氧化锌促进的醛与[Ph_3P~+CF_2H·Br~-]的Wittig偕二氟烯基化反应（英文）

以氧化锌为碱实现了醛与二氟甲基鏻盐[Ph_3P~+CF_2H·Br~-]的Wittig偕二氟烯基化反应.虽然鏻盐中二氟甲基上的氢原子具有一定酸性,但是碱不一定就会与其发生中和反应而使鏻盐转化为叶立德.碱也有可能进攻磷原子而产生具有亲核性的二氟甲基物种,从而发生亲核二氟甲基化.以氧化锌为碱可抑制二氟甲基化,有利于Wittig反应;此外,氧化锌及其产生的锌盐都可经简单过滤而除去,方便产物纯化.     

dl-六甲基化丹酚酸A甲酯的合成

以2,3二-甲氧基苯甲醛为原料,经还原、溴化、Wittig反应、在正丁基锂作用下醛基化、Knoevenagel反应生成四甲基化丹酚酸F(9),9再与草酰氯反应成酰氯后与甲基化丹参素甲酯反应得到dl-六甲基化丹酚酸A甲酯,其结构经1HNMR和MS表征,总收率44.7%。     

5-三氟甲基胡椒醛的合成研究

以香草醛为起始原料,经碘代、脱甲基、亚甲基醚化、三氟甲基化反应以较高收率合成了5-三氟甲基胡椒醛,产物结构经过了1H NMR,13C NMR,19F NMR和HRMS的确证.重点研究了三氟甲基化反应,考察了不同三氟甲基化试剂、溶剂、催化剂用量、反应温度以及反应时间对三氟甲基化反应收率的影响,确定了最佳反应条件.随后,该方法成功运用于3,4位不同取代的5-碘苯甲醛的三氟甲基化反应,制得了三种5-三氟甲基胡椒醛的衍生物.     

人脑乙酰胆碱酯酶的分离纯化及特性

人脑纹状体及部分丘脑AChE在低盐缓冲液中以1％Triton X-100溶脱后,经Con A、短臂及长臂凝胶配基亲和层析纯化在还原条件下SDS-PAGE呈一主带,纯化的AChE比活性可达3384U/mg,产率20％,其单体分子量66 kD,聚丙烯酰胺凝胶电泳显示有单体及二、四、六、八聚体存在,等电点在pH5.3—6.0之间,人脑AChE活性大部分能用Con A亲和层析法回收说明为糖蛋白,纯化的人脑AChE与抗电鳐电器官AChE单克隆抗体3F3无抗原抗体反应,而与IH11及2G 8有弱的交叉反应,以Con A及短臂凝胶配基亲和层析纯化的人小脑AChE为抗原免疫Balb/c小鼠产生的抗血清与电鳐电器官AChE有较强的免疫交叉反应而与人红细胞膜AChE反应较弱,纯化的人脑AChE经还原羧甲基化及TPCK处理的胰蛋白酶切割后,再用反相HPLC分离,显示几个大肽峰及许多小肽峰,几个大肽峰以ELISA法测定有抗原性。     

煤中碳硫键的室温选择性断裂

通过室温下高硫煤的Ｓ甲基化反应,可使煤结构中的一种碳硫键选择性断裂。煤样先经Ｏ甲基化反应,使酚羟基转变为甲基醚,然后再经由碘甲烷和四氟硼酸银组成的Ｓ甲基化试剂进行Ｓ甲基化反应。断裂后硫以四氟硼酸三甲基锍的形式用１３ＣＮＭＲ进行检测。以模型化合物４,４二甲氧基二苄基硫醚进行Ｓ甲基化反应,亦可高产率地生成四氟硼酸三甲基锍。提出一个由苄基碳正离子和硫醚组成的离子偶极集合物作为反应中间体的反应机理。最后,１３ＣＮＭＲ定量分析结果表明,烟煤中含有约２％的４,４二甲氧基二苄基型硫醚或４,４二羟基二苄基型硫醚。     

羧甲基牛膝多糖的制备、结构及生物活性研究

在NaOH水溶液中,以ClCH_2COOH为羧甲基化试剂,对牛膝多糖(AbPS)进行了羧 甲基化,粗产物经DEAE-Cellulose及Sephadex G-25两次柱层析纯化,得到羧甲基 牛膝多糖(CM-AbPS)纯品,经高效液相法（HPLC）及毛细管电泳法（CE）检测表明 具有较好的均一性,并通过样品甲基化和GC-MS分析,对羧甲基牛膝多糖链中羧甲 基的分布进行了研究,结果表明羧甲基牛膝多糖中羧甲基主要取代的糖链中呋喃果 糖的4-位上。该产物具有抗肿瘤活性。     

(±)-金锦香酸二甲酯甲醚的合成

本文以呋喃甲酸甲酯为原料, 经羟烷基化反应, 醇解反应和O-甲基化反应合成(±)-金锦香酸二甲酯甲醚。同时, 还发现了制备2-乙烯基呋喃衍生物的新方法。     

3-亚甲基六氢苯并呋喃-2(3H)-酮的简便合成

以氧化环己烯为原料,在正丁基锂作用下与乙腈经开环反应制得2-羟基环己基乙腈(2);2依次经水解、内酯化、二甲胺甲基化、甲基化和Hofmann降解反应合成了α-亚甲基-γ-丁内酯类化合物--3-亚甲基六氢苯并呋喃-2(3H)-酮,总收率30.4%,其结构经¹H NMR,¹³C NMR和HR-MS(EI)确证。     

过渡金属催化芳香化合物三氟甲基化反应

近年来,过渡金属催化芳香化合物三氟甲基化反应迅速发展,底物适用范围不断扩展,新方法、新型三氟甲基化试剂的应用也不断涌现。本文综述了近年来过渡金属催化芳香化合物三氟甲基化的最新研究进展,包括卤代芳香化合物的三氟甲基化,芳香硼酸的三氟甲基化和芳烃C—H活化三氟甲基化反应。此外,对过渡金属催化三氟甲基化反应中涉及的机理也进行了详细地讨论。     

间氨基茴香醚的合成

以间氨基苯酚为原料,经乙酰化、甲基化和碱水解合成了间氨基茴香醚,3步反应的收率分别为90.7%,82.8%和88.2%。最佳的甲基化反应条件为:间羟基乙酰苯胺56 mmol,n(间羟基乙酰苯胺)∶n(M e2SO4)∶n(NaOH)=1.0∶1.5∶1.2,回流反应8 h,四氯化碳为溶剂。     

离子热法合成沸石咪唑骨架材料及其溶解-结晶机理研究

基于沸石咪唑骨架材料在离子液体和低共熔溶剂中冷却结晶的析出方式,开发了一种离子热法合成沸石咪唑骨架材料的新途径,采用X射线衍射、扫描电镜、核磁共振光谱、红外光谱以及热重分析等方法对制备的产物进行了表征,研究了合成条件对产物结晶度、尺寸和形貌的影响,探讨了沸石咪唑骨架材料在离子热合成体系中的溶解-结晶析出机理.研究发现,冷却速率能够影响产物形貌,急速冷却时,sod(RCSR代码)型产物的形貌为球形,zni(RCSR代码)型产物为棒状或平板状;程序控制冷却时,sod型产物的形貌为多面体,zni型产物呈团簇状.     

Amine-catalyzed Michael reactions of an aminoaldehyde derivative to nitroolefins

Catalytic enantioselective Michael addition reactions of α-amino functionalized aldehydes to nitroolefins have been developed. The Michael product was obtained in up to 98% ee, but the enantiomeric purity of the Michael product was decreased during isolation of the product.     

Control of self-aldol condensation by pressure manipulation under compressed CO2

Under supercritical CO2 conditions, simple adjustment of the pressure was found to successfully control the ratio of aldol to enal product in the self-aldol condensation of aldehyde, in which the enal product was obtained in a maximum selectivity of 94% at the critical pressure of 12MPa, whereas 85% selectivity to the aldol product was achieved at the subcritical region.     

Spectroelectrochemistry study on the electrochemical reduction of ethidium bromide.

The electrochemical reduction mechanism of ethidium bromide was first studied by spectroelectrochemistry. This reduction was proved to be a two-step process by cyclic voltammetry, differential pulse voltammetry and spectroelectrochemistry, in which each step was proved to be a one-electron transfer process by a spectropotentiostatic fluorescence technique. Hydroethidine was confirmed to be the final product by comparing the spectrum of the product of the electrochemical reduction to that of the product of the chemical reduction of ethidium bromide, and a carbon-centered radical was concluded to be a reasonable intermediate product during the electrochemical reduction of ethidium bromide.     

Ultramicro enzyme assays in a capillary electrophoretic system.

This paper describes an ultramicro method for achieving enzyme assays. Enzyme saturating concentrations of substrate, coenzyme when appropriate, and running buffer were mixed and used to fill a deactivated fused-silica capillary in a capillary zone electrophoresis apparatus. The enzyme glucose-6-phosphate dehydrogenase was injected by either electrophoresis or siphoning and mixed with the reagents in the capillary by electrophoretic mixing. Enzyme activity was assayed by electrophoresing the product, reduced nicotinamide adenine dinucleotide phosphate, to the detector where it was detected at 340 nm. Under constant potential, the transport velocity of enzyme and the product was generally different. This caused product to be separated from the enzyme after it was formed. Because product formation was much faster than the rate of enzyme-product separation, product accumulated. The amount of accumulated product was inversely related to operating potential. In the extreme case, the operating potential was zero. Zero potential assays were generally carried out by electrophoresing the enzyme partially through the capillary and then switching to zero potential. This capillary was left at zero potential for several minutes to allow additional product to accumulate. After this additional amplification step, potential was again applied and the product transported to the detector. Product formed under constant potential appears as a broad peak with a flat plateau. When the voltage is switched to zero at intermediate migration distance, a peak will be observed on top of this plateau. Either the eight of the plateau or the area of the peak may be used to determine enzyme concentration. The lower limit of detection was 4.6.10(-17) mol of glucose-6-phosphate dehydrogenase.     

双单体固相共聚改性聚丙烯技术及其机理研究

在马来酸酐(MAH)固相接枝改性聚丙烯(PP)的过程中加入合适比例的异氰脲酸三烯丙酯(TAIC)作为共聚单体,可以大大提高MAH在PP上的接枝率,同时可以有效抑制在普通固相接枝过程中PP的严重降解,得到了性能较好的高极性PP.与普通固相接枝法与熔体接枝法对比,双单体固相共聚接枝改性PP是一种得到高极性PP的有效方法.本文同时对双单体在固相接枝反应中的作用机理进行了探讨.     

纳米纤维状微结构乙炔聚合物的相变研究

在真空中对由乙炔聚合制备的纳米纤维采用两种处理工艺进行升温相变处理，即及抽出反应产生的气体以保持真空度和不抽出反应产生条件。ＴＥＭ观察发现相变前后的微观形态均为纤维状，ＩＲ实验结果表明在两种不同处理工艺条件下得到的产物不同。在第一处理工艺条件下，随温度升高纳米纤维发生链断裂和碳化，且相变产物的电阻越来越小，在７００℃以上得到具有较高电性的纳米导电纤维，ＸＲＤ实验表明盯变后产物虽未石化但结晶性增强，     

Modeling Nd-Catalyzed Butadiene Rubber Production

Summary: A simulation tool was developed for the industrial solution polymerization of 1,3-butadiene with a Nd-based homogeneous Ziegler-Natta catalyst system. Insight into underlying reaction mechanisms was gained from laboratory experiments. Besides the chain growth reaction, the following steps were identified: catalyst formation, deactivation reactions, and molecular weight control reactions. A kinetic model based on this reaction scheme was developed to quantitatively describe butadiene conversion and product molecular weight distribution. By including process characteristics, the laboratory (batch) model was transferred to the industrial production process. A correlation function relates product molecular weight to the relevant product property Mooney viscosity. This polymerization model was successfully applied, e.g. to optimize product grade transitions and to maintain high product quality by predicting the influence of process changes.     

Ligase-based ultrasensitive detection of DNAzyme cleavage product using molecular beacon

Detection for deoxyribozyme(DNAzyme) cleavage usually needs complex and time-consuming radial labeling,gel electrophoresis and autoradiography.A new approach was reported for detection DNAzyme cleavage product based on molecular beacon (MB).Part of the loop of MB was designed to complementary to DNAzyme cleavage product.MB was employed to monitor ligation process of RNA/DNA complex and to convert directly cleavage product information into fluorescence signal.Detection limit of the assay is 0.02 nmol/L.The cleavage product of 8 -17 DNAzyme against HCV-RNA was detected perfectly based on this assay.The method is fast,simple and ultrasensitive,which might hold great promise in DNAzyme reaction and DNAzyme gene therapy.     

氮氧自由基的研究(Ⅳ)——氮氧自由基对半胱氨酸的氧化反应

氮氧自由基是目前最广泛采用的自旋标记物^[1-2]。2,2,6,6-四甲基哌啶氮氧自由基虽然在许多情况下是很稳定的,但是仍然可以发生歧化、单电子氧化还原等反应^[3-4]。