Process for the Preparation of Fluoroolefin Compounds

Abstract

The subject of the invention is a process for the preparation of fluoroolefin compounds. It relates more particularly to a process for manufacturing 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 located on adjacent carbon atoms, into contact with potassium hydroxide in a stirred reactor, containing an aqueous reaction medium, equipped with at least one inlet for the reactants and with at least one outlet, in order to give the (hydro)fluoroolefin compound, which is separated from the reaction medium in gaseous form, and potassium fluoride, (ii) bringing the potassium fluoride formed in (i) into contact, in an aqueous medium, with calcium hydroxide in order to give potassium hydroxide and to precipitate calcium fluoride, (iii) separation of the calcium fluoride precipitated in step (ii) from the reaction medium and (iv) optionally, the reaction medium is recycled after optional adjustment of the potassium hydroxide concentration to step (i).

1 - 11 . (canceled) 
     
     
         12 . A process for the manufacture of a fluoroolefin comprising:
 (a) dehydrofluorinating a fluoroalkane in the presence of KOH to produce a fluoroalkene;   (b) withdrawing a reaction stream comprising spent KOH; and   (c) recovering spent KOH.   
     
     
         13 . The process of  claim 12  wherein the fluoroalkane is comprised of a compound of formula CF 3 CYRCR′X n H p , in which Y represents a hydrogen atom or a halogen atom chosen from fluorine, chlorine, bromine or iodine and X represents a halogen atom chosen from fluorine, chlorine, bromine or iodine; n and p are integers and may independently take the value zero, 1 or 2 provided that (n+p)=2, and R represents a fluorine atom when R′ represents a hydrogen atom or R represents a hydrogen atom when R′ represents a fluorine atom. 
     
     
         14 . The process of  claim 13  wherein the fluoroalkane is 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) or 1,1,1,2,3-pentafluoropropane (HFC-245eb). 
     
     
         15 . The process of  claim 12  wherein the fluoroalkene is comprised of a compound of formula CF 3 CY═CX n H p  in which Y represents a hydrogen atom or a halogen atom chosen from fluorine, chlorine, bromine or iodine and X represents a halogen atom chosen from fluorine, chlorine, bromine or iodine; n and p are integers and may independently take the value zero, 1 or 2 provided that (n+p)=2. 
     
     
         16 . The process of  claim 15  wherein the fluoroalkene is 2,3,3,3-tetrafluoropropene (HFO-1234yf) or 1,2,3,3,3-pentafluoropropene (HFO-1225ye). 
     
     
         17 . The process of  claim 12  wherein the dehydrofluorination occurs using a continuously stirred tank reactor. 
     
     
         18 . The process of  claim 12  wherein the spent KOH is withdrawn from the reactor continuously or intermittently. 
     
     
         19 . The process of  claim 12  wherein the spent KOH is purified using at least one separation method. 
     
     
         20 . The process of  claim 19  wherein the separation method is phase separation. 
     
     
         21 . The process of  claim 12  further comprising, optionally, concentrating the purified KOH and recycling it back to the dehydrofluorination reaction. 
     
     
         22 . The process of  claim 12  wherein the reaction stream further comprises KF. 
     
     
         23 . The process of  claim 22  further comprising converting KF to KOH in the presence of Ca(OH) 2 . 
     
     
         24 . The process of  claim 23  further comprising, optionally, concentrating the converted KOH and recycling it back to the dehydrofluorination reaction. 
     
     
         25 . A process for the manufacture of a fluoroolefin comprising:
 (a) dehydrohalogenating 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) or 1,1,1,2,3-pentafluoropropane (HFC-245eb) in the presence of KOH to produce 2,3,3,3-tetrafluoropropene (HFO-1234yf) or 1,2,3,3,3-pentafluoropropene (HFO-1225ye);   (b) withdrawing a reaction stream comprising spent KOH; and   (c) recovering spent KOH.   
     
     
         26 . The process of  claim 25  wherein the dehydrohalogenation occurs using a continuously stirred tank reactor. 
     
     
         27 . The process of  claim 25  wherein the spent KOH is withdrawn from the reactor continuously or intermittently. 
     
     
         28 . The process of  claim 25  wherein the spent KOH is purified using at least one separation method. 
     
     
         29 . The process of  claim 28 , wherein the separation method is phase separation. 
     
     
         30 . The process of  claim 25  further comprising, optionally, concentrating the purified KOH and recycling it back to the dehydrohalogenation reaction. 
     
     
         31 . The process of  claim 25  wherein the reaction stream further comprises KF. 
     
     
         32 . The process of  claim 31  further comprising purifying KF from the reaction stream. 
     
     
         33 . The process of  claim 25  further comprising converting KF to KOH in the presence of Ca(OH) 2 , optionally, concentrating the KOH and recycling it back to the dehydrohalogenation reaction. 
     
     
         34 . A process for the manufacture of a fluoroolefin comprising:
 (a) dehydrohalogenating a haloalkane in the presence of KOH to produce a haloalkene;   (b) withdrawing a reaction stream comprising spent KOH; and   (c) recovering spent KOH.