苯乙烯间规聚合催化剂进展

综述了苯乙烯间规聚合主催化剂的研究和开发状况。主要介绍茂、茚、多元稠合环，氟和非茂钛等较高活性催化剂的催化特性，从取代基的电子效应和空间效应以及活性种稳定性等方面阐述了不同催化剂的聚合活性差异。     

Highly Efficient Photosensitization of Mesoporous TiO_2 Electrode with a Cyanine Dye

Dye-sensitized mesoporous TiO2 photoelectrochemical cell has attracted much interest for photoelectric conversion1,2. The most efficient charge transfer dye studied so far is Ru(dcbpy)2(NCS)2 (dcbpy=4, 4'-dicarboxy-2, 2'-bipyridine), with which IPCE of about unity has been achieved3. Considering the low cost, low toxicity, easy handling, non-metal complex dyes should also be right candidates. Here we report the highly efficient photosensitization of mesoporous TiO2 electrode with a nov…     

TiO2/AC光催化剂上气体污染物降解的反应动力学模型

 利用二氧化钛与活性炭(AC)共水热处理的方法制备了TiO2/AC复合催化剂,采用空气净化评价装置对其催化降解低浓度气体污染物丁醛的性能进行了模拟评价实验. 基于Langmuir-Hindshelwood方程和一些假设,推导了循环反应系统气体污染物降解的瞬态模型. 结果表明,该动力学模型所得数据与丁醛的模拟评价实验结果基本相符,预示着该模型能够很好地预测污染物的降解行为.     

Effect of silver deposition on tio for photocatalytic oxidation of benzene in the gas phase

Summary Deposition of Ag on TiO₂ surface by photodeposition method improved the photooxidation rate of benzene in air by inhibiting the build-up of intermediate compounds on the catalyst surface. Although the reaction rate decreased with the increase in benzene concentration, the decrement of reaction rate became smaller by Ag deposition. The selectivities to CO₂ and CO were 95 and 5%, respectively, which were almost independent of Ag loading and benzene conversion.     

A novel Birch reduction of aromatic compounds using aqueous titanium trichloride: anions of trans-10b,10c-dimethyl-2,7,10b,10c-tetrahydropyrene

The Birch reduction of 10b,10c-dimethyl-10b,10c-dihydropyrene 1 and anthracene could be predicted on the basis of their reduction potentials and achieved readily with aqueous titanium trichloride in near quantitative yields. Controlled reduction of a nitro group could be achieved under these conditions with the aromatic hydrocarbon remaining intact. The anion derived from the hexane obtained from reduction of 1 provided synthetic routes to derivatives of 1 inaccessible from direct substitution reactions of 1. Oxidative dimerization of the anion led to the formation of a series of interesting products.     

室温下用新型NH4CO3沉淀剂制备纳米TiO2光催化剂

用Ti(SO4)2为原料，NH4HCO3为沉淀剂，室温下制备了活性较高、粒径9nm的TiO2催化剂。考察了不同原料浓度、沉淀pH值、焙烧温度、焙烧时间等制备条件对TiO2粒度及其光催化降解十二烷基苯磺酸钠催化活性的影响。     

CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

氢化钛的制备及其分解

钛是具有吸氢作用的金属元素之一，用于制备超纯氢气“’“，但纯金属钛作为储氢材料却一直认为没有实用价值“‘．近年来对钛与氢作用引起的微观缺陷及钛的氢化物结构和形成机制等方面进行了一些研究［‘，’j，但并未解决钛与氢作用的实用性问题．本文对在常压下钛与氢气的化学反应、所生成氢化物的结构形态，及分解释放氢气的条件和热力学关系进行了研究．取海绵钛颗粒于石墨舟中，然后将石墨舟推入430X2mm的1．5m长石英反应管，该反应管置于管式炉中．在持续氢气流中缓慢加热升温，随时调节氢气流量，以维持系统恒压，并在35OC恒温3Om…     

Catalytic asymmetric allylation of aldehydes and related reactions with bis(((S)-binaphthoxy)(isopropoxy)titanium) oxide as a mu-oxo-type chiral Lewis acid

A new, chiral bis-Ti(IV) oxide of type 3 has been designed and can be utilized for strong activation of aldehyde carbonyls, thereby allowing a new catalytic enantioselective allylation of aldehydes with allyltributyltin. The chiral bis-Ti(IV) catalyst (S,S)-3 can be readily prepared either by treatment of bis(triisopropoxy)titanium oxide with (S)-BINOL or by treatment of ((S)-binaphthoxy)isopropoxytitanium chloride with silver(I) oxide. Treatment of hydrocinnamaldehyde with allyltributyltin under the influence of chiral bis-Ti(IV) oxide (S,S)-3 generated in situ (10 mol %) in CH(2)Cl(2) afforded an allylation product in 84 % yield and with 99 % ee. This asymmetric allylation with non-racemic bis-Ti(IV) oxide 3 and partially resolved (S)-BINOL shows a positive nonlinear effect in correlation of the enantiopurity of the allylation product with the ee of the (S)-BINOL. Chiral bis-Ti(IV) oxide (S,S)-3 can also be utilized for related reactions such as asymmetric methallylation and propargylation of aldehydes with high enantioselectivity. This asymmetric approach provides a very useful way of obtaining high reactivity and selectivity through the simple introduction of the M-O-M unit into the design of chiral Lewis acid catalysts.     

Titan(IV)-Komplexe mit dreizähnigen diaciden Liganden. Kristallstruktur von Bis[2,6-diphenacylpyridinato(2 –)]titan(IV)

Titanium(IV) Complexes with Tridentate Diacidic Ligands. Crystal Structure of Bis[2,6-diphenacylpyridinato(2–)]titanium(IV) The titanium(IV) chelates with 2,2′-dihydroxy-azobenzene, salicylaldehyde-2-hydroxyanil, 2-(2′-hydroxyphenyl)-8-quinolinol, 2,6-diphenacylpyridine as well as with aroylhydrazones of salicylaldehyde, benzoylacetone and thenoyltrifluoroacetone were synthesized by ligand exchange reactions of titanium(IV)-isopropoxide. The compounds are red or black in colour and were identified by distinct molecular peaks in the mass spectra. The crystal and molecular structure was determined for bis[2,6-diphenacylpyridinato(2–)] titanium(IV). Crystallographic data see “Inhaltsübersicht”.