Method for producing 1, 1-dichloro-2,2,3,3,3-pentafluoropropane

Abstract

To provide a method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca) at a high content ratio, which is useful as e.g. a starting material to obtain 1,1-dichloro-2,3,3,3-tetrafluoropropene (R1214ya). The method comprises subjecting a starting material comprising one isomer or a mixture of at least two isomers of dichloropentafluoropropane (HCFC-225) and having a HCFC-225ca content of less than 60 mol%, to an isomerization reaction in the presence of a Lewis acid catalyst or a metal oxide catalyst so as to increase the HCFC-225ca content in the product to be higher than the content in the starting material.

1 . A method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane, which comprises subjecting a staffing material comprising one isomer or a mixture of at least two isomers of dichloropentafluoropropane and having a 1,1-dichloro-2,2,3,3,3-pentafluoropropane content of less than 60 mol %, to an isomerization reaction in the presence of a Lewis acid catalyst or a metal oxide catalyst so as to increase the 1,1-dichloro-2,2,3,3,3-pentafluoropropane content in the product to be higher than the content in the starting material. 
   
   
       2 . The method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to  claim 1 , wherein the starting material contains 1,3-dichloro-1,2,2,3,3-pentafluoropropane, and the 1,3-dichloro-1,2,2,3,3-pentafluoropropane is subjected to an isomerization reaction to form 1,1-dichloro-2,2,3,3,3-pentafluoropropane. 
   
   
       3 . The method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to  claim 2 , wherein the starting material further contains 2,2-dichloro-1,1,1,3,3-pentafluoropropane. 
   
   
       4 . The method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to  claim 1 , wherein the isomerization reaction is carried out in a liquid phase in the presence of a Lewis acid catalyst at a temperature of from 0 to 150° C. 
   
   
       5 . The method for producing 1,1-dichloro-2,2,3,3,3-pentafluoropropane according to  claim 1 , wherein the isomerization reaction is carried out in a gas phase in the presence of a metal oxide catalyst at a temperature of from 50 to 500° C. 
   
   
       6 . A method for producing 1,1-dichloro-2,3,3,3-tetrafluoropropene, which comprises bringing the 1,1-dichloro-2,2,3,3,3-pentafluoropropane obtained by the method as defined in  claim 1  into contact with an aqueous alkali solution in the presence of a phase transfer catalyst. 
   
   
       7 . A method for producing 2,3,3,3-tetrafluoropropene, which comprises reacting the 1,1-dichloro-2,3,3,3-tetrafluoropropene obtained by the method as defined in  claim 6  with hydrogen in the presence of a catalyst. 
   
   
       8 . The method for producing 2,3,3,3-tetrafluoropropene according to  claim 7 , which is carried out in the presence of an inert gas.