FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Sulfur Mercaptan (F510000) Thiol (F510000) Alkyl thiol (F511000) Primary alkyl thiol (F511100) Secondary alkyl thiol (F511200) Tertiary alkyl thiol (F511300) Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin