烯烃的催化环氧化反应

烯烃的环氧化反应,不论在实验室还是在工业生产中,都是烯烃功能团转化的重要途径。低级烯烃的环氧化物,如环氧乙烷和环氧丙烷,是合成聚氨基甲酸乙酯、聚酯、氨基醇、表面活性剂的原料或半成品。氧化苯乙烯可用于合成玫瑰油;丙烯醇的环氧化是制备甘油的一条途径,由此得到的缩水甘油也有重要用途,如合成特种聚合物;由不对称环     

金属卟啉-聚乙二醇催化烯烃环氧化反应

研究了聚乙二醇在模拟细胞色素P-450酶、CH_2Cl_2-H_2O两相体系中的相转移催化作用;并和季铵盐类相转移催化作用进行了比较。把PEG-400键联到金属卟啉上,进一步考察了连接大分子后对金属卟啉的催化活性及稳定性的影响;同时比较了键联后的聚乙二醇和自由聚乙二醇所起的相转移催化作用;最后,对反应机理进行了讨论。     

生物催化烯烃不对称环氧化反应

手性环氧化物在合成上具有重要的应用价值。近年来,制取这些手性合成物的合成方法取得了很大的发展。文章重点讨论了生物催化手性前体烯烃不对称合成光学活性环氧化合物的发展状况。     

溴代烯烃在金属催化偶联反应中的应用

溴代烯烃是一类重要的有机合成中间体,通过金属催化的偶联反应可以有效地形成碳-碳及碳-杂键.本文综述了溴代烯烃在金属催化偶联反应中应用的最新进展.     

镁基复合氧化物催化烯烃环氧化反应

 制备了一系列镁基复合氧化物 MgM-n 样品 (M = Sn, Al, Ti, La, Ce, Zr; n 为 Mg/M 原子比), 用 X 射线衍射、N2 吸附-脱附、CO2 程序升温脱附、紫外可见漫反射光谱和电子自旋共振等手段表征了它们的结构和表面性质, 并考察了其以过氧化氢为氧化剂催化烯烃环氧化反应性能. 结果表明, MgM-n 样品表面碱量和催化性能与其中 M 的种类及含量密切相关. MgSn-4 样品的表面碱量比 MgAl-4 低, 虽两者在催化苯乙烯环氧化反应中, 苯乙烯转化率和环氧化物选择性均为 95% 左右, 过氧化氢利用率大于 80%, 但在循环使用过程中 MgSn-4 的催化性能更为稳定, 并在不同结构烯烃的环氧化反应中表现出优良的催化性能. 这除与 MgSn-4 表面碱强度适当有关外, 还与其中存在高分散的 Sn4+物种及其结构特性有关.     

烯烃的有机催化不对称环氧化反应

介绍了用手性酮，手性亚胺盐为催化剂以及手性胺为催化剂前体的新型有机催化不对称环氧化反应。     

氟插层水滑石催化烯烃环氧化反应

制备了一系列不同Mg/Al比氟插层的水滑石(LDH-F),并用X射线衍射、傅里叶变换红外光谱、扫描电镜和BET比表面积检测法对催化剂进行了表征,考察了不同Mg/Al比的LDH-F在苯乙烯环氧化反应中的催化活性.结果表明,Mg/Al=5的LDH-F具有最佳催化活性.通过以乙腈和苯甲腈分别作为反应用腈的对比实验发现,苯甲腈的效果优于乙腈.以Mg/Al=5的LDH-F为催化剂,H2O2和苯甲腈为氧化剂对不同官能团化烯烃进行环氧化反应,结果表明,此催化体系具有良好的催化性能,在苯乙烯、茚、丙烯醇和烯丙基氯环氧化反应中转化率和选择性均在95%以上。     

缺位类型磷钨酸盐催化的烯烃环氧化反应

主要合成了两种杂多磷钨酸盐环氧化催化剂,分别是由单缺位Keggin类型磷钨酸阴离子或者饱和结构的磷钨酸阴离子与十六烷基三甲基季铵盐阳离子构成,即[n-C16H33N(CH3)3]4Na3PW11O39(PW11)以及[n-C16H33N(CH3)3]3PW12O40(PW12),将其与低毒性的乙酸乙酯、30%的双氧水、烯烃构成催化环氧化反应体系,以环辛烯的环氧化反应为模型反应,着重探讨了PW11与PW12的催化性能产生明显差异的原因,并通过傅里叶变换-红外光谱,核磁共振谱以及催化剂溶解性实验给出了合理的解释.首先,在进行环辛烯的环氧化反应的动力学研究中,我们发现相同的反应条件下,PW11的催化活性明显高于PW12的催化活性,当反应进行至10min,以PW11为催化剂的反应体系,环辛烯的转化率已达到89%,而相应的采用PW12为催化剂的反应体系,环辛烯的转化率仅仅为11%.通过核磁磷谱(31PNMR)表征证明:当PW11和PW12与双氧水反应10min时PW11已降解产生大量的活性物种,而PW12的31PNMR谱并没有显示降解产物的谱峰.溶解性实验则更近一步说明,两个催化剂在双氧水的作用下均可降解形成小分子的物...     

金属卟啉在催化氧化反应中的研究进展

金属卟啉作为P-450酶的有效模拟物,因在仿生催化氧化体系中具有效率高、选择性好、条件温和等特点,备受人们关注.本文详细介绍了近年来金属卟啉配合物作为催化剂在氧化反应方面的应用,主要包括烷烃、烯烃、醇、酮等底物的氧化,并对可能的反应机理、活性物种进行了总结.最后,展望了金属卟啉在氧化反应中的挑战与前景.     

手性酮催化的烯烃不对称环氧化反应

手性酮是催化非官能化烯烃不对称环氧化的一类重要催化剂 ,它与过氧硫酸氢钾可原位产生对贫电子和富电子烯烃均很有效的氧化剂———手性二氧杂环丙烷 .综述了各种结构的手性酮在反式烯烃、三取代烯烃和顺式烯烃等的不对称环氧化反应中的应用研究进展 ,总结了手性酮结构及反应条件对其催化活性和不对称诱导作用的影响     

Oxidation of Alkenes by Peroxydisulphate-copper Sulphate

A novel oxidative cleaved product and addition product were obtained from the oxidation of alkenes with peroxydisul-phate-copper(II) systems.     

烃类选择氧化制低碳烯烃的研究进展

在探索替代传统的烃类蒸汽热裂解制取低碳烯烃工艺的众多研究中,烃类经选择氧化制取低碳烯烃是具有发展前景的方法之一.本文重点介绍了国内外烃类选择氧化制低碳烯烃近年来的研究进展和新的研究热点,对现存的主要问题以及未来发展方向也作了概述.     

钯-手性膦配体催化剂在烯烃不对称催化反应中的应用

综述了钯-手性膦配体催化剂在烯烃的不对称氢氰化、不对称羰基化、不对称交叉偶联、不对称氢化硅氢化等方面的研究进展。参考文献36篇。     

Oxidation of Alkenes and Sulfides with Transition Metal Catalysts

Alkenes and sulfides were oxidized with transition-metal catalysts. The oxidant sources include molecular dioxygen, air and iodosylbenzene. The metal ions Mn(III), Fe(III), Co(II) and Ni(II) were used. The Catalysts 1-18 of 1,3-dioxo-, β-ketoimine- or salen-types were prepared and their efficacy was examined. 1,2-Dihydronaphthalene is most efficiently epoxidized with O₂/Me₂CHCHO or PhIO in the presence of Mn(III)-salen catalysts. The Ni(II)-, Co(II)- and Fe(III)-catalysts of either β-ketoimine- or salen-types are useful for epoxidation of styrene, (E)-stilbene and (E)-benzalacetone in the O₂/Me₂HCHO system; these epoxidations are stereospecific without formation of corresponding diastereomeric epoxides. Oxidation of methyl p-tolyl sulfide with O₂/Me₂CHCHO is facilitated by the 1,3-dioxo-catalyst Co(II)-1. Monooxidation is achieved with Me₂CHCHO in equimolar proportions to give the corresponding sulfoxide, whereas overoxidation is realized with excess Me₂CHCHO to give the sulfone. These epoxidation and sulfide oxidations all occur at 25 °C and are complete in less than a day.     

Chemoselective Oxidation of Alkenes by Metal-Organic Framework-Supported Copper Catalyst

Oxidation of alkenes to carbonyls or diols compounds is important in synthesizing fine chemicals and pharmaceutical intermediates. We report the synthesis and characterization of an aluminum metal-organic framework node-supported copper(II) chloride (DUT-5-CuCl), which is an efficient heterogeneous catalyst for the oxidation of alkenes using H₂O₂ as an oxidizing agent. Styrene and various substituted styrenes were transformed into the corresponding carbonyl compounds in excellent selectivity and yields. DUT-5-CuCl is tolerant with various functional groups and could be recycled and reused at least 5 times in the oxidation of α-methylstyrene. Unlike the oxidation of styrene derivatives, DUT-5-Cu catalyzed oxidation of aliphatic and cyclic alkenes produced 1,2-diols compounds selectively. The mechanism of the DUT-5-Cu catalyzed oxidation of styrene to benzaldehyde was investigated in detail by various experiments such as the determination of reaction intermediates and characterization of the catalyst after catalysis, and computational studies. This work highlights the importance of MOF-supported earth-abundant metal catalysts for oxidation reactions to produce fine chemicals.     

Catalytic Allylic Oxidation of Alkenes Using an Asymmetric Kharasch-Sosnovsky Reaction

Kharasch and Sosnovsky reported the allylic oxidation of alkenes to give racemic allylic benzoates. This could be achieved efficiently using a tert-butyl perester as the oxidant, in the presence of a copper or cobalt salt. The use of C(2)-symmetric bis(oxazoline) ligands in the presence of copper(I) triflate with cyclic olefinic substrates gave the first synthetically useful asymmetric variant. The enantioselective control was good (up to 84 % ee) although yields were variable. In all cases the facial preference of the newly formed C-O bond was the same giving an S configuration at the allylic stereocenter. Lower stereocontrol was observed for large-ring alkenes and substantially reduced enantioselectivities were found with open-chain alkenes. This reaction has been further screened using a variety bis(oxazoline) and proline-derived ligands, which give a direct correlation between the chirality of the ligand and the enantioselectivity obtained. Individual substrates were found to be extremely sensitive to both the ligand structure and copper salt used as well as the presence of additives such as zinc, hydrazine, and molecular sieves.     

Atom-Efficient Oxidation of Alkenes with Molecular Oxygen: Synthesis of Diols

Dihydroxylations of simple alkenes were carried out for the first time in excellent yields and selectivities with molecular oxygen as oxidant [(Eq. (a)]. Both oxygen atoms are used productively and are incorporated into the product in this transition metal catalyzed alkene oxidation.     

Kinetics,Substrate Selectivity and Mechanism of the Oxidation of Alkenes by Peroxynitrous Acid

The kinetic features of the oxidation of alkenes by peroxynitrous acid (HOONO) generated in the H₂O₂–HNO₂/acetate buffer (pH 4.27) system, are quantitatively explained assuming simultaneous reactions in the gas and liquid phases. A remarkable similarity is found for the substrate selectivities of the gas-phase reactions of alkenes as well as of alkanes and arenes with HOONO and with ^·OH radicals. The reaction mechanism is discussed.     

Palladium‐Catalyzed anti‐Markovnikov Oxidation of Terminal Alkenes

The palladium‐catalyzed oxidation of alkenes, the Wacker–Tsuji reaction, is undoubtedly a classic in organic synthesis and provides reliable access to methyl ketones from terminal alkenes under mild reaction conditions. Methods that switch the selectivity of the reaction to provide the aldehyde product are desirable because of the access they provide to a valuable functional group, however such methods are elusive. Herein we survey both the methods which have been developed recently in achieving such selectivity and discuss common features and mechanistic insight which offers promise in achieving the goal of a general method for anti‐Markovnikov‐selective olefin oxidations.