IO operations or processor-intensive operations may be canceled, interrupted, or otherwise terminated without corrupting an overriding process. The impact member comprises axially opposing impacting portion and connecting portion and a radial flange locating between the impacting portion and the connecting portion. The recycle stream is divided into two substreams: the first substream for prepurifying pure 1,3-butadiene feedstream by removing high boilers relative to 1,3-butadiene in a stripping column and the second substream in an extractive distillation plant.