Stereospecific radical polymerization of <i>N</i>‐<i>tert</i>‐butoxycarbonylacrylamide in the presence of fluorinated alcohols

Hirano, Tomohiro; Yamaoka, Ryosuke; Miyazaki, Takamasa; Ute, Koichi

doi:10.1002/pola.24373

Cited by 4 publications

(5 citation statements)

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“…The chemical shift of the H 1 vinylidene proton of DMAAm alone at the corresponding concentration was denoted δ(H 1 ) f , because chemical shifts can vary slightly with concentration. 55 The mechanism for the induced isotactic specificity of this reaction currently remains unclear. The chemical shift for the saturated mixture, δ(H 1 ) c , was calculated from the intercept of the cubic fit to the data.…”

Section: Relationship Between Complex Structure and Stereospecificitymentioning

confidence: 99%

“…Similar phenomena concerning the control of the stereospecificity through the stoichiometry of monomer complexes were observed in our previous studies on the radical polymerization reactions of N-isopropylacrylamide (NIPAAm) in the presence of phosphates 54 and N-tert-butoxycarbonylacrylamide in the presence of fluorinated alcohols. 55 The mechanism for the induced isotactic specificity of this reaction currently remains unclear. However, it is assumed that a helical conformation could be induced by the electrostatic repulsion between the Li + ion binding to the carbonyl groups of the antepenultimate, penultimate and chain-end monomeric units.…”

Section: Relationship Between Complex Structure and Stereospecificity...mentioning

confidence: 99%

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Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

et al. 2015

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The radical polymerization of N,N-dimethylacrylamide (DMAAm) has been investigated in the presence of several alkali metal salts, including lithium bis(trifluoromethanesulfonyl)imide (LiNTf 2 ). The addition of an alkali metal salt led to a significant increase in the yield and molecular weight of the resulting polymer.NMR analysis of mixtures of DMAAm and LiNTf 2 suggested that DMAAm was being activated by the coordination of Li + to its CvO group. Electron spin resonance analysis of the DMAAm polymerization in the presence of LiNTf 2 suggested that the propagating radical was being stabilized by Li + through a single-electron lithium bond, because a signal for the propagating radical of the acrylamide derivatives was observed for the first time in solution when LiNTf 2 was added. Based on these results, we have proposed a mechanism for this polymerization, where the propagation steps occur between a lithium ionstabilized propagating radical and a lithium ion-activated incoming monomer. Furthermore, polymers with a wide range of stereoregularities, such as isotactic, syndiotactic and heterotactic systems, were successfully prepared using this method by carefully selecting the appropriate combination of solvent and alkali metal salt. † Electronic supplementary information (ESI) available: Dependence of polymer yield on the added amount of LiNTf 2 in toluene, additional 1 H NMR spectra of the main-chain methylene groups of the poly(DMAAm)s prepared in this study and changes in the chemical shifts of DMAAm in the presence of MNTf 2 . See View Article Online a [Monomer] 0 = 1.0 mol L −1 , [MAIB] 0 = 1.0 × 10 −2 mol L −1 , [alkali metal salts] 0 = 1.0 mol L −1 . b Determined from 1 H NMR signals. c Determined by SEC (PMMA standards). d Alkali metal salt was not completely dissolved. e Polymer precipitated during polymerization reaction. Polymer Chemistry PaperThis journal is

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Section: Relationship Between Complex Structure and Stereospecificitymentioning

confidence: 99%

Section: Relationship Between Complex Structure and Stereospecificity...mentioning

confidence: 99%

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

et al. 2015

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“…One of the strategies involves alcohol compounds, which form complexes with the monomers through hydrogen bonding interactions. This strategy has been used to induce stereospecificity in the radical polymerization of vinyl monomers, such as vinyl esters,6, 7 methacrylates,8, 9 N ‐vinylamides10, 11 and acrylamides 12–16…”

Section: Introductionmentioning

confidence: 99%

Syndiotactic‐specific radical polymerization of N‐isopropylacrylamide in toluene at low temperatures in the presence of silyl alcohols

Hirano

Kamikubo

Ute

2012

Polymer International

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The radical polymerization of N-isopropylacrylamide was carried out in toluene at low temperatures in the presence of silyl alcohols, such as triethylsilanol. Poly(N-isopropylacrylamide) with a racemo dyad content of 75% was obtained at −80 • C with a 4 : 1 triethylsilanol to monomer ratio loading. NMR analysis suggests that the mechanism for syndiotactic induction, in the presence of silyl alcohols, may be similar to that observed with alkyl alcohols. In this case, a 1 : 2 complex formation, via hydrogen bonding interactions, leads to the induction of syndiotactic specificity. EXPERIMENTAL MaterialsNIPAAm (Tokyo Chemical Industry Co. Ltd, Tokyo, Japan) was recrystallized from a hexane-toluene mixture. Toluene was purified by washing with sulfuric acid, water and 5% aqueous NaOH, followed by fractional distillation. Triethylsilanol (TESiOH), diethyl(isopropyl)silanol (DEIPSiOH), 3-ethyl-3pentanol (3Et3PenOH), trimethylsilylmethanol (TMSiMeOH), 2-(trimethylsilyl)ethanol (TMSiEtOH) (Tokyo Chemical Industry Co.

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“…Furthermore, isotactic and syndiotactic specificities were induced by adding Lewis bases14, 15 or alkyl alcohols16, 17 to the radical polymerizations of NIPAAm and N ‐ n ‐propylacrylamide (NNPAAm). Adding fluorinated alcohols induced heterotactic specificity,18, 19 indicating that fluorine‐containing compounds as additives also played a determining role in the stereospecificity of the radical polymerizations of N ‐monosubstituted acrylamides. It is therefore assumed that introducing fluorine atoms at the α‐positions of N ‐monosubstituted acrylamides further influences the stereospecificity induced by polar solvents, Lewis bases, alkyl alcohols, silyl alcohols, or fluorinated alcohols.…”

Section: Introductionmentioning

confidence: 99%

Syndiotactic‐ and heterotactic‐specific radical polymerizations of N‐n‐propyl‐α‐fluoroacrylamide and phase‐transition behaviors of aqueous solutions of poly(N‐n‐propyl‐α‐fluoroacrylamide)

Hirano

Furutani

Oshimura

et al. 2012

J. Polym. Sci. A Polym. Chem.

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Radical polymerization of N-n-propyl-a-fluoroacrylamide (NNPFAAm) was investigated in several solvents at low temperatures in the presence or absence of Lewis bases, Lewis acids, alkyl alcohols, silyl alcohols, or fluorinated alcohols. Different effects of solvents and additives on stereospecificity were observed in the radical polymerizations of NNPFAAm and its hydrocarbon analogs such as N-isopropylacrylamide (NIPAAm) and N-n-propylacrylamide (NNPAAm); for instance, syndiotactic (and heterotactic) specificities were induced in radical polymerization of NNPFAAm in polar solvents (and in toluene in the presence of alkyl and silyl alcohols), whereas isotactic (and syndiotactic) specificities were induced in radical polymerizations of the hydrocarbon analogs under the corresponding conditions. In contrast, heterotactic specificity induced by fluorinated alcohols was further enhanced in radical polymerization of NNPFAAm.The effects of stereoregularity on the phase-transition behaviors of aqueous solutions of poly(NNPFAAm) were also investigated. Different tendencies in stereoregularity were observed in aqueous solutions of poly(NNPFAAm)s from those in solutions of the hydrocarbon analogs such as poly(NIPAAm) and poly (NNPAAm). The polymerization behavior of NNPFAAm and the phase-transition behavior of aqueous poly(NNPFAAm) are discussed based on possible fluorine-fluorine repulsion between the monomer and propagating chain-end, and neighboring monomeric units.

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Stereospecific radical polymerization of N‐tert‐butoxycarbonylacrylamide in the presence of fluorinated alcohols

Cited by 4 publications

References 22 publications

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

Syndiotactic‐specific radical polymerization of N‐isopropylacrylamide in toluene at low temperatures in the presence of silyl alcohols

Syndiotactic‐ and heterotactic‐specific radical polymerizations of N‐n‐propyl‐α‐fluoroacrylamide and phase‐transition behaviors of aqueous solutions of poly(N‐n‐propyl‐α‐fluoroacrylamide)

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