稀土化合物催化内酯开环聚合 Ⅱ．异丙氧基稀土催化D．L－丙交酯开环聚合

系统地研究了异丙氧基稀土催化Ｄ．Ｌ－两交酯（ＬＡ）开环聚合的规律．实验表明：在甲苯溶剂中，异丙氧基稀土对Ｄ．Ｌ－丙交酯聚合有较高的催化活性，可获得较高的分子量（Ｍη＝４．０×１０４）不同稀土元素的活性次序如下：Ｌａ＞Ｎｄ＞Ｄｙ＞Ｙ．异丙氧基稀土催化Ｄ·Ｌ－两支酯聚合的合适条件为：［ＬＡ］＝１．９５ｍｏｌ／ｌ，［Ｌｎ（Ｏ－ｉ－Ｐｒ）３］＝６．５×１０－３ｍｏｌ／ｌ，甲苯，９０℃，聚合反应速度与单体和催化剂浓度均成一级关系，聚合反应表现活化能为着６７．７ｋＪ／ｍｏｌ．     

稀土化合物催化内酯开环聚合 Ⅱ．异丙氧基稀土催化D．L－丙交酯开环聚合

 系统地研究了异丙氧基稀土催化Ｄ．Ｌ－两交酯（ＬＡ）开环聚合的规律．实验表明：在甲苯溶剂中，异丙氧基稀土对Ｄ．Ｌ－丙交酯聚合有较高的催化活性，可获得较高的分子量（Ｍη＝４．０×１０^４）不同稀土元素的活性次序如下：Ｌａ＞Ｎｄ＞Ｄｙ＞Ｙ．异丙氧基稀土催化Ｄ·Ｌ－两支酯聚合的合适条件为：［ＬＡ］＝１．９５ｍｏｌ／ｌ，［Ｌｎ（Ｏ－ｉ－Ｐｒ）３］＝６．５×１０^－３ｍｏｌ／ｌ，甲苯，９０℃，聚合反应速度与单体和催化剂浓度均成一级关系，聚合反应表现活化能为着６７．７ｋＪ／ｍｏｌ．     

稀土配位催化合成聚乳酸

本文开发了合成聚乳的一类新型催化剂, 它是由稀土化合物-三烷基铝-水组的配位催化剂。试验表明稀土配位催化剂可以使丙交酯在甲苯溶液中以高转化率聚合, 得到分子量可控的聚乳酸。并研究了稀土元素种类、不同配位基团及聚合条件变化对丙交酯开环聚合的影响。     

Schiff碱二价钐配合物[2-OC_6H_4CH═N(2,6-~iPr_2C_6H_3)]_2Sm(THF)_2催化己内酯开环聚合

(取代 )水杨醛缩合的 Schiff碱作为一种辅助配体广泛用于过渡金属有机化学中 ,如 Salen Al可以催化丙交酯、己内酯等环酯的开环聚合 [1]。近来 ,Grubbs等 [2 ]发现 ,(取代 )水杨醛和芳胺缩合的 Schiff碱后过渡金属 Ni配合物 ,在不加助催化剂的条件下 ,作为单组分催化剂 ,对乙烯等α-烯烃的聚合具有很高的催化活性[2 ] 。虽然类似的 Schiff碱稀土配合物也有一些报道 ,但有关其催化聚合反应性能的研究还很少见 [3]。我们选用 Sm I2 为起始原料 ,合成了 Schiff碱二价 Sm配合物 ,并发现这种配合物对己内酯开环聚合有高催化活性 ,生成聚合物…     

丙交酯开环均聚合

生物可降解脂肪族聚酯--聚丙交酯由可再生资源获得.聚丙交酯独特的物理性质使得它在包装、涂层、纤维、薄膜等方面有着广泛的应用.聚丙交酯低成本、大规模的生产及应用将极大地减轻对石油产品的依赖.高分子量的聚丙交酯主要由丙交酯开环聚合制备.本文总结了催化丙交酯开环聚合的3大类催化剂及其反应机理;综述了近年来国内外在丙交酯均聚合催化剂开发上的研究进展,并重点论述了稀土催化剂在丙交酯开环聚合中的优势及由其催化合成的聚丙交酯在生物学应用中的优点.     

二(芳氧基)稀土(Ⅱ)配合物催化ε-己内酯开环聚合

系统地研究了二（２，６ 二叔丁基 ４ 甲基酚基）钐［（ＡｒＯ）２Ｓｍ（ＴＨＦ）４］催化ε 己内酯的开环聚合，发现它具有很高的催化活性并显示“活性”聚合的特点，在甲苯中，当［Ｍ］／［Ｉ］＝２０００（摩尔比），６０℃，１ｈ，转化率可达９８％．并比较了不同的两价稀土化合物的催化活性．通过核磁分析末端基结构的方法，研究了（ＡｒＯ）２Ｓｍ催化己内酯开环聚合的引发机理，发现催化剂首先与己内酯反应，生成三价烯醇式稀土化合物，后者引发己内酯聚合．     

稀土乙酰丙酮盐催化聚合ε－己内酯和丙交酯

稀土乙酰丙酮盐催化聚合ε－己内酯和丙交酯刘建飞，沈之茎，孙俊全（浙江大学高分子科学与工程系杭州３１００２７）关键词ε－己内酯，丙交酯，稀土乙酰丙酮盐，开环聚合聚己内酯和聚丙交酯具有良好的生物相容性，在生物医药领域有广泛用途，因而丙交酯和己内酯的催化开...     

茂基稀土胺化物催化ε-己内酯开环聚合

聚己内酯（ＰＣＬ）是一种可生物降解的高分子材料,有良好的相溶性,可用于药物的缓释放．近年来,用稀土化合物作为单组分催化剂催化己内酯开环聚合的研究,已成为人们关注的热点．杜邦公司的ＭｃＬａｉｎ等［１,２］最早发现了单组分烷氧基稀土化合物可以在室温下催化...     

席夫碱-铝配合物的合成及对丙交酯的立体选择性聚合

设计、 合成了一系列不对称席夫碱配体, 得到了相应的金属铝配合物. 研究了配合物在外消旋丙交酯的开环聚合反应中的催化性能. 结果表明, 系列配合物对外消旋丙交酯(rac-LA)的聚合催化活性明显提高, 并具有立体选择性.     

三亚甲基环碳酸酯及2,2-二甲基三亚甲基环碳酸酯开环均聚合*

生物降解聚合物聚三亚甲基环碳酸酯（PTMC）及聚2,2-二甲基三亚甲基环碳酸酯（PDTC）在药物控释载体及其它生物医学技术领域有着良好的应用前景。与脂肪族聚酯不同,PTMC、PDTC降解时,不会产生有害的酸性化合物。PTMC、PDTC主要由三亚甲基环碳酸酯（TMC）及2,2-二甲基三亚甲基环碳酸酯（DTC）开环均聚合制备。本文总结了催化TMC、DTC开环均聚合的不同催化剂及其聚合机理,综述了近年来国内外在TMC、DTC均聚合催化剂开发上的研究进展,并对生物相容性催化剂如稀土催化剂、Ca、Mg、Zn、Fe催化剂以及酶催化剂催化TMC、DTC开环聚合的优缺点进行了比较。     

(ArO)2Sm(THF)4催化N-苯基马来酰亚胺聚合

发现二价稀土配合物二 ( 2 ,6 二叔丁基 4 甲基苯氧基 )钐 [(ArO) 2 Sm (THF) 4]能较好地引发N 苯基马来酰亚胺 (N PMI)的聚合 ,溶剂对聚合的影响较大 ,在四氢呋喃中聚合转化率最高 ,且聚合转化率随单体浓度的提高而提高 ,而温度对聚合的影响不大。     

Synthesis and Crystal Structure of [（ArO）2Sm（OPPh3）（μ—OH）]2（ArO=2,6—tBu—4—Me—C6H2O）

1 INTRODUCTION In recent years, the syntheses, structures and reactivities of aryloxo lanthanide complexes have attracted a great deal of attention due to their various applications as homogeneous catalysts for organic reactions and precursors for organolan- thanide syntheses[1]. However, the reactivity of divalent lanthanide aryloxides has seldom been studied[2]. We have previously reported that (ArO)2- Sm(THF)4 (ArO = OC6H2-2,6-di-tert-butyl-4-Me) can efficiently initiate the poly…     

Synthesis and Crystal Structure of [(ArO)_2(THF)Sm(μ-OH)]_2·2THF(Ar=C_6H_(2-)~tBu_3-2,4,6)

1 INTRODUCTION Sm(II) chemistry has been extensively studied due to the strong reduction potential of this 4f6 ion[1]. The transformation of unsaturated substrates by Sm (II) complexes into products with unusual structures is one of the most interesting research areas. For the successful examples reported, Sm(II) starting mate- rials were restricted primarily to cyclopentadienyl complexes[2]. The reactivity of Sm(II) complex with phenolate ligands has seldom been explored. Recen- tl…     

Synthesis and molecular structure of the cationic samarium phenoxide complex [(ArO)2Sm(DME)2][BPh4] · THF and its catalytic activity for the polymerization of ε-caprolactone

The first cationic samarium phenoxide complex, [(ArO)₂Sm(DME)₂][BPh₄] · THF (ArO = 2,6-di-tert-butyl-4-metyl-phenoxide) (1), has been synthesized by one-electron oxidation reaction of (ArO)₂Sm(THF)₃ with AgBPh₄ in high yield and structurally characterized. The complex 1 can be used as a single-component catalyst for the ring-opening polymerization of ε-caprolactone (ε-CL) with high activity. The activity of the complex 1 is much higher than that of the parent neutral complex (ArO)₃Sm(THF)₂, and is comparable to that of the divalent complex (ArO)₂Sm(THF)₃. A coordination-insertion polymerization mechanism was supposed according to the end-group analysis.     

配合物(ArO)2Yb(NPh2)2K(THF)4(Ar=C6H2-t-Bu3-2,4,6)的合成、分子结构和催化行为

Reaction of anhydrous YbC13 with 2 equiv, of sodium 2,4,6-tri-tert-butylphenoxide (ArONa, Ar=C6H2-t-Bu3-2,4,6) and 2 equiv, of potassium diphenyl amide in THF afforded the first bis(aryloxo) amido-lanthanide complex of (ArO)2Yb(NPh2)2K(THF)4 (1). In 1, the ytterbium and potassium were bridged via diphenyl amido ligands.The ytterbium metal center was coordinated to two oxygen atoms of aryloxide ligands and two nitrogen atoms of diphenyl amido ligands in a conventional distorted tetrahedral fashion, while the potassium interacted in η^2-fashion with two phenyl rings of the diphenyl amido ligands besides four THF molecules. 1 displayed moderate catalytic activities for the polymerization of methyl methacrylate and acrylonitrile.     

Polymerization of n‐phenyl maleimide by lanthanide complexes

N‐Phenyl maleimide (N‐PMI) was successfully polymerized by divalent rare‐earth complexes (ArO)₂Sm(THF)₄ (ArO = 2,6‐di‐tert‐butyl‐4‐methyl phenoxo‐; THF = tetrahydrofuran) and (Ar′O)₂Ln(THF)₃ (Ar′O = 2,6‐di‐tert‐butyl phenoxo‐; Ln = Sm, Yb, or Eu). The central metals greatly affected the reactivity, and the reactivity order was Sm(II) > Yb(II) > Eu(II). The activity of (Ar′O)₂Sm(THF)₃ was higher than that of (ArO)₂Sm(THF)₄. The polymerization yields were higher in THF than in other solvents, and the maximum yields were obtained around 25 °C. A proposed mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3966–3972, 2005     

Vanadium-based Ziegler-Natta catalyst supported on MgCl2(THF)2 for ethylene polymerization

A supported magnesium-vanadium-aluminium catalyst was prepared by depositing –with the use of a milling technique–VOCl₃ on the MgCl₂(THF)₂ support and subsequent activation with diethylaluminium chloride. Catalytic activity of the obtained system for ethylene polymerization was evaluated as a function of Mg/V and Al/V ratios as well as catalyst ageing time and polymerization temperature. High concentrations of THF in the catalytic system and considerable excess of an organoaluminium co-catalyst were found to have no deactivating action on vanadium active sites. The catalyst obtained is stable and its activity for ethylene polymerization is high. It yields polyethylene with higher molecular weight and higher melting point than offered by the materials produced with the use of a corresponding unsupported vanadium catalyst or a titanium-based system on the same magnesium support. Kinetic investigations confirmed stability of this catalyst irrespective of its concentration in the polymerization medium or of monomer concentration. Moreover, analysis of the kinetic findings revealed that over 80% of vanadium employed forms active polymerization sites.     

Divalent lanthanide complexes: highly active precatalysts for the addition of N-H and C-H bonds to carbodiimides

Various divalent lanthanide complexes with the formula LnL2(sol)x (L = N(TMS)2, sol = THF, x = 3, Ln = Sm (I), Eu (II), Yb (III); L = MeC5H4, sol = THF, x = 2, Ln = Sm (IV); L = ArO(Ar = [2,6-((t)Bu)2-4-MeC6H2]), sol = THF, x = 2, Ln = Sm (V)), especially complexes I- III, serve as excellent catalyst precursors for catalytic addition of various primary and secondary amines to carbodiimides, efficiently providing the corresponding guanidine derivatives with a wide range of substrates under solvent-free condition. The reaction shows good functional groups tolerance. Complexes I- III are also excellent precatalysts for addition of terminal alkynes to carbodiimides yielding a series of propiolamidines. The active sequence of Yb < Eu < Sm for metal and MeC5H4 < ArO < N(TMS)2 for ligand around the metal was observed for both reactions. The first step in both reactions was supposed to include the formation of a bimetallic bisamidinate samarium species originating from the reduction-coupling reaction of carbodiimide promoted by lanthanide(II) complex. The active species is proposed to be a lanthanide guanidinate and a lanthanide amidinate.     

SmCl_3(THF)_4的晶体结构

标题化合物SmCl_3(THF)_4(M_r=545.2)晶体属正交晶系,空间群为Pdd 2。晶胞参数为a=9.211(4),6=16.436(6),c=29.666(12);V=4491(3) ~3;Z=8,D_c=1.61g.cm~(-3),F(000)=2184,μ_c=30.3cm~(-1)。最终的偏因子R=0.063,R_(to)=0.062。Sm~(3+)与三个Cl~-及四个四氢呋喃分子中氧原子配位,形成一个五角双锥的空间结构,其中二个氯原子分别位于二个顶点位置。分子中有一个通过Sm~(3+)及Cl~-的C_2轴。Sm-Cl及Sm-0的平均键长分别为2.683(5)及2.469(11)。