Copolymerization of 1, 3-Cyclooctadiene and Acrylonitrile in the Presence of Zinc Chloride

Nagai, Katsutoshi; Machida, Shuji

doi:10.1295/koron.34.603

“…1,3-Cyclooctadiene again gave both copolymer and cycloadduct. 16 Nagai proposed that the ratio of copolymer to cycloadduct is related to the dihedral angle between the double bonds in the 1,3cyclodienes.…”

Section: Introductionmentioning

confidence: 99%

Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Mikhael¹,

Padías²,

Hall³

1994

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The reactions of the mildly electron-poor olefin methyl acrylate (MA) with three electron-rich substituted hydrocarbon 1,3-dienes, namely 2,3-dimethyl-1,3-butadiene (DMB), 4-methyl-1,3-pentadiene (MPD) and isoprene (IP) were investigated in 1,2-dichloroethane in the presence of various amounts of zinc chloride at different temperatures. ZnC1, complexes with the ester group of MA and increases the MA's electron-poor character and therefore its tendency towards reactions with electron-rich dienes. In the absence of ZnCl,, no reaction occurs between the investigated dienes and MA under the used reaction conditions. Both alternating copolymers and [4+2] cycloadducts formed spontaneously in the presence of ZnC1, even at room temperature.The structure ofthe diene and its nucleophilicity control the product distribution.For the DMB and IP systems, raising the reaction temperature and increasing the ZnC1, concentration enhance the overall reaction rate and in most cases also favor the cycloaddition over the copolymerization. IP is less reactive than DMB. With MPD only copolymer is formed because the two terminal methyl groups retard the concerted [4+2] cycloaddition.These results are in agreement with a postulated mechanism involving competition between the formation of a n-allyl2-hexene-1,6-diradical, capable of initiating free radical copolymerization, and concerted [4+2] Diels-Alder cycloaddition.

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Effect of ZnCl₂ on the spontaneous copolymerization of methyl acrylate with substituted 1,3‐dienes

Mikhael

¹

,

Padías

²

,

Hall

³

1996

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The reactions of the mildly electron-poor olefin methyl acrylate (MA) with three electron-rich substituted hydrocarbon 1,3-dienes, namely 2,3-dimethyl-1,3-butadiene (DMB), 4-methyl-1,3-pentadiene (MPD) and isoprene (IP) were investigated in 1,2-dichloroethane in the presence of various amounts of zinc chloride at different temperatures. ZnC1, complexes with the ester group of MA and increases the MA's electron-poor character and therefore its tendency towards reactions with electron-rich dienes. In the absence of ZnCl,, no reaction occurs between the investigated dienes and MA under the used reaction conditions. Both alternating copolymers and [4+2] cycloadducts formed spontaneously in the presence of ZnC1, even at room temperature.The structure ofthe diene and its nucleophilicity control the product distribution.For the DMB and IP systems, raising the reaction temperature and increasing the ZnC1, concentration enhance the overall reaction rate and in most cases also favor the cycloaddition over the copolymerization. IP is less reactive than DMB. With MPD only copolymer is formed because the two terminal methyl groups retard the concerted [4+2] cycloaddition.These results are in agreement with a postulated mechanism involving competition between the formation of a n-allyl2-hexene-1,6-diradical, capable of initiating free radical copolymerization, and concerted [4+2] Diels-Alder cycloaddition.

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New developments in bond‐forming initiation: Lewis acids accelerate spontaneous initiation of copolymerizations of olefins and dienes

Hall

¹

,

Padías

²

,

Srisiri

³

et al. 1995

Macromolecular Symposia

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Lewis acids have long been known to influence the free radical propagation of donor‐acceptor olefin monomer pairs, changing random copolymers into strictly alternating ones, by complexing to the lone pair electrons of the acceptor monomer, and enhancing its electron‐poor character. This work reports that this same interaction enhances the rates of the spontaneous initiation in these systems. In agreement with earlier literature, we found that styrene‐acrylonitrile copolymerizations proceed readily in the presence of ZnCl2 at 40° where no copolymerization occurs in the absence of the Lewis acid. p‐Methoxystyrene and isobutyl vinyl ether with AN gave more complicated results, due to competitive complexation of oxygen lone pairs with ZnCl2. Reaction of more electrophilic olefins with these donor monomers gave steadily increasing rates and a shift in product from spontaneous copolymer to inverse Diels‐Alder adduct (in the case of ester substituents) to cyclobutane. As for substituted diene monomers as the donor component, reactions of isoprene and 2,3‐dimethylbutadiene with AN are accelerated in the presence of ZnCl2 and the Lewis acid affects the competition between the [4+2] cycloaddition and the copolymerization. All of these results are interpreted in the context of formation of Lewis‐acid complexed initiating diradicals by bond‐formation.

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Copolymerization of 1, 3-Cyclooctadiene and Acrylonitrile in the Presence of Zinc Chloride

Cited by 8 publications

References 0 publications

Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Effect of ZnCl₂ on the spontaneous copolymerization of methyl acrylate with substituted 1,3‐dienes

New developments in bond‐forming initiation: Lewis acids accelerate spontaneous initiation of copolymerizations of olefins and dienes

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Copolymerization of 1, 3-Cyclooctadiene and Acrylonitrile in the Presence of Zinc Chloride

Cited by 8 publications

References 0 publications

Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Effect of ZnCl2 on the spontaneous copolymerization of methyl acrylate with substituted 1,3‐dienes

New developments in bond‐forming initiation: Lewis acids accelerate spontaneous initiation of copolymerizations of olefins and dienes

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Effect of ZnCl₂ on the spontaneous copolymerization of methyl acrylate with substituted 1,3‐dienes