芳卤化合物的邻位锂化反应和锂卤交换反应

介绍了芳卤化合物的邻位锂化反应和锂卤交换反应的反应机制、控制因素及应用实例,并且比较两种反应的异同点,从而使读者能够更好地掌握这两种非常重要的合成方法,并加以灵活运用。     

邻烷氧基苯酚的相转移催化合成及其锂化合物的性质

前文曾报导邻位取代苯酚锂化合物的质谱和红外光谱性质,通过同位素~6Li和~7Li化合物的红外光谱差异,提出了在这类化合物中存在内锂键的可能性.对邻位甲氧基苯酚锂的低温红外光谱研究表明,这类锂化合物中可能存在有网状结构性质.为进一步深入了解这一性质,我们通过相转移催化反应合成了7个邻烷氧基苯酚,制得它们的~6Li和~7Li化合物,考察了它们的红外光谱和质谱性质.     

(一)-Sparteine辅助的邻位锂化反应对映选择性合成具有平面手性的非对称二茂铁胺

以非对称的N-乙基-N-异丙基-二茂铁酰胺为底物,利用(一)-sparteine辅助的邻位锂化反应制备具有平面手性的二茂铁衍生物,得到了很高的产率和对映选择性.并测定了1-(N-乙基-N-异丙基)酰胺-2-碘-二茂铁(10a)的晶体结构.研究发现,非对称的二茂铁底物有利于强化底物的手性环境,进而提高反应的对映选择性.     

高邻位高分子量热塑性酚醛树脂研制

改变传统合成工艺,在高温高压无催化剂条件下,合成了无金属杂质的高邻位高分子量热塑性酚醛树脂。考察了苯酚与甲醛加成缩合反应过程中原料种类、原料配比、反应温度及反应压力等因素对酚醛树脂结构性能的影响。通过软化点测试仪、核磁共振谱仪等研究了酚醛树脂合成过程中各个参数对酚醛树脂结构性能的影响。在酚／醛比为1：0．7,210℃、...     

直接邻位锂化反应的新进展

在取代芳香环邻位上引入新取代基的一般方法是 Friedal-Crafts 反应及其它亲电取代反应。然而由于这些反应对芳香化合物活性的要求及产物中存在对位异构体等原因,使得亲电     

卤化吡啶具有区域选择性的锂化反应与2,6-二甲氧基-3-溴-4-二苯基膦基吡啶的合成

在卤化吡啶的锂化反应的区域选择性研究基础上,以2,6-二甲氧基吡啶为原料,经溴化反应、邻位锂化反应和亲电取代反应制备了2,6-二甲氧基-3-溴-4-二苯基膦基吡啶,最终收率可达57．9％。     

(-)-Sparteine辅助的邻位锂化反应对映选择性合成具有平面手性的非对称二茂铁胺

以非对称的N-乙基-N-异丙基-二茂铁酰胺为底物,利用(-)-sparteine辅助的邻位锂化反应制备具有平面手性的二茂铁衍生物,得到了很高的产率和对映选择性.并测定了1-(N-乙基-N-异丙基)酰胺-2-碘-二茂铁(10a)的晶体结构.研究发现,非对称的二茂铁底物有利于强化底物的手性环境,进而提高反应的对映选择性.     

固相配位化学反应研究──LXX．二水醋酸镉与邻氨基苯甲酸的分步固相反应

二水醋酸镉与邻氨基苯甲酸(HOAB)在室温下发生固-固相化学反应生成Cd(OAB)₂,用等温DSC、等温电导法跟踪研究反应过程发现,上述固相反应分两步进行.     

固相配位化学反应研究──LXX．二水醋酸镉与邻氨基苯甲酸的分步固相反应

二水醋酸镉与邻氨基苯甲酸（ＨＯＡＢ）在室温下发生固—固相化学反应生成Ｃｄ（ＯＡＢ）２，用等温ＤＳＣ、等温电导法跟踪研究反应过程发现，上述固相反应分两步进行．     

邻甲氧基苯酚锂络合物的低温红外光谱研究

由于温度的大幅度变化,分子的某些吸收带的强度将会产生明显的改变,但关于分子的红外吸收光谱与温度关系的研究尚少.在有机锂络合物的红外光谱研究中,我们发现邻甲氧基苯酚锂络合物显示了与其他锂络合物明显不同的特性^[1,2],在改变温度过程中,这种不同结构效应的特性更加明显.为此我们从+100～-130℃的较宽温度变化区域内,测定了它的变温红外光谱.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。     

Synthesis and structure of hydroxyisoxazolidines and derivatives of hydroxylamine and alkenals

The reactions of N-substituted hydroxylamines with alkenals serve as a method for the synthesis of the corresponding 2-substituted 3(5)-hydroxyisoxazolidines. The reaction pathway is determined by the nature of the substituent attached to the nitrogen atom. Ring-chain isomerism has been detected in these newly obtained compoundsTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1270–1276, September, 1987.     

红霉素9,11-亚胺醚和乙腈分子加合物的合成和晶体结构

通过控制红霉素A (E)肟的贝克曼重排反应条件合成了一种关键中间体红霉素9,11-亚胺醚, 该化合物可与乙腈形成稳定的分子加合物(摩尔比为1∶1), 未见文献报道. 阐述了该化合物的合成、晶体结构、晶体学数据和结构参数. 该化合物为无色透明晶体, 属单斜晶系, 空间群P2₁. 对该加合物和已知化合物红霉素6,9-亚胺醚晶体结构的对照解析, 有助于对重排反应机理、异构化机理和两异构体还原差异性的分析, 对重排反应和还原反应起到积极的指导作用.     

Sizes of atoms and ions and covalency of bonding in molecules and crystals

A new system of atomic radii for the elements up to barium inclusive is constructed. Values of the radii are chosen so as the dependence between the dissociation energy of diatomic homonuclear molecules and a depth of atom overlapping is monotonous, and the scatter of data is minimal. The depth of overlapping is calculated as a difference between the sum of atomic radii and an experimental interatomic distance. Conclusions are made that: the radii of free atoms and ions are determined by the value of the electron density equal to 0.01 au; they considerably change in molecules and crystals only as a result of the charge transfer from cation to anion; covalent bonding is well described by the overlapping of free atoms (ions), confined by the surface of the given radius, and its energy depends upon the depth of overlapping of valence electron densities of atoms. A method of overlapping atoms is proposed for the approximate estimation of ionic sizes and charges in bound systems.     

Interaction and Stability of Mixed Micelle and Monolayer of Nonionic and Cationic Surfactant Mixtures

Interaction and stability of binary mixtures of cationic surfactants hexadecyltrimethylammonium bromide (HTAB) or hexadecylpyridinium bromide (HPyBr) with nonionic surfactant decanoyl-N-methyl-glucamide (Mega-10) have been studied at different mole fraction of cationic surfactants by using interfacial tension measurements and fluorescence probe techniques. From interfacial tension measurements, the critical micellar concentration and various interfacial thermodynamic parameters have been evaluated. The experimental cmc's were analyzed with the pseudophase separation model, the regular solution theory, and the Maeda's approach. These approaches allowed us to determine the interaction parameter and composition in the mixed state. By using the static quenching method, the mean micellar aggregation numbers of pure and mixed micelles of HTAB + Mega-10 were obtained. It has been observed that the aggregation number of mixed micelles deviates negatively from the ideal behavior. The micropolarity of the micelle was monitored with pyrene fluorescence intensity ratio and found to be increase with the increase of ionic content. The polarization of fluorescence probe Rhodamine B was monitored at different mole fraction of cationic surfactants.     

Ni(Ⅱ)和Zn(Ⅱ)的乙基黄原酸盐与吡啶碱配合物的合成及性质的研究

乙基黄原酸基的结构为:(简写为Exan,它是一个双齿配体,能和许多金属离子形成稳定配合物。 本文依据实验结果,对3种Ni(Ⅱ)和2种Zn(Ⅱ)的乙基黄原酸盐混合配合物的性质作一些系统的比较.应用红外光谱讨论这些混合配合物的C—O及C—S键振动频率位移;用热谱讨论它们的热稳定性及失重过程的变化;通过组成分析用电子光谱及磁学方     

Synthesis and Photochemistry of Diphenylchlorin and Diphenylbacteriochlorin

5, 15-Diphenylporphyrin (DPP), a novel porphyrin model compound, was always inaccessible in quantities suitable for study1 because the difficulty of synthesis. So that the characteristic of this molecule had not been explored until a novel method developed for the preparation of DPP recently2. Therefore it will be possible for the synthesis of DPP-based photosensitizers, and investigation of their photodynamic properties. Here we reported the synthesis of novel photosensitizers 5, 15-diphe…     

固相法合成苯胺与邻甲氧基苯胺共聚物及其性能

以苯胺和邻甲氧基苯胺为单体,甲磺酸为掺杂酸,用固相法合成了甲磺酸掺杂苯胺与邻甲氧基苯胺共聚物。 通过红外光谱、紫外可见吸收光谱、X射线衍射、透射电子显微镜、循环伏安和电导率等对共聚物进行了结构表征和性能测试。 结果表明,不同摩尔比的苯胺与邻甲氧基苯胺共聚物处于中间氧化态,随邻甲氧基苯胺含量的增大,共聚物的掺杂率降低。 共聚物具有较高的结晶性和纤维状形貌,当苯胺与邻甲氧基苯胺摩尔比为1∶1时,具有较高的电化学活性,其导电率为1.65 S/cm。     

卟啉钴分子筛的制备,表征和催化性能的研究

用液－固相分步合成法将新型四卤四甲基卟啉诱捕在经Ｃｏ＾２＋交换的ＮａＸ分子筛超笼内，利用索式提取器洗净分子筛外表面吸附的卟啉后，采用ＵＶ－Ｖｉｓ、ＩＲ、ＳＥＭ、ＤＴＡ、Ｘ射线衍射分析、吸附等手段对诱捕在超笼内的卟啉予以表征。进一步对比研究了卟啉、分子筛和诱捕卟啉分子筛的催化性能。结果表明，卟啉与分子筛结合后，催化活性大大提高。     

Structure and Function of Nucleosides and Nucleotides

The nucleosides participating in biological processes consist of a sugar and a heterocyclic nucleobase; the nucleotides, which occur as monomers and as building units of polymeric nucleic acids, contain an additional phosphoester group. The complexity of the molecules leads to a complex stereochemistry with which the present progress report is concerned. Particular attention will be devoted to conformational considerations at the sugar groups, the syn-anti conformation, the position of the C(5′)? O(5′) bond relative to the sugar group, and the conformation of the phosphoester bonds. The article touches upon base pairing and base stacking, as well as forces stabilizing the syn conformation, and also deals with the reaction mechanism of the enzyme pancreatic ribonuclease as established from the stereochemistry of nucleotides and the mechanisms of action of the antileukemia drug 6-azauridine and the antibiotic actinomycin D. Views on the effects of the unusual structures of the “rare” nucleosides 4-thiouridine, isopentenyladenosine, and dihydrouridine on the structure of transfer ribonucleic acid are also presented.