Study On Clean Synthesis Of 5-Ethylidene-2-Norbornene

In recent years,5-ethylidene-2-norbornene was widely applied as third monomer of ethylene-propylene-diene elastomer manufacturing, and its demand was increased dramatically in domestic market with the rapid growth of Chinese economy. However, the key technologies for the synthesis of 5-ethylidene-2-norbornene are still monopolized by few foreign companies, as result neither the quantity nor quality of 5-ethylidene-2-norbornene manufactured by Chinese companies could meet the domestic requirements. The most mature synthetic route of 5-ethylidene-2-norbornene at present was the isomerization reaction of 5-vinyl-2-norbornene generated from the Diels-Alder reaction of cyclopentadiene and 1,3-butadiene. However, there are still some drawbacks on this route. For instance, low conversion rate, too many by-products and difficult separation. Thus, in this thesis we systematically studied on the clean synthesis of 5-ethylidene-2-norbornene:1. The vapor-phase cracking of dicyclopentadiene with the dilution of carbon dioxide was studied for the first time. Based on this, an equipment for dicyclopentadiene decomposition was designed and rationalized on laboratory scale. A yield of cyclopentadiene higher than 93% was obtained with almost 100% purity under the optimized conditions.2. The synthesis of 5-vinyl-2-norbornene from cyclopentadiene and 1,3-butadiene in supercritical carbon dioxide was explored for the first time. Through this study,29% yield of 5-vinyl-2-norbornene was obtained with the selectivity higher than 50% under optimized conditions. Moreover, the generation of undesired oligomers and polymers were well inhibited by the dilution of supercritical carbon dioxide without any inhibitor.3. The direct synthesis of 5-vinyl-2-norbornene from dicyclopentadiene and 1,3-butadiene in supercritical carbon dioxide was investigated. It was found that a comparable yield and selectivity of 5-vinyl-2-norbornene was achieved as cyclopentadiene was used under the same conditions.4. Isomerzation of 5-vinyl-2-norbornene into 5-ethylidene-2-norbornene was investigated by using sodium alkoxide as the catalyst. It was found that 5-vinyl-2-norbornene could almost quantitatively conversed into 5-ethylidene-2-norbornene in the presence of sodium alkoxide as the catalyst under the optimized conditions.