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1.
刘奉岭 《结构化学》2002,21(2):210-213
采用量子化学中的DFT理论方法,在B3LYP/6-311G*水平上全优化得到了不饱和类碳烯H2C=CLiCl的平衡结构。结果表明,不饱和类碳烯H2C=CLiCl只有2种平衡结构。对这2种平衡结构之间相互转化的过渡态进行计算,同时,采用统计热力学及过渡态理论,研究了2种平衡结构之间相互转化的热力学及动力学性质,进而讨论了2种平衡结构在不同温度下的稳定性问题,结果表明在所研究的100-600K温度范围内,只有一种平衡结构能够存在,在计算得到振动频率及吸收强度的基础上,模拟了稳定平衡结构的红外光谱图。  相似文献   

2.
合成了三种二芳基碘翁氟硼酸盐,并用IR,NMR,紫外光谱及元素分析进行了结构表征,研究了它们引发环氧聚硅氧烷的阳离子光固化及光敏剂浓度、结构及促进剂等因素对光固化速度的影响。  相似文献   

3.
合成了三种二芳基碘weng氟硼酸盐,并用IR,NMR,紫外光谱及元素分析进行了结构表征,研究了它们引发环氧聚硅氧烷的阳离子光固化及光敏剂浓度、结构及促进剂等因素对光固化速度的影响。  相似文献   

4.
胡昌玉  许禄 《分析化学》1994,22(8):775-780
结构产生器是有机化合物结构自动解析专家系统的核心部分,它从分子式出发,穷举生成结构基元向量,结构片断向量,最后对接成整体结构。本文详细介绍了ESESOC-II系统的结构基元和结构片断的定义,并阐述了如何利用组合数学原理从分子式出发穷举生成结构基元向量和结构片断向量及结构片断集的算法。  相似文献   

5.
有机化学品的生物降解性及构效关系   总被引:6,自引:0,他引:6  
陆光华  赵元慧  汤洁 《化学通报》2002,65(2):113-118
介绍了描述生物降解性的主要测定参数,测定过程的影响因素及常用的结构描述符,并结合实例综述了目前应用比较广泛的定量结构-生物降解性关系(QSBR)技术,最后,分析了QSBR工作存在的主要问题及研究前景。  相似文献   

6.
三明治型稀土金属卟啉络合物的研究进展   总被引:5,自引:2,他引:5  
本文论述了现代无机化学领域中一个重要的独立分支-三明治夹心稀土金属卟啉络合物的研究进展,详细论述了该类大环络合物的合成,结构及光谱学性质,并根据结构和性质阐述了其对生物学,医学及大环配位化合物理论研究的重要意义。  相似文献   

7.
用FTIR和XPS研究ACF的表面结构   总被引:3,自引:1,他引:3  
采用红外光谱(FTIR)及X光电子能谱(XPS),系统分析了纤维碳化各阶段的结构、不同程度活化的ACF的结构以及低温氧化后和热处理后ACF的结构,提出了ACF表面结构模型。  相似文献   

8.
用选区电子衍射和高分辨电子显微术研究钙稀土氟碳酸盐矿物及其衍生物多晶体结构,发现三种不同的氟碳铈矿与直氟碳钙铈矿具8:6新规则混层结构,确定了各自的晶体结构类型,晶胞参数,堆垛模式及晶体化学式等。高分辨像的观察分析,揭示出了三种B8S6规则混层结构中的Ce-F离子层以及两个Ce-F离子层之间的CO3离子组具有不同的排列方式,观察和讨论了上述规则支结构中的无序夹层及堆垛层错等非均匀结构现象。  相似文献   

9.
含Sn—N键的混合三烃基锡氮杂环化合物的研究   总被引:1,自引:0,他引:1  
杨志强  周秀中 《合成化学》1995,3(4):323-328
报道了15个含Sn-N键的混合三烃基锡环衍生物合成及结构表征。随含氮杂环的不同。化合物分别是五配位的聚合结构和四配位的单体结构,对化合物的质谱作了较为详细的讨论,测定了化合物的生物活性,并对生物活性与结构的关系进行了讨论。  相似文献   

10.
合成了14种含有氮芥结构及芳基取代硫脲基的磷酰胺酯,其结构经^1HNMR、IR、MS和元素分析证实研究了它们的波谱性质及结构和化学位移的关系,讨论了磷原子上取代基对反应的影响,初步生测结果表明,部分化合物具有良好的抗TMV病毒活性和良好的抗肿瘤活性。  相似文献   

11.
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%.  相似文献   

12.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.  相似文献   

16.
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.  相似文献   

17.
A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.  相似文献   

18.
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%).  相似文献   

19.
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.  相似文献   

20.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.  相似文献   

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