Processes for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene and 2,3,3,3-tetrafluoropropene

To provide a simple and economical process for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene, which does not require purification of the raw material component obtained in the form of a mixture of isomers, and a process for producing 2,3,3,3-tetrafluoropropene from the product thereby obtained. A process for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene, characterized by bringing a mixture of dichloropentafluoropropane isomers which contains 1,1-dichloro-2,2,3,3,3-pentafluoropropane into contact with an aqueous alkali solution in the presence of a phase transfer catalyst, and thereby selectively dehydrofluorinating only the 1,1-dichloro-2,2,3,3,3-pentafluoropropane in the mixture, and a process for producing 2,3,3,3-tetrafluoropropene from the 1,1-dichloro-2,3,3,3-tetrafluoropropene thereby obtained.