Equilibrium Polymerization of 7-(Alkoxycarbonyl)-7-cyano-1,4-benzoquinone Methides, Substituent Effect on Polymerizability, and Copolymerization with Styrene

Itoh, Takahito; Fujinami, Hideyuki; Yamahata, M; Konishi, Hiroyuki; Kubo, Masataka

doi:10.1021/ma9711093

Cited by 14 publications

(15 citation statements)

References 16 publications

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“…First of all, let us examine the simplest case of equilibrium polymerization where the only equilibrium step (Scheme ) is the propagation/depropagation one: the monomer/polymer equilibrium. This type of equilibrium polymerization is observed for a number of chain polymerizations, including the anionic polymerization20 of α ‐methylstyrene and the radical polymerization of 7‐(alkoxycarbonyl)‐7‐cyano‐1,4‐benzoquinone methides. An analysis of the thermodynamics of the polymerization process21 leads to Equation (2) which describes the relationship between enthalpy, entropy, temperature, and the equilibrium monomer concentration [M] e .…”

Section: Equilibrium (Dynamic) Polymerizationsmentioning

confidence: 84%

Dynamic Covalent Chemistry

Rowan,

Cantrill,

Cousins

et al. 2002

Angew. Chem. Int. Ed.

2,426

1,334

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Dynamic covalent chemistry relates to chemical reactions carried out reversibly under conditions of equilibrium control. The reversible nature of the reactions introduces the prospects of “error checking” and “proof‐reading” into synthetic processes where dynamic covalent chemistry operates. Since the formation of products occurs under thermodynamic control, product distributions depend only on the relative stabilities of the final products. In kinetically controlled reactions, however, it is the free energy differences between the transition states leading to the products that determines their relative proportions. Supramolecular chemistry has had a huge impact on synthesis at two levels: one is noncovalent synthesis, or strict self‐assembly, and the other is supramolecular assistance to molecular synthesis, also referred to as self‐assembly followed by covalent modification. Noncovalent synthesis has given us access to finite supermolecules and infinite supramolecular arrays. Supramolecular assistance to covalent synthesis has been exploited in the construction of more‐complex systems, such as interlocked molecular compounds (for example, catenanes and rotaxanes) as well as container molecules (molecular capsules). The appealing prospect of also synthesizing these types of compounds with complex molecular architectures using reversible covalent bond forming chemistry has led to the development of dynamic covalent chemistry. Historically, dynamic covalent chemistry has played a central role in the development of conformational analysis by opening up the possibility to be able to equilibrate configurational isomers, sometimes with base (for example, esters) and sometimes with acid (for example, acetals). These stereochemical “balancing acts” revealed another major advantage that dynamic covalent chemistry offers the chemist, which is not so easily accessible in the kinetically controlled regime: the ability to re‐adjust the product distribution of a reaction, even once the initial products have been formed, by changing the reaction's environment (for example, concentration, temperature, presence or absence of a template). This highly transparent, yet tremendously subtle, characteristic of dynamic covalent chemistry has led to key discoveries in polymer chemistry. In this review, some recent examples where dynamic covalent chemistry has been demonstrated are shown to emphasise the basic concepts of this area of science.

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Section: Equilibrium (Dynamic) Polymerizationsmentioning

confidence: 84%

Dynamic Covalent Chemistry

Rowan,

Cantrill,

Cousins

et al. 2002

Angew. Chem. Int. Ed.

2,426

1,334

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“…Generally, asymmetric anionic polymerizations of prochiral monomers are carried out in nonpolar solvents at low temperatures 11. Therefore, the anionic polymerization was carried out at temperatures below 0 °C and also at high monomer concentrations ([ 1 ]) because QMs show typical equilibrium polymerization behavior 5. Table 1 shows the results of the anionic polymerizations with n ‐BuLi as an initiator.…”

Section: Resultsmentioning

confidence: 99%

“…However, the addition of substituents to the exocyclic carbon or quinonoid skeleton of QM reduces its reactivity and makes it an isolable monomer as a crystal. For example, 7,7‐dicyano‐1,4‐benzoquinone methide,2, 3 7‐(alkoxycarbonyl)‐7‐cyano‐1,4‐benzoquinone methides,3–5 7,7‐bis(alkoxycarbonyl)‐1,4‐benzoquinone methides,6 7,7‐diphenyl‐1,4‐benzoquinone methide,7 and 7‐cyano‐7‐phenyl‐1,4‐benzoquinone methide8 have already been synthesized and isolated. Previously, we investigated the polymerization behavior of these isolable QMs and found that the radical and anionic polymerizations of many QMs take place between the substituted exomethylene carbon atom and exocarbonyl oxygen with the formation of a stable aromatic structure to afford polymers with characteristic main‐chain structures, such as poly(oxy‐1,4‐phenylene‐substituted methylene).…”

Section: Introductionmentioning

confidence: 99%

Asymmetric anionic polymerization of 2,6‐dimethyl‐7‐phenyl‐1,4‐benzoquinone methide

Uno

Minari

Kubo

et al. 2004

J. Polym. Sci. A Polym. Chem.

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Asymmetric anionic polymerizations of 2,6‐dimethyl‐7‐phenyl‐1,4‐benzoquinone methide (1) were performed with various chiral anionic initiators, and the specific rotations of the obtained polymers were investigated. Optically active poly(1)s with configurational chirality were obtained with all the initiators, and a complex of fluorenyllithium (FlLi) with (−)‐sparteine [(−)‐Sp] produced poly(1) with the largest negative specific rotation ([α]435 = −26.8°). The specific rotations of poly(1)s obtained with FlLi/(−)‐Sp depended on the initiator concentration and the solvent polarity. The maximum specific rotations were obtained at an almost constant initiator concentration (ca. 0.03 mol/L), regardless of the monomer concentration, in toluene, whereas a higher initiator concentration was required in more polar solvents. These results suggested that the aggregation state of the propagating chain end significantly affected the specific rotation of poly(1). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4548–4555, 2004

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“…9 The polymerization behaviors of these isolable QMs have been investigated, and we found that the radical and anionic polymerizations and the solid-state polymerizations of many QMs take place between the substituted exomethylene carbon atom and exocabonyl oxygen with formation of stable aromatic structure to afford the polymers with characteristic main-chain structure, poly(oxy-1,4-phenylene-substituted methylene)s, 4,5,7,9,10 and that the polymerizations of some substituted QMs are a typical equilibrium polymerization involving a considerable degree of depolymerization. 11 Moreover, we reported spontaneous alternating copolymerization of nonhomopolymerizable substituted quinone methides with styrene and p-methoxystyrene, and the spontaneous initiation mechanism. [12][13][14] As QMs having two different substituents on the exomethylene carbon are prochiral monomers, stereocenters are generated in the main-chain through the Correspondence to: T. Itoh (E-mail: itoh@chem.mie-u.ac.jp) polymerization process.…”

Section: Introductionmentioning

confidence: 98%