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1.
This work deals with the cationic ring‐opening polymerization of cyclic thiocarbonates with a norbornene or norbornane moiety, that is, 5,5‐(bicyclo[2.2.1]hept‐2‐ene‐5,5‐ylidene)‐1,3‐dioxane‐2‐thione ( TC1 ) or 5,5‐(bicyclo[2.2.1]heptane‐5,5‐ylidene)‐1,3‐dioxane‐2‐thione ( TC2 ), respectively. The reaction of TC1 initiated by trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), boron trifluoride etherate (BF3OEt2), or triethyloxonium tetrafluoroborate (Et3OBF4) afforded unidentified products; however, TC1 underwent cationic ring‐opening polymerization with methyl iodide as an initiator to afford polythiocarbonate because the propagating end was stabilized by the covalent‐bonding property. The polymerization of TC2 initiated by TfOH, TfOMe, BF3OEt2, or Et3OBF4 afforded polythiocarbonate with good solubility in common organic solvents and a narrow molecular weight distribution because of the absence of a double‐bond moiety. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1698–1705, 2002  相似文献   

2.
Cationic ring‐opening polymerization of ϵ‐thionocaprolactone was examined. The corresponding polythioester with the number‐average molecular weight (Mn ) of 57,000 was obtained in the polymerization with 1 mol % of BF3 · OEt2 as an initiator in CH2Cl2 at 28 °C for 5 h with quantitative monomer conversion. The Mn of the polymer increased with the solvent polarity and monomer‐to‐initiator ratio. No polymerization took place below −30 °C, and the monomer conversion and Mn of the polymer increased with the temperature in the range of −15 to 28 °C. The increase of initial monomer concentration was effective to improve the monomer conversion and the Mn of the obtained polymer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4057–4061, 2000  相似文献   

3.
Abstract

1,5-Dioxepane-2-one (DXO) was coordinatively ring-opening polymerized with different Lewis acids in bulk and solution. The reactivities of a series of initiators (SnCl4, FeCl3, AlCl3, BCl3, and BF3OEt2) at different temperatures and reaction times were analyzed. Polymerization of DXO in bulk with SnCl4, FeCl3, AlCl3, and BCl3 gave only oligomers or low molecular weight polymers irrespective of temperature and/or reaction time. Polymerization of DXO with BF3OEt2 at 70°C gave yields of nearly 100% and molecular weights up to M w = 10,000. The polymerization temperature was increased to 100°C and the reaction time prolonged, which resulted in nearly equal molecular weights as at 70°C but with lower yields, higher polydispersity, and generally not full conversion. In addition, side reactions, such as backbiting, transesterification and thermal degradation, occurred to a larger extent at higher reaction temperatures. Solution polymerization using the same initiators and THF, dioxane, or nitrobenzene as the solvent gave polymers of low molecular weights and of low yields, except with FeCl3 and BF3OEt2. The rates of polymerization were significantly higher in nitrobenzene than in dioxane and THF due to polarity and coordination of these solvents to the growing chain. Comparison of the initiators BF3OEt2 and SnCl4 in solution polymerization showed equal reactivity in nitrobenzene for both of them. The BF3OEt2-initiated systems give polymers with lower molecular weights than SnCl4-initiated systems, but with narrower polydispersity.  相似文献   

4.
Cationic copolymerization of l-menthyl vinyl ether (l-MVE) with indene (IN) was carried out with several catalysts in toluene (Tol) at 0°C. The catalysts used were BF3OEt2, CH3COClO4, and SnCl4. l-Menthyl residue, an optically active side chain of the copolymer obtained, was removed with dry hydrogen bromide gas by the ether cleavage reaction. Ether-cloven copolymers [vinyl alcohol(VA)–IN] also had optical rotation. The efficiency of asymmetric induction to the polymer main chain was in the order of BF3OEt2 > CH3COClO4 > SnCl4.  相似文献   

5.
BF3·OEt2-initiated polymerizations of 2-methylene-1,3-dioxepane gave polymers composed of both ring-retained and ring-opened structures. The ring-opening content increased with an increase in polymerization temperature. Poly(4,7-dimethyl-2-methylene-1,3-dioxepane) propagated slower during BF3·OEt2-initiated polymerization and had a lower ring-opened content than poly(2-methylene-1,3-dioxepane). The type of acid initiator used also affected the amount of ring opening observed. Stronger acids gave less ring opening. Attempted BF3·OEt2-initiated copolymerizations of these seven-membered ring cyclic ketene acetals with isobutyl vinyl ether at room temperature resulted in formation of the two homopolymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 873–881, 1998  相似文献   

6.
p‐Toluenesulfonic acid (TsOH) and several alkyl p‐toluenesulfonates, that is, methyl p‐toluenesulfonate (TsOMe), cyclohexyl p‐toluenesulfonate (TsOCH), and neopentyl p‐toluenesulfonate (TsONP), were evaluated as initiators for the ring‐opening polymerization of benzoxazines. TsOH and TsOMe were highly efficient initiators that induced the polymerization at 60 and 80 °C, respectively. In contrast, TsOCH and TsONP did not initiate the polymerization below 100 °C, while they induced the polymerization at elevated temperatures, 120 and 150 °C, respectively. When TsOCH was used as an initiator, the corresponding polymerization rate was comparable to that observed for the polymerization with using TsOH as an initiator. These results suggested that neutral TsOCH and TsONP can be regarded as “thermally latent initiators,” which underwent the thermal dissociation at the elevated temperatures to generate the corresponding alkyl cations and/or TsOH as the initiators of the polymerization. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

7.
Cationic ring‐opening polymerization of a five‐membered cyclic dithiocarbonate having benzoxymethyl group; 5‐benzoxymethyl‐1,3‐oxathiolane‐2‐thione, was carried out with TfOH or TfOMe as an initiator in PhCl at rt – 60 °C. The molecular weight distribution (Mw/Mn) of the polymer obtained with TfOMe was very narrow even at 60 °C (Mw/Mn 1.14), and the Mn value of the polymers estimated by GPC was in good agreement with the molecular weight determined from ¹H‐NMR. The living nature of the polymerization was confirmed by the conversion dependence of the Mn (Mw/Mn) and the correlation of the experimental and theoretical Mn (Mw/Mn) values.  相似文献   

8.
α-Hydroxyisopropylferrocene, HPF, was synthesized in good yield and polymerized at 20°C with either SnCl4 or BF3OEt2. The polymerization proceeds by self-alkylation of the stable intermediate ferrocenylcarbenium ion on the cyclopentadienyl ring to form oligomers that contain both homoannular and heteroannular links. The unusually high stability of the α-isopropylferrocenylcarbenium ion was demonstrated by synthesizing and isolating α-isopropylferrocenylcarbenium tetrafluoborate from HPF and using it to initiate the polymerization of styrene. Initiation was successful at 20° and at 0°C, but no polymerization occurred ?78°C. The condensation of ferrocene and acetone in the presence of AlCl3 gave oligomers having structures very similar to those obtained from the cationic polymerization of isopropenylferrocene.  相似文献   

9.
Pseudo block and triblock copolymers were synthesized by the cationic ring‐opening copolymerization of 1,5,7,11‐tetraoxaspiro[5.5]undecane (SOC1) with trimethylene oxide (OX) via one‐shot and two‐shot procedures, respectively. When SOC1 and OX were copolymerized cationically with boron trifluoride etherate (BF3OEt2) as an initiator in CH2Cl2 at 25 °C, OX was consumed faster than SOC1. SOC1 was polymerized from the OX‐rich gradient copolymer produced in the initial stage of the copolymerization to afford the corresponding pseudo block copolymer, poly [(OX‐grad‐SOC1)‐b‐SOC1]. We also succeeded in the synthesis of a pseudo triblock copolymer by the addition of OX during the course of the polymerization of SOC1 before its complete consumption, which provided the corresponding pseudo triblock copolymer, poly[SOC1‐b‐(OX‐grad‐SOC1)‐b‐SOC1]. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3233–3241, 2006  相似文献   

10.
Abstract

The imide-amide rearrangement of cyclic phosphorirnidates 1 leads to the formation of phosphoramidates 3, either thermally (> 180°C) or by the action of a Lewis acid (BF3 OEt2, 60°C)1. In an attempt to develop a synthetic pathway to β aminoalcohols based on this rearrangement, we have thoroughly studied the influence of the structure of the reactants on the Lewis acid catalysed rearrangement. This study brought some insight into the mechanism of this particular reaction, namely the identification of a new polymeric structure 2. not yet described, which is converted into 3 by thermolysis2. The formation of 2 at rt was followed by 3 P NMR. In the case of R′? Ph, the reactivity observed for R2N was: i-Pr2N > Pyrrolidine > n-Bu2N For R2=i-Pr2, the observed R′ group effect was: Bn > 4-NO2Bn > Ph. No reaction was observed for R′ ? Ts, n-Oct. In the case of the groups R′ ? Bn and R2=i Pr2 the Lewis acid effect was also studied: BF3OEt2, BF3MeOr-Bu, Sc(OTf)3 or CITi(Oi-Pr)3 or Me2SnCl2.  相似文献   

11.
The cationic polymerizations of dimethyl-1,3-butadienes with various catalysts in methylene chloride and toluene have been investigated. The activity of catalysts decreased in the order WCl6 > AcClO4 > SnCl4·TCA > BF3OEt2. The homopolymerization rate of dimethyl-1,3-butadienes with WCl6, AcClO4, and SnCl4·TCA decreased in the order 1,3-dimethyl-1,3-butadiene > 2,3-dimethyl-1,3-butadiene > 1,2-dimethyl-1,3-butadiene > 2,4-hexadiene. The polymers prepared with WCl6, SnCl4.TCA, and BF3OEt2 were rubberlike polymers or white powders, whereas those prepared with AcClO4 were oily oligomers. The 1,4-propagation increased in the order 1,2-dimethyl-1,3-butadiene < 1,3-dimethyl-1,3-butadiene < 2,3-dimethyl-1,3-butadiene < 2,4-hexadiene. This order may indicate that the steric effect of methyl group determine primarily the microstructure of the polymer. The relative reactivity of dimethyl-1,3-butadienes toward a styryl cation decreased in the order 1,3-dimethyl-1,3-butadiene > 1,2-dimethyl-1,3-butadiene > 2,3-dimethyl-1,3-butadiene > 2,4-hexadiene. This order may be explained in terms of the stability of the resulting allylic cation.  相似文献   

12.
A series of cyclopentadiene (CPD)‐based polymers and copolymers were synthesized by a controlled cationic polymerization of CPD. End‐functionalized poly(CPD) was synthesized with the HCl adducts [initiator = CH3CH(OCH2CH2X)Cl; X = Cl ( 2a ), acetate ( 2b ), or methacrylate] of vinyl ethers carrying pendant functional substituents X in conjunction with SnCl4 (Lewis acid as a catalyst) and n‐Bu4NCl (as an additive) in dichloromethane at −78 °C. The system led to the controlled cationic polymerizations of CPD to give controlled α‐end‐functionalized poly(CPD)s with almost quantitative attachment of the functional groups (Fn ∼ 1). With the 2a or 2b /SnCl4/n‐Bu4NCl initiating systems, diblock copolymers of 2‐chloroethyl vinyl ether (CEVE) and 2‐acetoxyethyl vinyl ether with CPD were also synthesized by the sequential polymerization of CPD and these vinyl ethers. An ABA‐type triblock copolymer of CPD (A) and CEVE (B) was also prepared with a bifunctional initiator. The copolymerization of CPD and CEVE with 2a /SnCl4/n‐Bu4NCl afforded random copolymers with controlled molecular weights and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight = 1.3–1.4). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 398–407, 2001  相似文献   

13.
A matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectroscopy analysis of polythiourethanes obtained by the cationic ring‐opening polymerization of a six‐membered cyclic thiourethane [3‐benzyltetrahydro‐1,3‐oxazine‐2‐thione (BTOT)] is described. A MALDI‐TOF mass spectrum of a polymer obtained by the polymerization of BTOT with boron trifluoride etherate (BF3OEt2) as the initiator in nitrobenzene at 50 °C for 24 h followed by an end‐capping reaction with diethyldithiocarbamic acid diethylammonium salt showed a series of well‐resolved signals that were assignable to polythiourethanes possessing an amino group at the initiating end and a diethyldithiocarbamate group at the terminating end. In comparison with the MALDI‐TOF mass spectra of polymers obtained by polymerization with trifluoromethanesulfonic acid or methyl trifluoromethanesulfonate, the plausible initiating species in the polymerization with BF3OEt2 was estimated to be a proton, which successively eliminated carbonyl sulfide to produce a secondary amine group at the initiating end. The secondary amine group in the obtained telechelic polymer was converted to a tertiary amine group by a reaction with benzyl bromide in the presence of triethylamine, and this was confirmed by MALDI‐TOF mass spectroscopy. Furthermore, a telechelic polymer with a pyrrole end group was successfully synthesized by the end‐capping reaction of the growing species in the polymerization of BTOT with sodium 1‐pyrrolecarbodithioate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4281–4289, 2006  相似文献   

14.
Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis revealed that the precision control (or the living nature) of the cationic polymerization of vinyl ethers with SnCl4 or TiCl4 critically depends on the Lewis acid concentration and temperature. Specifically, at an extremely low Lewis acid concentration, for example, the polymerization with the HCl–vinyl ether adduct (an initiator) is living at ?78 °C in CH2Cl2 solvent, whereas side reactions occurred at a higher concentration of SnCl4 or at a higher temperature, ?15 °C. This was more pronounced with SnCl4 than with TiCl4, which was due to a stronger Lewis acidity of SnCl4 as suggested by NMR analysis of the model reactions. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1258–1267, 2001  相似文献   

15.
Cationic polymerizations of three 2‐substituted 1,3‐oxathiolanes, 2,2‐diphenyl‐1,3‐oxathiolane ( 1a ), 5‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane ( 1b ), and 4‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane ( 1c ), were carried out with boron trifluoride etherate (BF3 · OEt2) in dichloromethane at 30 °C to obtain poly(alkylene sulfide)s accompanying the elimination of benzophenone. In the cationic polymerization of 1b and 1c , the consumption of the monomers and formation of benzophenone proceeded simultaneously. The obtained poly(propylene sulfide)s from 1b and 1c contain 41% head–head units, which is in good agreement with that of the polymer from methylthiirane with BF3 · OEt2. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2943–2949, 2004  相似文献   

16.
Tri‐block copolymers of linear poly(ethylene glycol) (PEG) and hyperbranched poly‐3‐ethyl‐3‐(hydroxymethyl)oxetane (poly‐TMPO) are reported. The novel dumb‐bell shaped polyethers were synthesized in bulk with cationic ringopening polymerization utilizing BF3OEt2 as initiator, via drop‐wise addition of the oxetane monomer. The thermal properties of the materials were successfully tuned by varying the amount of poly‐TMPO attached to the PEG‐chains, ranging from a melting point of 54 °C and a degree of crystallinity of 76% for pure PEG, to a melting point of 35 °C and a degree of crystallinity of 12% for the polyether copolymer having an average of 14 TMPO units per PEG chain. The materials are of relatively low polydispersity, with Mn/Mw ranging from 1.2 to 1.4. The materials have been evaluated for usage with the energetic oxidizer ammonium dinitramide. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6191–6200, 2009  相似文献   

17.
Cationic copolymerization of seven-membered cyclic sulfite, 1,3,2-dioxathiepane-2-oxide (1) and oxetane (2) in one-shot feeding was carried out to obtain the corresponding copolymer. When a mixture of equimolar amount of 1 and 2 reacted at 0°C in the presence of methyl trifluoromethanesulfonate (T fOMe) as a cationic initiator, T fOMe and 2 were completely consumed without the consumption of 1. After rising the polymerization temperature up to 25°C, 1 started to be consumed to obtain the corresponding copolymer of 1 and 2. The obtained copolymer showed a unimodal GPC curve, and it afforded a polyether showing a unimodal GPC after alkaline hydrolysis. These results strongly suggested the occurrence of the block copolymerization in one-shot feeding. From the molecular orbital examination, the formation of block copolymerization in one-shot feeding was discussed to be caused by the much larger polymerizability of 2 than that of 1. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1007–1012, 1997  相似文献   

18.
Cationic polymerization of 2-vinyloxyethyl phthalimide ( 1 ) in CH2Cl2 at ?15°C with hydrogen iodide/iodine (HI/I2) as initiator led to living polymers of a narrow molecular weight distribution (M?w/M?n = 1.1–1.25). The number-average molecular weight of the polymers was in direct proportion to monomer conversion and could be controlled in the range of 1000–6000 by regulating the 1 /HI feed ratio. However, when a fresh monomer was supplied to the completely polymerized reaction mixture, the molecular weight of the polymers was not directly proportional to monomer conversion. The polymerization of 1 by boron trifluoride etherate (BF3OEt2) in CH2Cl2 at ?78°C gave polymers with relatively high molecular weight (M?w > 20,000) and broad molecular weight distribution (M?w/M?n ~ 2). The HI/I2-initiated polymerization of 1 was an order of magnitude slower than that of ethyl vinyl ether, probably because of the electron-withdrawing phthalimide pendant. Hydrazinolysis of the imide functions in poly( 1 ) gave a water-soluble poly(vinyl ether) ( 3 ) with aliphatic primary amino pendants.  相似文献   

19.
The stereoselective allylation of acyclic chiral α-amino aldimines affording vicinal diamines, mediated by various Lewis acids (TiCl4, SnCl4, MgBr2·OEt2, BF3·OEt2, ZnCl2), is described. The TiCl4-mediated allylation of an α-N-Boc aldimine afforded the allylation product with syn-selectivity, which in turn was used for the synthesis of an intermediate of an oseltamivir derivative.  相似文献   

20.
Stereoselective allylation reactions of acyclic and chiral α-amino-β-hydroxy aldehydes affording chiral β-amino-α,γ-diols are described. Several Lewis acids (BF3·OEt2, SnCl4, TiCl4, ZnCl2, and MgBr2·OEt2) were employed to mediate the allylation reactions. The reactions of anti-α-NHCbz-β-OTBS substrates mediated by SnCl4 afforded syn-selective products. The same reaction conditions also gave satisfactory results for the reactions of syn-α-NHCbz-β-OTBS substrates. The mechanism involves α-chelation between the amido group and aldehyde oxygen.  相似文献   

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