distillation is conducted in two steps first flash distillation is conducted at a temperature less than the reaction temperature under a pressure preferably under vacuum to remove any unreacted ccl 4 and or vcm followed by another vacuum flash distillation at a lower pressure to remove the hcc 240fa reaction product the u201c bottoms u201d stream is recycled back to the reactor the distilled unreacted ccl 4 and vcm may be recycled back to the reactor periodic purges may be applied to avoid accumulation of heavy by products such as hcc 470 isomers in catalyst recycle stream in a later step of the process the present invention provides for the purification of the crude product by distillation fractional vacuum distillation is carried out at about 5 to about 200 mm hg and a temperature of about 50 u00b0 c to about 150 u00b0 c to recover the product it has been discovered that when this purification step is carried out in the presence of a trialkyl phosphate such as tributyl phosphate or other metal chelating compound the distillation yield of purified product is significantly improved while not wishing to be bound by any particular theory it is believed that the tributylphosphate acts to prevent the decomposition of the hcc 240fa product thus in a preferred embodiment the purification step includes the addition of an amount of a metal chelating compound sufficient to improve the hcc 240fa product yield preferably 5 weight percent of tributyl phosphate is used as used herein the singular forms u201c a u201d u201c an u201d and u201c the u201d include plural unless the context clearly dictates otherwise moreover when an amount concentration or other value or parameter is given.