Patent ID: 7405333

Claim:
In a process for the preparation of a substantially pure, liquefied stream of 1,1,1,2-tetrafluoroethane by the steps of 1) reacting hydrogen fluoride with trichloroethylene in the presence of a hydrofluorination catalyst at a temperature below 200° C. for a time sufficient to form a 2-chloro-1,1,1-trifluoroethane-containing reaction stream and hydrogen chloride as a first by-product of said reacting and then 2) reacting the 2-chloro-1,1,1-trifluoroethane of said reaction stream with hydrogen fluoride in the presence of a hydrofluorination catalyst at a temperature above 200° C. to form a 1,1,1,2-tetrafluoroethane-containing reaction stream and hydrogen chloride as a second by-product of said reacting, the improvement comprising (a) liquefying the first by-product hydrogen chloride and then (2) countercurrently passing said liquefied hydrogen chloride through said 1,1,1,2-tetrafluoroethane-containing reaction stream thereby forming a substantially pure, liquefied stream of 1,1,1,2-tetrafluoroethane and an effluent comprising gaseous hydrogen chloride.