθ＾ｅ中ε的选值问题进行了详细的实验验证和讨论，并与前文＜７＞     

环型聚苯乙烯的表征

用GPC-LALLS等方法对环型聚苯乙烯进行了系统的表征。环型聚苯乙烯(RPS)是由两端具有活性基团的线型聚苯乙烯通过环化反应制备的,分子量由3×10⁴至2.7×10⁵。结果表明在θ溶剂和良溶剂中RPS与线型聚苯乙烯(LPS)特性粘数之比g(=[η]_r/[η]₁)分别约为0.63和0.65;RPS与LPS无扰均方回转半径之比(< R² >_oτ/< R² >_o1)为0.55—0.59,两者都与大环的理论值相近。实验结果还表明环型高分子符合GPC普适标定原理,此外,求出了RPS在环已烷,甲苯和四氢呋喃溶液中的粘度-分子量方程。     

聚二甲基硅氧烷在混合溶剂中的粘度和光散射

用Elias沉淀点法求取聚二甲基硅氧烷25℃在乙苯-邻苯二甲酸二乙酯体系,庚烷-二氧六环体系的θ-溶剂组成。测定了聚二甲基硅氧烷八个级份在甲苯溶液中光散射和两种θ-溶剂中特性粘数,得到 [η]_θ=7.62×10~(-2)(?)_ω~(0.50)乙苯-邻苯二甲酸二乙酯体系γ_ω=19.0％ [η]_θ=8.28×10~(-2)(?)_ω~(0.50)庚烷-二氧六环体系γ_ω=77.2％ 聚二甲基硅氧烷分子无扰尺寸存在溶剂介质依赖性。     

AB_2型星形杂臂偶氮液晶聚合物的合成及表征

通过原子转移自由基聚合(ATRP)与ATRP衍生物化学修饰结合的方法,合成了一系列AB2型星形杂臂偶氮液晶聚合物.其中,A为聚苯乙烯,B为聚6-[4-(4′-甲氧基苯基)偶氮苯氧基己酯](PMMAZO).合成分三步进行.首先,以ATRP方法得到ω-溴聚苯乙烯活性链PS(Br).然后对PS(Br)进行化学改性,得到带两个末端溴原子的聚苯乙烯活性链PS(Br)2·最后,以PS(Br)2作为双官能团大分子引发剂,引发6-[4-(4′-甲氧基苯基)偶氮苯氧基]己酯(MMAZO)发生ATRP聚合,得到星形杂臂PS(PMMAZO)2聚合物.进一步对聚合产物进行了GPC和1H-NMR分析.结果表明合成产物是预期的星形杂臂聚合物,产物分子量可控且分子量分布狭窄.同时,以DSC和POM表征了星形杂臂聚合物的液晶性.     

四臂星形聚苯乙烯在良溶剂和0溶剂中分子扩散的光子相关光谱的研究

用光子相关光谱研究了四臂星形聚苯乙烯在良溶剂(四氢呋喃THF)和θ溶剂(环己烷CH)中扩散系数与溶剂的浓度和温度的依赖关系。用累积量方法分析光子相关数据给出了多分散样品的Z均扩散系数。在θ溶剂中,高于或低于θ温度时,聚合物在溶液中的分子扩散分别表现出具有在良溶剂与不良溶剂中的行为。外推浓度至零,得到无限稀时不同温度的分子扩散系数,借助Stokes-Einstein方程,给出了聚合物的流体力学半径。通过InD对I/T作图,得到了星形聚苯乙烯在THF与CH中的扩散活化能。     

环形聚苯乙烯的稀溶液性质——Ⅰ.环己烷溶液的θ温度

本工作采用光散射测定第二维利系数的方法,确定了环形聚苯乙烯在环己烷溶液中的θ温度为30℃,比线形聚苯乙烯的θ温度低4.5℃。在此温度下及35℃,环形聚苯乙烯(1×10~4<(?)_W<22.7×10~4)的Mark-Houwink方程分别为:[η]=5.10×10~(-2)(?)_(W~(0.508)),cm~3g~(-1) [η]=2.70×10~(-2)(?)_(W~(0.576)),cm~3g~(-1)     

聚甲基丙烯酸甲酯混合溶剂体系 Ⅴ.在乙酸甲酯-乙醇中的特性粘数与末端距关系

1.一个聚甲基丙烯酸甲酯级分(M=2.63×10~6)在等折射率的溶剂-非溶剂体系(乙酸甲酯-乙醇)中测定粘度和光散射,得到的结果证实dlog[η]/dlog(?)~(1/2)=3。 2.试样的乙酸甲酯溶液粘度在通常的测定条件下已达到低切变速度区域的牛顿流动范围。 3.在25.0°时θ-溶剂组分是γ_w(乙醇)=0.509。 4.从θ-溶剂中测定试样的沉降系数累积分布I(s),再结合_w,[η]_θ实验值,可以计算单分散体系的 s=(?)_sM~(1/2),[η]_θ=(?)_θM~(1/2)关系中的(?)_s,(?)_θ值。25.0°时聚甲基丙烯酸甲酯的 (?)_s=3.02×10~(-15),(?)_θ=4.59×10~(-2)。 5.经多分散性改正后的Flory常数Φ=1.6_1×10~(23),聚甲基丙烯酸甲酯高分子链的((?)/M)~(1/2)=66×10~(-10)。     

聚苯乙烯-丁酮-正己烷体系稀溶液性质的研究

测定了五个聚苯乙烯级分((?)_η3.2×10~5—2.7×10~6)在丁酮-正己烷体系中的特性粘数,发现高分子量级分的特性粘数-组成曲綫在γ=0.13处出现极大值。简要叙述了自制光电式散射光度计的结构。聚苯乙烯级分在上述混合溶剂体系内光散射测定的结果表明,A_2也在γ=0.13处出现极大。应用溶度参数解释了上述结果。本工作所得聚苯乙烯溶度参数实验值为8.8。 根据在θ-溶剂中A_2=0及Mark-Houwink方程参数α=1/2的条件,从粘度及光散射所测得的聚苯乙烯-丁酮-正己烷体系(30℃)的θ溶剂组成是一致的,γ_θ=0.45。     

聚二甲基硅氧烷-溴代环己烷体系沉降系数的压力改正与s-M,[η]-M单分散关系

对聚二甲基硅氧烷-溴代环己烷θ溶液(28℃)体系进行了沉降速度法测定分子量分布及沉降系数压力改正的研究。提出了一种新的直接测定沉降系数的压力改正的方法,即在沉降池中加入不同量的溶液以得到不同的液柱高来改变静压,测定溶液界面在不同静压下的浮升速度计算压力系数。所得适用 于静压为200大气压以下的沉降系数的压力改正系数α=1.44×10~(-3)_(大气压)~(-1)。从沉降系数分布、(?)_ω、[η]_θ及[η]_(甲苯)的测定,订定了聚二甲基硅氧烷在28℃θ条件下的s-M,[η]_θ-M及在甲苯(25℃,良溶剂)中的[η]-M单分散关系为。 s_1=6.30×10~(16)M~(0.50)(溴代环己烷,28℃) [η]=7.41×10~(-2)M~(0.50)(溴代环己烷,28℃) [η]=9.53×10~(-3)M~(0.71)(甲苯,25℃)     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.