Stereospecific Anionic Polymerization of α‐(Hydroxymethyl)acrylate with Protective Group

Abstract

Summary: Anionic polymerizations of hydroxyl-protected α-(hydroxymethyl) acrylates were investigated. The methyl ester with methoxymethyl (1-MOM) and allyl (1-allyl) protecting groups were polymerized by isopropyl α-lithioisobutyrate (Li-iPrIB) in toluene at 78 °C, affording highly isotactic polymers. Similarly, the polymerization of ethyl ester (2-MOM) gave an isotactic polymer, while those of t-butyl (3-MOM) and isobutyl (4-MOM) ester did not form any polymeric products. The hydrolysis of poly(2-MOM) in acidic conditions resulted in the deprotection of MOM group, although the acid also catalyzed the ester exchange between the neighboring units to form lactone units, as observed by 1 H NMR analysis, IR spectroscopy and thermogravimetric analysis. A film of poly(2-MOM) exposed to HCl vapor for 2 h became insoluble in any organic solvents due to the lactonization in solid state.

α‐exomethylene lactone possessing acetal–ester linkage: Polymerization and postpolymerization modification for water‐soluble polymer

“…α‐(Alkoxymethyl)acrylate, acyclic analogues of DMDO, is known to undergo spontaneous termination in anionic polymerization via the elimination of the respective alkoxide anion to afford a polymer with terminal chain‐end of an α,β‐unsaturated ester [Scheme (a)] …”

“…In the previous work, we have found that the acid‐hydrolysis of the polymer of a methoxymethyl acetal‐protected α‐ (hydroxymethyl)acrylate prepared by anionic polymerization caused a side reaction, that is, lactonization between the neighboring two units via ester exchange reaction . In contrast, P1 , the cyclic‐acetal protected poly[α‐(hydroxymethyl)acrylate], underwent clean deprotection to generate hydrophilic α‐hydroxymethyl groups together with carboxylic groups, indicating that the cyclic‐acetal protection is effective for the protection of α‐(hydroxymethyl)acrylate derivatives.…”

“…Recently, we have been interested in the polymerization chemistry of α‐functionalized acrylates, as the α‐functionality bound to the vinyl groups leads to unique polymerization behaviors that facilitate the controls of end‐functionality and monomer sequence as well as the excellent polymer properties, such as fluorescence and pH/temperature‐responsiveness . Along the line of this concept, herein, we have designed a new monomer; that is, an α‐functionalized acrylates which has a feature of EMLs possessing acetal–ester (A–E) linkage in its lactone skeleton.…”

Termination of Living Anionic Polymerization of Butyl Acrylate with α‐(Chloromethyl)acrylate for End‐Functionalization and Application to the Evaluation of Monomer Reactivity

“…We have been interested in the polymerization behavior of α‐substituted acrylates and recently have found that α‐(halomethyl)acrylate and α‐(alkoxymethyl)acrylate functioned as an efficient terminator in stereospecific anionic polymerizations of methyl methacrylate (MMA); the poly(methyl methacrylate) (PMMA) living anion attacks the vinylidene group of the terminators, and the subsequent elimination of halogen atom or alkoxy group generates PMMA with α,β‐unsaturated ester moiety at the ω‐end. For example, the polymerization initiated by isopropyl α‐lithioisobutyrate (Li‐­ i PrIB) in the presence of ethylaluminum bis(2,6‐di‐ tert ‐butylphenoxide) [EtAl(ODBP) 2 ] could be terminated with ethyl α‐(chloromethyl)acrylate (ECMA) to afford highly syndiotactic ( st ‐) PMMA with ω‐functionality (termination efficiency: F ≈ 99%) .…”

Anionic alternating copolymerization of α-arylacrylates with methyl methacrylate: Effect of monomer sequence on fluorescence

“…Recently, we have been interested in α‐substituted acrylates as functional monomers or functional terminating agents in anionic polymerization. As an extensive research in this line, the unique reactivity of MPhA has attracted our interest in designing new functional polymers with aromatic substituents directly attached to the polymer backbones.…”