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Highly stereospecific protonation of stereoregular living PMMA anions with several alcohols
Author(s) -
Ute Koichi,
Asada Takeshi,
Miyatake Nobuo,
Hatada Koichi
Publication year - 1993
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19930670112
Subject(s) - protonation , stereospecificity , tacticity , toluene , chemistry , polymer chemistry , medicinal chemistry , polymer , ion , organic chemistry , polymerization , catalysis
Living and highly isotactic poly(methyl methacrylate) (PMMA) anion ( M̄n = 2.5 × 10 3 ) prepared with t ‐C 4 H 9 MgBr as an initiator was protonated with phenol in toluene at −78°C. The reaction was stereospecific toward meso addition, and the meso/racemo ratio at the chain‐end of the resultant polymer was 89/11. Addition of 1,4‐dioxane to the living isotactic PMMA anion in toluene at −78°C remarkably reduced the viscosity of the system, and protonation of the PMMA anion with phenol in the presence of 1,4‐dioxane enhanced the meso ‐specificity to 94%. On the other hand, the protonation reaction of the living syndiotactic PMMA anion ( M̄n = 2.5 × 10 3 ), which was generated by t ‐C 4 H 9 Li/( n ‐C 4 H 9 ) 3 Al in toluene at −93°C, with t ‐butanol was found to be 97% racemo ‐specific. These highly stereospecific protonation reactions of the stereoregular PMMA anions were in contrast to the protonation of the anions with methanol or benzyl alcohol which was almost non‐stereospecific.