Stereochemistry of the free-radical polymerization of zinc methacrylates coordinated with a bidentate ligand

Abstract

Supramolecular multilayered ferromagnets in which metal layers are interleaved with iminonitroxide benzoate radical anions have been synthesized and characterized by the authors. The structure of these novel compounds (see cover) consists of stacks of alternating organic–inorganic layers. Long‐range ferromagnetism is evidenced by magnetic and electroparamagnetic resonance (EPR) measurements, and shows clear interaction between the two sub‐networks. In this respect, this new class of hybrid magnets differs markedly from classical intercalated layer compounds.

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

“…Among them, the zinc dimethacrylate with 2,2′-isopropylidenebis(4,4-dimethyl-2-oxazoline) (IM-10) or (-)-sparteine (IM-11) afforded polymers with a somewhat specific feature, whereas that with 2,2′-bipyridine (IM-9) showed no significant effects. 419 The zinc dimethacrylate with (-)-sparteine (IM-11) was also employed for the copolymerization with various common monomers to give copolymers with an optical activity similar to the copolymerization of chiral divinyl compounds. 420 Recently, it was reported that the divalent calcium(II) salt of MAA (IM-12) could be polymerized into isotactic-rich polymers by the judicious choice of solvents.…”

Effects of Ionization on Tacticity and Propagation Kinetics in Methacrylic Acid Polymerization

“…Some of the most effective (and elegant) strategies, such as stereoregular templating (2)(3)(4), are impractical and could not be readily applied to grams scale polymer synthesis. The strategy that is best able to balance the competing demands of effectiveness and practicality is monomer modification to incorporate bulky (5)(6)(7)(8), chiral (9,10) and ionic auxiliaries (11)(12)(13)(14)(15)(16)(17)(18)(19)(20).…”

Isotactic Regulation in the Radical Polymerization of Calcium Methacrylate: Is Multiple Chelation the Key to Stereocontrol?

“…As the COOH groups of methacrylic acid (MAA) can be readily ionized by both organic and inorganic bases, stereoselectivity in the radical polymerization of methacrylate salts has been investigated in numerous studies over last five decades (see Table ) . A majority of these studies have examined the stereochemical effect of various counter‐cations in aqueous solutions, where ionic interactions are weakened by the high dielectric constant of water (ε ~ 78) .…”

“…Under these conditions, polymers with syndiotactic triad fractions ( rr ) ranging from 39 to 92% are obtained, depending on the counter‐cation identity and polymerization temperature . Although there are a plethora of studies that investigate the stereoregulating effect of different counter‐cations in aqueous conditions, there are comparatively few studies in other solvents …”

“…Around 25 years ago, Okamoto and coworkers found that the radical polymerization of the dimethylacrylic salt of trans 1,2‐diaminocyclohexane in CHCl 3 at 60 °C afforded polymer with a slightly lower syndiotactic content ( rr = 35%), compared with bulk MAA polymerization ( rr = 45%) . Subsequently, Ishigaki found that the resultant polymer stereochemistry in the radical polymerization of zinc methacrylate in CHCl 3 could be influenced by various bidentate ligands, although the stereochemistry of the polymers obtained was not highly regulated . More recently, Kadokawa et al reported that the radical polymerization of the calcium methacrylate hydrate (CaMA) in N,N ‐dimethylformamide (DMF) afforded polymer with an isotactic triad fraction (mm) of 60% .…”