Abstract
The synthesis of 5-ethylidene-2-norbornene (1), a crosslinking agent for synthetic rubbers, by Diels-Alder reaction of 1, 2-butadiene (1, 2-BD) with cyclopentadiene (CP) was investigated. The cycloaddition of 1, 2-BD with CP occurred stereoselectively to yield mainly (1) and 6-methyl-5-methylene-2-norbornene (2). The product ratio of 1 to 2 at 190°C was approximately constant, 2.3-2.4, independent of reaction time. Under the optimum reaction conditions, at 230°Cfor 3hr in benzene, the yield of 1 for equimolar reaction of 1, 2-BD and CP was about 32% and 43% for the reaction of 2 moles of 1, 2-BD and 1 mole of CP.
