Abstract: The present invention provides a process for producing a polyester ether copolymer which comprises conducting polycondensation after or while melting and mixing a polyester, of 0.3 (dl/g) or more in intrinsic viscosity, and a polyether having hydroxy groups or their derivatives at its terminals and having a molecular weight of 200 or more. The present invention can dispense with the steps of esterification, transesterification, etc., because of the use of the preformed polyester. Moreover, it shortens the reaction time so that only a small quantity of polyester is produced as a by-product. In addition, since the thermal history of the polyesterh is so small, deterioration of the polymer during production is suppressed. Furthermore, this process enables continuous production of products with good quality, which serves to markedly improve productivity.

Abstract: A method of producing cyclopentene comprising the steps of depolymerizing dicyclopentadiene to produce raw cyclopentadiene; feeding the raw cyclopentadiene to a distillation tower having an upper part cooled to a temperature near the boiling point of the cyclopentadiene and an outlet maintained at 35.degree. to 60.degree. C and a lower part at a temperature of 40.degree. to 150.degree. C; thereby to produce highly pure gaseous cyclopentadiene at the top outlet and impure components having high boiling point at the lower outlet which are removed continuously; mixing the highly pure cyclopentadiene obtained thereby with hydrogen and reacting in a first hydrogenation reactor using a palladium containing catalyst, then mixing the resulting product with hydrogen and reacting in a second hydrogenation reactor with a palladium containing catalyst; cooling the resulting product and separating the liquid phase from the gas phase and recirculating the gas phase for use in the hydrogenation reactions.