一般的A_aB_b缩聚反应的固化理论——Ⅰ.溶胶分数和凝胶化条件

本文讨论了最一般的A_aB_b缩聚反应,包括A基和A基、B基和B基、以及A基和B基的反应,给出了溶胶-凝胶分配公式和相应的凝胶化条件。     

《多酸基功能配合物》

本书共分为8章,主要按照多酸的结构类型将配合物划分为八大类:Keggin型多酸基功能配合物、Wells-Dawson型多酸基功能配合物、Lindqvist型多酸基功能配合物、Anderson型多酸基功能配合物、多钼酸盐基功能配合物、多钨酸盐基功能配合物、多钒酸盐基功能配合物、P2Mo5和P4Mo6基功能配合物。比较系统地介绍了每种多酸基功能配合物的结构特点和合成方法,总结了合成规律,并有选择性地介绍了各类多酸基功能配合物的一些代表性性质。     

多酸基功能配合物

正本书共分为8章,主要按照多酸的结构类型将配合物划分为八大类:Keggin型多酸基功能配合物、Wells-Dawson型多酸基功能配合物、Lindqvist型多酸基功能配合物、Anderson型多酸基功能配合物、多钼酸盐基功能配合物、多钨酸盐基功能配合物、多钒酸盐基功能配合物、P2Mo5和P4Mo6基功能配合物。比较系统地介绍了每种多酸基功能配合物的结构特点和合成方法,总结     

生物基弹性体研究进展

出于对节约石油资源、保护环境、发展循环经济等考虑,用可再生的生物资源代替石油化学品生产高分子材料已成为人们研究的热点。弹性体是一类应用领域非常广泛的材料,但是绝大多数的弹性体都是以石油基化学品为原料合成的,因此研究生物基弹性体对节约石油资源及保护环境具有重要意义。本文对目前研究较多的三类生物基弹性体—生物基聚氨酯弹性体、生物基聚酰胺弹性体、生物基聚酯弹性体作了简要的综述。主要介绍了合成生物基弹性体的原料、合成路线以及相关的生物基弹性体的性能比较。     

不饱和取代环戊二烯基钛衍生物的合成和反应

利用不同方法合成了烯丙基、环戊烯-[2]-基、甲基(或乙基)环戊烯-[2]-基、环已烯-[2]-基和环已基等不饱和取代茂基茂基二卤化钛。烯丙基茂基钛衍生物中的环上烯丙基呈现正常的亲电加成反应,它们与HBr,Br_2,ICl和IBr反应生成对应的卤代衍生物。     

生物基可聚合单体及其聚合物制备与性能研究进展

对化石资源的过渡开采导致了严重的能源危机及环境问题,发展生物基聚合物代替石油基聚合物是缓解当前危机的有效途径之一.本文总结了国内外研究人员在生物基聚合物研究领域的最新进展,重点介绍了生物基脂肪族单体、芳香族单体的制备,包括生物基羧酸单体、生物基二醇单体、生物基烃类单体、呋喃基单体、香草醛单体,比较了不同制备方法的选择性及产率;采用传统及新型的聚合方法,如熔融缩聚、自由基聚合、酶催化聚合等,可以将生物基单体转化为各种生物基聚合,包括聚酯、聚酰胺、聚碳酸酯等,并比较了聚合条件对生物基聚合物制备的影响.生物基聚合物具有优良的机械性能及热性能,并展现出各种优异特性,如形状记忆、自修复功能等,有望代替传统的石油基聚合物.最后,对国内外生物基质聚合物的前景做了展望.     

有机硅化合物在α-D-葡二糖合成上的应用

三苯基硅基作为葡萄糖1-C位羟基保护基, 在对硝基苯甲酰基存在下形成和脱保护基反应均易进行, 而且有产率高、在反应过程中保持1-C构型不变等特点, 并研究了三苯基硅基保护基在葡二糖上的应用。     

噻吩基1,2-迁移制备2-噻吩基酸类的研究

以α-卤代烷基噻吩基酮为原料,制得2-(2-噻吩基)丙酸、2-(5-溴-2-噻吩基)丙酸和2-(5-乙基-2-噻吩基)丙酸,研完了α-卤代烷基噻吩基酮的迁移基团、烷基、离去基、催化剂、温度和溶剂等对重排的影响,以及光学活性的2-(5-乙基-2-噻吩基)丙酸的制备,证明噻吩基1,2-迁移属邻基参与的S_N2缺电子重排。     

含活性端基聚芳醚砚的合成

本文总结了将乙炔基、乙烯基、丙烯基、氨基、马来酰亚胺基、氰酸酯基、环氧基等活性基团引入聚芳醚砜链端的方法。引用参考文献27篇。     

某些胆酸及去氧胆酸肟类化合物的合成

从胆酸和去氧胆酸出发,经过不同反应,将甾核以及支链上的取代基分别转化为羰基及酯基,然后和盐酸羟胺反应引进肟基,合成了六个新的甾体肟类化合物:7-羟基-12-氧代-3-肟基胆酸甲酯(5)、7,12-二氧代-3-肟基胆酸甲酯(6)、12-氧代-3,7-二肟基胆酸甲酯(7)、3,7,12-三肟基胆酸甲酯(8)、12-氧代-3-肟基去氧胆酸甲酯(12)、3,12-二肟基去氧胆酸甲酯(13)。通过NMR和IR对合成物5~10的结构进行了表征。     

含有杂环基侧链的新型聚硅氧烷

含有功能性基团的聚硅氧烷的研究一直是有机硅化学中十分活跃的研究领域之一。当含N、S等杂环引入聚硅氧烷链中后，由于杂环基的生理活性、催化活性及光电特性，因而含不同杂环基团的聚硅氧烷（POS）可分别用作催化剂、光电材料、医学材料等。当用作药物载体时，可提高药物的利用率和靶向性，也可降低某些药物的毒性。含环糊精侧基、冠醚侧基的POS亦可应用于气相色谱固定相、相转移催化剂。本文对近年来有关侧链含有吡啶、咪唑等杂环及环糊精基团等功能性侧基的聚硅氧烷结构、合成、及应用作一详细的评述并进行了展望。     

A selective and operationally simple approach for removal of methoxy-, allyloxy-, and benzyloxycarbonyl groups from carbinols

LiI in refluxing pyridine can remove within a few hours methoxy-, allyloxy-, and benzyloxycarbonyl groups from saccharidic carbinols under conditions compatible with the maintenance of acyl groups. Addition of a stoichiometric excess of acetic acid to the reaction mixture minimizes or even suppresses intramolecular transesterifications. The procedure broadens the scope of some alkoxycarbonyl groups in organic synthesis.     

Chemical applications of topology and group theory

This paper characterizesforbidden polyhedra, which are polyhedra with fewer than 9 vertices which cannot be formed using only the 9s,p, andd atomic orbitals. In this connection polyhedra are of particular interest if their symmetry groups are direct product groups of the typeR × C′ _s in whichR is a group containing only proper rotations andC′ _s is eitherC _s orC _i in which the non-identity element is an inversion center or a reflection plane which is called theprimary plane of the groupR ×C′ _s . Using this terminology polyhedra of the following types are shown always to be forbidden polyhedra: (1) Polyhedra having 8 vertices, such direct product symmetry point groups, and either an inversion center or aprimary plane fixing either 0 or 6 vertices; (2) Polyhedra having a 6-fold or higherC _n rotation axis. However, these conditions are not necessary for a polyhedron to be forbidden since in addition to one 7-vertex polyhedron and ten 8-vertex polyhedra satisfying one or both of the above conditions there are two forbiddenC _3v 8-vertex polyhedra which satisfy neither of the above conditions. For part 15 of this series see reference 1.     

Packing modes in crystals of mesogenic biphenyl esters with normal alkyl and/or alkoxy chains

Crystal structures determined for eight compounds R-C₆H₄-C₆H₄-COO-C₆H₄-R ', where R and R ' are achiral, four with octyloxy and/or octyl chains and four with a methyl or methoxy group at one end, are classified into three modes. First is a smectic-like layer composed of parallel molecules with closely arranged ester linkages; second is a layer comprising two crystallographically independent molecules, among which the ester linkages are close. Compounds with an octyloxy chain take these modes. Thirdly, for molecules with alkyl chains, the ester linkages are far apart among the parallel molecules. Melting and clearing points suggest stronger intermolecular interactions in the former two modes than in the last mode.     

Determination of OH groups in humic acids using methylation with dimethylsulfate

The methylation of humic acids (HA) with dimethylsulfate in acetone and methanol followed by the iodometric determination of the methoxy groups (Zeisel reaction) were applied to determine the contents of –OH groups in solid samples of HA of different origins. For the coal- and peat-derived HA samples, the contents of –OH groups determined after methylation in acetone ranged from 6.6 to 8.7 mmol/g, whereas the contents of –OH groups determined after methylation in methanol ranged from 4.0 to 5.0 mmol/g. These differences may be related to the content of carboxylic groups in the HA molecule that were not methylated in methanol, as confirmed by a comparison with results of conventional titrimetric determinations. Observed differences were interpreted as results of different polarity of both solvents and alkalinity of the reaction mixture during the methylation. The contents of alcoholic groups as well as some other minor –OH groups can be estimated using the –OH group contents obtained after methylation in both solvents together with the results of the conventional determinations of acidic functional groups. A repeatability of the –OH groups determination as estimated from a series of triplicate analyses of different HA samples (n = 7) was in range of 0.15–0.73 mmol/g and 0.08–1.06 mmol/g (standard deviations) for methylation in acetone and methanol, respectively. Thus, the average repeatability of the –OH groups determination was estimated to be 0.38 and 0.50 mmol/g for methylation in acetone and methanol, respectively.     

Water Sorption to Hydroxyl and Carboxylic Acid Groups in Carboxymethylcellulose (CMC) Studied with NIR-spectroscopy

In carbohydrate systems which contain polar groups such as hydroxyl and carboxylic acid groups, water molecules are adsorbed in a specific way which varies with the type of polar group. Near infrared Spectroscopy (NIR) combined with multivariate statistical analysis was used to study the interactions between water molecules and carboxymethylated cellulose (CMC) with various degrees of substitution of the carboxylic acid groups, in two ionic forms (CMC-Na and CMC-Ca). The adsorbed water molecules were clearly influenced by the counterion; i.e. the nature of the ion-pair. A principle component analysis (PCA) identified variations in the registered spectra related to: the nature of the counter-ion, the degree of substitution (DS), the relative humidity (RH) and the type of polar group to which water was adsorbed. It was, possible furthermore, through the use of partial least square analysis (PLS), to extract spectral information related to the non-freezing bound water adsorbed on hydroxyl and carboxyl groups respectively. Loading spectra indicated that the obtained spectral information indeed correlated to the two kinds of polar groups studied (hydroxyl groups and carboxylic acid groups). The results support the view that, in the humidity range of 0–100%, water molecules are specifically adsorbed to individual polar groups, which characteristics are dependent on the nature of the polar group.     

Fast removal of Pb2+ from water using new chelating fiber modified with acylamino and amino groups

The graft copolymerization of acrylic acid（AA） onto polyethylene glycol terephthalate（PET） fiber initiated by benzoy peroxide （BPO） was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber（PET-AA） was done by changing the carboxyl group into acylamino and amino groups through the reaction with ethylenediamine.The new modified chelating fiber （NDWJN6） was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curve indicated that NDWJN6 could fastly remove Pb²⁺ from water,and adsorption isotherm also indicated that NDWJN6 had high equilibrium adsorption capacity for Pb²⁺.     

流化床热解煤焦油的降黏研究

对循环流化床热电气焦油多联产热解所得煤焦油流动性差的问题采取了一系列的降黏研究。通过X射线衍射测试可以排除室温下蜡结晶影响煤焦油黏度的可能,对比了煤焦油和煤沥青的黏度和族组分差异,考察了喹啉不溶物对软化点的影响,结果表明,采取馏分油降黏是合理的。分别添加四种馏分油对煤焦油进行了降黏实验,通过色谱质谱联机分析馏分油的成分,认为既含亲水基又含憎水基的分子具有很好的降黏效果,而且含量越多降黏效果越好。通过添加四种单组分化合物的降黏实验和分析,进一步验证了所得到的降黏理论,而且可以判断同时含有亲水基和憎水基的分子降黏效果优于只含憎水基不含亲水基的分子。     

Gas transport properties of polycarbonates and polysulfones with aromatic substitutions on the bisphenol connector group

The effect that substitution of aromatic groups on the bisphenol connector unit of bisphenol-A based polycarbonate and polysulfone materials has on their gas transport properties was assessed. Replacement of a methyl group by a phenyl ring (bisphenol acetophenone polycarbonate, PC-AP, and bisphenol acetophenone polysulfone, PSF-AP) gives a small increase in permeability coefficients with similar or slightly higher selectivity for all gases compared to bisphenol-A polycarbonate, PC, or polysulfone, PSF. Substitution of two locked phenyl rings (fluorene bisophenol polycarbonate, FBPC, and fluorene bisphenol polysulfone, FBPSF) in place of the methyl groups in the connector unit leads to permeability and solubility coeffcients that are about twice those observed for PC or PSF. Increases in permeability for the polycarbonate and polycarbonate and polysulfone materials with aromatic substitutions are related to their larger fractional free volume. FBPC and FBPSF have the largest fractional free volume and the largest permeability coefficients. Thermal measurements show that the fluorene based polycarbonate and polysulfone materials have the highest thermal and oxidative stability. Such aromatic substitutions can be useful for developing gas separation membranes to be used in harsh thermal or oxidative environments. © 1993 John Wiley & Sons, Inc.