Cyclic alternating copolymerization

Maleic anhydride and vinyl ether undergo a radical-catalyzed cyclic alternating copolymerization in a 2 1 ratio. This copolymer, frequently designated in the literature as DIVEMA or as pyran copolymer, has shown unusual and exciting biological activity, and has therefore undergone intensive investigation. 

Cyclic acylpalladation. Another major subtopic of carbopalladation is acylpalladation. In the mid-1960s, two seemingly independent papers were published by J. Tsuji [24] and P.R. Hughes [25,26]. The former reported a perfectly alternating copolymerization of norbornadiene with CO (Scheme 8), while the latter described two related Pd-catalyzed carbonylation cyclizations shown in Scheme 9. 

Ruthenium complex (4a) provided a new general route to alternating copolymerization utilizing cyclooctene and diacrylates via olefin metathesis (equation 65). Nuclear magnetic resonance (NMR) studies demonstrated that under the reaction conditions cyclic monomers like cyclooctene... 

Via metal catalysis, cyclic monomers such as TV-substituted maleimides M-40, M-41, and M-42 do not homopolymerize but can copolymerize with vinyl monomers, among which alternating copolymers can be obtained with styrene via a radical mechanism. The 1-13 (X = Br)/CuBr/L-l system induced alternating copolymerizations with styrene to give controlled molecular weights and narrow MWDs (Mw/Mn =1.1 — 1.4) in the bulk or anisole at 80—110 °C.219-222... 

C02, or from epoxide and cyclic acid anhydride. Because preliminary studies indicated that trlphenylphosphlne was converted to a quaternary salt in the reaction, the effect of a quaternary phosphonlum or eumnonlum salt separately prepared was examined. As a result of this investigation, the system containing an aluminum porphyrin and phosphonlum or ammonium salt was found to be a novel, effective catalyst for these alternating copolymerization reactions and to yield products with narrow molecular weight distribution. 

Dienes, allenes, and alkynes react with carbon dioxide to yield cyclic lactones—the catalysts include various Ni and Pd complexes.4 With certain diynes, alternating copolymerization with C02 results in the formation of poly (2-pyrones) (Scheme 6.16). 

Alternating copolymerization is possible in other systems because new, more stable chemical bonds are formed. Copolymerization of cyclic anhydride and THF (above Tc) to a polyester may serve as an example 89) ... 

Subjects specifically excluded are cycloolefin polymerizations catalyzed by naked nickel catalysts, palladium-catalyzed ethylene/carbon monoxide alternating copolymerizations, metathesis polymerizations of cyclic olefins, and diene polymerizations... 

Cyclic Olefin/Maleic Anhydride (COMA) Free Radical Alternating Copolymerization... 

Configuration of atoms C2/C3 in the ring of E—N copolymers can be either 5// or R/S, so two subsequent norbomene units can be either erythro di-isotactic (meso) or erythro di-syndiotactic (racemic). The possible stereochemical environments of norbomene in alternating sequences, diads, and triads are illustrated in Fig. 4. Erythro di-isotactic and erythro di-syndiotactic microstmctures of ENENE and ENNE segments can be obtained, depending on the catalyst stracture (for a recent review on catalysts for cyclic olefin copolymerization see [42]). The microstmcture of the copolymer can be controlled by the appropriate choice of reaction conditions and catalyst stmcture. 

These copolymerizations are closely related to the alternating copolymerization of cyclic phosphite 20 with o(-keto acid which Is discussed In the following section. 

Spontaneous alternating copolymerizations of two cyclic phosphorus compounds, 2-phenyl-l,3,2-dloxaphospholane 11 and 2-phenoxy-1,3,2-dloxaphospholane 20, with several electrophilic monomers were discussed. As the electrophilic monomers, /3-proplolactone 13, 3-hydroxypropanesulfonlc acid lactone (propane-sultone) 15, acrylic acid 16, acrylamide 17, acrylate were sucessfully copolymerized with 11. At temperatures lower than those of copolymerization, the combinations of 11—13, 11—16, 11—-17 and 11—acrylate produced trioxyphosphorane derivatives having spiro-ring structures, which were significant in two... 

We previously showed that well-defined, structurally characterized P-diiminate (BDI) zinc complexes (Figure 1) catalyze the ring-opening polymerization of cyclic esters (22,23) and the alternating copolymerization of... 

Initially PDPs were synthesized by stepwise polycondensation of linear activated depsipeptide [93]. In 1985, Helder, Feijen and coworkers reported the synthesis of PDPs by ROP of a morpholine-2,5-dione derivative (cyclic dimer of ot-hydroxy- and a-amino acid cyclodepsipeptide, cDP) [94, 95]. The ROP method gives an alternative type of PDP by homopolymerization and also allows the copolymerization with other monomers (lactones and cyclic diesters) including LA, GA, and CL to give a wide variety of functional biodegradable materials. The synthesis of PDPs as functional biomaterials has been recently reviewed [17]. 

Epoxides readily undergo anionic copolymerization with lactones and cyclic anhydrides because the propagating centers are similar—alkoxide and carboxylate [Aida et al., 1985 Cherdron and Ohse, 1966 Inoue and Aida, 1989 Luston and Vass, 1984]. Most of the polymerizations show alternating behavior, with the formation of polyester, but the mechanism for alternation is unclear. There are few reports of cationic copolymerizations of lactones and cyclic ethers other than the copolymerizations of [5-propiolactone with tetrahydrofuran and... 

Some copolymerizations have been studied where one of the reactants is a compound not usually considered as a monomer. These include copolymerizations of epoxides and higher cyclic ethers with carbon dioxide, episulhdes with carbon dioxide and carbon disulhde, and epoxides with sulfur dioxide [Aida et al., 1986 Baran et al., 1984 Chisholm et al., 2002 Inoue and Aida, 1989 Soga et al., 1977]. The copolymers are reported to be either 1 1 alternating copolymers or contain 1 1 alternating sequences together with blocks of the cyclic monomer. 

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