Hydrocarbon
They occur in a diverse range of molecular structures and phases: they can be gases (such as methane and propane), liquids (such as hexane and benzene), low melting solids (such as paraffin wax and naphthalene) or polymers (such as polyethylene and polystyrene).
C6 through C10 alkanes, alkenes, cycloalkanes, and aromatic hydrocarbons are the main components of gasoline, naphtha, jet fuel, and specialized industrial solvent mixtures.
With the progressive addition of carbon units, the simple non-ring structured hydrocarbons have higher viscosities, lubricating indices, boiling points, and solidification temperatures.
At the opposite extreme from methane lie the heavy tars that remain as the lowest fraction in a crude oil refining retort.
They are collected and widely utilized as roofing compounds, pavement material (bitumen), wood preservatives (the creosote series) and as extremely high viscosity shear-resisting liquids.
Some large-scale non-fuel applications of hydrocarbons begin with ethane and propane, which are obtained from petroleum and natural gas.
Some eusocial arthropods, such as the Brazilian stingless bee, Schwarziana quadripunctata, use unique cuticular hydrocarbon "scents" in order to determine kin from non-kin.
[6] There is also potential to harvest hydrocarbons from plants like Euphorbia lathyris and E. tirucalli as an alternative and renewable energy source for vehicles that use diesel.
Unsaturated hydrocarbons (alkanes, alkenes and aromatic compounds) react more readily, by means of substitution, addition, polymerization.
Benzene burns with sooty flame when heated in air: Saturated hydrocarbons react with chlorine and fluorine.
The reactions proceed via free-radical pathways, in which the halogen first dissociates into a two neutral radical atoms (homolytic fission).
all the way to CCl4 (carbon tetrachloride) all the way to C2Cl6 (hexachloroethane) Aromatic compounds, almost uniquely for hydrocarbons, undergo substitution reactions.
Alkenes and some alkynes also undergo polymerization by opening of the multiple bonds to produce polyethylene, polybutylene, and polystyrene.
The vast majority of hydrocarbons found on Earth occur in crude oil, petroleum, coal, and natural gas.
Petroleum-derived hydrocarbons are mainly consumed for fuel, but they are also the source of virtually all synthetic organic compounds, including plastics and pharmaceuticals.
Lakes of liquid methane and ethane have been found on Titan, Saturn's largest moon, as confirmed by the Cassini–Huygens space probe.
[18] Burning hydrocarbons as fuel, which produces carbon dioxide and water, is a major contributor to anthropogenic global warming.
[22] Bacteria in the gabbroic layer of the ocean's crust can degrade hydrocarbons; but the extreme environment makes research difficult.
