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

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.