Monomer-isomerization oligomerization of 2-ethyl-1,3-butadiene by acid catalysts |
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Authors: | Toshinobu Higashimura Hiroshi Hasegawa |
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Abstract: | The cationic oligomerization of 2-ethyl-1,3-butadiene (2EBD) by a superacid (CF3SO3H) and a superacid derivative (CH3COClO4) accompanied monomer isomerization to 3-methyl-1,3-pentadiene (3MPD) before propagation to yield oligomers of the isomerized monomer as main products in benzene at 50°C. Detection of 3MPD in the reaction mixture and 1H-NMR structural analysis of the produced oligomers confirmed the occurrence of this “monomer-isomerization oligomerization.” On the other hand, in the presence of a metal halide catalyst (BF3OEt2) 2EBD reacted without isomerization and yielded oligomers that were different from those produced by the foregoing superacid catalysts. Monomer isomerization was suppressed in a polar solvent (CH2Cl)2] or at lower temperatures. The mechanism of the oligomerization with monomer isomerization was discussed. |
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