Homopolymerization and Copolymerization of Adipic Anhydride with ε-Caprolactone Catalyzed by Rare Earth Trisphenolate

The ring-opening polymerization of adipic anhydride and the ring-opening copolymerization of adipic anhydride with ε-caprolactone catalyzed by single component rare earth trisphenolate have been reported. The structure of the copolymer poly（CL-b-AA） has been characterized by SEC, ^1H NMR and DSC.     

Lanthanocene Diolate Complexes: Synthesis,Structures and Catalytic Property for ε-Caprolactone Polymerization

Reaction of LnCl₃ first with three equivalent of C₅H₅Na in THF, then with one equivalent of N‐phenyldiethanolamine in THF‐DME afforded complexes of {[(C₅H₅)Ln((‐OCH₂CH₂)₂N(C₆H₅)]₄((₄‐Cl)}[Na(DME)₄] (Ln=Sm ( 1 ), Yb ( 2 )), being characterized by infrared spectra, elemental analyses and X‐ray crystallography. They are ionic pair compounds. The anionic part is a cluster, which can be viewed as a cyclic tetramer with four (C₅H₅)Ln units bridged by four pairs of OR groups, forming a pinwheel structure. Both the complexes can catalyze the ring‐opening polymerization of ε‐caprolactone under mild conditions, and complex 1 is more active than complex 2 . The polymerization accords with one order reaction kinetics for monomer concentration. The molecular weight increases with the yield increasing, and the molecular weight distribution is rather narrow (1.19相似文献   

Aluminum and Titanium Complexes Containing Pyrrole-imine Ligands: Syntheses,Structures, and Ring-opening Polymerization of ε-Caprolactone

Syntheses and properties of aluminum and titanium complexes incorporating the pyrrole-imine ligands, N-((~1H-pyrrol-2-yl)methyl)-1-(~1H-pyrrol-2-yl)methanimine(H_2L1) and 2-cyano-~1H-pyrrole(HL2), have been investigated. Addition of one equiv of H_2L1 to AlMe3 and AlEt_3, respectively results in the formation of dinuclear complexes [Al2(L1)2 Me2](1) and [Al2(L1)2 Et2](2). Treatment of Ti(NMe2)4 with one equiv of HL2 and two equiv of iPrOH or three equiv of BnOH results in the production of complexes [Ti(HL3)2(OiPr)2](3) and [Ti2(HL3)2(OBn)6](4)(H_2L~3 = N,N-dimethyl-~1H-pyrrole-2-carboximid-amide). HL_3 anion is an intermediate which is in situ formed from the reaction of HL2 and Ti(NMe2)4. The structures of 1～4 were characterized by single crystal X-ray diffraction. The catalytic properties of 1～4 toward ring-opening polymerization(ROP) of ε-caprolactone were studied. All of the compounds could effectively initiate the polymerization reactions with good activities.     

L-Lactide Homopolymerization and Copolymerization with ε-Caprolactone by Tetrahydrosalen Stabilized Yttrium Borohydride Complex

L-lactide（LLA） homopolymerization and copolymerization with ε-caprolactone（CL） in toluene initiated by tetrahydrosalen-supported yttrium borohydride complex were systematically investigated. A possible mechanism of LLA homopolymerization was proposed according to the 1H-NMR result. In addition, PCL-b-PLLA copolymers were synthesized by sequential addition of monomers and their structure was characterized by GPC, 1H-NMR and 13C-NMR.     

Enolic Schiff Base Zinc Amide Complexes: Highly Active Catalysts for Ring-Opening Polymerization of Lactide and ε-Caprolactone

A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and ε-caprolactone, exhibiting notably high activity at ambient temperature. The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4 a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading(0.025 mol%) within 18 min. The influence of various monomers as well as the polymerization mechanism have also been discussed.     

Protonation of γ-Butyrolactone and γ-Butyrolactam

Abstract : γ-Butyrolactone and γ-butyrolactam were reacted in the superacidic systems XF/MF₅ (X=H, D; M=As, Sb). Salts of the monoprotonated species of γ-butyrolactone were obtained in terms of [(CH₂)₃OCOH]⁺[AsF₆]⁻, [(CH₂)₃OCOH]⁺[SbF₆]⁻ and [(CH₂)₃OCOD]⁺[AsF₆]⁻ and the analogous lactam salts in terms of [(CH₂)₃NHCOH]⁺[AsF₆]⁻, [(CH₂)₃NHCOH]⁺[SbF₆]⁻ and [(CH₂)₃NDCOD]⁺[AsF₆]⁻. The salts were characterized by low temperature Raman and infrared spectroscopy and for both protonated hexafluoridoarsenates, [(CH₂)₃OCOH]⁺[AsF₆]⁻ and [(CH₂)₃NHCOH]⁺[AsF₆]⁻, single-crystal X-ray structure analyses were conducted. In addition to the experimental results, quantum chemical calculations were performed on the B3LYP/aug-cc-pVTZ level of theory. As in both crystal structures C⋅⋅⋅F contacts were observed, the nature of these contacts is discussed with Mapped Electrostatic Potential as a rate of strength.     

Homo-and Copolymerization of ε-Caprolactone and 2,2-Dimethyltrimethylene Carbonate by Rare Earth Initiators

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Anionic Copolymerization of ε-Caprolactam with ω-Laurolactam

Polyamide 6/12 copolymers were prepared by employing two different initiation systems containing activator N-benzoyl-ε-caprolactam (BzCL) and initiator either sodium salt of ε-caprolactam (CLNa) or ε-caprolactam magnesium bromide (CLMgBr). Materials prepared by initiation with CLNa show one melting endotherm and are random copolymers. Materials prepared by initiation with CLMgBr show two melting endotherms and are probably composed from random copolymer and block copolymer containing blocks of random copolymer and blocks of copolymer with ε-caprolactam rich segments. The character of copolymers and fractionalized materials was evaluated by means of DSC and NMR.     

Mononuclear and Dinuclear Yttrium Complexes Supported by Pyrrolide Ligands: Syntheses,Structures and Catalytic Behaviors towards the Ring-opening Polymerization of ε-Caprolactone

The syntheses, structures and catalytic activities of two yttrium complexes supported by pyrrolide ligands are reported. Treatment of Y(N(Si Me3)2)3 with one equivalent of H3bptd(H3bptd = 1,9-bis(2-pyrrolyl)-2,5,8-triazanona-1,8-diene) in THF gave a complex of composition [Y(bptd)(THF)]2(1). Reaction of Y(N(Si Me3)2)3 with one equivalent of H3tpa(H3tpa = tris(pyrrolyl-?-methyl)amine) in THF generated [Y(tpa)(THF)3](2) in good yield. Complexes 1and 2 have been characterized by single-crystal X-ray diffraction, elemental analyses and NMR spectroscopy. Complex 1 is dinuclear. The two metal centers are doubly bridged by two amine nitrogen atoms to form a Y–N–Y–N four-membered rhombus ring. The geometries of Y3+ ions in 1and 2 are well described as pentagonal bipyramid and capped octahedron, respectively. The ring-opening polymerization reactions of ?-caprolactone initiated by 1 and 2, respectively, were investigated. They both exhibited good catalytic activity for the polymerization of ?-caprolactone. All of the obtained polymers have high molecular weights and relatively narrower PDIs. The polymers generated by 2 possessed polydispersity close to 1.1. The good catalytic activities of 1 and 2 reveal their potential applications in polymer industry.     

Copolymerization Kinetics of N-Carboxyanhydrides of ε-Benzyloxycarbonyl-L-Lysine and L-Valine

Random copolypeptides have been considered as model compounds to understand, for instance, the conformational preference of individual monomers and the effect of comonomers on the folding of polypeptide chains [1,2]. The kinetics of copolymerization of N-carboxyanhydrides (NCA) of a-amino acids were reviewed earlier [3]. Reactivity ratios have been used in a few cases to determine the sequence length distribution and interchain heterogeneity [4] to arrive at the most probable primary structure for the polypeptide backbone. In the present communication we report the kinetics of copolymerization of e-benzyloxycarbonyl-Llysine NCA and Lvaline NCA in two solvents, dioxane and benzene/methylene chloride.     

Ring-Opening Copolymerization of 2,2-Dimethyltrimethylene Carbonate and ε-Caprolactone Using Rare Earth Aryloxides Substituted by Various Alkyl Groups

A variety of single component rare earth aryloxides substituted by various alkyl groups [Ln(OAr)₃] such as methyl, isopropyl, tert‐butyl have been surveyed in the ring‐opening copolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (ε‐CL). It was worthwhile to note that activity of the catalyst varied with both the ligands' structure and the number of alkyl groups on phenyl ring. The stronger ability of electron‐donation of alkyl groups on phenyl ring, and the more numbers of alkyl groups on phenyl ring, the higher catalytic activity. The experimental results show that lanthanum tris(2,4,6‐tri‐tert‐butylphenolate) [La(OTTBP)₃] exhibits highest activity in all lanthanum aryloxides. ¹H NMR spectral data of copolymer obtained showed that the polymerization mechanism is in agreement with the coordination insertion mechanism.     

Synthesis and Characterization of Monomeric Salicylaldiminato Lanthanide Complexes and Their Catalytic Behavior for Polymerization of ε—Caprolactone

IntroductionSchiffbaseligandscanbeusedtoprovideastereochem icallyrigidligandframeworkinhomogenousprecatalystsofsomemetals,suchassalenCrcatalystsinasymmetricring openingreactionofepoxide1andsalenAlinring openingpolymerizationoflactideandrelatedcyclicesters .2 Recently ,itwasreportedthatthebidentateSchiffbasecomplexesofearlyandlatetransitionmetalscanserveaspromisingalterna tivestometallocenecatalystsforthepolymerizationofα olefins.3Therefore ,theapplicationsofSchiffbaseligandsinorganometallic…     

Synthesis and Characterization of ABBA Block Copolymer of Glycolide and ε-Caprolactone

A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-Scaprolactone (CL, B) and glycolide (A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL prepolymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide (A) to PCL pre-polymer(BB). The block copolymers were characterized by ^1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.     

Synthesis and Characterization of ABBA Block Copolymer of Glycolide and ε-Caprolactone

A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.     

Inclusion Complexes of Manidipine with γ-Cyclodextrin and Identification of Photodegradation Products

The paper presents results of a study of photochemical decomposition of manidipine and its inclusion complexes with γ-cyclodextrin and identification of photodegradation products. The process was qualitatively assessed by the UV spectrophotometry and by HPLC-MS. The quantitative assessment of its efficiency was performed on the basis of kinetic parameters and quantum yields. The main product of photodegradation was nitrophenylpyridine derivative, while the concentration of nitrozophenylpyridine derivative being the other product of this process, was about 20 times lower. The inclusion complexes of manidipine with γ-cyclodextrin were obtained in the liquid phase. The stoichiometry of the complexes was determined from the Benesi–Hildebrand equation. The photochemical stability of manidipine in inclusion complexes was compared with that of manidipine in non-complexed form.This revised version was published online in July 2005 with a corrected issue number.     

Ring-opening Copolymerization of ε-Caprolactone and δ-Valerolactone Catalyzed by a 2,6-Bis(amino)phenol Zinc Complex

In combination with methyllithium,a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization ofδ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency,mainly producing cyclic and linear polyvalerolactones,respectively.On the basis of homopolymerization,the ring-opening copolymerization ofε-caprolactone andδ-valerolactone was investigated.The P(CL-co-VL)random copolymers,PCL-b-PVL and PVL-b-PCL diblock copolymers,were prepared by varying the feeding strategy(premixing or sequential feeding).The copolymer composition was adjusted by varying the feeding ratio of two monomers.The structure and thermal properties of obtained polymers were characterized by GPC,1 H-NMR,13 C-NMR,MALDI-TOF mass spectroscopy,and DSC,respectively.     

Flexible Gradient Poly(ether-ester) from the Copolymerization of Epoxides and ε-Caprolactone Mediated by a Hetero-bimetallic Complex

Copolymerization is a commonly employed method for optimizing the properties of polymer materials. Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether, and to develop more high-performance, multi-purpose polymer materials. Herein, the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-Al complex in the presence of PPNCl for the copolymerization of epoxides and ε-caprolactone(CL). Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL, affording copolymers with a gradient sequence structure. The dynamic thermomechanical analysis(DMA) study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio. This study provides a theoretical basis for the preparation of high-performance polymer materials.     

Ethylene–Norbornene Copolymerization by Rare-Earth Metal Complexes and by Carbon Nanotube-Supported Metallocene Catalysis

E–N copolymerization with a number of half-sandwich rare-earth metal compounds [M(η5-C₅Me₄SiMe₂R)(η1-CH₂SiMe₃)₂(L)] (M = Sc, Y, Lu) has been achieved. Mainly atactic alternating E N copolymers are obtained with all catalytic systems. Interestingly, copolymers arising from [Sc(η5-C₅Me₄SiMe₂C₆F₅)(η¹-CH₂SiMe₃)₂(THF)]/[/[Ph₃C][B(C₆F₅)₄] possess narrower molar mass distributions than those from [Sc(η⁵-C₅Me₄SiMe₃)(η¹-CH₂SiMe₃)₂(THF)] / [Ph₃C][B(C₆F₅)₄]. In addition, homogeneous surface coating of multi-walled carbon nanotubes is accomplished for the first time by in situ E–N copolymerization as catalyzed by rac-Et(Ind)₂ZrCl₂/MMAO-3A anchored onto the carbon nanotube surface. The copolymerization reaction allows for the destructuration of the native nanotube bundles. The relative quantity of E N copolymer can be tuned up as well as the norbornene content in the formed copolymers and accordingly their glass transition temperature. By melt blending with an ethylene-vinyl-co-acetate copolymer (27 wt.-% vinyl acetate comonomer) matrix, high performance polyolefinic nanocomposites are obtained.     

Synthesis of Mixed-ring Zirconocene Complexes Containing Alkenyl Group and Ethylene Polymerization Catalyzed with Them

Four new mixed‐ring zirconium completes, [CH₂ = CH(CH₂)_n ‐C₅H₄](RC₅H₄)ZrCl₂ [n = l, R = CH₃OCH₂CH₂(3); n = 2, R = CH₃OCH₂CH₂ (4); n = 2, R=Me₃Si (5); n = 2, R = allyl (6)], have been prepared by the reaction of CH₂ = CH(CH₂)_n C₅H₄ZrCl₃, DME[n = l (1); n = 2 (2)] with RC₅H₄Li. When activated with methylaluminoxane (MAO), the catalytic activities of the above complexes in ethylene polymerization were tested. Complexes 5 and 6 show high activities similar to Cp₂ZrCl₂. Introduction of methoxyethyl group into Cp‐ligand dramatically decreases the catalytic activities of complexes 3 and 4, which can be overcome by increasing the amount of MAO. For complex 5, the dependence of activity and molecular weight (Mη) on the Al/Zr ratio, the polymerization time (t_P), polymerization temperature (T_P) and the polymerization solvent volume (V) was investigated.     

Reaction of imidazole and its 2-alkyl derivatives with γ-butyrolactone

Reaction of imidazole with -butyrolactone gives N-alkylation and N-acylation products depending upon the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1491–1493, November, 1992.