Hydrocarbons are also abundant in nebulae forming polycyclic aromatic hydrocarbon (PAH) compounds. Uses liquid propylene instead of liquid inert hydrocarbon diluent. Burning of hydrocarbon fuels emits carbon dioxide and other pollutants. Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Toluene reacts as a normal aromatic hydrocarbon in electrophilic aromatic substitution. Natural gas is lighter than liquid hydrocarbon. Whiting Petroleum Corporation is a company engaged in hydrocarbon exploration. Methane is the simplest hydrocarbon with the molecular formula CH. Anadarko Petroleum Corporation was a company engaged in hydrocarbon exploration. Certain hydrocarbon bromine compounds gave good results. Other monocyclic aromatic hydrocarbon include Cyclotetradecaheptaene or Cyclooctadecanonaene. Cenospheres are present in smoke from liquid hydrocarbon fuels. As such, naphthalene is classified as a benzenoid polycyclic aromatic hydrocarbon (PAH). Generally speaking, unsaturated hydrocarbon is healthier for body comparing to saturated hydrocarbon. Alkenes cause instability of hydrocarbon fuels.