FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Sulfur Sulfate (F574000) Sulfuric acid (F574100) Sulfate ester (F574200) Imine sulfate (F574910) Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin