固相研磨合成4,4''''-联吡啶季铵盐

采用室温固相研磨的方法,4,4'-联吡啶与连有阻塞基的乙氧乙醇磺酸酯(或苄溴)反应,得到单取代的4,4'-联吡啶六氟磷酸盐(2),2再与α,α'-二(溴甲基)-2,2'-联吡啶反应,得到哑铃型化合物--2,2'-联吡啶桥连的双-4,4'-联吡啶六氟磷酸盐(3),收率约90%.2和3的结构经1H NMR, 13C NMR和MS表征.     

手性联萘基-2,2'-联吡啶及其衍生物的合成及其在不对称合成中的应用

利用Kröhnke方法,以芳基乙酮为原料一锅法简洁地合成了6-芳基-6'-溴-2,2'-联吡啶2b~2d。 通过(R)-3-(4,4,5,5-四甲基-1,3,2-二噁唑硼烷基)-2,2'-乙氧基-1,1'-联萘((R)-1)与6-溴-2,2'-联吡啶及其衍生物2a~2d的Suzuki偶联, 合成了4种手性6-[3-((R)-2,2'-二乙氧基-1,1'-联萘)基]-2,2'-联吡啶(R)-3a~3d。 将配体(R)-3a~3d应用于苯乙酮的不对称氢转移反应中,配体(R)-3a给出92%的转化率和4%的对映体过量(ee)值。     

用于三价锕镧分离的萃取剂的合成与表征

以6,6'-二氰-2,2'-联吡啶为原料,经两步反应,合成了6,6'二(5,6二乙基-1,2,4-三嗪-3-基)-2,2'-联吡啶.第一步改变条件使反应时间由17d缩短到3d,得到的中间体和目标产物经元素分析、IR,1 HNMR和MS等表征确认.此外,对反应机理进行了初步探讨.     

4,4'-二(对氨基苯乙炔基)-6,6'-二[N,N-二(乙氧基羰甲基)氨甲基]-2,2'-联吡啶的合成与表征

以4,4'-二硝基-2,2'-联吡啶-6,6'-二亚甲基双三氟乙酸酯作为起始原料, 经水解、 溴化、 酯化和对氨基苯乙炔取代4步反应合成了4,4'-二(对氨基苯乙炔基)-6,6'-二[N,N-二(乙氧基羰甲基)氨甲基]-2,2'-联吡啶. 通过红外光谱、 核磁共振波谱、 高分辨质谱等表征了该化合物的结构. 该化合物经水解后与铕离子形成稀土荧光螯合物, 在紫外光激发下, 发射出具有铕离子特征的荧光光谱.     

Synthesis and Characterization of 4,4'-Di (p-aminophenylethynyl)-6,6'-bis[ N,N-bis(ethoxycarbonylmethyi) amino methyl ]-2,2'-bipyridine

以4,4'-二硝基-2,2'-联吡啶-6,6'-二亚甲基双三氟乙酸酯作为起始原料,经水解、溴化、酯化和对氨基苯乙炔取代4步反应合成了4,4'-二.(对氨基苯乙炔基)-6,6'-二[N,N-二(乙氧基羰甲基)氨甲基]-2,2'-联吡啶.通过红外光谱、核磁共振波谱、高分辨质谱等表征了该化合物的结构.该化合物经水解后与铕离子形成稀土荧光螯合物,在紫外光激发下,发射出具有铕离子特征的荧光光谱.     

氮对位取代基对联吡啶与Eu(Ⅲ)络合的影响

采用吸收光谱法测定了在CH3CN溶剂中,4,4'-二甲基[2,2']联吡啶、4,4'-二己基[2,2']联吡啶、4,4'-二壬基[2,2']联吡啶、[2,2']联吡啶-4,4'-二羧酸甲酯等氮原子对位含不同电性能取代基的联吡啶与Eu(Ⅲ)的络合物稳定常数。在实验条件下,含烷基取代基(-CH3,-C6H13,-C9H19)的配体观察到1∶3和1∶2两种络合物,而含吸电基(-COOCH3)的仅观察到一种1∶3络合物。以1∶3络合物生成反应为模型反应,采用密度泛函方法计算了络合反应的自由能变化,证实不同电性能对位取代基对络合反应的影响,络合反应自由能变化与取代基的供电性强弱顺序相一致。     

2,2'-联吡啶参与的分子梭合成与1H NMR研究

2-{2-[4-苯基-二(4-特丁基苯基)甲基]苯氧基}乙氧乙醇磺酸酯(1)与4,4'-联吡啶在乙腈中回流36 h, 随后通过阴离子交换得到N-{2-{2-[4-苯基-二(4-特丁基苯基)甲基]苯氧基}乙氧乙基}-4,4'-联吡啶六氟磷酸盐(3), 产率为93.4%. 3与4,4'-二(溴甲基)-2,2'-联吡啶在乙腈中、70 ℃下反应72 h, 生成哑铃型化合物5, 产率为45%. 5与冠醚BPP34C10在55 ℃下搅拌5 d, 得到分子梭6和7, 产率分别为42.3%和27.3%. ¹H NMR数据表明, 富电子冠醚BPP34C10与哑铃型组分上贫电子4,4'-联吡啶的非键作用使4,4'-联吡啶上氢的化学位移向高场有较大移动.     

1,9-双(1''''-苯基-3''''-甲基-5''''-氧代吡唑-4''''-基)-壬二酮-[1,9] 与含氮中性配体对镨(Ⅲ)的协同萃取

研究了1,9-双(1'-苯基-3'-甲基5'-氧代吡唑-4'-基)壬二酮-[1,9](H2A)与含氮中性萃取剂(B),如1,10-菲啰啉、2,9-二甲基-4,7-二苯基-1,10-菲哕啉、5-硝基-1,10-菲哕啉、2,2'-联吡啶和4,4'-联吡啶,对镨(Ⅲ)的协同萃取行为,确定了协萃配合物组成为PrA@HA@B,求出了协同萃取平衡常数,制得了固态协萃络合物,并用元素分析、IR、UV、TG-DTA对其组成和性质进行了表征.     

固相研磨合成4,4′-联吡啶季铵盐

采用室温固相研磨的方法,4,4′-联吡啶与连有阻塞基的乙氧乙醇磺酸酯(或苄溴)反应,得到单取代的4,4′-联吡啶六氟磷酸盐(2),2再与α,α′-二(溴甲基)-2,2′-联吡啶反应,得到哑铃型化合物——2,2′-联吡啶桥连的双-4,4′-联吡啶六氟磷酸盐(3),收率约90%。2和3的结构经1HNMR,13CNMR和MS表征。     

2,2′-联吡啶与锌电极作用的表面增强拉曼光谱研究

利用表面增强拉曼光谱(SERS)对2,2′-联吡啶分子在锌电极表面的吸附进行了研究. 实验表明, 2,2′-联吡啶和锌电极有较强的相互作用, 2,2′-联吡啶和锌表面的氧物种存在竞争吸附, 起始电位较正时, 氧物种的吸附使2,2′-联吡啶吸附电位负移；起始电位较负时, 2,2′-联吡啶的吸附抑止氧物种的吸附, 使其吸附电位正移, 且相同电位下氧化种的吸附量大大减少. 同时当电极电位由正往负移时, 吸附在锌表面的2,2′-联吡啶会发生构型转化, 在－1.3 V下以顺式构型垂直吸附, 而当电位负移至－1.4 V时则以反式构型吸附；而电极电位由负往正移时, 在研究电位区间内2,2′-联吡啶都以反式构型吸附, 不存在构型的转化.     

2,2′-联吡啶类催化铬酸氧化异丙醇的动力学研究

铬酸氧化醇类的反应广泛应用于分析和有机合成中。为了加速铬酸的氧化作用或提高反应产率,试验过一些共氧化剂,和催化剂。2,2＇—联吡啶(简作BPy)能与铬离子螯合,显著地提高了铬酸的氧化速率。反应动力学研究的结果说明,2,2＇—联吡啶类、Cr(VI)和异丙醇的三分子螫合物分解为产物一步为限速步骤(见反应式4)。限速步骤产生的Cr(Ⅳ)仍能与2,2＇—联吡啶类螫合,这种作用使Cr(Ⅳ)稳定化,延长了Cr(Ⅳ)的寿命,利于电子转移因而促进反应4的进行。     

Structural Regulation of the Catalytic Activity of Polymetalorganosiloxanes

Linear polycopperorganosiloxanes (PCOSs) with phenyl and nonyl substituents at the silicon atom immobilized on oxide supports catalyze the addition of CCl₄ to alkenes. It was found that PCOSs with nonyl substituents supported on zirconia exhibited a maximum catalytic activity, whereas catalysts containing phenyl fragments were less active. Supporting PCOSs on titania resulted in a complete loss of activity.     

Modification of diphenylamine-linked bis(oxazoline) ligands: Tuning of electronic effect and rigidity of ligand skeleton

The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.     

Hydrogenation of Olefins Catalyzed by Highly Active Titanocene/NaH or n-BuLi Catalyst Systems

IntroductionTitanium metallocenes have been widelystudied as the catalysts for the hydrogenation ofunsaturated hydrocarbons[1— 13 ] .In 1 963,Sloan etal.[1] reported that alkoxyltitanium compounds orCp2 Ti Cl2 with trialkylaluminium acted as goodcatalysts for the hydrogenation of olefins.Then,many active catalystsystems have been developed.The anchoring of titanocene species on supportsyields even more active and more stablehydrogenation catalysts[12 ,13 ] .Various reductives,such as Li Al…     

Kinetics of 2,2′-Bipyridyl-Catalyzed Oxidation of Isopropyl Alcohol with Chromic Acid

2,2′-Bipyridyl and some substituted compounds catalyze effectively the oxidation of isopropyl alcohol by chromic acid. The reaction is first order in chromium(VI), alcohol and 2,2′-bipyridyl; it is first order in hydrogen ions at high acidity and slightly alters to second order at low acidity. The proposed mechanism shows that the rate-limiting step is mainly the decomposition of a termolecular complex to products. However, at low acidity, the formation step of this complex is a little less reversible and hence somewhat rate-limiting. Electron-donating substituents at the 4-position enhance the catalytic activity. Electron-withdrawing substituents at the 4- and 2-positions diminish the reaction rates by electronic and steric factors.     

Remote electronic control of the ligand in the enantioselective palladium-catalyzed allylic alkylation with chiral oxazolinylpyridines

New chiral oxazolinylpyridines bearing electron-donating and withdrawing groups in the 4-position of the pyridine ring have been prepared and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. The electronic properties of substituents strongly affect the catalytic activity and only slightly affect the enantioselectivity of the substitution reaction. Enantioselectivity up to 93% was obtained.     

Synthesis of rhodium N-heterocyclic carbene complexes and their catalytic activity in the hydrosilylation of alkenes in ionic liquid medium

Rhodium complexes bearing N-heterocyclic carbene (NHC) ligands were prepared from bis(η⁴-1,5-cyclooctadiene) dichlorodirhodium and 1-alkyl-3-methylimidazolium-2-carboxylate, and the catalytic properties of rhodium complexes prepared in the hydrosilylation of alkenes in ionic liquid media were investigated. It was found that both the catalytic activity and selectivity of the rhodium complexes bearing NHC ligands were influenced by the attached substituents of the imidazolium cation. Additionally, rhodium complexes bearing NHC ligands in ionic liquid BMimPF₆ could be reused without noticeable loss of catalytic activity and selectivity.     

Ferrocenylimidazoline palladacycles as efficient catalysts for the aza‐Claisen rearrangement reaction of allylic imidates

Chloride‐bridged palladacycle dimers 1 have been evaluated as catalysts for the aza‐Claisen rearrangement of allylic imidates 2 to the corresponding allyl amides 3 . Cyclopalladated complexes 1b–e bearing electron‐donating substituents on imidazoline ring were identified as being superior catalysts because excellent yields were obtained without using silver salts for activation. In addition, a correlation between substituents on the imidazoline ring and catalytic activity of palladacycles was established. The electron‐deficient ligands and good solubility of catalysts in the reaction solution increase the catalytic activity. Copyright © 2008 John Wiley & Sons, Ltd.     

水杨醛亚胺镍配合物催化的乙烯水相聚合

在含表面活性剂的水相体系中, 用一系列水杨醛亚胺镍配合物催化乙烯聚合, 得到了高分子量低支化度聚乙烯. 研究表明水杨醛亚胺镍配合物中苯环上取代基的电子效应和空间位阻对乙烯聚合活性和聚合物的分子量有所影响. 提高配合物酚氧环上取代基的吸电子性, 聚合活性相应增加, 但聚乙烯的分子量降低; 而增加苯胺环上取代基的空间位阻, 聚合活性和聚乙烯的分子量均增加. 粘度法测得由水相聚合得到的聚乙烯的分子量在10⁴～10⁵范围内. DSC测得该聚乙烯的结晶度在50%～70%之间, 熔点在115～137 ℃范围内. GPC分析表明用环辛二烯合镍[Ni(COD)₂]助催化乙烯, 聚乙烯的分子量分布随酚氧环上取代基电负性增加而从双峰到单峰变化, 动态流变学研究进一步说明了聚乙烯分子量及其分布的变化.     

PREPARATION AND CATALYTIC BEHAVIOUR OF POLYMER-BOUND METALLOPORPHYRIN IN HYDROGENATION OF OLEFIN

The meso- tetraarylporphyrin has been anchored to styrene- divinylbenzenecopolymers by reaction of meso- tetra (4-hydroxylphenyl ) porphyrin with chloromethylatedresin under mild condition. A number of polymer transition metal complexes have beenprepared with the polymer ligand and metal salts. The polymeric ligand and its complexeshave been characterized by electronic spectra, and vibrational spectra. Cyclohexene can behydrogenated with the polymeric porphyrin palladium complex(P-THPPPd) as catalyst,and its catalytic activity was influenced by the polarity of solvents, the contents of water inethanol or reaction temperature. However, its catalytic activity was lower for nitro groups,carbonyl groups and olefins with steric hindrance substituents, and showed no activity foraromatic rings under these conditions.