Ppg Industries, Inc.

W Eugene Wimer

J Douglas Mansell

Robert K Pertuit

Henry W Schussler

Fred C Trager

J Boyd Alleman

Perchloroethylene containing contaminating amounts of dichlorobutadiene is treated with bromine, e.g., elemental bromine, in the presence of a free-radical initiator, thereby to produce perchloroethylene substantially-free of dichlorobutadiene and without significant loss of perchloroethylene. A bromine scavenger, e.g., trichloroethylene, can be added to the treated perchloroethylene to react with excess bromine that may be present in the perchloroethylene.

Method for purifying perchloroethylene containing dichlorobutadiene

A gaseous feed stream comprising hydrogen fluoride and 1,1-difluoroethane is contacted with liquid organic barrier material in a condensing zone to partially condense the feed stream. The gaseous phase remaining after the partial condensation comprises most of the 1,1-difluoroethane originally present in the feed stream while the liquid condensate comprises most of the hydrogen fluoride originally present in the feed stream. The gaseous phase and the liquid condensate are removed from the condensing zone as separate streams. Less than about 50 percent of the 1,1-difluoroethane originally present in the feed stream reacts with hydrogen fluoride to form 1,1,1-trifluoroethane during the partial condensation and the removal of the separate streams from the condensing zone. The preferred liquid organic barrier material is 1,1,-trifluoroethane.

Separation of hydrogen fluoride from 1,1-difluoroethene

The water content of crude 1,2-dichloroethane compositions containing chloral hydrate is reduced by stripping under superatmospheric pressure.

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Delmont, PA, United States of America

W Eugene Wimer