高物质的量比低游离酚热塑性酚醛树脂的合成工艺

为降低耐火材料用酚醛树脂中游离酚的含量,选择苯酚与甲醛物质的量比1∶1.5,分步加入甲醛,醋酸锌为催化剂,添加质量分数2%,糠醇为溶剂,在60～85℃下制备了液态热塑性酚醛树脂,对产品的物化性能进行了测试并以红外光谱对其结构作了表征。结果表明,该工艺合成的酚醛树脂存在高邻位取代结构,残炭量达到45.66%,游离酚质量分数为1.87%。以原料中苯酚的量计算,产率可达到148.8%。     

高选择识别铜和铁的冠醚类化合物

冠醚类化合物选择性识别金属阳离子。在大量调研文献的基础上,设计合成了冠醚类化合物,通过对蒽醌化合物进行修饰,合成了冠醚环和吡唑啉,将产物进行了荧光测定,发现该化合物能够很好的识别铜离子和铁离子。对该化合物进行了进一步的干扰离子测定,发现其基本不受影响,得到了较好的识别效果。     

Thermal Properties of Macrocyclic Polyethers: Implications for the Design of Crown Ether-Based Ionic Liquids

The most commonly studied classes of ionic liquids (ILs) comprise relatively large and asymmetric heterocyclic cations (e.g., diakylimidazolium or N-alkylpyridinium) in combination with any of a wide variety of inorganic (e.g., BF₄^?, Cl^?) or organic (e.g., bis[(trifluoromethyl- sulfonyl)imide], Tf₂N^?) anions. Recently it has been shown that ILs can also be formed by complexation reactions of metal cations (e.g., Li⁺, as its Tf₂N^? salt) with various neutral ligands (e.g., cyclohexano-15-crown-5 or alkylamines). Because the upper limit of the useful temperature range of any IL is governed by its thermal stability, and because the thermal stability of a neutral ligand (i.e., its propensity to either volatilize or decompose) is of obvious importance in determining that of an IL prepared from it, a systematic examination of the thermal properties of a series of macrocyclic polyethers of potential utility in the synthesis of new ILs has been undertaken. The results show that the temperature corresponding to the onset of mass loss upon heating (i.e., evaporation and/or decomposition) varies with the ring size, substitution, nature of the donor atoms, and stereochemistry of the macrocycle, but is most strongly influenced by the molecular weight and aromatic content of the compound.     

Synergistic Enhancement and Separation of Zirconium(IV) and Hafnium(IV) with 3-Phenyl-4-Benzoyl-5-Isoxazolone in the Presence of Crown Ethers

Abstract

3-Phenyl-4-benzoyl-5-isoxazolone (HPBI) was synthesized and examined with regard to the synergistic solvent extraction behavior of zirconium(IV) and hafnium(IV) in the presence of various crown ethers (CEs), namely, 18-crown-6 (18C6), dicylohexano-18-crown-6 (DC18C6) and benzo-15-crown-5 (B15C5) from hydrochloric acid solutions. The results demonstrated that zirconium(IV) and hafnium(IV) were synergistically extracted into chloroform with mixtures of HPBI and CEs as ZrO(PBI)₂ · CE and HfO(PBI)₂ · CE, respectively. The complexation strength follows the order DC18C6 >18C6 > B15C5. The addition of CEs not only enhances the extraction efficiency of zirconium(IV) and hafnium(IV) but also significantly, especially in the presence of B15C5, improves the selectivity (Zr/Hf = 4.73) between these metal ions as compared to HPBI alone (Zr/Hf = 2.09). On the other hand, selectivity has been moderately decreased by the addition of 18C6 or DC18C6 to the metal-chelate system.     

Liquid-Liquid Extractions of Microamounts of 137Cs and 85Sr with Chlorinated Dicarbollide and Crown Ethers into Mixed Dodecanenitrile/n-dodecane Nonpolar Diluent

New methods of extraction of ¹³⁷Cs and ⁸⁵Sr into solvent mixture of dodecanenitrile with n-dodecane in the presence of various crown ethers and chlorinated dicarbollide are described. This is the first time when extraction with chlorinated dicarbollide anion was accomplished into a judiciously chosen nonpolar solvent. The theoretical reasoning leading to the choice of such nonpolar solvent is outlined. New crown ethers with laterally branched alkyl chain were synthesized and tested. These, when the same crown moiety is compared, are more effective for Sr²⁺ extraction than the commonly used DC18C6 (18C6 ring moiety), but less effective for Cs⁺ extraction compared with DB21C7 (21C7 moiety). The systems may be used both in analytical applications and, hopefully, after further development, as well in a nuclear reprocessing industry.     

有机醇胺-水体系混合热和气液平衡的测定与计算

作为酸性气体吸收剂,醇胺水溶液在气体混合物分离过程中被广泛应用。选择吸收速率高、吸收能力强的新型醇胺吸收剂,对于二氧化碳捕获技术发展尤为重要。醇胺水溶液对二氧化碳的吸收性能与其热力学性质直接相关,因此对于新型吸收剂的选择,必须首先确定体系的气液平衡和溶解热等重要热力学性质。文章利用C-80微量热仪在全浓度范围内,测定了303.15,323.15 K下2-乙氨基乙醇和水的混合热,并用沸点仪测量了30—100 kPa条件下该体系的气液平衡数据,用非随机双流体NRTL方程关联计算了混合热和气液平衡数据,并给出了方程模型参数。气液平衡和混合热数据的拟合结果和实验值能很好地吻合,表明该模型能用于醇胺水溶液吸收二氧化碳过程,并有助于吸收剂性能评价、新型吸收剂的选择以及吸收流程的模拟优化。     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

Influence of synthesis conditions on the properties of Y2O3–MgO nanopowders and sintered nanocomposites

In this study, a citrate–nitrate combustion method was applied to synthesize composite Y₂O₃–MgO nanopowders. In order to optimize the synthesis condition to support sufficient combustion, the molar ratio of citric acid to nitrate (c/n molar ratio) used in the reaction mixtures was varied between 0.17 and 0.34. Nanopowders with an average particle size of 17 nm were achieved. The properties of these nanopowders indicated that the higher molar ratios decreased the unreacted organic components and increased the amount of carbide on the surface of the oxides, which helped to inhibit the formation of carbonate groups. The amount of carbonate groups was reduced with the increasing c/n molar ratio. Y₂O₃–MgO nanocomposites fabricated through hot-isostatic-pressing sintering showed a uniform distribution of Y₂O₃ and MgO grains, which had an average size of ∼180 nm. In addition, the absorption peaks at 1410 and 1511 cm⁻¹ disappeared until the c/n molar ratio reached 0.28. A high average infrared transmittance of 83% in the range of 4000–1667 cm⁻¹ (2.5–6 μm) was obtained in the nanocomposites.     

Fabrication of zirconia all-ceramic crown via DLP-based stereolithography

Zirconia ceramics have shown a wide applicable prospect in dental prosthetics because it possesses excellent mechanical performance and biocompatibility. The rheological behavior and curing properties of zirconia stereolithography slurry were studied, as well as the microstructure of the green, pyrolyzed, and sintered body. Variquat CC-42 NS was proved to be effective for zirconia powder dispersing in photocurable resin (SP-RC700). The curing characteristic of slurry showed that the depth of penetration tended to increase with the solid loading. Finally, the zirconia all-ceramic crowns were fabricated via DLP-based stereolithography printer. Results showed that the particles were evenly distributed in the cured resin matrix without obvious agglomeration, and the interlayered structure disappeared after binder burnout. The sample with a major crystalline phase of tetragonal zirconia and a porosity of 10(1)% were obtained after sintering at 1550°C.     

2-甲基-3-丁烯-2-醇+直链一元醇二元体系的过量摩尔体积和表观摩尔体积298.15 K)

Excess molar volumes (Vm^E) of binary mixtures of 2-methyl-3-buten-2-ol[CH3C(OH)(CH3)CHCH2] with four 1-alcohols:methanol,ethanol,1-propanol and 1-butanol at 298.15K and atmospheric pressure are derived from density measurements with a vibrating-tube densimeter.All the excess volumes are negative in the systems over the entire composition range. The results are correlated with the Redlich-Kister equation.The effects of chain length of 1-alcohols on Vm^E are discussed.The apparent molar volumes of 2-methyl-3-buten-2-ol and 1-alcohols are calculated respectively.