丙烯环氧化反应中失活钛硅分子筛的无氧脱附研究

采用无氧脱附方法对丙烯环氧化中失活的薄层钛硅分子筛(即Spent EPO-4)和环氧丙烷(PO)与丙二醇单甲醚(MME)浸渍的TS-1催化剂(即PO／TS-1和MME／TS-1)进行了研究，脱附产物由气相色谱定性分析，无氧脱附后的催化剂以丙烯环氧化为探针反应进行再生性能评价，同时在无氧条件下考察了TS-1在300℃时催化裂化PO反应．实验结果表明：PO浸渍TS-1可使其活性明显下降，PO在TS-1上不是简单的弱吸附，存在着化学强吸附和自聚．失活催化剂(Spent EPO-4和PO／TS-1)经无氧脱附后，其催化活性可显著恢复．通过对失活催化剂脱附产物的比较，推测了丙烯环氧化反应过程中钛硅分子筛失活原因．     

钛硅沸石TS－1在丙烯环氧化反应环境中的水热稳定性

 通过1200h模拟实验，考察了CH3OH－H2O2丙烯环氧化水热环境对廉价法合成的大晶粒钛硅沸石TS－1（1μm×2μm×6μm，n（Si）／n（Ti）＝53．6）结构的影响．通过XRF，XRD，FT－IR，UV－Vis，NH3－TPD，SEM，N2物理吸附和丙烯环氧化探针反应等表征手段发现，在丙 烯环氧化反应的水热环境中，TS－1沸石的晶体结构和骨架钛较稳定，TS－1沸石长时间与H2O2作用，其表面也不会被酸化；处理后的TS－1样品的催化活性和选择性不变．这些结果表明，用廉价法合成的大晶粒钛硅沸石TS－1与H2O2的作用是可逆的．这可能与TS－1沸石的合成条件有关．     

钛硅分子筛催化1-丁烯环氧化反应溶剂效应和酸碱效应研究

研究了用双氧水为氧化剂，钛硅分子筛TS-1催化1-丁烯环氧化反应的溶剂效应．研究发现，在质子性溶剂中1-丁烯环氧化反应活性高于非质子性溶剂，而以甲醇为溶剂H2O2转化率最高．分别利用碱性添加物稀氨水溶液和酸性添加物稀盐酸溶液调变反应介质的pH值，考察了介质的pH值对1-丁烯环氧化反应的影响，结果表明，随pH值提高，1，2-环氧丁烷(B0)的选择性略提高，但是过量稀氨水的加入会导致催化剂失活，双氧水的转化率及利用率明显下降．与钛硅分子筛催化丙烯环氧化相比，酸性添加物的加入对反应结果的影响不大，随反应介质的pH值降低1，2-环氧丁烷的选择性没有明显下降．     

钛硅分子筛TS-1催化氯丙烯环氧化反应动力学研究

 摘要：研究了钛硅分子筛催化氯丙烯环氧化反应的条件及动力学行为．\r\n结果表明，以钛硅分子筛为催化剂，氯丙烯可被高选择性地氧化为环氧\r\n氯丙烷．环氧化反应速度与分子筛中骨架钛的含量及分子筛的用量呈正\r\n比关系，是一级反应．对于氧化剂H2O2，只有当c（H2O2）＜0．4mol／\r\nL时，环氧化反应为一级反应；而c（H2O2）＞1．0mol／L时，为零级反\r\n应．对于氯丙烯，随着其浓度的变化，环氧化反应的级数在1和0之间．\r\n然而，只有当氯丙烯浓度很高时，环氧化反应的级数才有明显的降低．\r\n根据实验结果和Eley－Rideal单分子吸附方程，提出了氯丙烯环氧化反\r\n应的动力学模型．\r\n关键词：钛硅分子筛，氯丙烯，过氧化氢，环氧化，环氧氯丙烷，反应\r\n动力学     

烯丙基氯氧化制环氧氯丙烷的研究进展

环氧氯丙烷是一种重要的有机化工原料和中间体。本文综述了以H2O2为氧源的烯丙基氯直接环氧化制备环氧氯丙烷的研究进展。分别介绍了以TS-1、Ti-MWW和磷钨杂多酸盐为催化剂的不同催化体系用于烯丙基氯环氧化反应的研究现状,阐述了各种不同催化体系的优缺点和未来的发展方向。     

Au/NTS-1催化丙烯气相直接环氧化(英文)

以高温氨气处理制得含氮微孔钛硅分子筛(NTS-1)为载体,用沉积-沉淀法制得了一系列纳米金催化剂.考察了纳米金催化剂在氢气和氧气共存下催化丙烯气相环氧化制环氧丙烷反应中的催化性能.结果表明,高温氨气处理钛硅分子筛(TS-1)载体降低了其酸性,提高了纳米金催化剂制备中金的利用率和纳米金催化剂中金的分散度,显著提高纳米金催化剂的催化活性.载体酸性降低和载体表面–NH2配位效应增强了催化剂活性.     

用不同方法合成的钛硅分子筛TS-1的拉曼光谱研究

采用不同方法合成了钛硅分子筛ＴＳ－１,Ｒａｍａｎ光谱表征表明,不同方法合成的ＴＳ－１分子筛中钛的分散状态不同,当钛的含量低于１．５％,不同方法合成的ＴＳ－１中的钛主要以高分散状态存在,当钛含量达到２．０％以上时,不同方法合成的钛硅分子筛中钛的分散状态显著不同,其中以ＴｉＣｌ３合成的分子筛中骨架钛的含最高,而杂晶相锐钛矿含量最低,同时催化氯丙烯环氧化活性也最高,而以正钛酸四丁酯为钛源,在静止态下晶化的钛硅分子筛中锐钛矿含量最高,催化活性最低。     

环氧环己烷的电化学合成

环氧环己烷的电化学合成何俊翔＊周锦成（温州师范学院化学系温州３２５００３）关键词电化学环氧化，环氧环己烷，环己烯，钛基氧化物电极１９９６－１１－２２收稿，１９９７－０６－０５修回间接电解氧化合成环氧化合物的研究已有报道［１～４］．它们均在铂电极上完成...     

Ti-MWW催化氯丙烯环氧化固定床工艺研究

以Ti-MWW分子筛为催化剂,H2O2为氧化剂,研究了氯丙烯环氧化制环氧氯丙烷固定床工艺过程的反应规律.结果表明,H2O2的空速对该反应过程起着非常重要的作用.优化的反应参数为:以乙腈为溶剂,氯丙烯/H2O2摩尔比为5,反应温度为333K,H2O2空速为0.44h-1.在该条件下氯丙烯转化率、环氧氯丙烷选择性、H2O2转化率及有效利用率分别达到19.0%,99.9%,98.0%和97.0%。     

Ti—Si沸石表面吸附物种的TPSR—TPD研究

氯丙烯在不同催化剂表面上吸附的ＴＰＤ结果表明在ＴＳ－１上有三重附峰，而在ＴｉＯ２／Ｓｉｌｉｃａｌｉｔｅ上仅有单峰，Ｈ２Ｏ２或分子Ｏ２在催化剂表面吸附后，在脱附物种中可用质谱检测到原子Ｏ（１６）物种；说明Ｈ２Ｏ２或分子Ｏ２在样品表面存在解离吸附；并发现解离子分子Ｏ２的活性很低，ＴＳ－１能同时吸附内烯和Ｈ２Ｏ２，而在ＳｉＯ２／Ｓｉｌｉｃａｌｉｔｅ表面的吸附却与吸附顺序有关，环氧化活性顺序如下：ＴＳ－１     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.