Stereospecific polymerization of trityl methacrylate

Yuki, Heimei; Hatäda, Koichi; Kikuchi, Y.; Niinomi, Toshikazu

doi:10.1002/pol.1968.110061014

Cited by 46 publications

(13 citation statements)

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“…In a previous communication 11 we briefly reported the polymerization of trityl methacrylate by anionic and radical initiators and found that this monomer gave a highly isotactic polymer regardless of the polymerization medium, the temperature and the type of initiator. In the present work the polymerizations of trityl (TMA), diphenylmethyl (DMA) and benzyl (BMA) methacrylates were carried out mainly by n-butyllithium (n-BuLi) and the effect of the bulkiness of the ester group on the tacticity of the polymer was investigated.…”

Section: Methodsmentioning

confidence: 99%

Stereospecific Polymerization of Trityl, Diphenylmethyl and Benzyl Methacrylates

Yuki

Hatäda

Niinomi

et al. 1970

Polym J

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128

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ABSTRACT:Polymerizations of trityl (TMA), diphenylmethyl (DMA) and benzyl (BMA) methacrylates were carried out mainly by n-butyllithium (n-BuLi) and the tacticities of the polymers were studied by NMR spectroscopy. Polymerization of TMA by n-BuLi gave a highly isotactic polymer in toluene as well as in tetrahydrofuran (THF). The polymer obtained in radical polymerization by AIBN catalyst had about 60 % isotacticity in triads.From these results the growing-chain-controlled mechanism was proposed to this polymerization. In the polymerization of DMA by n-BuLi a highly isotactic polymer was obtained in toluene at lower temperatures and a highly syndiotactic one in THF. The radical polymerization gave a predominantly syndiotactic polymer. Temperature dependence of the NMR signal-width of the isotactic polymer indicates that the conformational arrangement of the polymer chain in solution is much rigid up to a fairly higher temperature. These results suggest that the growing-chain-controlled mechanism may contribute to some extent to the stereoregulation of DMA in toluene. BMA behaved very similarly to methyl methacrylate in the polymerization by n-BuLi. Probably the same polymerization mechanisms can be applied for both monomers. Polymerization ofTMA, DMA and BMA by phenylmagnesium bromide or diethylaluminum diphenylamide was also investigated.KEY WORDS Stereospecific Polymerization / Poly (Trityl Methacrylate) / Poly (Diphenylmethyl Methacrylate) / Poly (Benzyl Methacrylate) / Poly (Methyl Methacrylate) / n-Butyllithium / Phenylmagnesium bromide / Diethylaluminum Diphenylamide / Growing-Chain-Controlled Mechanism of Stereoregulation / NMR Spectroscopy / Stereospecific polymerizations of methyl 1 -3 and other alkyl methacrylates 4 -9 by anionic initiator have been extensively studied. However there have been few systematic studies 10 concerning the effect of the ester group on the tacticity of polymer. EXPERIMENTAL MaterialsTMA was prepared from silver methacrylate and trityl chloride in diethyl ether. 12 The crude product was purified by recrystallization from petroleum ether. mp 102-103°C (lit. 12 101-1030C), Anal. Found: C, 84.00; H, 6.08%. Calcd for C23H 200 2 : C, 84.12; H, 6.14%. The NMR spectrum (10 % CC14 solution) showed peaks at 1.90 ppm (singlet, 2.95H) assigned to the methyl protons, 5.49 and 6.13 ppm (two singlets 2.00H) assigned to the p-protons of the vinyl group and about 7.20 ppm (multiplet, 15.2H) assigned to the phenyl protons.In a previous communication 11 we briefly reported the polymerization of trityl methacrylate by anionic and radical initiators and found that this monomer gave a highly isotactic polymer regardless of the polymerization medium, the temperature and the type of initiator. In the present work the polymerizations of trityl (TMA), diphenylmethyl (DMA) and benzyl (BMA) methacrylates were carried out mainly by n-butyllithium (n-BuLi) and the effect of the bulkiness of the ester group on the tacticity of the polymer was investigated. 36DMA was prepared by the reaction of 45 g of silve...

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Section: Methodsmentioning

confidence: 99%

Stereospecific Polymerization of Trityl, Diphenylmethyl and Benzyl Methacrylates

Yuki

Hatäda

Niinomi

et al. 1970

Polym J

Self Cite

128

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“…The dynamics of polymer chains are extremely fast at room temperature in solution; therefore, the polymers cannot maintain a helical conformation. However, Yuki and coworkers 1,2 reported that triphenylmethyl methacrylate (TrMA) is a unique monomer that forms a highly isotactic polymer in anionic polymerization and that even radical polymerization affords a polymer rich in isotacticity. The sterical repulsion of bulky side groups such as the triphenylmethyl group is large enough to maintain a stable helical conformation.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric anionic polymerization of maleimides bearing bulky substituents

Oishi

Onimura

Isobe

et al. 2000

J. Polym. Sci. A Polym. Chem.

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“…The larger for polymerization of DMF. It is surprising characteristics because the dependence on the structure of ester groups was scarcely observed for polymerization of alkyl methacrylates 11 except for triphenylmethyl methacrylate, 12 which shows the different behaviors originated from the formation of stable helical conformation in the polymerization solution. 13 In the polymerization of DRFs, the effect of the structure of the ester substituents on AG!…”

Section: Activation Enthalpies and Entropies For Meso And Racemo Addimentioning

confidence: 99%

Meso and racemo Additions in Propagation for Radical Polymerization of Dialkyl Fumarates I. Stereoregularity of Poly(dialkyl fumarate)s

Yoshioka

Otsu

1991

Polym J

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ABSTRACT:The polymerization temperature dependence of the stereochemical configuration of some poly(dialkyl fumarate)s as poly(substituted methylene) was investigated by the use of 13 C NMR spectroscopy in order to clarify the propagation process in radical polymerization of dialkyl fumarates. The probability of mesa addition (Pm) for polymerization of di-tert-butyl fumarate increased from 0.68 to 0.80, when the polymerization temperature decreased from 120°C to 0°C. On the other hand, it was revealed that Pm for dimethyl fumarate and diisopropyl fumarate decreased by the decreasing polymerization temperature, and that it was almost independent of the temperature for methyl tert-butyl fumarate. From the differences in activation enthalpies and entropies for mesa and racemo additions, the effect of the ester alkyl groups on the propagation manner was discussed.KEY WORDS Dialkyl Fumarate / Radical Polymerization/ Poly(substituted methylene)/ 13 C Nuclear Magnetic Resonance/ Stereoregularity / Activation Enthalpy / Activation Entropy / It has been reported that dialkyl fumarates (DRF) with bulky ester alkyl groups homopolymerize readily to give high molecular weight polymers in a radical mechanism despite of the 1,2-disubstituted ethylene structure, and that the resulting poly(DRF)s consist of a semiflexible poly(substituted methylene) structure. 1 -5 The polymerization reactivity (polymerization rate and molecular weight of the polymer) and the flexibility of poly(DRF)s depend intensively upon the structure (bulkiness) of the ester substituents, indicating that the polymerization of DRF shows unique characteristics different from ordinary vinyl polymerizations. It has been also revealed that stereochemical structure of poly(DRF)s is dependent of the structure of the ester alkyl groups. 6 • 7 The tacticity of poly(DRF)s is dominated by both opening mode of carbon-to-carbon double bond and direction of monomer addition to the propagating polymer radical.As each carbon atom in the mam chain of poly(DRF) as poly(substituted methylene) is pseudo-asymmetric, the stereochemistry based on the methylene unit should be considered as is shown in Figure 1. When Bernoullian probability is applied to the stereochemistry of poly(DRF)s, two parameters, Pm (P,) and P ',,, (P~) are required, which represent the probability of meso (racemo) addition and opening, respectively. However, because the opening of double bond is restricted to trans mode for polymerization of DRF, i.e., P',,, = 1 and P~ = 0, the stereoregularity of poly(DRF) can be determined with solely Pm· 6 • 7 In the previous paper,7 we investigated the Pm values for polymerization of di-tert-butyl fumarate (DtBF), methyl tert-butyl fumarate (MtBF) and dimethyl fumarate (DMF) by the use of 13 C NMR spectroscopy, and confirmed that meso addition was preferable in the propagation ofDRF having a tert-butyl group as is shown in Figure 2. Furthermore, pre-1191

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Stereospecific polymerization of trityl methacrylate

Cited by 46 publications

References 14 publications

Stereospecific Polymerization of Trityl, Diphenylmethyl and Benzyl Methacrylates

Stereospecific Polymerization of Trityl, Diphenylmethyl and Benzyl Methacrylates

Asymmetric anionic polymerization of maleimides bearing bulky substituents

Meso and racemo Additions in Propagation for Radical Polymerization of Dialkyl Fumarates I. Stereoregularity of Poly(dialkyl fumarate)s

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