三氟甲磺酸稀土催化ε-己内酯开环聚合

采用三氟甲磺酸稀土(镧、钕、铒)作为单组分催化剂催化了ε-己内酯的本体开环聚合反应. 考察了稀土元素种类、催化剂浓度、聚合时间及温度对单体转化率和聚合产物分子量的影响. 该类催化剂在催化聚合过程中具有单一活性中心, 且催化活性较高. 此聚合反应可能是通过阳离子活性末端链聚合机理进行的.     

咪唑烷基桥联双芳氧基稀土胺化物高效催化ε-己内酯开环聚合

研究了一系列咪唑烷基桥联双芳氧基稀土金属胺化物催化ε-己内酯开环聚合反应性能。通过对聚合物的分子量和分子量分布进行分析,结果显示,这些稀土胺化物能在相对较温和的条件下高活性引发ε-己内酯开环聚合,其催化活性随着稀土金属离子半径变大而增强,但所得聚合物的分子量分布较宽(PDI=1.21~1.89),显示它们不是可控聚合体系。加入异丙醇原位转化成稀土金属烷氧基配合物后,聚合的可控性得到了明显的改善,显示了可控聚合的特点。通过分析齐聚物的末端基,研究了这类稀土胺化物加醇体系催化ε-己内酯聚合的机制。     

席夫碱-铝化合物催化己内酯的开环聚合

设计合成了一系列不对称席夫碱-铝化合物1a~3a,考察了化合物在己内酯(CL)开环聚合反应中的催化性能,研究发现,配合物对CL聚合具有较高的反应活性,并具有活性聚合的特点,聚合反应均符合一级动力学反应特征.在其它条件相同时,吸电子取代的配合物的催化速率约为无吸电子的配合物的4倍,表明席夫碱配体上吸电子基团的存在可以提高配合物催化聚合的活性.     

二(叔丁基环戊二烯基)钕甲基配合物催化ε-己内酯开环聚合

二（叔丁基环戊二烯基）钕甲基配合物催化ε 己内酯开环聚合罗云杰姚英明沈琪（苏州大学化学化工学院苏州２１５００６）关键词开环聚合，ε 己内酯，茂基稀土甲基配合物聚ε 己内酯（Ｐｏｌｙｃａｐｒｏｌａｃｔｏｎｅ，ＰＣＬ）是一种生物降解材料，有良好的相...     

席夫碱铝双核配合物的合成及其对ε-己内酯的催化作用

采用中性双席夫碱配体与异丙氧基铝反应制备了席夫碱铝配合物。经NMR和X射线晶体结构衍射分析证明,该配合物是双核结构。席夫碱配体上的氧和氮原子同时与铝原子配位形成独立单元。2个铝单元由甲氧基基团桥联形成双金属结构。其中铝原子与甲氧基氧原子构成一个平行四边形,它也包含该配合物分子的对称中心。该配合物可以催化ε-己内酯开环聚合。动力学研究表明,单体的转化率和聚合产物的数均分子量均随反应时间的延长而线性增加,并与理论计算值接近,而分子量分布没有明显变化,反应呈活性聚合的特征。NMR分析证明,寡聚物的端基为甲氧基和羟基,因此聚合反应为配位插入机理。     

茂基二价钐配合物高效催化己内酯开环聚合

研究了二茂基二价钐配合物(C5H5)2Sm(THF)作为单组分催化剂催化己内脂开环聚合反应,考察了催化剂用量、聚合反应时间、聚合反应温度对己内酯聚合反应的影响。结果表明,配合物(C5H5)2Sm(THF)对己内酯聚合有极高的催化活性且产物的数均分子量较高,当催化剂与单体摩尔比为1：5000时,聚合产率仍可达50.3%,数均分子量可高达32.4万;温度升高,聚合反应的转化率增加,聚合产物数均分子量降低;催化剂用量增加,聚合转化率增加,聚合产物分子量降低;聚合产物的分子量分布较窄;通过凝胶色谱法对聚合产物的分子量及分子量分布进行了表征。     

取代茚基二价稀土配合物催化己内酯开环聚合反应

研究了1-环戊烷基茚基二价镱配合物(1-C5H9C9H6)2Yb(THF)2作为单组分催化剂催化己内酯开环聚合反应, 考察了催化剂用量、聚合反应时间、聚合反应温度对己内酯聚合反应的影响. 结果表明, 配合物(1-C5H9C9H6)2Yb(THF)2对己内酯聚合有较高的催化活性; 温度升高, 聚合反应的转化率增加, 但产物的数均分子量及分子量分布无明显变化; 所得聚合物分子量分布较窄. 其它几种取代茚基稀土配合物也显示出较高的催化活性, 其活性有下列次序: (1-C2H5C9H6)2Sm(THF)2>(1-C5H9C9H6)2Sm(THF)>KSm(1-C5H9C9H6)3(THF)3>(1-PhCH2C9H6)2Sm(THF)2>(1-C5H9C9H6)2Yb(THF)2, 二价钐配合物较二价镱配合物具有较高的催化活性. 通过凝胶渗透色谱法测定了聚合产物的数均分子量及其分布.     

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…     

甲氧基桥联的铝-锂杂金属配合物的合成、表征及在催化ε-己内酯开环聚合中的应用

以四氢呋喃为溶剂,将2,6-二(3,5-二叔丁基-2-羟苯甲基)-4-叔丁基苯酚(H3-L)与正丁基锂和三甲基铝以摩尔比1∶1∶1进行络合反应,合成了甲基铝锂杂金属配合物[(L)Al(CH3)Li],利用空气中的氧气氧化甲基铝锂杂金属配合物,得到甲氧基桥联的铝-锂杂金属配合物[(L)Al(μ2-OMe)Li(THF)3]2(1),并表征了其结构.将配合物1应用于ε-己内酯的开环聚合,考察其催化性能.结果表明,在敞开体系下,配合物1催化ε-己内酯开环聚合仍然能够得到较高的单体转化率和较窄的聚酯分子量分布.     

稀土化合物催化内酯开环聚合（Ⅲ）──氯化钕－环氧化合物体系催化ε

稀土化合物催化内酯开环聚合（Ⅲ）──氯化钕－环氧化合物体系催化ε－己内酯本体聚合申有青，沈之荃，沈建良，张富尧，张一烽（浙江大学高分子科学与工程学系，杭州，３１００２７）关键词氯化钕，环氧化合物，ε－己内酯，本体聚合聚己内酯（ＰＣＬ）和聚丙交酯（ＰＬ...     

Schiff碱镧配合物的合成及其催化烷基异氰酸酯聚合

通过氯化镧与Schiff碱钠盐(NaSalen)的交换反应制备了4种镧的Schiff碱配合物La(HSalen1-4)3,对其中以3,5-二叔丁基水杨醛缩苯胺为配体的配合物La(HSalen2)3进行了X-射线单晶衍射分析,测定其单晶结构为五角双锥构型,七配位的镧金属中心与氮和氧原子相连.将所得的La(HSalen)3...     

HETEROCYCLIC SCHIFF BASE NEODYMIUM COMPLEX AS CATALYST FOR RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

An aromatic heterocyclic Schiff base neodymium complex bearing thizole was synthesized and its activity in the ring-opening polymerization of ε-caprolactone (CL) was examined. The conditions of the CL/Nd molar ratio, monomer concentration, polymerization time and temperature were investigated. Activities of ca.171 kg/Nd·h were obtained under the optimum condition (CL/Nd = 1600 (molar ratio), |CL] = 2.26 mol L-1, 1 h at 50℃), giving a poly(ε-caprolactone) (PCL) of number-average molecular weight Mn = 5.4 × 104 and molecular weight distribution MWD = 1.96. The conversion of CL monomer as high as 94% was observed after polymerized for one hour. The mechanism of coordination polymerization has also been illustrated.     

Anionic lanthanide phenoxide complexes as novel single‐component initiators for the polymerization of ε‐caprolactone and trimethylene carbonate

The anionic lanthanide‐sodium‐2,6‐di‐tert‐butyl‐phenoxide complexes [Ln(OAr)₄][Na(DME)₃]·DME (Ln = Nd 1 (neodymium), Sm 2 (samarium), or Gd 3 (gadolium); DME = dimethoxyethane) were synthesized by the reaction of anhydrous LnCl₃ with 4 equiv of sodium‐2,6‐di‐tert‐butyl‐phenoxide NaOAr in high yields and structurally characterized. These complexes showed high catalytic activity in the ring‐opening polymerizations of ?‐caprolactone (?‐CL) and trimethylene carbonate (TMC). The catalytic activity profoundly depended on the lanthanide metals. The active order of Gd < Sm < Nd for the polymerization of ?‐CL and TMC was observed. The polymers obtained with these initiators all showed a unimodal molecular weight distribution, indicating that the [Ln(OAr)₄][Na(DME)₃]·DME anionic complexes could be used as single‐component initiators. The anionic complex was more efficient than the corresponding neutral complex, Ln(OAr)₃(THF)₂. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1210–1218, 2007     

Rare-earth metal complexes supported by 1,omega-dithiaalkanediyl-bridged bis(phenolato) ligands: synthesis, structure, and heteroselective ring-opening polymerization of rac-lactide

Monomeric yttrium and lutetium bis(phenolato) complexes [Ln(OSSO){N(SiHMe 2) 2}(THF)] (Ln = Y, Lu) were prepared from the reaction of silylamido complexes [Ln{N(SiHMe 2) 2} 3(THF) 2] with 1 equiv of tetradentate 1,omega-dithiaalkanediyl-bridged bis(phenol) (OSSO)H 2 1- 9 in moderate to high yields. In contrast to the rigid configuration of scandium analogues, the yttrium complexes 2b and 3b and the lutetium complex 3c that contain a C 2 bridge between the two sulfur donors of the ligand are symmetric in solution. The monomeric nature of these complexes was indicated by an X-ray diffraction study of the yttrium complex 6b. The yttrium center in 6b is coordinated to the tetradentate [OSSO]-type ligand, one silylamido group and one THF ligand with the two oxygen donors of the [OSSO]-type ligand located trans. Corresponding bis(phenolato) silylamido complexes of larger rare-earth metals could not be obtained from similar reactions: Reaction of [La{N(SiHMe 2) 2} 3(THF) 2] with 1,2-xylylene-linked bis(phenol) gave a dinuclear lanthanum complex 6d of the formula [La 2(OSSO) 3] with two inequivalent eight-coordinate metal centers. The yttrium and lutetium complexes efficiently initiated the ring-opening polymerization (ROP) of lactides in THF. The heteroselectivity during the ROP of rac-lactide was enhanced when the steric demand of the bis(phenolato) ligand was increased, either by extending the bridge length or by introducing bulky ortho-substituents in the phenoxy units. A C 3 bridge within the ligand backbone is essential to allow configurational interconversion of the active site between Lambda and Delta configuration during polymerization, allowing accommodation of both enantiomers of the monomer in an alternating fashion.     

HETEROCYCLIC SCHIFF BASE NEODYMIUM COMPLEX AS CATALYST FOR RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

An aromatic heterocyclic Schiff base neodymium complex bearing thiazole was synthesized and its activity in the ring-opening polymerization ofε-caprolactone(CL)was examined.The conditions of the CL/Nd molar ratio,monomer concentration,polymerization time and temperature were investigated.Activities of ca.171 kg/Nd·h were obtained under the optimum condition(CL/Nd=1600(molar ratio),[CL]=2.26 mol L~(-1),1 h at 50℃),giving a poly(ε-caprolactone)(PCL)of number-average molecular weight M_n=5.4×10~4 and molecular weight distribution MWD=1.96.The conversion of CL monomer as high as 94% was observed after polymerized for one hour.The mechanism of coordination polymerization has also been illustrated.     

Homoleptic lanthanide metallocenes and their derivates: syntheses,structural characterization and their catalysis for ring‐opening polymerization of ε‐caprolactone

Homoleptic lanthanide metallocenes Cp′₃Ln [Cp′ = methylcyclopentadienyl, Ln = Y ( 1 ), Er ( 2 ), Sm ( 3 ); Cp′ = cyclopentadienyl, Ln = Er ( 4 ) and Sm ( 5 )] have been found to be a novel type of initiators for the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL). Among them, complex 1 shows the highest catalytic activity for ROP of ε‐CL. In addition, a novel neutral trifluoroethoxo yttrium complex [(MeC₅H₄)₂Y(µ‐OCH₂CF₃)]₂ ( 6 ) has been synthesized by the reaction of 1 with trifluoroethanol in 1:1 molar ratio in toluene and characterized by single‐crystal X‐ray structural analysis. Preliminary study shows that the catalytic activity of tris(methylcyclopentadienyl)yttrium complex 1 is higher than that of bis(methylcyclopentadienyl)yttrium complex 6 . The mechanism of the present polymerization was studied by NMR spectra. Copyright © 2006 John Wiley & Sons, Ltd.     

Homopolymerization of cyclic esters initiated by lanthanide isopropoxides supported by 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenolate) ligands

Lanthanide isopropoxides supported by carbon‐bridged bisphenolate ligands of 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenoxo) {[(EDBP)Ln(μ‐OPrⁱ)(THF)₂]₂, where Ln is Nd ( 1 ), Sm ( 2 ), or Yb ( 3 ) and THF is tetrahydrofuran} were synthesized by protic exchange reactions in high yields with Cp₃Ln compounds as raw materials, and complex 1 was structurally characterized. Complexes 1 – 3 were shown to be efficient initiators for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC). Complexes 1 – 3 could initiate the controlled polymerization of ε‐CL, and the polymerization rate was first‐order with respect to the monomer. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. End‐group analyses of the oligomers of ε‐CL and DTC showed that the polymerization underwent a coordination–insertion mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4409–4419, 2006     

原位生成三苄氧基钇催化ε-己内酯可控开环聚合

本文研究了以烷基钇[Y(CH2SiMe3)3(THF)2]与苯甲醇原位反应生成的三苄氧基钇为引发剂的ε-己内酯(CL)可控开环聚合。研究结果表明,随着聚合体系中单体/引发剂摩尔比的增大,由1H-NMR计算和GPC测定得到的产物聚己内酯(PCL)的数均分子量均随之线性增加,且分子量分布(Mw/Mn =1.4～1.1)逐渐变窄;1H-NMR计算所得PCL的数均分子量与由单体/引发剂投料比计算得到的理论值一致,表明该体系催化的CL开环聚合具有很好的可控性。1H-NMR分析显示产物PCL的端基分别为苯甲醇酯和醇羟基,由此提出了可能的开环聚合机理。     

Synthesis, characterization of neodymium chloride complex of amine-bis(phenolate) ligand and its reactivity in the ring-opening polymerization of ε-caprolactone

The neodymium chloride complex[Nd（ONN’O）Cl（THF）]₂ supported by amine-bis（phenolate） ligand was synthesized by the metathesis reaction of anhydrous NdCl₃ with Li₂（ONN’O）[H₂ONN’O = Me₂NCH₂CH₂N（CH₂-3-Bu₂^t-5-Me-C₆H₂OH）₂]in high yield.X-ray structural determination shows[Nd（ONN’O）Cl（THF）]₂ complex consists of two seven-coordinate neodymium centers linked throughμ-Cl bridges.And this complex was successfully used to initiate the ring-opening polymerization（ROP） ofε-caprolactone.     

Ring‐opening polymerization of cyclic esters promoted by phosphido‐diphosphine pincer group 3 complexes

Phosphido‐diphosphine Group 3 metal complexes 1–4 [(o‐C₆H₄PR₂)₂P‐M(CH₂SiMe₃)₂; R = Ph, 1 : M = Y, 2 : M = Sc; R = iPr, 3 : M = Y, 4 : M = Sc] are very efficient catalysts for the ring‐opening polymerization (ROP) of cyclic esters such as ε‐caprolactone (ε‐CL), L ‐lactide, and δ‐valerolactone under mild polymerization conditions. In the ROP of ε‐CL, complexes 1–4 promote quantitative conversion of high amount of monomer (up to 3000 equiv) with very high turnover frequencies (TOF) (～4 × 10⁴ mol_CL/mol_I h) showing a catalytic activity among the highest reported in the literature. The immortal and living ROP of ε‐CL and L ‐lactide is feasible by combining complexes 1–4 with 5 equiv of 2‐propanol. Polymers with controlled molecular parameters (M_n, end groups) and low polydispersities (M_w/M_n = 1.05–1.09) are formed as a result of fast alkoxide/alcohol exchange. In the ROP of δ‐valerolactone, complexes 1–4 showed the same activity observed for lactide (L ‐ and D ,L ‐lactide) producing high molecular weight polymers with narrow distribution of molar masses. Complexes 1–4 also promote the ROP of rac‐β butyrolactone affording atactic low molecular weight poly(hydroxybutyrate) bearing unsaturated end groups probably generated by elimination reactions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011