Abstract: A process for producing an ethylene-.alpha.-olefin copolymer which includes subjecting ethylene to an oligomerization reaction in the presence of an oligomerization catalyst to convert a part of the ethylene to .alpha.-olefin, and thereby obtaining a reaction solution, a reaction gas or a mixture of the reaction solution and the reaction gas containing .alpha.-olefin and unreacted ethylene; distilling the reaction solution, the reaction gas or the mixture of the reaction solution and the reaction gas to obtain a mixture consisting mainly of ethylene and .alpha.-olefin from the top of the distillation column; and feeding a starting material containing the mixture obtained from the distillation column into a polymerization reactor, thereby copolymerizing the ethylene and .alpha.-olefin in the presence of a polymerization catalyst to obtain an ethylene-.alpha.-olefin copolymer.

Abstract: A process for producing 5-vinyl-2-norbornene which comprises the steps of subjecting a liquid raw material in which tetrahydroindene/dicyclopentadiene ratio (by weight) falls within the range of from 5/100 to 80/100 to a thermal decomposition in liquid phase in the presence of an aromatic hydrocarbon solvent having a boiling point of from 250.degree. C. to 300.degree. C. at a reaction temperature of not lower than 200.degree. C. and lower than 240.degree. C.