Kinetic Studies of the Alternating Copolymerization of Butadiene with Acrylonitrile Catalyzed by the Ethylaluminum Dichloride–Vanadyl Chloride System

Haga

et al. 1971

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ABTSRACT:The relation between the alternating copolymerization of butadiene with acrylonitrile and the Diels-Alder addition reaction was investigated. It was found that the acidity of the Lewis acids as complexing agents affects not only the former reaction but also the latter one, but the selectivity towards both reactions is little affected. On the other hand, the addition of the vanadyl compound as a cocatalyst or the irradiation of UV-light enhances the selectivity towards the alternating copolymerization preventing the formation of the Diels-Alder adduct. Experiments at varied temperatures show that the Diels-Alder reaction is a thermal reaction, whereas the alternating polymerization is enhanced by UV-irradiation with the low activation energy. However, the yields of the products in both reactions attain their maxima at a 1 : I-monomer composition and at the same moderate acidity of the complexing agent such as aluminum halide. It is concluded that both reactions arise from the same intermediate such as the ternary complex and the difference may consist in the energy state of the intermediate. According to the Woodward-Hoffmann rule, the energy state of butadiene is normal for the Diels-Alder reaction, whereas it is triplet transoid for the alternating copolymerization.KEY WORDS Alternating Copolymerization / Diels-Alder Reaction/ Acrylonitri!e-Methyl Methacrylate-Butadiene / Lewis Acid Catalyst/ AIBN /UV-Irradiation/ Vanadyl Chloride/ Activation Energy/ Reaction Mechanism / Alder adduct. 1 In the alternating copolymerization of acrylic monomer with diolefin, an appreciable amount of Diels-Alder adduct was formed as a byproduct when the reaction temperature was raised above room temperature. In the case with aluminum chloride(A1Cl 3) as a complexing agent, the polymerization requires the much higher temperature because of its low activity, and as a result the much larger amount of Diels-Alder adduct is formed. The reaction between butadiene(BD) and acrylic compound accelerated by aluminum chloride at elevated temperature was already attempted by Inukai, et al., and the main product was the Diels-

“…3 As metal halides and azobisisobutylonitrile, all commercial products of guaranteed grade were used. The reaction under UV -irradiation was conducted in a sealed test tube of hard glass.…”

Section: Almentioning

confidence: 99%

The Relation between the Alternating Copolymerization and the Diels–Alder Reaction

Haga

et al. 1971

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“…1 Consequently, the present copolymerization proceeds through the mechanism analogous to that for the previous one. It is likely that the active species is proportional both to the square root of aluminum and vanadium compounds, and this suggests that rapid initiation takes place through a redox mechanism between both catalyst components.…”

Section: Discussionmentioning

confidence: 87%

“…1 The polymerization proceeds through a step-growth mechanism by the reaction of a growing radical with the BD-AN-EtA1Cl2 complex. Vanadium compounds act not only as a regenerator of aluminum compounds but also as a cocatalyst forming a redox system with aluminum compounds.…”

mentioning

confidence: 99%

Alternating Copolymerization of Butadiene and Acrylic Compounds

Iseda

et al. 1970

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ABSTRACT:A kinetic investigation on the alternating copolymerization of butadiene (BD) and methyl methacrylate (MMA) was undertaken by using EtAlClz (Al) and VOCh (V) as catalysts. The rate orders with respect to both components were the same as those for the butadiene (BD)-acrylonitrile (AN) system as reported previously; the rate of polymerization, Rp,o These relations are interpreted in terms of the mechanism involving a rapid initiation followed by stepwise propagation through a BD-MMA-Al complexed monomer. The formation of a benzene-MMA-Al complex as well as a MMA-Al complex is supposed. The rate order with respect to BD and acrylic monomer (A) was found to be complicated, i.e., in the BD-AN system Rp,o is proportional to [BD][ANJ-2, whereas in the BD-MMA system Rp,o depends on neither [BD] nor [MMA]. This fact may be accounted for in terms of the equilibrium of the BD-A-Al complex and the (A)n-Al complex. It is assumed that in a BD-AN-Al system the equilibrium constant for the (AN)n-Al complex is very large, whereas in a MMA-BD-Al system the equilibrium constant for the (MMA)n-Al complex is smaller than that of the BD-MMA-Al complex.KEY WORDS Alternating Copolymerization / Butadiene-Acrylonitrile / Butadiene-Methyl Methacrylate / Vanadyl Chloride-Ethylaluminum Dichloride/ Rate/ Molecular Weight/ Mechanism/ NMR of Copolymer/ A kinetic study on the alternating copolymerization of butadiene (BD) and acrylonitrile (AN) with an EtAlCl2-VOC13 catalyst system was described in a previous report. 1 The polymerization proceeds through a step-growth mechanism by the reaction of a growing radical with the BD-AN-EtA1Cl2 complex. Vanadium compounds act not only as a regenerator of aluminum compounds but also as a cocatalyst forming a redox system with aluminum compounds. amount of AN monomer.This report deals with an alternating copolymerization of BD and methyl methacrylate (MMA) in relation to the BD-AN system, because the former polymer is quite soluble in the system in a wide range of monomer composition. A complex formation between MMA and EtAlCl2 and a ternary complex among MMA, benzene and EtAlCl2 were supposed.However, the detailed mechanism of polymerization, especially the participation of monomer in the alternating copolymerization, is not yet discussed, since the polymer is sparingly soluble except in the reaction system containing a large EXPERIMENTALThe procedure of the catalyst purification and the polymerization are almost the same as those in the preceding report 1 unless otherwise described. MonomersThe purification of BD and AN is the same as in the previous report1 and MMA is purified by conventional method.

“…4 * Institute for Chemical Research, Kyoto University, Uji, Japan. ** On leave from Tokyo Research Institute, Bridgeston Tire Co., Ltd., Tokyo, Japan.…”

Section: Methodsmentioning

confidence: 99%

“…We have reported on the preparation methods of gel-free alternating copolymers of conjugated diolefins and polar acrylic at rather low temperature such as 0°C, 1 ' 2 mechanical properties of the alternating copolymer of butadiene and acrylonitrile, 3 kinetic studies on the alternating copolymerization of butadiene with acrylonitrile or methyl methacrylate with use of ethylaluminum dichloride-vanadyl trichloride (VOC13 or V) catalyst at 0°C, 4 ' 5 and the alternating copolymerization of butadiene with acrylonitrile under . UV irradiation in the presence of Lewis acid.…”

mentioning

confidence: 99%

Alternating Copolymerization of Butadiene with Acrylic Compounds; Monomer–Catalyst Complexes

Iseda

1971

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ABSTRACT:Complex formations among butadiene(BD), acrylic compounds(A) such as acrylonitrile(AN) and methyl methacrylate(MMA), and ethylaluminum dichloride (EtAICI2 or AI) were investigated with cryoscopic measurement, NMR and UV spectroscopies.From the cryoscopic study on the benzene solution of ethylaluminum dichloride and acrylic monomers such as methacrylonitrile(MAN), acrylonitrile, and methyl methacrylate, the existence of some complexes such as [MAN·Al]