甲基丙烯酸-2,2,2-三氟乙酯的制备

采用一锅法的工艺通过甲基丙烯酸先酰氯化,再与2,2,2-三氟乙醇在催化剂4-二甲氨基吡啶的催化下酯化的方法,方便快捷地制备了甲基丙烯酸-2,2,2-三氟乙酯,并根据实验结果讨论了影响反应的主要因素。最佳反应条件是:二甲基甲酰胺(DMF)和4-二甲氨基吡啶(DMAP)的用量为5%~10%(质量比),甲基丙烯酸∶氯化亚砜∶2,2,2-三氟乙醇=1.1∶1∶0.9(摩尔比),反应温度为50~60℃,收率达到95%以上。     

生产乙炔对电石的要求及乙炔清净

目前国内外乙炔大部分仍是由电石制得。然而由于工业电石除CaC2 外还含有很多杂质 ,所以生产乙炔不仅要求电石的纯度、粒度 ,还要求水温。一般电石的块度采用 8～ 2 5mm ,发生器温度控制在 85± 5℃ ,乙炔气体中含H2 S、H3 P、NH3 等气体会使氯乙烯合成氯化催化剂活性下降。因此 ,必须对乙炔气体进行清洁。采用次氯酸钠液体的氧化性将乙炔中的杂质氧化成酸性物质而除去。     

叔丁基苯乙腈肟碳酸酯的合成

叔丁基苯乙腈肟碳酸酯(1)化学名称为2-(叔丁氧羰基氧亚氨基)-2-苯基乙腈,简称Boc-ON,是一种优良的氨基保护试剂.通常的合成方法为苯乙腈与硝基甲烷缩合成肟,然后与光气生成酰氯,最后与叔丁醇成酯而得.本文以苯乙腈为原料,     

N-己酰氨基葡萄糖合成方法的改进

改进了N-己酰氨基葡萄糖的合成方法，产率为91%；并研究了不同温度和不同比例时，产物在水和乙醇中的溶解度。     

2-甲基-2-噁唑啉的合成研究

以N-(2-羟基乙基)乙酰胺为原料,在二水乙酸锌的催化作用下,脱水缩合生成2-甲基-2-噁唑啉,考察了温度、催化剂用量、压力、时间对反应的影响。最佳工艺条件为:m(催化剂):m(N-(2-羟基乙基乙酰胺))=0.15∶1,反应温度为185℃,压力为0.01 MPa,反应时间为2 h,收率可达到95%。并考察了催化剂的重复使用情况。产物经质谱进行了结构表征。     

TiO2对R2O-MgO-Al2O3-SiO2-ZrO2系微晶玻璃析晶及性能的影响

以花岗岩废渣为主要原料,用熔融法制备了添加TiO2的R2O-MgO-Al2 O3-SiO2-ZrO2(RMASZ)系微晶玻璃.采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、电子万能材料试验机和显微硬度测试仪研究了TiO2对RMASZ系微晶玻璃的晶相组成、显微结构以及力学性能的影响.结果表明:当TiO2含量为0wt％、0.5wt％、1wt％时析出的主晶相为t-ZrO2和顽火辉石;当TiO2含量为2wt％和3wt％时析出假蓝宝石相,顽火辉石相减少.当TiO2为0.5wt％时晶粒细致均匀,其四点抗弯强度达到122.41 MPa,显微硬度为9.35 GPa.     

Li2O-Na2O-K2O-CaO-MgO-Al2O3-SiO2系统乳浊釉的研究

对Li2O-Na2O-K2O-CaO-MgO-Al2O3-SiO2系统釉进行了较全面的正交试验研究,找到了影响该系统釉乳浊及釉面质量的主次因素,获得了性能良好的乳浊釉及其较优乳浊釉配方.     

多卤代吡啶选择性合成醚类的反应

以KOH为碱,DMSO为溶剂,在空气中,温度为50℃的条件下,多卤代吡啶和苯酚类化合物反应,形成相应的醚类化合物,该反应具有很好的收率以及区域选择性,是一种有效构建C-O键的方法;以K_2CO_3为碱,DMSO和H_2O为溶剂,在空气中,室温下,多卤代吡啶和苯硫酚类化合物反应,形成相应的的吡啶硫醚化合物,该反应也具有很好的收率以及区域选择性,是一种有效构建C-S键的方法。     

SO2-Na2S-H2O体系热力学分析

利用Na<,2>S溶液吸收SO<,2>是湿法烟气脱硫中具有良好应用前景的新方法.为了能更好地利用Na<,2>S溶液进行烟气深度脱硫,文中通过热力学计算,对Na<,2>S溶液吸收SO<,2>烟气所构成的SO<,2>-Na<,2>S-H<,2>O体系中气液固三相组成与pH值的关系进行了分析.结果表明,pH值大于6时,SO<...     

氢氧直接合成法制过氧化氢技术进展

氢气和氧气直接合成过氧化氢是典型的原子经济性反应，因过程简单、产品清洁、生产成本低而成为催化领域研究开发的一个热点。总结了该法近年来在催化剂活性组分的选取及载体方面的进展；详细介绍了溶剂的选取和反应机理；讨论了各种反应器的安全性。指出今后的研究重点是提高氢气利用率、开发新型的反应器、提高过程的安全性。     

Structural-chemical mechanism of formation of solid solutions in the La2SrAl2O2-Ho2SrAl2O7 system

The processes of phase formation in the La₂O₃-Ho₂O₃-SrO-Al₂O₃ system are investigated in the temperature range 1200–1500°C. The structural characteristics of the compounds described in the studied system are presented. It is established that the formation of (La_1?x Ho_x)₂SrAl₂O₇ solid solutions proceeds through the formation of LaAlO₃, LaSrAlO₄, SrAl₂O₄, and SrHo₂O₄ compounds. An increase in the holmium content and the temperature leads to a crossover from the mechanism in which the interaction of LaAlO₃ and LaSrAlO₄ is a limiting stage to the mechanism in which the decisive role is played by the interactions of SrAl₂O₄ with Ho₂O₃ and SrHo₂O₄ with Al₂O₃.     

Structure and microwave dielectric properties of BaAl2−2xLi2xSi2O8-2x ceramics

BaAl_2-2xLi_2xSi₂O_8-2x (x = 0, 0.005, 0.0075, 0.01, 0.02, 0.03) ceramics were synthesized by solid-state sintering method. Based on density functional theory, the first-principle calculations provided by the Cambridge Sequential Total Energy Package (CASTEP) software were introduced to the BaAl₂Si₂O₈ (BAS) system. In an effort to confirm the site occupied by Li⁺, we discussed the formation energy and final energy of different positions of Li⁺ doped BAS. The result demonstrated that Li⁺ should substitute Al³⁺ to promote the hexacelsian-to-celsian transformation with the aid of generated oxygen vacancies. The sintering behavior, crystal structure, surface appearance, and microwave dielectric properties of samples were investigated. Completely transformed celsian could be obtained when x = 0.005–0.03, which lowered the sintering temperature from 1400 °C (x = 0) to 1300 °C (x = 0.03), as well as strikingly improved the compactness, quality factor (Q × f) value and temperature coefficient of resonant frequency (τ_f) of BAS ceramics. When x = 0.1, unveiling the significant effects of Al-position ion substitution, BaAl_1.98Li_0.02Si₂O_7.98 ceramic sintered at 1350 °C for 5 h exhibited a supreme Q × f value of 48,620 GHz, and the ε_r and τ_f values were 6.99 and -23.29 × 10^?6 °C^?1, respectively.     

Crystallization Hierarchy of CaO-P2O5-SiO2-Al2O3-TiO2 Glass-Ceramics

Glasses in the tricalcium phosphate-anorthite (Ca₃(PO₄)₂-CaAl₂Si₂O₈ or TCP-CAS₂) system with additional TiO₂ were melted. Crystallization was investigated using thermal analysis, X-ray diffraction, and transmission optical and electron microscopies. During the heat treatment, as the growth temperature increases, successive crystalline phases separate from the glass matrix. The phases present in the fully heat-treated glass-ceramic are ß-TCP, anor-thite (CAS₂), and rutile (TiO₂). Apart from TiO₂, these phases evolve from other polymorphs during the heat treatment. The metastable phases, pseudo-orthorhombic CAS₂ and alpha-TCP, appear first around 880°C and transform into the stable phases, triclinic anorthite CAS₂ and ß-TCP, around 940° and 1000°C, respectively. The material crystallizes in stages. The first stage is the separation from the glass matrix of rutile and what is believed to be a calcium phosphate phase, with crystal sizes varying from 20 to 200 nm. This is followed by the appearance of larger crystals (1-2 µm) of the metastable pseudo-orthorhombic CAS₂, surrounding the previously crystallized phases. Finally, this pseudo-orthorhombic CAS₂ phase transforms to anorthite (15-20 µm) spherulites. TiO₂ does not act as a direct nucleating agent in the glass composition studied: no sign of heterogeneous nucleation and growth from TiO₂ crystals has been found, and moreover, TiO₂-free base glass crystallizes in a manner similar to that of the glass containing TiO₂.     

Al2O3-SiO2-TiO2-ZrO2复合陶瓷膜的制备与表征

采用Sol-Gel法制备出掺杂SiO2,TiO2及ZrO2改性的γ-Al2O3膜,并通过SEM,EPMA,AFM等测试手段对膜结构和性能进行表征.探讨了制膜工艺条件对膜性能及结构的影响.制备的Al2O3复合膜膜厚为1～2μm,结构均匀无缺陷.     

Electrorheological response behavior of H2Ti2O5@MoS2@SiO2 core-shell nanoparticles

In this paper, a novel H₂Ti₂O₅@MoS₂@SiO₂ ternary composite material was prepared by a combination of dual hydrothermal method and controlled hydrolysis method, in which H₂Ti₂O₅ nanotubes are tightly combined with hierarchical molybdenum disulfide, and the unique structure of titanate nano whiskers, including the loosely bound alkali metal ions between the titanate layers with high dielectric constant and the large aspect ratio, which induce active response to the electric field. Flower-like molybdenum disulfide provides electrical conductivity, and silicon dioxide as a insulative coating layer can suppress excessive the electrical conductivity of the two-dimensional material. The morphological evolution was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of showed that the sheet-shaped molybdenum disulfide coated with curved H₂Ti₂O₅ nanotubes showed a honeycomb structure with uniform size. Silicon oxide acts as a cladding layer to increase the thickness of the flakes. The existence of H₂Ti₂O₅, molybdenum disulfide and silicon dioxide is confirmed by X-ray powder diffractometer (XRD) and Fourier transform infrared spectroscopy (FT-IR). The prepared product was confirmed by XPS, BET test and electrorheological rheometer. Core/shell nanoparticles not only exert the active response characteristics of titanate nanoparticles and molybdenum disulfide to electric field, but also inherit the excellent characteristics of a core-shell structure produced by the interface polarization and the synergistic effect of the polar groups on the surface of the two-dimensional material further enhance the electrorheological effect.     

2,2‘-二硫代二苯并噻唑的精制

用溶剂萃取和重结晶相结合的方法对橡胶促进剂2,2'-二硫代二苯并噻唑(DM)进行精制,用测熔点的方法来检验纯度.实验结果:加入溶剂甲苯与粗DM以7:1(质量比)的比例,设置温度为120℃,在高压釜中加热,然后冷却结晶,烘干,得到浅黄色晶体,熔点达183℃,收率达92%.     

相转移催化合成2,2-二羟甲基丙酸(DMPA)的研究

以甲醛和丙醛为原料,在相转移催化作用下经羟醛缩合及氧化反应合成了2,2一二羟甲基丙酸(DMBA)。缩合反应在30℃,n(甲醛)/n(丙醛)=2.2,催化剂为十六烷基三甲基溴化铵(HDTMA),用Na2CO3和Na0H的混合碱调pH=9,反应2h。反应后立即加盐酸中和调pH=5;氧化反应在70℃、反应时间2.5h。反应产物的结构用红外光谱(IR)表征。     

Electrochemical reduction of 2-chloro-2-cyclohexenones

The electrochemical reduction of the 2-chloro-2-cyclohexenones 2a–2c (mercury cathode, CH₃CN,Bu₄NBF₄) was studied by means of cyclic voltammetry, dc polarography, coulometry and chemical product analysis. The results were compared to those obtained with the analogous 2-cyclohexenones 1a–1c. Due to the chloro-substituent on C—2 the half wave potentials E_1/2 for the first electron transfer step become less cathodic and the overall mechanism of reduction of a chloro-substituent on C—6 is modified. In addition, strong inhibition effects were observed in the cyclic voltammograms of compound 2 and it was found that other 2-halogeno-2-cycloalkenones exhibit a similar behaviour.