Substituent Effect on the Anionic Equilibrium Polymerization of Six-Membered Cyclic Carbonates

Abstract

Anionic equilibrium polymerization behavior of several six-membered cyclic carbonates was examined. The conversions of the monomers reached a constant below 100%, and the final conversion decreased in the order of 1,3-dioxan-2-one (1) > 5,5-dimethyl-1,3-dioxan-2-one (2) > 5,5-diethyl-1,3-dioxan-2-one (3) ≥ 5-methyl-5-phenyl-1,3-dioxan-2-one (4) > 5-ethyl-5-phenyl-1,3-dioxan-2-one (5). The reactions of 2,2-disubstituted-1,3-propanediols were carried out with phosgene dimer to find that the cyclic carbonate (5) was formed quantitatively in the reaction of 2-ethyl-2-phenyl-1,3-propanediol, while the corresponding polycarbonate was formed in the reaction of 2,2-diethyl-1,3-propanediol in 24% yield besides 3. Thermodynamic parameters were estimated in the anionic ring-opening polymerizations of cyclic carbonates (1−5) by Dainton's equation. The obtained ΔH p value in the ring-opening polymerization of each cyclic carbonate reflected the polymerizability. Molecular orbital calculations of the model compounds of the polymers were carried out to find that the polymerizabilities of the cyclic carbonates correlated with the stabilities of the corresponding polymer structures. The concentrations of the monomers formed in the depolymerizations well agreed with the equilibrium monomer concentrations in the anionic ring-opening polymerizations.

Carbonic Esters

“…In the absence of compounds to be alkylated, these cyclic carbonates can be broken down to oxiranes and carbon dioxide, which is the reverse of the formation reaction [11]. Aliphatic and aromatic cyclic carbonate can easily be polymerized to a variety of homopolymers and copolymers with high molecular masses [12][13][14][15], [17][18][19][20][21][22]. Openchain carbonic esters can be broken down catalytically at high temperatures to form alcohols, carbon dioxide, and olefins [23].…”

Development and application of novel ring‐opening polymerizations to functional networked polymers

“…This polymerization exhibits equilibrium nature, which can be controlled by bulkiness of the substituents. 62 One of the advantages of 6CC is its structural diversity, owing to the utilization of various 1,3-diols as starting materials. For example, 6CC having styrene moiety was easily synthesized (Scheme 20).…”

The anionic ring-opening polymerization of five-membered cyclic carbonates fused to the cyclohexane ring

“…[1][2][3] For their synthesis, various procedures have been used, that is, (i) the polycondensation between the carbonate derivatives and diols, 4 (ii) the ring-opening polymerization of cyclic carbonates, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and (iii) the alternating polymerization of epoxides with carbon dioxide. Among these procedures, the ring-opening polymerizations of cyclic carbonates have the potential to control the molecular weight and to induce copolymerization with other cyclic monomers.…”

“…Six-membered cycles (or larger) using anionic initiators tend to polymerize smoothly, yielding the corresponding polycarbonate at a lower temperature (o100 1C). [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] In contrast, the anionic ring-opening polymerization of the fivemembered ring is thermodynamically unfavorable and proceeds at a higher temperature (4150 1C), causing the elimination of carbon dioxide to produce a copolymer that consists of both carbonate and ether linkages. [20][21][22][23][24][25] However, we reported that the anionic ringopening polymerization of a five-membered cyclic carbonate (MBCG) (Figure 1) possessing the a,D-glucopyranoside structure proceeded even at 0 1C to produce an aliphatic polycarbonate without the elimination of carbon dioxide.…”