Group Transfer Polymerization of Methyl Crotonate

Ute, Koichi; Tarao, Toshiyuki; Hatäda, Koichi

doi:10.1295/polymj.29.957

Cited by 24 publications

(10 citation statements)

References 14 publications

(3 reference statements)

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“…However, there had been no distinctive evidence of any special stereocontrol responsible to ''group transfer'', 4-7 until we have reported a Lewisacid catalyzed GTP of methyl crotonate with HgI 2 -iodotrialkylsilanes (R 3 SiI) as catalysts, which produces disyndiotactic poly(methyl crotonate) (Scheme 1); the stereoregularity of the polymer depends on the structure of trialkylsilyl transferring groups. [8][9][10][11] During the investigation of Lewis-acid mediated stereoregulation of GTP, we found a stereospecific GTP of MMA catalyzed by aluminum phenoxide with R 3 SiI as a co-catalyst, which gives PMMA with a bimodal distribution of molecular weight (MW), the high MW fraction of which had high syndiotacticity (Scheme 2). Though the overall products had a lower syndiotacticity, it is evident that there exists highly syndiotactic-specific and highly active species in this GTP system.…”

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confidence: 99%

Stereospecific Group Transfer Polymerization of Methyl Methacrylate with Lewis-Acid Catalysis—Formation of Highly Syndiotactic Poly(methyl methacrylate)

Ute

Ohnuma

Shimizu

et al. 2006

Polym J

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confidence: 99%

Stereospecific Group Transfer Polymerization of Methyl Methacrylate with Lewis-Acid Catalysis—Formation of Highly Syndiotactic Poly(methyl methacrylate)

Ute

Ohnuma

Shimizu

et al. 2006

Polym J

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“…The ratio of HgI 2 and TBSI employed is close to the optimized value for the previously reported GTP of methyl crotonate. 11 The results are summarized in Table I. The polymerizations at 0 and À20 C gave PMCs with fairly narrow molecular weight distribution (MWD) with the maximum yield, while the yield decreased and MWD became broader with decreasing polymerization temperature.…”

Section: Resultsmentioning

confidence: 98%

“…11 Later, the GTP of other alkyl crotonates (alkyl = ethyl, n-propyl, isopropyl, or n-butyl) was also found successful. 12 The combined catalyts HgI 2 /R 3 SiI has been known effective for the GTP of acrylates.…”

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confidence: 99%

Enhanced Stereocontrol in Disyndiotactic-specific Group Transfer Polymerization of Methyl Crotonate—Stereochemical Evidence of Group Transfer

Ute

Tarao

Kitayama

2005

Polym J

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ABSTRACT:Group transfer polymerization (GTP) of methyl crotonate was examined by using a ketene silyl acetal with tert-butyldimethylsilyl group in the presence of HgI 2 and tert-butyldimethylsilyl iodide as a catalyst and a co-catalyst, respectively. Under optimized conditions, the GTP produced disyndiotactic polymers with narrow molecular weight distribution in quantitative yields. The trialkylsilyl group in the initiator components was found to exert control over the stereochemical process of the GTP; the bulky tert-butyldimethylsilyl group leads to the highest disyndiotacticity. The results provide a direct evidence for the transferring silyl group to be involved in the propagation steps in the GTP. [DOI 10.1295/polymj.37.578] KEY WORDS Ditacticity / Stereoregularity / Methyl Crotonate / Ketene Silyl Acetal / 1-Methoxy-1-(tert-butyldimethylsiloxy)-1-propene / Group transfer polymerization (GTP), disclosed in early 1980's by Webster, 1 is one of the versatile living polymerizations for acrylic monomers. The GTP involves ketene silyl acetals as initiators and nucleophilic or Lewis acidic catalysts and has been claimed to proceed through migration or transfer of the silyl group to maintain ketene silyl acetal units at the propagating polymer chain-ends during the polymerization. The proposed mechanism, so-called ''associative mechanism'', assumes active intermediates carrying the silyl group.1-3 On the other hand, a dissociative mechanism has also been proposed, which regards the active intermediate as an enolate as in the case of classical anionic polymerizations. [4][5][6] The above mechanistical argument has urged several researchers to examine the stereochemistry of GTP with the expectation of any specific effects of the ketene silyl acetal ends on the stereochemical aspect of the propagation reaction, if the associative mechanism dominates the GTP. For example, Müller and Sticker reported that syndiotacticity of poly(methyl methacrylate) (PMMA) obtained by the GTP using nucleophilic catalyst was slightly lower than that of PMMA obtained by radical polymerization.7 Mechanism and stereospecificity of the GTP were also discussed for cyclization polymerization of a binaphthyl dimethacrylate by Nakano and Sogah based on the results that the isotacticity of the polymer obtained by the GTP was higher (34%) than that that of the polymer obtained by radical polymerization.8 GTP giving stereoregular polymers was reported for the polymerization of triphenylmethyl methacrylate using a nucleophilic catalyst (mm ¼ 91%).9 Judging from the fact that radical and anionic polymerizations of this monomer also give the isotactic polymers, 10 however, the result is hardly regarded as ''stereocontrol by GTP''.We have reported the GTP of methyl crotonate, a structural isomer of methyl methacrylate, using ketene silyl acetals (1) and (2) (Scheme 1), in the presence of HgI 2 and trialkylsilyl iodides (R 3 SiI) as catalysts. 11Later, the GTP of other alkyl crotonates (alkyl = ethyl, n-propyl, isopropyl, or n-butyl) was also found s...

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“…Although the reaction mechanism is unclear, the combination of NaCo(CO) 4 and amine realized the selective synthesis of the oligoester with a crotonate end group. Because anionic or group‐transfer polymerization has been reported for alkyl crotonate,19–22 the macromonomers produced in this work have potential applications as comblike polymers and graft copolymers. Furthermore, because the ring opening of propylene oxide selectively proceeds at the unsubstituted carbon, the use of a single enantiomer of propylene oxide should enable the production of an optically active macromonomer 11…”

Section: Discussionmentioning

confidence: 99%

Synthesis of a polyester macromonomer via the cobalt‐catalyzed alternating copolymerization of propylene oxide and carbon monoxide

Nakano

Kondo

Nozaki

2004

J. Polym. Sci. A Polym. Chem.

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The alternating copolymerization of propylene oxide and carbon monoxide was investigated with cobalt complexes. The NaCo(CO)4/amine catalyst system selectively yielded oligo(3‐hydroxybutyrate)s bearing a polymerizable crotonate end group, whereas the use of Co2(CO)8 as a cobalt source resulted in a smaller concentration of the crotonate end group and a high degree of polymerization. The high selectivity for the oligoesters with the crotonate end group with the NaCo(CO)4/amine system was attributed to its more basic reaction condition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4666–4670, 2004

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Group Transfer Polymerization of Methyl Crotonate

Cited by 24 publications

References 14 publications

Stereospecific Group Transfer Polymerization of Methyl Methacrylate with Lewis-Acid Catalysis—Formation of Highly Syndiotactic Poly(methyl methacrylate)

Stereospecific Group Transfer Polymerization of Methyl Methacrylate with Lewis-Acid Catalysis—Formation of Highly Syndiotactic Poly(methyl methacrylate)

Enhanced Stereocontrol in Disyndiotactic-specific Group Transfer Polymerization of Methyl Crotonate—Stereochemical Evidence of Group Transfer

Synthesis of a polyester macromonomer via the cobalt‐catalyzed alternating copolymerization of propylene oxide and carbon monoxide

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