Method for Preparing Olefin Fluorine Compounds

Abstract

The invention relates to a method for preparing olefin fluorine compounds. Specifically, the invention relates to a method for producing a (hydro)fluoroolefin compound, including: (i) in an agitated reactor provided with at least one reactant inlet and at least one outlet, contacting, with potassium hydroxide in an aqueous reaction medium, at least one compound containing three to six carbon atoms, at least two fluorine atoms, and at least one hydrogen atom, with the proviso that at least one hydrogen atom and one fluorine atom are located on adjacent carbon atoms, so as produce the (hydro)fluoroolefin compound, separated in a gaseous state from the reaction medium and from potassium fluoride; (ii) in an aqueous medium, contacting the potassium fluoride formed in step (i) with calcium hydroxide in a second reactor so as to produce potassium. hydroxide and to precipitate calcium tluoride; (iii) separating the calcium fluoride precipitated in step (ii) from the reaction medium; and (iv) optionally recirculating the reaction medium after optionally recirculating the reaction medium after optionally adjusting the concentration of potassium hydroxide in step (i), characterized in that potassium hydroxide, with regard to the reaction medium of step (ii), is between 10 and 35 wt % of the weight of the water/potassium hydroxide mixture of the medium.

1 . Process for the continuous or semicontinuous manufacture of a (hydro)fluoroolefin compound comprising (i) bringing at least one compound comprising from three to six carbon atoms, at least two fluorine atoms and at least one hydrogen atom, provided that at least one hydrogen atom and one fluorine atom are situated on adjacent carbon atoms, into contact with potassium hydroxide in an aqueous reaction medium in a stirred reactor equipped with at least one inlet and with at least one outlet, to give the (hydro)fluoroolefin compound, which is separated from the reaction medium in the gaseous form, and potassium fluoride, (ii) bringing the potassium fluoride formed in (i) into contact in an aqueous medium with calcium hydroxide in a second reactor, to give potassium hydroxide and calcium fluoride precipitate, (iii) separating the calcium fluoride precipitated in stage (ii) from the reaction medium and (iv) optionally recycling the reaction medium to stage (i) after optional adjustment of the concentration of potassium hydroxide, characterized in that the potassium hydroxide represents, in the reaction medium of stage (ii), between 10 and 35% by weight, with respect to the weight of the water and potassium hydroxide mixture of the medium. 
     
     
         2 . Process according to  claim 1 , characterized in that the (hydro)fluoroolefin comprises a compound of formula (1)
   CF 3 CY=CX n H p   (I)
   
       in which Y represents a hydrogen atom or a halogen atom chosen from fluorine, chlorine, bromine or iodine, X represents a halogen atom chosen from fluorine, chlorine, bromine or iodine, and n and p are integers and can independently take the value zero, 1 or 2, provided that (n+p)=2, and said at least one compound comprises a compound of formula CF 3 CYRCR′X n H p , where R represents a fluorine atom when R′ represents a hydrogen atom or R represents a hydrogen atom when R′ represents a fluorine atom. 
     
     
         3 . Process according to  claim 1 , characterized in that the (hydro)fluoroolefin comprises a compound of formula (Ia)
   CF 3 CF=CHZ  (Ia)
   
       in which Z represents a hydrogen atom or a fluorine atom, and said at least one compound comprises a compound of formula CF 3 CFRCHR′Z, where R represents a fluorine atom when R′ represents a hydrogen atom or R represents a hydrogen atom when R′ represents a fluorine atom. 
     
     
         4 . Process according to  claim 1 , characterized in that said (hydro)fluoroolefin comprises 2,3,3,3-tetrafluoropropene and said at least one compound comprises 1,1,1,2,3-pentafluoropropane into contact with potassium hydroxide and/or 1,2,3,3,3-pentafluoropropene. 
     
     
         5 . Process according to  claim 1 , characterized in that the potassium hydroxide represent between 20 and 75% by weight, with respect to the weight of the water and KOH mixture present in the aqueous reaction medium of stage (i). 
     
     
         6 . Process according to  claim 1 , characterized in that the temperature at which stage (i) is carried out is between 80 and 180° C. 
     
     
         7 . Process according to  claim 1 , characterized in that the temperature of stage (ii) is between 50 and 150° C. 
     
     
         8 . Process according to  claim 1 , characterized in that stage (ii) is fed with potassium fluoride via the reaction medium originating from stage (i). 
     
     
         9 . Process according to  claim 1 , characterized in that the potassium fluoride represents between 4 and 45% by weight of the reaction medium from stage (i). 
     
     
         10 . Process according to  claim 8 , further characterized in that water is added to the reaction medium of stage (ii). 
     
     
         11 . Process according to  claim 1 , characterized in that the calcium fluoride in stage (iii) is filtered off after an optional settling stage. 
     
     
         12 . Process according to  claim 11 , characterized in that, during settling, a portion of the concentrated calcium fluoride suspension is recycled to stage (ii). 
     
     
         13 . Process according to  claim 1 , characterized in that said (hydro)fluoroolefin comprises 1,2,3,3,3-pentafluoropropene and said at least one compound comprises 1,1,1,2,3,3-hexafluoropropane. 
     
     
         14 . Process according  claim 1 , characterized in that the potassium hydroxide represent between 55 and 70% by weight, with respect to the weight of the water and KOH mixture. 
     
     
         15 . Process according to  claim 1 , characterized in that the temperature at which stage (i) is carried out is between 125 and 180° C. 
     
     
         16 . Process according to  claim 1 , characterized in that the temperature at which stage (i) is carried out is between 145 and 165° C. 
     
     
         17 . Process according to  claim 1 , characterized in that the temperature of stage (ii) is Between 70 and 120° C. 
     
     
         18 . Process according to  claim 1 , characterized in that the temperature of stage (ii) is between 70 and 100° C.