Kinetics and mechanism of ɛ-caprolactone and l,l-lactide polymerization coinitiated with zinc octoate or aluminum acetylacetonate: The next proofs for the general alkoxide mechanism and synthetic applications

Kowalski, Adam; Libiszowski, Jan; Majerska, Katarzyna; Duda, Andrzej; Penczek, Stanisław

doi:10.1016/j.polymer.2007.05.007

Cited by 61 publications

(46 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The surprising [36] release of {LO 1 }H implied that another tin species was necessarily co-generated, most probably a homoleptic tin(II) bis-alkoxide complex of the type [Sn-A C H T U N G T R E N N U N G (OiPr) 2 ] n (10). However, in our previous experiments, all of the room temperature 119 Sn{ 1 H} NMR spectra seemingly exhibited only one resonance at d = À351 ppm, which corresponded to that of compound 4.…”

Section: }A C H T U N G T R E N N U N G (Optmc)] (13)mentioning

confidence: 99%

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Poirier

Roisnel

Sinbandhit

et al. 2012

Chemistry A European J

View full text Add to dashboard Cite

Several new heteroleptic Sn(II) complexes supported by amino-ether phenolate ligands [Sn{LO(n)}(Nu)] (LO(1)=2-[(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)methyl]-4,6-di-tert-butylphenolate, Nu=NMe(2) (1), N(SiMe(3))(2) (3), OSiPh(3) (6); LO(2)=2,4-di-tert-butyl-6-(morpholinomethyl)phenolate, Nu=N(SiMe(3))(2) (7), OSiPh(3) (8)) and the homoleptic Sn{LO(1)}(2) (2) have been synthesized. The alkoxy derivatives [Sn{LO(1)}(OR)] (OR=OiPr (4), (S)-OCH(CH(3))CO(2)iPr (5)), which were generated by alcoholysis of the parent amido precursor, were stable in solution but could not be isolated. [Sn{LO(1)}](+)[H(2)N{B(C(6)F(5))(3)}(2)](-) (9), a rare well-defined, solvent-free tin cation, was prepared in high yield. The X-ray crystal structures of compounds 3, 6, and 8 were elucidated, and compounds 3, 6, 8, and 9 were further characterized by (119)Sn Mössbauer spectroscopy. In the presence of iPrOH, compounds 1-5, 7, and 9 catalyzed the well-controlled, immortal ring-opening polymerization (iROP) of L-lactide (L-LA) with high activities (ca. 150-550 mol(L-LA) mol(Sn)(-1) h(-1)) for tin(II) complexes. The cationic compound 9 required a higher temperature (100 °C) than the neutral species (60 °C); monodisperse poly(L-LA)s were obtained in all cases. The activities of the heteroleptic pre-catalysts 1, 3, and 7 were virtually independent of the nature of the ancillary ligand, and, most strikingly, the homoleptic complex 2 was equally competent as a pre-catalyst. Polymerization of trimethylene carbonate (TMC) occurs much more slowly, and not at all in the presence of LA; therefore, the generation of PLA-PTMC copolymers is only possible if TMC is polymerized first. Mechanistic studies based on (1)H and (119)Sn{(1)H} NMR spectroscopy showed that the addition of an excess of iPrOH to compound 3 yielded a mixture of compound 4, compound [Sn(OiPr)(2)](n) 10, and free {LO(1)}H in a dynamic temperature-dependent and concentration-dependent equilibrium. Upon further addition of L-LA, two active species were detected, [Sn{LO(1)}(OPLLA)] (12) and [Sn(OPLLA)(2)] (14), which were also in fast equilibrium. Based on assignment of the (119)Sn{(1)H} NMR spectrum, all of the species present in the ROP reaction were identified; starting from either the heteroleptic (1, 3, 7) or homoleptic (2) pre-catalysts, both types of pre-catalysts yielded the same active species. The catalytic inactivity of the siloxy derivative 6 confirmed that ROP catalysts of the type 1-5 could not operate according to an activated-monomer mechanism. These mechanistic studies removed a number of ambiguities regarding the mechanism of the (i)ROPs of L-LA and TMC promoted by industrially relevant homoleptic or heteroleptic Sn(II) species.

show abstract

Section: }A C H T U N G T R E N N U N G (Optmc)] (13)mentioning

confidence: 99%

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Poirier

Roisnel

Sinbandhit

et al. 2012

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Initiation with zinc-alkoxide formed via carboxylate-alkoxide ligand exchange reactions. R denotes H or alkyl group, OctH is the 2-ethylhexanoic acid, M is the lactide or glycolide molecules and m is the polyester repeating unit [9] Figure 3. Ring-opening polymerization of lactones: lactide and glycolide [8] Química) pellets prepared by a manual hydraulic press (Perkin Elmer, Spain) and heated in oven at 70ºC oven 30 min to allow the solvent to evaporate, leaving a solid film.…”

Section: Polymer Characterizations 231 Ftirmentioning

confidence: 99%

“…and ROP process is shown in Figure 2 and Figure 3 [8,9]. In a previous study ZnOct 2 and methanol were determined as interesting catalyst and initiator respectively for the copolymerization of D,L-lactide and glycolide [10].…”

mentioning

confidence: 94%

Optimizing the bulk copolymerization of D,L-lactide and glycolide by response surface methodology

Cabezas¹,

Mazarro

Gracia³

et al. 2013

Express Polym. Lett.

View full text Add to dashboard Cite

Poly(D,L-lactide-co-glycolide), PLGA, is a biodegradable polyester with high interest in medical industry, especially when zinc (II) 2-ethylhexanoate (ZnOct2) is used as catalyst substitute in polymerization processes as a substitute of the toxic tin (II) 2-ethylhexanoate (SnOct2) together an initiator such as methanol to improve the reaction rate. This article shows the optimization of the bulk copolymerization method by using a factorial design approach on three experimental parameters: temperature (T), molar ratio monomers/catalyst (MC ratio) and molar ratio initiator/catalyst (IC ratio). Their influence on mass conversion (X) and number-average molecular weight (Mn) was also discussed. Also it provides a useful tool to select in a fast way the proper experimental conditions for the obtaining of this polymer as a previous stage in the synthesis and impregnation of biodegradable scaffolds. This analysis revealed that the most relevant variable in the process is the temperature, being desirable to use the high value (160ºC) in order to obtain high values of conversion and molecular weight

show abstract

“…The mechanism is also true for other similar catalysts such as zinc octoate (Zn(Oct) 2 ) and aluminum acetylacetonate (Al(Acac) 3 ). 8 Two main pieces of evidence support this mechanism. The first is the characteristics of the polymerization kinetics.…”

Section: Introductionmentioning

confidence: 97%

Mechanistic study of Sn(Oct)₂‐catalyzed ε‐caprolactone polymerization using Sn(Oct)₂/BF₃ dual catalyst

Jiang

Jones

Rudd

et al. 2009

J of Applied Polymer Sci

View full text Add to dashboard Cite

A novel method was used to investigate the mechanism of Sn(Oct)2‐catalyzed ε‐caprolactone polymerization by using Sn(Oct)2/BF3 dual catalyst. The bulk polymerization was conducted at 110 and 130°C with different Sn(Oct)2/BF3 ratios. The polymerization kinetics was followed using gel permeation chromatography, and the molecular structures of the low‐molecular weight polymers were examined using 1H‐nuclear magnetic resonance (NMR). A polymerization induction period was observed in polymerizations containing the Sn(Oct)2 catalyst, but it was not observed in the system containing only BF3. After the induction period, BF3 and Sn(Oct)2 initiated the polymerization separately. For Sn(Oct)2 catalyst with no purposely added alcohol, the actual initiation species is a tin hydroxide species formed in situ by the reaction of Sn(Oct)2 and adventitious water. For BF3 catalyst, the active species is the protonic acid formed by the reaction of BF3 with the adventitious water. When mixed, the Sn(Oct)2 reacts with the adventitious water faster than the BF3, preventing the BF3 catalyzing any polymerizations during the induction period. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

show abstract

Kinetics and mechanism of ɛ-caprolactone and l,l-lactide polymerization coinitiated with zinc octoate or aluminum acetylacetonate: The next proofs for the general alkoxide mechanism and synthetic applications

Cited by 61 publications

References 31 publications

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Optimizing the bulk copolymerization of D,L-lactide and glycolide by response surface methodology

Mechanistic study of Sn(Oct)₂‐catalyzed ε‐caprolactone polymerization using Sn(Oct)₂/BF₃ dual catalyst

Contact Info

Product

Resources

About

Kinetics and mechanism of ɛ-caprolactone and l,l-lactide polymerization coinitiated with zinc octoate or aluminum acetylacetonate: The next proofs for the general alkoxide mechanism and synthetic applications

Cited by 61 publications

References 31 publications

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Synthetic and Mechanistic Aspects of the Immortal Ring‐Opening Polymerization of Lactide and Trimethylene Carbonate with New Homo‐ and Heteroleptic Tin(II)‐Phenolate Catalysts

Optimizing the bulk copolymerization of D,L-lactide and glycolide by response surface methodology

Mechanistic study of Sn(Oct)2‐catalyzed ε‐caprolactone polymerization using Sn(Oct)2/BF3 dual catalyst

Contact Info

Product

Resources

About

Mechanistic study of Sn(Oct)₂‐catalyzed ε‐caprolactone polymerization using Sn(Oct)₂/BF₃ dual catalyst