Epoxides, copolymerization with

Although acetonitrile is one of the more stable nitriles, it undergoes typical nitrile reactions and is used to produce many types of nitrogen-containing compounds, eg, amides (15), amines (16,17) higher molecular weight mono- and dinitriles (18,19) halogenated nitriles (20) ketones (21) isocyanates (22) heterocycles, eg, pyridines (23), and imidazolines (24). It can be trimerized to. f-trimethyltriazine (25) and has been telomerized with ethylene (26) and copolymerized with a-epoxides (27). 

The reaction of OF2 and various unsaturated fluorocarbons has been examined (35,36) and it is claimed that OF2 can be used to chain-extend fluoropolyenes, convert functional perfluorovinyl groups to acyl fluorides and/or epoxide groups, and act as a monomer for an addition-type copolymerization with diolefins. 

Propylene oxide can be copolymerized with other epoxides, such as ethylene oxide (qv) (25,29,30) or tetrahydrofiiran (31,32) to produce copolymer polyols. Copolymerization with anhydrides (33) or CO2 (34) results in polyesters and polycarbonates (qv), respectively. 

An alternative method for generating enriched 1,2-diols from meso-epoxides consists of asymmetric copolymerization with carbon dioxide. Nozaki demonstrated that a zinc complex formed in situ from diethylzinc and diphenylprolinol catalyzed the copolymerization with cyclohexene oxide in high yield. Alkaline hydrolysis of the isotactic polymer then liberated the trans diol in 94% yield and 70% ee (Scheme 7.20) [40]. Coates later found that other zinc complexes such as 12 are also effective in forming isotactic polymers [41-42]. 

Besides olefin epoxidation, C02/epoxide copolymerization reactions were catalyzed with Zn-complex catalyst 10 (Figure 23) [91] as well as a silsesquinoxane-based Zn-complex [92] synthesized via multi-step in situ synthetic strategies. 

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... 

Phenolic derivatives were prepared and then converted into thioether analogs using ethanedithol followed by oxidation of this intermediate to the disulfide. Phenolic resins were prepared by electrophilic substitution of allyl phenol derivatives with formaldehyde and then flee radically copolymerizing with ethanedithol. Epoxidation was performed using epichlarohydrine. 

Little is known about the reactivity of anhydrides in copolymerizations connected with ring opening. Tsirkin et al.53) have reported a decrease in the reactivity of anhydrides in anionic copolymerization with epoxides with increasing gelation time maleic > phthalic > tetrahydrophthalic > methyltetrahydrophthalic anhydrides. 

For the copolymerization of epoxides with cyclic anhydrides and curing of epoxy resins, Lewis bases such as tertiary amines are most frequently used as initiators. In this case, terminal epoxides react with cyclic anhydrides at equimolar ratios. The time dependence of the consumption of epoxide and anhydride is almost the same for curing 35-36> and for model copolymerizations 39,40,45). The reaction is specific 39,40) to at least 99 %. In contrast, the copolymerization with non-terminal epoxides does not exhibit this high specificity, probably because of steric hindrances. The copolymerization of vinylcyclohexene oxide or cyclohexene oxide is specific only to 75-80 % and internal epoxides such as alkylepoxy stearates react with anhydrides only to 60-65 %. On the other hand, in the reaction of epoxy resins with maleic anhydride the consumption of anhydride is faster 65the products are discoloured and the gel is formed at a low anhydride conversion 39). Fischer 39) assumes that the other resonance form of maleic anhydride is involved in the reaction according to Eq. (33). 

Antoon and Koenig671 reject this isomerization of epoxides in copolymerization with anhydrides on the basis of IR spectra. However, in the monomer feed, proton... 

Propylene oxide represents a very attractive epoxide monomer for copolymerization with C02, as polypropylene carbonate) is industrially valuable. The low glass transition temperature (Tg) of 313 K, the sharp and clean decomposition above 473 K, and biodegradability of this copolymer are the reasons for its attracting interest in several applications. On a similar basis, H NMR spectroscopy is useful for assessing the coupling products resulting from the reaction of PO and C02 (Figure 8.21). 

D. Seebach, Preparation of dendritic and non-dendritic styryl-substituted Salens for cross-linking suspension copolymerization with styrene and multiple use of the corresponding Mn and Cr complexes in enantioselective epoxidations and hetero-Diels-Alder reactions, Chem - Eur.J. 2001, 7, 2873-2887. 

Ferulic acid, a phenolic acid that can be found in rapeseed cake, has been used in the synthesis of monomers for ADMET homo- and copolymerization with fatty acid-based a,co-dienes [139]. Homopolymerizations were performed in the presence of several ruthenium-based olefin metathesis catalysts (1 mol% and 80°C), although only C5, the Zhan catalyst, and catalyst M5i of the company Umicore were able to produce oligomers with Tgs around 7°C. The comonomers were prepared by epoxidation of methyl oleate and erucate followed by simultaneous ring opening and transesterification with allyl alcohol. Best results for the copolymerizations were obtained with the erucic acid-derived monomer, reaching a crystalline polymer (Tm — 24.9°C) with molecular weight over 13 kDa. 

The prepolymer contains epoxide rings and hydroxyl groups. Copolymerization with a triamine occurs at the epoxide ends of the prepolymer. 

The copolymerization with CO2 is a general reaction for epoxides unsubsti tuled, munosubstituted and disubstituted epoxides, such as propylene oxide or cydohexene oxide, are readily copolymerizable. Four membered ring ethers (oxetanes) or five membercd ring ethers (tetrahydrofuran), however, do not copolymerizc in the presence of the organozinc catalyst system. 

In another approach to copolymers, linear H-terminated polysiloxanes are hydrosilated to introduce reactive groups. Examples are the addition of allylamine to give reactive intermediates that can be converted to polysiloxane-polyimides or polyamides, and the hydrosilylation of allyl glycidyl ether to produce a silicone that can be copolymerized with epoxides or acrylates (equations 29 and 30). 

Multifunctional POSS, containing four epoxide groups on the periphery, copolymerized with aliphatic diepoxides and an amine-curing agent increased and broadened the Tg, increased the tensile modulus, but lowered the flexural modulus over that of the neat epoxy resin [2] (Fig. 3). 

Switchable polarity solvents have recently been used in two chemical syntheses the polymerization of styrene (Figure 9.7) and carbon dioxide-epoxide copolymerization (Figure 9.8). In the first study,a non-stoichiometric mixture of DBU and 1-propanol was used as this gave a less viscous reaction mixture, which facilitated the filtration step and the isolation of the polystyrene. The recovered ionic liquid was turned back into the less polar mixture using nitrogen and could be reused four times with the addition of some makeup solvent to replace that lost in the filtration step. 

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