Living Coordination Polymerization of Allene Derivatives in Protic Solvents:  Remarkable Acceleration of Polymerization and Increase of 1,2-Polymerization Selectivity

Abstract

The allylnickel-catalyzed living coordination polymerization of allene derivatives was carried out in protic solvents such as EtOH to figure out their effect on the polymerization behavior. For example, the coordination polymerization of methoxyallene (2a) by [(allyl)NiOCOCF3]2 (1)/PPh3 in EtOH proved to proceed in a living fashion giving a narrowly dispersed polymer in a high yield. In this case, a remarkable acceleration of the polymerization and the higher selectivity of the 1,2-polymerization were observed compared to the case of the polymerization in aprotic solvents such as toluene. That is, the polymerization of 2a (50 equiv, [2a]0 = 1.0 M) was complete within 2 h in EtOH to give a polymer in 95% yield (M n = 4400, M w/M n = 1.10, 1,2-:2,3-polymerizations = 63:37), while it required 12 h in toluene to obtain a polymer having higher content of the 2,3-polymerized unit in a 99% yield (M n = 4100, M w/M n = 1.07, 1,2-:2,3-polymerizations = 27:73). In protic solvents, the actual propagating species was supposed to be a cationic π-allylnickel complex on the basis of its 1H NMR and 19F NMR spectra. The use of protic sources such as pyrrole, indole, and phenol was also found to be effective to accelerate the polymerization and to increase the 1,2-polymerization selectivity.

Polymerization of n‐Octylallene with Rare Earth Catalyst Composed of Ln(P204)3/Al(i‐Bu)3

“…The polymer yield in solvent polymerization is lower than that in bulk, and the yield of polymerization in polar solvent is even lower. It was interesting to find that in contrast to the previously work, 7 the M w and yield of polymers increase with the solvent polarity. However, the polymer obtained in THF shows lower M w Table 1).…”

“…This result was consistent with the previous report. 7 Figure 7. It can be concluded that the apparent polymerization rate is first-order with respect to the concentration of n-octylallene.…”

“…3 Endo and co-workers developed the living coordination polymerization of allene derivatives by π-allylnickel catalysts. [4][5][6][7] Recently, we reported the polymerization of n-octylallene with the coordination catalyst system composed of bis[N,N-(3,5-di-tertbutylsalicylidene)anilinato] titanium(IV) dichloride (Ti(Salen) 2 Cl 2 ) and Al(i-Bu) 3 . 8 Further, possibilities for the designed synthesis of allene monomers with a wide variety of substituents having various functional groups may indicate the potential applicability of polymers from allene derivatives as novel reactive polymers as well as novel functional materials.…”

Synthesis of well‐defined block copolymer composed of flexible amphiphilic poly(ethylene glycol) and hydrophobic liquid crystalline segments by living coordination polymerization of allene derivatives and its application to thin film with perpendicularly oriented cylindrical nanostructure

“…In the laboratory of the coauthors, the allylnickel‐catalyzed living polymerization of allene derivatives has been studied, in which a wide variety of allene monomers including both nonpolar and polar functional groups can be polymerized in a living mechanism in both polar and non‐polar polymerization media . In addition, this living polymerization can be applied to the synthesis of copolymers of plural allenes, and allenes with other monomers such as butadiene and isocyanides .…”

Well-defined polymer microspheres formed by living dispersion polymerization: precisely functionalized crosslinked polymer microspheres from monomers possessing cumulated double bonds

“…In fact, this living polymerization can be applied to monomers bearing diverse functional groups such as alkyl, aryl, alkoxy, carboalkoxy, hydroxy and amide to produce welldefined polymers bearing the corresponding functional groups. [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] Additionally, this living polymerization can be carried out in protic polar media such as alcohols without any deactivations of the growing species. 47 In this paper, we describe the results of the π-allylnickelcatalyzed living dispersion polymerization of allene derivatives that enables the precision synthesis of well-defined polymer microspheres.…”