a portion of a production recycle stream was analyzed and the portion distilled to recover a 10 percent by weight cut of the portion containing essentially all the compounds boiling at a lower temperature than 1 , 2 - dichloroethane contained in the portion . the 10 percent cut was hydrogenated for 2 . 2 hours over 0 . 1 percent by weight palladium on silica at about 80 psig hydrogen pressure and 60 ° c . three molecules of hydrogen were fed to the hydrogenation reactor per molecule of chloroprene . the analysis of the so hydrogenated cut is set forth below . combination of the bottoms of a distillation of this hydrogenated cut with the 90 percent bottoms from the first distillation illustrates the marked reduction in chloroprene , particularly , as well as other partially chlorinated hydrocarbons in the portion . table for example 1__________________________________________________________________________ stream d stream b analysis of 90 % stream a analysis of a bottoms cut from analysis of a 10 % by weight stream c stream a combined typical pro - distillation analysis of with bottoms from duction recycle cut of stream stream b after distillation of stream a hydrogenation stream c__________________________________________________________________________ethane -- -- 0 . 16 -- butane -- -- 0 . 25 -- vinyl chloride -- -- -- -- ethyl chloride -- -- 0 . 34 -- vinylidene chloride 0 . 06 0 . 59 -- -- 1 - chlorobutene - 1 -- -- 0 . 59 -- 1 - chlorobutene - 2 -- -- -- -- trans - 1 , 2 - dichloroethylene 0 . 08 0 . 83 0 . 56 -- 2 - chlorobutene - 1 -- -- 4 . 01 tracechloroprene 0 . 47 4 . 67 0 . 14 -- 2 - chlorobutane -- -- 0 . 02 -- 1 , 1 - dichloroethane 0 . 05 0 . 47 0 . 30 -- 2 - chlorobutene - 2 -- -- 0 . 17 -- 1 - chloro - 1 , 3 - butadiene 0 . 07 0 . 73 -- -- 1 - chlorobutane -- -- 0 . 06 -- carbon tetrachloride 0 . 02 0 . 24 0 . 11 -- cis - 1 , 2 - dichloroethylene 0 . 10 1 . 03 0 . 72 -- benzene -- -- -- -- chloroform 0 . 10 1 . 03 0 . 70 -- trichloroethylene 0 . 01 trace trace trace1 , 2 - dichloroethane 98 . 06 90 . 4 91 . 87 99 . 02perchloroethylene 0 . 20 trace trace 0 . 201 , 1 , 2 - trichloroethane 0 . 78 -- -- 0 . 78__________________________________________________________________________ a portion of a production recycle stream was analyzed and the entire portion hydrogenated over 1 percent by weight palladium on silica bed . the analysis of the recycle stream before and after hydrogenation and reaction conditions are shown below : table for example 2______________________________________hydrogen rate , liter / hour 2 . 0recycle 1 , 2 - dichloroethane rate , liter / hour 0 . 191catalyst 1 % pdreactor volume , liter 0 . 300reactor pressure , psig 200reaction temperature 150 ethylene ethylene dichloride dichloride production production recycle recycle stream stream before after hydro - hydro - component genation genation______________________________________ethane -- 0 . 07butane -- 0 . 57vinyl chloride -- -- ethyl chloride trace 0 . 03vinylidene chloride 0 . 02 -- 1 - chlorobutene - 1 -- trace1 - chlorobutene - 2 -- tracetrans - 1 , 2 - dichloroethylene 0 . 04 0 . 022 - chlorobutene - 1 -- 0 . 05chloroprene 0 . 60 -- 2 - chlorobutane -- 0 . 061 , 1 - dichloroethane 0 . 02 0 . 022 - chlorobutene - 2 -- 0 . 011 - chloro - 1 , 3 - butadiene 0 . 09 trace1 - chlorobutane -- -- carbon tetrachloride trace tracecis - 1 , 2 - dichloroethylene 0 . 11 0 . 02benzene -- -- chloroform 0 . 03 0 . 02trichloroethylene trace trace1 , 2 - dichloroethane 98 . 69 98 . 75perchloroethylene 0 . 03 0 . 021 , 1 , 2 - trichloroethane 0 . 37 0 . 36______________________________________ a portion of a production recycle 1 , 2 - dichloroethane stream was analyzed and hydrogenated over 0 . 5 percent by weight palladium on charcoal . the analysis of the recycle before and after hydrogenation is set forth below . these analyses illustrate the elimination of trichloroethylene as well as other partially chlorinated compounds . operation of the foregoing procedure resulted in a 3 percent by weight increase in 1 , 2 - dichloroethane . table for example 3______________________________________reaction temperature , ° c . 200reaction pressure , psig 300catalyst volume , liters 0 . 1ethylene chloride feed , liter / hour 0 . 2hydrogen rate , mole / hour 1 . 0 ethylene ethylene dichloride dichloride recycle recycle before after hydro - hydro - component genation genation______________________________________ethylene 0 . 01 -- ethane -- 0 . 99vinyl chloride 0 . 01 -- ethyl chloride -- 0 . 74unknowns -- -- vinylidene chloride 0 . 01 -- trans - 1 , 2 - dichloroethylene 0 . 02 -- methylene chloride 0 . 01 0 . 121 , 1 - dichloroethane 0 . 04 -- chloroprene 0 . 01 -- methyl chloroform 0 . 06 -- carbon tetrachloride 0 . 03 -- cis - 1 , 2 - dichloroethylene 0 . 10 -- benzene 0 . 04 0 . 14chloroform 0 . 15 -- trichloroethylene 4 . 34 -- 1 , 2 - dichloroethane 95 . 17 98 . 01______________________________________