手性相转移催化剂及其不对称催化反应

综述了手性季铵盐和手性冠醚两类手性相转移催化剂及其在不对称催化反应（包括加成，取代，氧化及还原等反应）中的应用，参考文献９７篇。     

相转移催化法实现聚苯乙烯的功能化转变

以对羟基苯甲醛的钠盐为亲核取代试剂,采用相转移催化进行了大分子氯甲基聚苯乙烯的亲核取代反应,将其转变为侧链带有功能性基团醛基的聚苯乙烯;考察了反应条件(如有机溶剂的极性、催化剂种类及用量、有机相与水相之比等)对大分子相转移催化反应的影响,并根据相转移催化反应机理与相关的动力学规律进行了分析.结果表明,通过相转移催化亲核取代反应,可将氯甲基聚苯乙烯大分子链上的氯原子转化,制得侧链带有醛基的聚苯乙烯;溶剂的极性越强,负离子的反应活性也越高;催化剂季铵正离子的亲脂性越强,相转移催化反应的速率越快.当催化剂浓度较低时,四丁基溴化铵比十六烷基溴化铵的催化效果好;当催化剂浓度较高时,十六烷基溴化铵比四丁基溴化铵的催化效果好.另外,有机相与水相之比对相转移催化反应有较大的影响.     

相转移催化反应中界面性能的研究

过去在研究相转移催化反应机理时仅考虑在相转移催化剂作用下反应物、中间体(离子)、产物在两相间的转移,并导致两相间反应进行。我们以研究结果证明水相的表面能和两相的界面能与相转移催化反应的结果有密切关系。     

线型聚氧乙烯化合物的相转移催化反应

线型聚氧乙烯化合物具有良好的相转移催化能力。以其作为相转移催化剂,不仅来源丰富,价廉无毒,化学稳定性好,而且反应条件温和,操作简便,产率也较高,是相转移催化反应中理想的冠醚替代物。文中综述了线型聚氧乙烯化合物作为相转移催化剂在有机合成中的应用进展,并对其相转移催化作用进行了讨论。     

采用相转移催化法制备苯二甲酰亚胺基甲基聚苯乙烯

以邻苯二甲酰亚胺钾盐为亲核取代试剂, 采用相转移催化体系通过Gabriel反应, 将氯甲基聚苯乙烯转变为苯二甲酰亚胺基甲基聚苯乙烯, 考察了各种因素对相转移催化反应的影响规律, 探讨了相转移催化机理. 结果表明, 采用相转移催化体系, 相转移催化剂将邻苯二甲酰亚胺负离子从水相中转移至油相, 与氯甲基聚苯乙烯发生亲核取代, 顺利地将氯甲基聚苯乙烯大分子链上的氯甲基转变成了甲基化的苯二甲酰亚胺基, 成功地实现了高分子的功能化转变. 影响相转移催化反应的主要因素有催化剂种类与用量、溶剂的极性、油相与水相比例及温度等. 当以十六烷基三甲基溴化铵为催化剂且以甲苯为有机相时, 反应效果最佳, 反应温度为50 ℃时, 反应8 h氯甲基的转化率可达到87%.     

反应过程相转移催化选择性氧化还原羰基化合成灭草隆除草剂

 研究了以硒为催化剂，三乙胺为助催化剂，对氯硝基苯和二甲胺水溶液（33%）为反应底物，经高选择性氧化还原羰基化一步合成灭草隆除草剂。在温度135℃和CO压力3.0 MPa条件下，反应4小时，转化率达到54%以上，灭草隆选择性达到99.5%以上。在本催化反应体系中，硒在反应前以固态存在，反应过程中与CO结合生成能溶于反应体系的羰基硒，反应结束后又以固态硒析出，兼具多相催化与均相催化的优点，产物易于分离，首次提出反应过程相转移催化概念。     

咪唑N-烷基化相转移催化反应动力学研究

本文报道在冠醚和季铵盐等相转移催化剂存在下咪唑N-正丁基化反应的动力学研究结果。在一定的催化剂浓度下,反应速度与烷基卤的浓度呈一级反应动力学关系,同时与催化剂浓度亦呈一级反应比例关系在60±0.05℃,以四丁基溴化铵为催化剂,咪唑N-正丁基化反应速率常数κ=(1.90±0.02)×10~(-2),活化能E_a=11.7±0.5 kcal/mol,此外还研究了不同类型冠醚和季铵盐对反应的影响。反应机理可设想为:在相转移催化反应条件下,由催化剂中的阳离子R_4N_ 和亲核试剂Im-形成的离子对转移到有机相中与烷基卤发生反应,因此反应速率对烷基卤浓度变化极为敏感,也与催化剂在两相间的分配系数α值有关。一般以α值为1左右的季铵盐的催化效果最好,这可能是选择有效相转移催化剂的一个标志。     

手性季铵盐类相转移催化剂的新进展

叙述了手性季铵盐类相转移催化剂在不对称催化反应（包括活性亚甲基的烷基 化、Michael加成、双键的环氧化、Darzens缩合、氮杂环丙烷的合成、羟醛缩合以 及Horner-Wadsworth-Emmons反应）中应用的新进展。     

接枝型三相相转移催化剂的制备及其催化作用

将苯乙烯（St）接枝聚合在微米级硅胶表面,制备了接枝微粒PSt／SiO2;使用新型氯甲基化试剂1,4-二氯甲氧基丁烷,对接枝在硅胶表面的聚苯乙烯进行了氯甲基化（CM）反应,制得了氯甲基聚苯乙烯／硅胶（CMPS／SiO2）接枝微粒;使三乙胺与CMPS分子链上的苄氯基团发生季铵化反应,制得了固载有季铵盐（Quaternary salt）的接枝微粒QPSt／SiO2,即制得了接枝型三相相转移催化剂．将此相转移催化剂用于氯化苄与乙酸钠合成乙酸苄酯的相转移催化反应,考察了催化活性、各种因素对相转移催化反应的影响及催化剂的重复使用性能．实验结果表明,接枝型三相相转移催化剂QPSt／SiO2对乙酸苄酯的合成具有较高的催化活性,在液-固-液之间即可有效地实现反应物种乙酸根的转移,在60℃的较低温度下反应7h,氯化苄的转化率可达66．1％;研究发现,固体催化剂QPSt／SiO2表面接枝聚合物PSt的季铵化程度对其催化活性有很大的影响,季铵化程度过大与过小催化活性都较低,当季铵化程度为20％左右时,催化剂的活性最高．     

反应控制相转移催化剂的研究进展

反应控制相转移催化兼具均相和非均相催化的优点,有助于解决催化剂催化活性低及分离回收困难等问题,符合环境友好的要求,所以一直以来备受关注。反应控制相转移现象的形成与催化剂的阴、阳离子结构和溶剂等反应条件密切相关。本文就目前应用广泛的反应控制相转移催化剂的阴、阳离子的结构特点进行综述,最后就反应控制相转移催化体系可能存在的问题和创新方向作了展望。     

POLYMER—SUPPORTED SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS AS CATALYSTS FOR PHASE—TRANSFER REACTIONS

In this study was to investigate,by phase-transfer catalysis,the activity of single and mixed ammonium and phosphonium salts grafted on a “gel-type“ stryene-7% divinylbenzene copolymer in the oxidation of benzyl alcohol with hydrogen peroxide.A wide variety of catalysts with different quaternary groups and different quaternary chain length substitutents were examined.The activity of single“onium“salts increases as a consequence of the association of ammonium and phosphonium salts grafted onn the same polymeric support.The activity of polymer-supported ammonium and phosphonium salts increases with the number of carbon atoms contained in the alkyl radicals of the -onium and of the functionalization degree with phosphonium groups.     

聚乙二醇相转移催化法合成查耳酮

以聚乙二醇(polyethyleneglycol,PEG)为相转移催化剂进行了苯甲醛与苯乙酮的克莱森–施密特(Claisen-Schmidt)缩合反应,并就聚乙二醇用量、聚乙二醇相对分子质量和溶剂种类等影响因素进行了条件实验,在较优化的合成条件下,查耳酮产率可达80%。     

Ethanol to Acetaldehyde Conversion under Thermal and Microwave Heating of ZnO-CuO-SiO2 Modified with WC Nanoparticles

The nonoxidative conversion of ethanol to acetaldehyde under thermal and microwave heating was studied on mixed oxide ZnO-CuO-SiO₂ catalysts modified with additives of tungsten carbide nanoparticles. The results revealed that the WC-modified catalyst exhibited superior activity and selectivity under microwave heating conditions. It is assumed that when microwave heating is used, hot zones can appear at the contact points of WC nanoparticles and active centers of the mixed oxide ZnO-CuO-SiO₂ catalyst, which intensively absorb microwave energy, allowing the more efficient formation of acetaldehyde at moderate temperatures. Thermodynamic calculations of equilibrium concentrations of reagents and products allowed us to identify the optimal conditions for effective acetaldehyde production. The initial catalyst and the catalyst prepared by the coprecipitation of the oxides with the addition of WC were characterized by physicochemical methods (TPR-H₂, XRD, DRIFTS of adsorbed CO). The active centers of the oxide catalyst can be Cu⁺ cations.     

Organorhodium‐Functionalized Periodic Mesoporous Organosilica: High Hydrophobicity Promotes Asymmetric Transfer Hydrogenation in Aqueous Medium

Three organosilica‐bridged periodic mesoporous organosilicas were prepared by the immobilization of a chiral N‐sulfonylated diamine‐based organorhodium complex within their silicate network. Structural analysis and characterization confirmed their well‐defined single‐site active rhodium centers, whilst electron microscopy revealed their highly ordered hexagonal mesostructures. Among these three different organosilica‐bridged periodic mesoporous organosilicas, the ethylene‐bridged periodic mesoporous organosilica catalyst exhibited excellent heterogeneous catalytic activity and high enantioselectivity in the aqueous asymmetric transfer hydrogenation of aromatic ketones. This superior catalytic performance was attributed to its salient hydrophobicity, whilst its comparable enantioselectivity relative to the homogeneous catalyst was derived from the confined nature of the chiral organorhodium catalytic sites. Furthermore, this ethylene‐bridged periodic mesoporous organosilica could be conveniently recovered and reused at least 12 times without the loss of its catalytic activity. This feature makes this catalyst attractive for practical organic synthesis in an environmentally friendly manner. This study offers a general way of optimizing the bridged organosilica moiety in periodic mesoporous organosilicas, thereby enhancing its catalytic activity in heterogeneous catalysis.     

交联聚苯乙烯固载聚乙二醇树脂（PEG）含量与活性的依赖关系研究

将具有不同ＰＥＧ含量的交联聚苯乙烯固载聚乙二醇树脂用于催化环已稀的二氯卡宾加成和乙酰苯胺的Ｎ－丁基化反应，发现树脂ＰＥＧ含量与催化剂活性之间存在的依赖关系。通过测定不同ＰＥＧ含量的树脂分别在水和甲苯中的溶胀系数，用树脂亲油－亲水性的变化规律，解释树脂活性与ＰＥＧ含量之间的依赖关系。     

Catalytic Asymmetric Mannich‐Type Reaction of N‐Alkylidene‐α‐Aminoacetonitrile with Ketimines

Optically active vicinal diamines are versatile chiral building blocks in organic synthesis. A soft Lewis acid/hard Brønsted base cooperative catalyst allows for an efficient stereoselective coupling of N‐alkylidene‐α‐aminoacetonitrile and ketimines to access this class of compounds bearing consecutive tetra‐ and trisubstituted stereogenic centers. The strategic use of a soft Lewis basic thiophosphinoyl group for ketimines is the key to promoting the reaction, and aliphatic ketimines serve as suitable substrates with as little as 3 mol % catalyst loading.     

AN EFFICIENT SYNTHESIS OF POLYMETHYLENE-BIS-AROYL THIOUREA DERIVATIVES UNDER THE CONDITION OF PHASE-TRANSFER CATALYSIS

Reaction of polymethylene diamine with aroyl chloride and ammonium thiocyanate under the condition of solid–liquid phase-transfer catalysis using polyethylene glycol-400 (PEG-400) as the catalyst yielded polymethylene-bis-aroyl thiourea derivatives 3a–q in good-to-excellent yield. The products have been characterized by analytical and spectral (IR and H¹ NMR) data.     

Polymerization Kinetics of Propylene with the MgCl_2-Supported Ziegler-Natta Catalysts——Active Centers with Different Tacticity and Fragmentation of the Catalyst

The catalytic activity and stereospecificity of olefin polymerization by using heterogeneous TiCl_4/MgCl_2 Ziegler-Natta(Z-N) catalysts are determined by the structure and nature of active centers, which are mysterious and fairly controversial. In this work, the propylene polymerization kinetics under different polymerization temperatures by using Z-N catalysts were investigated through monitoring the concentration of active centers [C*] with different tacticity. SEM was applied to characterize the catalyst morphologies and growing polypropylene(PP) particles. The lamellar thickness and crystallizability of PP obtained under different polymerization conditions were analyzed by DSC and SAXS. The PP fractions and active centers with different tacticity were obtained with solvent extraction fractionation method. The catalytic activity, active centers with different tacticity and propagation rate constant k_p, fragmentation of the catalyst, crystalline structure of PP are correlated with temperature and time for propylene polymerizations. The polymerization temperature and time show complex influences on the propylene polymerization. The higher polymerization temperature(60 ℃) resulted higher activity, k_p and lower [C*], and the isotactic active centers C_i* as the majority ones producing the highest isotactic polypropylene(iPP) components showed much higher k_p when compared with the active centers with lower stereoselectivity. Appropriate polymerization time provided full fragmentation of the catalyst and minimum diffusion limitation. This work aims to elucidate the formation and evolution of active centers with different tacticity under different polymerization temperature and time and its relations with the fragmentation of the PP/catalyst particles, and provide the solutions to the improvement of catalyst activity and isotacticity of PP.     

Construction of a Chiral Silicon Center by Rhodium‐Catalyzed Enantioselective Intramolecular Hydrosilylation

Rhodium‐catalyzed enantioselective desymmetrizing intramolecular hydrosilylation of symmetrically disubstituted hydrosilanes is described. The original axially chiral phenanthroline ligand (S)‐BinThro (Binol‐derived phenanthroline) was found to work as an effective chiral catalyst for this transformation. A chiral silicon stereogenic center is one of the chiral motifs gaining much attention in asymmetric syntheses and the present protocol provides cyclic five‐membered organosilanes incorporating chiral silicon centers with high enantioselectivities (up to 91 % ee). The putative active Rh^I catalyst takes the form of an N,N,O‐tridentate coordination complex, as determined by several complementary experiments.     

相转移催化合成对甲氧基肉桂酸-2-乙基己酯的研究

对甲氧基肉桂酸 2 乙基己酯是一种有效的ＵＶＢ防晒剂[1 ,2 ] ,一般采用Ｃｌａｉｓｅｎ Ｓｃｈｍｉｄｔ缩合反应制得[3] ,但由于催化剂ＫＯＨ处于水相 ,对反应物不能充分起到催化作用导致产率较低[4] 。我们利用乙二醇 (ＰＥＧ)为相转移催化剂合成立体专一的反式对甲氧基肉桂酸 2 乙基己酯 ,产率提高到 72 .5 %。合成路线如下 :1　实验部分1 .1　仪器与试剂ＢＩＯ ＲＡＰＦＴ45 0红外光谱仪 ,用液膜法测试 ;Ｂｒｕｒｅｒ ＡＭ 30 0超导核磁共振仪 (溶剂ＤＣ Ｃｌ3) ;ＭＡＴ/44Ｓ ,ＧＣ ＭＳ型色质联用谱仪 ;试剂均为分析纯 ,上海化学试剂…