Ziegler-Natta配位聚合反应机理的量子化学研究——Cossee机理中活性中心的构型及其有关的关键步骤

本文采用ASED-MO理论对丙烯聚合的 Ziegler-Natta 催化过程的机理进行了理论研究。按照Cossee机理进行计算,得到了和实验事实基本一致的结果。认为该机理基本上是合理的,并对其中的关键步骤进行了理论解释,而对其中一些尚有争论的问题,如催化中心的稳定构型、丙烯分子和活性中心之间的配位作用、链增长过程和催化循环等问题提出了自己的见解。     

用NICOLET5SXC富里利叶变换红外光谱仪对中成药作GC/FTCR分析研究——Ⅱ.药用油的GC/FTIR快速分析

本文用Nicolet 5SXC对驱风油,本草油,白花油进行了GC/FTIR快速分析,在没有标准品的条件下,对其中十六个主组分进行了定性研究,用Aldrich Vapor Librasy进行了谱库检索,取得了较为满意的结果。     

一类以光度法进行检测的新型阴离子敏感化合物

对6种带羟基的分子内电荷转移化合物(其中化合物1,4,5,6含氰基基团)及与不同阴离子间的相互作用及其分子识别进行了研究.发现化合物2,3,5,6均对F^-离子有优良的检测能力,并对H₂PO₄^-有一定的响应能力,其中化合物2对AcO^-离子也有一定的响应.对实验结果进行了初步讨论,并对提高敏感化合物的灵敏度和选择性提出了看法.     

Ziegler-Natta配位聚合反应机理的量子化学研究——Cossee机理中活性中心的构型及其有关的关键步骤

 本文采用ASED-MO理论对丙烯聚合的 Ziegler-Natta 催化过程的机理进行了理论研究。按照Cossee机理进行计算,得到了和实验事实基本一致的结果。认为该机理基本上是合理的,并对其中的关键步骤进行了理论解释,而对其中一些尚有争论的问题,如催化中心的稳定构型、丙烯分子和活性中心之间的配位作用、链增长过程和催化循环等问题提出了自己的见解。     

高效液相色谱/大气压化学电离质谱分析新型复合抗氧剂

 应用高效液相色谱 /大气压化学电离质谱技术 ,其中包括直接进样技术、同时正负离子扫描方式、可编程的源内碰撞诱导解离 (CID)技术 ,以及红外光谱分析技术 ,对一种用于润滑油的新型复合抗氧剂进行了分离分析 ,并对其中的有效组分进行了定性鉴定。该方法简便、快速、可靠。     

遵照国家法制规定大力开发强化食品

介绍了我国食品营养强化剂使用卫生标准,特别是对其中一些重要备注和规定进行了归纳和说明.     

气相色谱—傅里叶变换红外光谱技术应用于冠心苏合丸中挥发性成分分析

本文应用气相色谱－傅里叶变换红外光谱联用技术对中成药冠心苏合丸中挥发性成分进行了库检索，鉴定了其中７种有效成分，并采内标法对其中龙脑、异龙脑的总量进行了含量测定，其平均回收率为９８．５３％。     

碳酸酐酶及其模型研究进展*

本文综述了近年来碳酸酐酶及其化学模型两方面的最新研究进展,对其中的问题和进一步的研究进行了简要的讨论。     

细菌介导重金属转化过程及金属组学研究方法

重金属污染依然是我国严重的环境问题之一。在重金属胁迫下,微生物可通过复杂的过程,对重金属进行转化,降低重金属的毒性,其中转化涉及的分子机制广受关注。目前,在上述机制相关研究中,对转化过程中重金属的衡量多局限于总量的测定,而对其赋存形态的研究不足,导致难以取得有效进展。对细菌介导重金属的转化过程及金属在其中的赋存形态进行综述,探讨了金属组学研究方法在其中的应用,重点针对重金属的颗粒态与蛋白质结合态进行分析、表征和鉴定,为微生物介导重金属的转化研究提供新视角。     

化学与防火涂料

通过介绍当前我国防火涂料的种类、用途及使用对象,揭示其中的化学知识;对当前我国防火涂料的发展现状进行了分析,并根据防火涂料的发展现状对其今后的发展方向进行了探讨.     

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%.     

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.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.