2-亚甲基-1,3-二氧己烷衍生物的合成及自由基开环聚合

本文报道了四种2-亚甲基-1,3-二氧己烷类单体:4-甲基-2-亚甲基-1,3-二氧己烷(Ⅱ)、4,6-二甲基-2-亚甲基-1,3-二氧己烷(Ⅳ)、5,5-二甲基-2-亚甲基-1,3-二氧己烷(Ⅵ)和5,5-二乙基-2-亚甲基-1,3-二氧己烷(V Ⅲ)的合成以及自由基开环聚合。结果表明,上述单体在聚合过程中出现异构化开环现象。Ⅲ和Ⅳ的甲基位置在环上氧原子的α-碳原子上时,显示对异构化反应的影响比Ⅵ及Ⅷ的甲基和乙基在β-碳原子上时更显著。上述现象与异构化开环形成仲碳自由基中间体的倾向更大有关。 Ⅳ在苯溶液中及过氧化二叔丁基存在下,120℃反应,得到全部是聚-δ-戊内酯骨架结构的聚合物。提出了一种合成聚-δ-戊内酯类链结构的聚酯的新的途径和方法。     

Structural studies of mono(pentamethylcyclopentadienyl)lanthanide complexes

The mono(pentamethylcyclopentadienyl) lanthanide complexes [(C₅Me₅)Yb(μ-I)(μ-η ⁵?: η ⁵-C₅Me₅)Yb(C₅Me₅)]_n (1), {[(C₅Me₅)Sm]₃(μ-Cl)₄(μ ₃-Cl)(μ ₃-OH)(THF)}₂ (2), {[(C₅Me₅)Sm]₂ (μ-OH)(μ-Cl)₄(μ ₃-Cl)Mg(THF)₂}₂ (3), [(C₅Me₅)₂Sm](μ-Cl)₆(μ ₃-Cl)₂(μ ₄-Cl)[(C₅Me₅)Sm]₄ (4), {[(C₅Me₅)Nd]₃(μ ₃-Cl)₄(μ ₄-Cl)₂(μ ₃-O₂CPh)₂K₂(η ⁶-C₇H₈)}₂ (5), [(C₅Me₅)Nd(C₈H₈)]₂(μ-dioxane) (6), [(C₅Me₅)Yb(MeO^tBu)]₂(μ-η ⁸?:?η ⁸-C₈H₈) (7), [(C₅Me₅)Dy(μ-I)₂]₃ (8), and [(C₅Me₅) Tm(MeCN)₆]I₂ (9), have been identified by X-ray crystallography. 1 is unusual in that it has a μ-η ⁵?:?η ⁵-C₅Me₅ ring that generates a local bent metallocene environment around ytterbium. Complexes 2–5 demonstrate the versatility of bridging chlorides in generating a variety of structures for mono(pentamethylcyclopentadienyl) lanthanide halides. Complex 6 shows how dioxane can generate a crystallographically-analyzable complex by bridging two mixed-ligand metallocene units that do not readily crystallize with THF. The structure of 7 shows how methyl tert-butyl ether (MTBE) ligates a lanthanide. Complex 8 is a trimeric cyclopentadienyl lanthanide halide unusual in that it has six bridging halides that roughly define a trigonal prism. Complex 9 constitutes an organometallic example of a lanthanide in which acetonitrile completely displaces iodide counterions.     

磺化聚乙烯离子交换膜渗透汽化分离二氧六环／水混合物研究

本文用非均相光化学氯磷化反应制得了亲水的耐有机溶剂耐酸碱的磺化聚乙烯离子交换膜．膜截面离子基因密度与反应程度有关．该膜对近恒沸组成的二氧六环／水混合液显示出很高的渗透汽化分离系数和透过速率．研究了对离子、离子交换容量、料液浓度和温度对分离性能的影响．通过膜内水合离子形成“水通道”模型讨论了渗透机理．膜内离子基团密度估计及水的表观渗透活化能的大小支持“水通道”的存在．     

Solubility in the Systems MCl (M = Na, K)–1,4-Dioxane–Water at 25 ^C

Phase equilibria in the ternary systems, sodium chloride–dioxane–water and potassium chloride–dioxane–water, have been studied at 25 ^C and a section method for the determination of the immiscibility boundary has been tested. The phase diagrams exhibit the difference between the two systems. In the sodium chloride system an area of two liquid phases occurs, whereas with potassium chloride only a smooth solubility curve exists.Dedicated to Prof. Jaroslav Podlaha, an extraordinary chemist and great human being, on the occasion of his 70th birthday.     

A Contactless Impedance Probe for Simple and Rapid Determination of the Ratio of Liquids with Different Permittivities in Binary Mixtures

Simple contactless cells with planar or tubular electrodes have been designed for measurement of the permittivity of solutions. The cells, connected to an integrated circuit of astable multivibrator, respond primarily to the capacitance component of the cell impedance, the multivibrator frequency depends in a defined manner on the solution permittivity and is readily used as the analytical signal in determinations of the ratios of components in binary liquid mixtures; water solution of methanol, ethanol and dioxane have been tested. The response of the cell with planar electrodes satisfies well the simple theoretical model and both the cells provide results with a sufficient sensitivity, a low LOD value (units of %vol) and a good precision (around 1%rel). The cell simplicity, small dimensions, long‐term stability and the possibility of powering them from a battery make them suitable for hand‐held meters. As an example of application in practice, the content of ethanol was determined in the car fuel petrol.     

Vibrational spectral studies of ion-ion and ion-solvent interactions. II. Zinc nitrate in water/dioxane mixtures

Raman and infrared spectral data have been collected forp-dioxane and solvated and bound nitrate ions for Zn(NO₃)₂/p-dioxane/water systems. It is concluded that Zn²⁺ is preferentially solvated by water and that this aquation is also responsible for a lower concentration of ion pairs than is found for methanol/Zn(NO₃)₂ solutions for which the dielectric constant of the bulk solvent is similar. Values of K₁ (M^–1), the association constant for Zn(NO₃)⁺, are 0.22±0.02 (2/1 solvent,D=12.6) and 0.071±0.01 (4/1 solvent,D=33.0). The log K₁ against 1/D plot is not linear.     

On the structure of the radical addition product of 2-benzoxypentafluoropropene with 1,4-dioxane

The structure of the addition reaction product of 2-benzoxypentafluoropropene [CF₂ = C(CF₃)OCOC₆H₅] with 1,4-dioxane was investigated by the crystallographic analysis of the single crystal to conclude that the 2,6-disubstitution of 1,4-dioxane took place, on the contrary to the assumption that the reaction would take place at the 2- and 5-positions based on the product structure of 2-benzoxypentafluoropropene with tetrahydrofuran. Modified polyaddition reaction mechanism of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF₂ = C(CF₃)OCO-C₆H₄-COOC(CF₃) = CF₂] with 1,4-dioxane including 1,5-radical shift mechanism is proposed.     

Zur Reaktion des Rhenium(VII)-oxids mit 1,4-Dioxan – Kristallstruktur von Re2O7(OH2)2 · 2(1,4-Dioxan)

Reaction of Rhenium(VII) Oxide with 1,4-Dioxane – Crystal Structure of Re₂O₇(OH₂)₂ · 2(1,4-Dioxane) By solvolysis of polymeric Re₂O₇ with 1,4-dioxane in the presence of small amounts of H₂O two products of compositions Re₂O₆(OH)₂ · 3(1,4-dioxane) ( 1 ) and Re₂O₇ · 2H₂O · 2(1,4-dioxane) ( 2 ) are formed. From a complete X-ray single-crystal structure analysis 2 could now be characterized structurally (monoclinic, space group P2₁/c, a = 6.828(3) Å, b = 9.530(2) Å, c = 26.421(8) Å, β = 91.71(3)°, Z = 4). The compound is important as a convenient precursor for the preparation of pure rhenium trioxide. It is to be formulated as Re₂O₇(OH₂)₂ · 2(1,4-dioxane) and contains, contrary to 1 , no 1,4-dioxane coordinated to Re. The crystalline phase consists of a supramolecular arrangement of Re₂O₇(OH₂)₂ units as in “solid perrhenic acid” and of 1,4-dioxane molecules associated through O? H …? O hydrogen bridges. Analogous to dirhenium heptoxide and to solid perrhenic acid one of the rhenium atoms is in tetrahedral, the other is in distorted octahedral coordination.     

Some Possibilities and Limitations of Contactless Impedimetric Determinations of Organic Liquids in Aqueous Solutions. The Interference from Ionic Compounds

The possibilities of impedimetric determinations of organic liquids in mixtures with aqueous solutions have been studied in detail, using a planar capacitor cell combined with multivibrator and operational amplifier circuits functioning as a differentiator and a system of dioxane with aqueous solutions of alkali halides. The experimental values have been compared with a simple model and the detector response has been characterized. The behaviour of the detection cell can be reliably predicted on this basis. This approach permits extremely simple, rapid and cheap analyses of binary liquid mixtures, however, it suffers from a serious limitation in that the overall electric conductivity of the mixture must be low.     

Intermolecularly Associated Carboxylic Acid Dimers in the Supramolecular Assembly of (R)-1,4-Benzodioxane 2-Carboxylic Acid

Abstract  The title compound, C₉H₈O₄, (I), crystallizes in the monoclinic space group P 21/c with unit cell parameters a = 7.3380(5) ?, b = 9.3790(7) ?, c = 12.3172(9) ?, β = 90.687(7)°, Z = 4. The molecule consists of a benzene ring fused to a 1,4 dioxane ring in a half-chair conformation with a carboxylic acid group bonded at the dioxane 2-position. The carboxylic acid group forms a classic O–H···O hydrogen bonded dimer with an O···O distance of 2.6292(12) ? in a R₂² (8) graph-set motif which links the molecules into pairs around inversion centers in a supramolecular assembly in the unit cell. The dihedral angle between the mean planes of the R₂² (8) graph-set motif’s of two adjacent dimers in the unit cell is 75.7(5)°. The mean plane of an R₂² (8) graph-set motif makes an angle of 88.4(5)° with the mean plane of the benzene ring in the same dimer and 13.1(2)° or 13.4(7)° with the mean plane of a benzene ring from an adjacent dimer. Additional weak Cg π-ring intermolecular interactions significantly influence the bond distances, bond angles and torsion angles of the dioxane ring and attached carboxyl group. Comparison to a MOPAC AM1computational calculation provides support to these observations. Graphical Abstract  The association of carboxylic acid dimers in the supramolecular assembly of (R)-1,4-benzodioxane 2-carboxylic acid is investigated by examination of its crystal structure. Its geometric and packing parameters are described and compared to a MOPAC AM1 computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.