Purification of 1,1,1,3,3-pentafluorobutane

Abstract

In the synthesis of 1,1,1,3,3-pentafluorobutane (R-365mfc), a mixture of R-365mfc and the impurity 1-chloro-3,3,3-trifluoropropene (R-1354zd) is purified and R-1354zd is removed from the mixture by contacting the mixture with 1-5 mols of chlorine for each mol of R-1354zd in the presence of ultraviolet light having a wavelength between about 300 to 400 nm which provides at least 0.02 watts-hour/kg of the mixture. The R-1354zd is reduced to below 10 wt. ppm as it is converted to 2,3-dichloro-1,1,1,3-tetrafluorobutane (R-354) or other butane containing more chlorine and having a higher boiling point than R-365mfc. The butane(s) may be separated more easily from R-365mfc. The photochlorination is effected in a manner such that at least about 96 weight percent of the starting amount of R-365mfc is maintained in the mixture.

1 . A process for removing 1-chloro-3,3,3-trifluoropropene (R-1354zd) or other olefinic impurities from 1,1,1,3,3-pentafluorobutane (R-365mfc) by photochlorination comprising 
 (a) contacting a mixture consisting substantially of a predetermined weight amount of R-365mfc and up to about 20,000 wt. ppm R-1354zd with about 1-5 mols of chlorine for each mol of R-1354zd or other olefins in the presence of ultraviolet light having wavelengths between about 300 and 400 nm providing an exposure greater than zero and at least about 0.02 watt-hour/kg of said mixture, said photochlorination being effective to reduce the concentration in the mixture of R-1354zd or other olefins to less than 100 wt. ppm by converting said R-1354zd to 2,3-dichloro-1,1,1,3-tetrafluorobutane (R-354) or other butane which contains greater amounts of chlorine, as at least about 96% of said predetermined weight amount of R-365mfc is maintained in the mixture; and    (b) separating the R-354 or other butane formed in (a) from R-365mfc.    
     
     
         2 . A process according to  claim 1  wherein the boiling point of said R-354 or other butane is at least about 40° C. above the boiling point of said R-365mfc and separating the R-365mfc and the R-354 or other butane by distillation.  
     
     
         3 . The process of  claim 1  effected as a batch process.  
     
     
         4 . The process of  claim 1  wherein said ultraviolet light provides an exposure of about 0.02 to 2 watts-hour/kg of said mixture.  
     
     
         5 . The process of  claim 1  wherein about 1 to about 1.5 mols of chlorine are present for each mol of R-1354zd.  
     
     
         6 . The process of  claim 1  wherein the contacting of (a) is carried out at a temperature and a pressure sufficient to assure that R-365mfc is liquid.  
     
     
         7 . The process of  claim 1  wherein the contacting of (a) is carried out at a temperature and a pressure at which R-365mfc is vapor.  
     
     
         8 . The process of  claim 1  wherein the temperature is in the range of about −50° C. to 200° C.  
     
     
         9 . The process of  claim 8  wherein the temperature is in the range of about 25° C. to 60° C.  
     
     
         10 . The process of  claim 1  wherein the separation of (b) is carried out by distillation.  
     
     
         11 . The process of  claim 1  wherein said other olefinic impurities comprise R-1353.  
     
     
         12 . The process of  claim 1  effected as a continuous process.