The interdependence among of the development of coal hydrogenation, the increase of the environmental pollution by phenol and the generation of the dephenolation will be shown by the illustration of the development of one of the most important enterprises in Central Germany - the ＇＇Leuna-Werke＇＇. First of all those reasons of the environmental load by phenol will be demonstrated which made the ecological recovery of ＇＇Leuna-Werke＇＇ necessary. Then different technologies of dephenolation will be introduced in their historical development.