Editing Hydrocarbon

{{short description|Organic compound consisting entirely of hydrogen and carbon}}
{{distinguish|Carbohydrate}}
{{pp-semi-indef|small=yes}}
[[File:Methane-3D-balls.png|thumb|upright|[[Ball-and-stick model]] of the [[methane]] molecule, CH{{sub|4}}. Methane is part of a [[homologous series]] known as the [[alkane]]s, which contain single [[Chemical bond|bonds]] only.]] 
In [[organic chemistry]], a '''hydrocarbon''' is an [[organic compound]] consisting entirely of [[hydrogen]] and [[carbon]].<ref name=Silberberg>{{cite book | author = Silberberg, Martin | title = Chemistry: The Molecular Nature Of Matter and Change | location = New York | publisher = McGraw-Hill Companies | date = 2004 | isbn = 0-07-310169-9}}</ref>{{rp|620}} Hydrocarbons are examples of [[group 14 hydride]]s. Hydrocarbons are generally colourless and [[Hydrophobe|hydrophobic]]; their odor is usually faint, and may be similar to that of [[gasoline]] or [[Naphtha|lighter fluid]]. They occur in a diverse range of molecular structures and phases: they can be [[gas]]es (such as [[methane]] and [[propane]]), [[liquid]]s (such as [[hexane]] and [[benzene]]), low melting [[solid]]s (such as [[paraffin wax]] and [[naphthalene]]) or [[polymer]]s (such as [[polyethylene]] and [[polystyrene]]).

In the [[fossil fuel]] industries, ''hydrocarbon'' refers to naturally occurring [[petroleum]], [[natural gas]] and [[coal]], or their hydrocarbon derivatives and purified forms. Combustion of hydrocarbons is the main source of the world's energy. Petroleum is the dominant raw-material source for organic [[commodity chemicals]] such as solvents and polymers. Most anthropogenic (human-generated) emissions of [[greenhouse gas]]es are either [[carbon dioxide]] released by the burning of [[fossil fuels]], or methane released from the handling of natural gas or from agriculture.

==Types==
As defined by the [[International Union of Pure and Applied Chemistry]]'s [[IUPAC nomenclature of organic chemistry|nomenclature of organic chemistry]], hydrocarbons are classified as follows:<ref name=Ullmann>{{cite book |doi=10.1002/14356007.a13_227.pub3 |chapter=Hydrocarbons |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2014 |last1=Schmidt |first1=Roland |last2=Griesbaum |first2=Karl |last3=Behr |first3=Arno |last4=Biedenkapp |first4=Dieter |last5=Voges |first5=Heinz-Werner |last6=Garbe |first6=Dorothea |last7=Paetz |first7=Christian |last8=Collin |first8=Gerd |last9=Mayer |first9=Dieter |last10=Höke |first10=Hartmut |pages=1–74 |isbn=978-3-527-30673-2 }}</ref>
# [[Saturated and unsaturated compounds|Saturated]] hydrocarbons, which are the simplest of the hydrocarbon types. They are composed entirely of [[single bond]]s and are saturated with hydrogen. The formula for [[open-chain compound|acyclic]] saturated hydrocarbons (i.e., [[alkanes]]) is C{{sub|''n''}}H{{sub|2''n''+2}}.<ref name=Silberberg/>{{rp|623}} The most general form of saturated hydrocarbons, (whether linear or branched species, and whether with or without one or more rings) is C{{sub|''n''}}H{{sub|2''n''+2(1-''r'')}}, where ''r'' is the number of rings. Those with exactly one ring are the [[cycloalkanes]]. Saturated hydrocarbons are the basis of [[petroleum fuels]] and may be either linear or branched species. One or more of the hydrogen atoms can be replaced with other atoms, for example chlorine or another halogen: this is called a substitution reaction. An example is the conversion of methane to [[chloroform]] using a [[chlorination reaction]]. Halogenating a hydrocarbon produces something that is not a hydrocarbon. It is a very common and useful process. Hydrocarbons with the same [[molecular formula]] but different [[structural formula]]e are called [[structural isomer]]s.<ref name=Silberberg/>{{rp|625}} As given in the example of [[3-methylhexane]] and its higher [[Homologous series|homologues]], branched hydrocarbons can be [[Chirality (chemistry)|chiral]].<ref name=Silberberg/>{{rp|627}} Chiral saturated hydrocarbons constitute the side chains of [[biomolecule]]s such as [[chlorophyll]] and [[tocopherol]].<ref>{{Cite book |last=Meierhenrich |first=Uwe |url=https://books.google.com/books?id=a2J23yPEaBQC |title=Amino Acids and the Asymmetry of Life: Caught in the Act of Formation |publisher=Springer |year=2008 |isbn=978-3-540-76886-9 |location=Berlin |oclc=288470227}}
</ref>
# [[Unsaturated hydrocarbon]]s, which have one or more double or triple bonds between carbon atoms. Those with one or more double bonds are called [[alkene]]s. Those with one [[double bond]] have the formula C{{sub|''n''}}H{{sub|2''n''}} (assuming non-cyclic structures).<ref name=Silberberg/>{{rp|628}} Those containing [[triple bond]]s are called [[alkyne]]. Those with one triple bond have the formula C{{sub|''n''}}H{{sub|2''n''−2}}.<ref name=Silberberg/>{{rp|631}}
# [[Aromatic hydrocarbon]]s, also known as [[arene]]s, which are hydrocarbons that have at least one [[aromatic ring]]. 10% of total nonmethane organic carbon emission are aromatic hydrocarbons from the exhaust of gasoline-powered vehicles.<ref>{{cite web |last1=Barnes |first1=I |title=TROPOSPHERIC CHEMISTRY AND COMPOSITION (Aromatic Hydrocarbons) |url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/aromatic-hydrocarbon |access-date=26 October 2020}}</ref>

The term 'aliphatic' refers to non-aromatic hydrocarbons. Saturated aliphatic hydrocarbons are sometimes referred to as 'paraffins'. Aliphatic hydrocarbons containing a double bond between carbon atoms are sometimes referred to as 'olefins'.

{| class="wikitable" style="text-align:center"
|+Variations on hydrocarbons based on the number of carbon atoms
!scope="col"|Number of<br />carbon atoms
!scope="col"|[[Alkane]] (single bond)
!scope="col"|[[Alkene]] (double bond)
!scope="col"|[[Alkyne]] (triple bond)
!scope="col"|[[Cycloalkane]]
!scope="col"|[[Alkadiene]]
|-
!scope="row"| 1
|[[Methane]] ||—||—||—||—
|-
!scope="row"| 2
|[[Ethane]] ||[[Ethene]] (ethylene)||[[Acetylene|Ethyne]] (acetylene)||—||—
|-
!scope="row"| 3
|[[Propane]] ||[[Propene]] (propylene)||[[Methylacetylene|Propyne]] (methylacetylene)|| [[Cyclopropane]] || [[Propadiene]] (allene)
|-
!scope="row"| 4
|[[Butane]] ||[[Butene]] (butylene)||[[Butyne]] || [[Cyclobutane]] || [[1,3-Butadiene|Butadiene]]
|-
!scope="row"| 5
|[[Pentane]] ||[[Pentene]] ||[[Pentyne]] || [[Cyclopentane]] || [[Piperylene|Pentadiene]] (piperylene)
|-
!scope="row"| 6
|[[Hexane]] ||[[Hexene]] ||[[Hexyne]] || [[Cyclohexane]] || [[Hexadiene]]
|-
!scope="row"| 7
|[[Heptane]] ||[[Heptene]] ||[[Heptyne]]|| [[Cycloheptane]] || [[Heptadiene]]
|-
!scope="row"| 8
|[[Octane]] ||[[Octene]] ||[[Octyne]] || [[Cyclooctane]] || [[Octadiene]]
|-
!scope="row"| 9
|[[Nonane]] ||[[Nonene]] ||[[Nonyne]] || [[Cyclononane]] || [[Nonadiene]]
|-
!scope="row"| 10
|[[Decane]] ||[[Decene]] ||[[Decyne]] || [[Cyclodecane]] || [[Decadiene]]
|-
!scope="row"| 11
|[[Undecane]] ||[[Undecene]]||[[Undecyne]]|| [[Cycloundecane]] || [[Undecadiene]]
|-
!scope="row"| 12
|[[Dodecane]] ||[[Dodecene]] ||[[Dodecyne]]|| [[Cyclododecane]] || [[Dodecadiene]]
|}

==Usage==
[[File:ShellMartinez-refi.jpg|thumb|upright=1.25|[[Oil refineries]] are one way hydrocarbons are processed for use. [[Crude oil]] is processed in several stages to form desired hydrocarbons, used as fuel and in other products.]]
[[File:2018-05-04 (303) Tank wagon 33 80 7920 362-0 with hydrocarbon gas at Bahnhof Enns.jpg|thumb|Tank wagon 33 80 7920 362–0 with hydrocarbon gas at Bahnhof Enns (2018)]]

The predominant use of hydrocarbons is as a combustible [[fuel]] source. Methane is the predominant component of natural gas. C<sup>6</sup> through C<sup>10</sup> alkanes, alkenes, cycloalkanes, and aromatic hydrocarbons are the main components of [[gasoline]], [[Petroleum naphtha|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 [[tar]]s that remain as the ''lowest fraction'' in a crude oil [[Refining industry|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.  These two gases are converted either to [[syngas]] or to [[ethylene]] and [[propylene]] respectively. Global consumption of benzene in 2021 is estimated at more than 58 million metric tons, which will increase to 60 million tons in 2022.<ref name="Chem-Systems-2010">{{Cite web|title=Benzene global market volume 2015-2026|url=https://www.statista.com/statistics/1245172/benzene-market-volume-worldwide/|access-date=2021-12-05|website=Statista|language=en}}</ref>

Hydrocarbons are also prevalent in nature. Some eusocial arthropods, such as the Brazilian stingless bee, ''[[Schwarziana quadripunctata]]'', use unique [[cuticular hydrocarbon]] "scents" in order to determine kin from non-kin. This hydrocarbon composition varies between age, sex, nest location, and hierarchal position.<ref name=nunes09>{{cite journal|last1=Nunes|first1=T.M.|last2=Turatti|first2=I.C.C.|last3=Mateus|first3=S.|last4=Nascimento|first4=F.S.|last5=Lopes|first5=N.P.|last6=Zucchi|first6=R.|year=2009|title=Cuticular Hydrocarbons in the Stingless Bee ''Schwarziana quadripunctata'' (Hymenoptera, Apidae, Meliponini): Differences between Colonies, Castes and Age|journal=Genetics and Molecular Research|volume=8|issue=2|pages=589–595|url=http://www.funpecrp.com.br/gmr/year2009/vol8-2/pdf/kerr012.pdf|doi=10.4238/vol8-2kerr012|doi-broken-date=14 May 2025 |pmid=19551647|url-status=live|archive-url=https://web.archive.org/web/20150926031231/http://www.funpecrp.com.br/gmr/year2009/vol8-2/pdf/kerr012.pdf|archive-date=26 September 2015|doi-access=free}}</ref>

There is also potential to harvest hydrocarbons from plants like ''[[Euphorbia lathyris]]'' and ''[[Euphorbia tirucalli|E.&nbsp;tirucalli]]'' as an alternative and renewable energy source for vehicles that use diesel.<ref>{{cite journal |last1=Calvin |first1=Melvin |title=Hydrocarbons from plants: Analytical methods and observations |journal=Naturwissenschaften |year=1980 |volume=67 |issue=11 |pages=525–533 |doi=10.1007/BF00450661 |bibcode=1980NW.....67..525C |s2cid=40660980 |url=https://digital.library.unt.edu/ark:/67531/metadc827749/ }}</ref> Furthermore, [[endophytic]] bacteria from plants that naturally produce hydrocarbons have been used in hydrocarbon degradation in attempts to deplete hydrocarbon concentration in polluted soils.<ref>{{cite journal |last1=Pawlik |first1=Malgorzata |title=Hydrocarbon degradation potential and plant growth-promoting activity of culturable endophytic bacteria of ''Lotus corniculatus'' and ''Oenothera biennis'' from a long-term polluted site |journal=Environmental Science and Pollution Research International |year=2017 |volume=24 |issue=24 |pages=19640–19652 |doi=10.1007/s11356-017-9496-1 |pmid=28681302 |pmc=5570797 |bibcode=2017ESPR...2419640P }}</ref>

==Reactions==
Saturated hydrocarbons are notable for their inertness. Unsaturated hydrocarbons (alkanes, alkenes and aromatic compounds) react more readily, by means of substitution, addition, polymerization. At higher temperatures they undergo dehydrogenation, oxidation and combustion.<ref name=Ullmann/>

===Saturated hydrocarbons===
====Cracking====
{{Main|Cracking (chemistry)}}
{{Further information|Steam reforming}}
The cracking of saturated hydrocarbons is the main industrial route to [[alkene]]s and [[alkyne]].  These reactions require [[heterogeneous catalyst]]s and temperatures >500 °C.
===Oxidation===
Widely practice conversions of hydrocarbons involves their reaction with oxygen.  In the presence of excess oxygen, hydrocarbons combust.  With, however, careful conditions, which have been optimized for many years, partial oxidation results.  Useful compounds can obtained in this way: [[maleic acid]] from [[butane]], [[terephthalic acid]] from [[xylene]]s, [[acetone]] together with [[phenol]] from [[cumene]] (isopropylbenzene), and [[cyclohexanone]] from [[cyclohexane]].  The process, which is called [[autoxidation]], begins with the formation of [[hydroperoxide]]s (ROOH).<ref>{{March6th|page=967}} </ref>

====Combustion====
{{Main|Combustion}}
Combustion of hydrocarbons is currently the main source of the world's energy for [[electric power|electric power generation]], heating (such as home heating), and transportation.<ref>{{Cite web|title=Generating Electricity|url=https://electricity.ca/learn/electricity-today/generating-electricity/|access-date=2021-12-05|website=Canadian Electricity Association|language=en-US}}</ref><ref>{{Cite journal|last1=Zou|first1=Caineng|last2=Zhao|first2=Qun|last3=Zhang|first3=Guosheng|last4=Xiong|first4=Bo|date=2016-01-01|title=Energy revolution: From a fossil energy era to a new energy era|journal=Natural Gas Industry B|language=en|volume=3|issue=1|pages=1–11|doi=10.1016/j.ngib.2016.02.001|issn=2352-8540|doi-access=free|bibcode=2016NGIB....3....1Z }}</ref> Often this energy is used directly as heat such as in home heaters, which use either [[petroleum]] or [[natural gas]]. The hydrocarbon is burnt and the heat is used to heat water, which is then circulated. A similar principle is used to create [[electrical energy]] in [[Power Plants|power plants]].  Both saturated and unsaturated hydrocarbons undergo this process.

Common properties of hydrocarbons are the facts that they produce steam, [[carbon dioxide]] and heat during [[combustion]] and that [[oxygen]] is required for combustion to take place. The simplest hydrocarbon, [[methane]], burns as follows:
:<chem>\underset{methane}{CH4} + 2O2 -> CO2 + 2H2O</chem>

In inadequate supply of air, [[carbon black]] and [[Water vapor|water vapour]] are formed:
:<chem>\underset{methane}{CH4} + O2 -> C + 2H2O</chem>

And finally, for any [[linear alkane]] of n carbon atoms,
:<math chem="">\ce{C}_n \ce{H}_{2n+2} + \left({{3n+1}\over 2}\right)\ce{O2->} n\ce{CO2} + (n+1)\ce{H2O}</math>

Partial oxidation characterizes the reactions of alkenes and oxygen. This process is the basis of [[rancidification]] and [[drying oil|paint drying]].

[[Benzene]] burns with [[soot]]y flame when heated in air:
:<chem>\underset{benzene}{C6H6} + {15\over 2}O2 -> 6CO2 {+} 3H2O</chem>

====Halogenation====
{{Main|Free-radical halogenation}}
Saturated hydrocarbons react with [[chlorine]] and [[fluorine]]. In the case of chlorination, one of the chlorine atoms replaces a hydrogen atom.  The reactions proceed via  [[free-radical pathway]]s, in which the halogen first dissociates into a two neutral radical atoms ([[Homolysis (chemistry)|homolytic fission]]).
:CH{{sub|4}} + Cl{{sub|2}} → CH{{sub|3}}Cl + HCl
:CH{{sub|3}}Cl + Cl{{sub|2}} → CH{{sub|2}}Cl{{sub|2}} + HCl
all the way to CCl{{sub|4}} ([[carbon tetrachloride]])

:C{{sub|2}}H{{sub|6}} + Cl{{sub|2}} → C{{sub|2}}H{{sub|5}}Cl + HCl
:C{{sub|2}}H{{sub|4}}Cl{{sub|2}} + Cl{{sub|2}} → C{{sub|2}}H{{sub|3}}Cl{{sub|3}} + HCl
all the way to C{{sub|2}}Cl{{sub|6}} ([[hexachloroethane]])

===Unsaturated hydrocarbons===
====Substitution====
{{Main|Substitution reaction}}
Aromatic compounds, almost uniquely for hydrocarbons, undergo substitution reactions. The chemical process practiced on the largest scale is the reaction of benzene and [[ethene]] to give [[ethylbenzene]]:
:{{chem2|C6H6 + C2H4 -> C6H5CH2CH3}}
The resulting ethylbenzene is dehydrogenated to [[styrene]] and then polymerized to manufacture [[polystyrene]], a common [[thermoplastic]] material.

====Addition====
{{Main|Addition reaction}}
{{Main|Hydrogenation}}
{{Main|Polyolefin}}
{{Further information|Addition polymer}}

Addition reactions apply to alkenes and alkynes.  It is because they add reagents that they are called unsaturated. In this reaction a variety of reagents add "across" the pi-bond(s).  Chlorine, hydrogen chloride, [[water]], and [[hydrogen]] are illustrative reagents.  

Polymerization is a form of addition. [[Alkenes]] and some alkynes also undergo [[polymerization]] by opening of the multiple bonds to produce [[polyethylene]], [[polybutylene]], and [[polystyrene]]. The alkyne [[acetylene]] polymerizes to produce [[polyacetylene]]. Oligomers (chains of a few monomers) may be produced, for example in the [[Shell higher olefin process]], where [[Alpha-olefin|α-olefin]]s are extended to make longer α-olefins by adding ethylene repeatedly.

===Metathesis===
Some  hydrocarbons undergo ''metathesis'', in which substituents attached by C–C bonds are exchanged between molecules. For a single C–C bond it is [[alkane metathesis]], for a double C–C bond it is [[Olefin metathesis|alkene metathesis]] (olefin metathesis), and for a triple C–C bond it is [[alkyne metathesis]].

==Origin==
[[File:Korna natural oil seep 1.JPG|thumb|upright=1.2|Natural oil spring in [[Korňa]], [[Slovakia]]]]

The vast majority of hydrocarbons found on [[Earth]] occur in [[crude oil]], petroleum, [[coal]], and natural gas.  For thousands of years they have been exploited and used for a vast range of purposes.<ref name ='van Dijk_2022, n'>van Dijk, J.P. (2022); Unravelling the Maze of Scientific Writing Through the Ages: On the Origins of the Terms Hydrocarbon, Petroleum, Natural Gas, and Methane. Amazon Publishers, 166 pp. PaperBack Edition B0BKRZRKHW.  {{ISBN|979-8353989172}}</ref> Petroleum ({{lit|rock oil}}) and coal are generally thought to be products of decomposition of organic matter.  Coal, in contrast to petroleum, is richer in carbon and poorer in hydrogen. Natural gas is the product of [[methanogenesis]].<ref>Clayden, J., Greeves, N., et al. (2001) ''Organic Chemistry'' Oxford {{ISBN|0-19-850346-6}}, p.&nbsp;21.</ref><ref>McMurry, J. (2000). ''Organic Chemistry'' 5th ed. Brooks/Cole: Thomson Learning. {{ISBN|0-495-11837-0}}. pp.&nbsp;75–81.</ref>

A seemingly limitless variety of compounds comprise petroleum, hence the necessity of refineries. These hydrocarbons consist of saturated hydrocarbons, aromatic hydrocarbons, or combinations of the two.  Missing in petroleum are alkenes and alkynes.  Their production requires refineries. Petroleum-derived hydrocarbons are mainly consumed for fuel, but they are also the source of virtually all synthetic organic compounds, including plastics and pharmaceuticals.  Natural gas is consumed almost exclusively as fuel. Coal is used as a fuel and as a reducing agent in [[Steelmaking|metallurgy]].

A small fraction of hydrocarbon found on earth, and all currently known hydrocarbon found on other planets and moons, is thought to be [[Abiogenic petroleum origin|abiological]].<ref>{{cite journal |doi=10.2138/rmg.2013.75.14 |title=On the Origins of Deep Hydrocarbons |year=2013 |last1=Sephton |first1=M. A. |last2=Hazen |first2=R. M. |journal=Reviews in Mineralogy and Geochemistry |volume=75 |issue=1 |pages=449–465 |bibcode=2013RvMG...75..449S}}</ref>

Hydrocarbons such as ethylene, isoprene, and monoterpenes are emitted by living vegetation.<ref>{{cite web |last1=Dewulf |first1=Jo |title=Hydrocarbons in the Atmosphere |url=https://www.eolss.net/Sample-Chapters/C06/E6-13-02-07.pdf |access-date=26 October 2020}}</ref>

Some hydrocarbons also are widespread and abundant in the [[Solar System]]. Lakes of liquid methane and ethane have been found on [[Titan (moon)|Titan]], [[Saturn]]'s largest moon, as confirmed by the ''[[Cassini–Huygens]]'' space probe.<ref>[http://www.jpl.nasa.gov/news/news.php?release=2013-364 NASA's Cassini Spacecraft Reveals Clues About Saturn Moon]. {{webarchive|url=https://web.archive.org/web/20140902080814/http://www.jpl.nasa.gov/news/news.php?release=2013-364 |date=2 September 2014 }}. NASA (12 December 2013).</ref> Hydrocarbons are also abundant in nebulae forming [[polycyclic aromatic hydrocarbon]] compounds.<ref>{{cite journal |doi=10.1093/mnras/stu454 |arxiv=1403.1856 |title=PAH formation in O-rich planetary nebulae |journal=Monthly Notices of the Royal Astronomical Society |volume=441 |issue=1 |pages=364–377 |year=2014 |last1=Guzman-Ramirez |first1=L. |last2=Lagadec |first2=E. |last3=Jones |first3=D. |last4=Zijlstra |first4=A. A. |last5=Gesicki |first5=K. |doi-access=free |bibcode=2014MNRAS.441..364G |s2cid=118540862}}</ref>

==Environmental impact==
Burning hydrocarbons as fuel, which produces [[carbon dioxide]] and [[water]], is a major contributor to anthropogenic [[global warming]].
Hydrocarbons are introduced into the environment through their extensive use as fuels and chemicals as well as through leaks or accidental spills during exploration, production, refining, or transport of fossil fuels. Anthropogenic hydrocarbon contamination of soil is a serious global issue due to contaminant persistence and the negative impact on human health.<ref>{{Cite web|url=https://www.researchgate.net/publication/226738847|title=Microbial Degradation of Alkanes (PDF Download Available)|website=ResearchGate|language=en|access-date=2017-02-23|url-status=live|archive-url=https://web.archive.org/web/20170224053341/https://www.researchgate.net/publication/226738847_Microbial_Degradation_of_Alkanes|archive-date=24 February 2017}}</ref>

[[File:Mechanisms involved in phytoremediation.png|thumb|upright=1.8|Mechanisms involved in hydrocarbon [[phytoremediation]]<ref>{{cite journal | last1=Rohrbacher | first1=Fanny | last2=St-Arnaud | first2=Marc | title=Root Exudation: The Ecological Driver of Hydrocarbon Rhizoremediation | journal=Agronomy | publisher=MDPI AG | volume=6 | issue=1 | date=2016-03-09 | issn=2073-4395 | doi=10.3390/agronomy6010019 | page=19| doi-access=free | bibcode=2016Agron...6...19R }}</ref>]]

When soil is contaminated by hydrocarbons, it can have a significant impact on its microbiological, chemical, and physical properties. This can serve to prevent, slow down or even accelerate the growth of vegetation depending on the exact changes that occur. Crude oil and natural gas are the two largest sources of hydrocarbon contamination of soil.<ref>{{Citation|title=Additives Affecting the Microbial Degradation of Petroleum Hydrocarbons|date=2000-06-09|work=Bioremediation of Contaminated Soils|pages=353–360|publisher=CRC Press|doi=10.1201/9781482270235-27|isbn=978-0-429-07804-0}}</ref>

===Bioremediation===
Bioremediation of hydrocarbon from soil or water contaminated is a formidable challenge because of the chemical inertness that characterize hydrocarbons (hence they survived millions of years in the source rock).  Nonetheless, many strategies have been devised, bioremediation being prominent.  The basic problem with bioremediation is the paucity of enzymes that act on them. Nonetheless, the area has received regular attention.<ref>{{cite journal |doi=10.1016/j.marpolbul.2016.04.023|title=A comprehensive guide of remediation technologies for oil contaminated soil — Present works and future directions|year=2016|last1=Lim|first1=Mee Wei|last2=Lau|first2=Ee Von|last3=Poh|first3=Phaik Eong|journal=Marine Pollution Bulletin|volume=109|issue=1|pages=14–45|pmid=27267117|bibcode=2016MarPB.109...14L }}</ref>
Bacteria in the [[Gabbro|gabbroic layer]] of the ocean's crust can degrade hydrocarbons; but the extreme environment makes research difficult.<ref>{{cite journal|vauthors=Mason OU, Nakagawa T, Rosner M, Van Nostrand JD, Zhou J, Maruyama A, Fisk MR, Giovannoni SJ |title=First investigation of the microbiology of the deepest layer of ocean crust.|date=2010|pmid=21079766|doi=10.1371/journal.pone.0015399|volume=5|issue=11|pmc=2974637|journal=PLOS ONE|pages=e15399|bibcode=2010PLoSO...515399M|doi-access=free}}</ref> Other bacteria such as ''[[Lutibacterium anuloederans]]'' can also degrade hydrocarbons.<ref>{{cite journal
| year=2007
| title=Obligate oil-degrading marine bacteria
| journal=Curr. Opin. Biotechnol.
| volume=18
| pages=257–266
| doi=10.1016/j.copbio.2007.04.006
| pmid=17493798
| issue=3|citeseerx=10.1.1.475.3300| last1=Yakimov
| first1=M. M.
| last2=Timmis
| first2=K. N.
| last3=Golyshin
| first3=P. N.
}}
</ref>
[[Mycoremediation]] or breaking down of hydrocarbon by [[mycelium]] and [[mushroom]]s is possible.<ref>{{cite web|last = Stamets|first =  Paul|title = 6 ways mushrooms can save the world|format = video|date = 2008|website = TED Talk|url = http://www.ted.com/talks/paul_stamets_on_6_ways_mushrooms_can_save_the_world?language=en |url-status = live|archive-url=https://web.archive.org/web/20141031151149/http://www.ted.com/talks/paul_stamets_on_6_ways_mushrooms_can_save_the_world?language=en |archive-date=31 October 2014 }}</ref><ref>{{cite book|last = Stamets|first = Paul|date = 2005|chapter = Mycoremediation|page = [https://archive.org/details/myceliumrunningh00stam_0/page/86 86]|title = Mycelium Running: How Mushrooms Can Help Save the World|isbn = 9781580085793|publisher = Ten Speed Press|chapter-url-access = registration|chapter-url = https://archive.org/details/myceliumrunningh00stam_0/page/86}}</ref>

==Safety==
{{main|Hydrocarbon poisoning}}
Hydrocarbons are generally of low toxicity, hence the widespread use of gasoline and related volatile products.  Aromatic compounds such as benzene and [[toluene]] are narcotic and chronic toxins, and benzene in particular is known to be [[carcinogen]]ic.  Certain rare polycyclic aromatic compounds are carcinogenic.
Hydrocarbons are highly [[flammable]].

==See also==
{{Div col}}
* [[Abiogenic petroleum origin]]
* [[Biomass to liquid]]
* [[Carbohydrate]]
* [[Energy storage]]
* [[Fractional distillation]]
* [[Functional group]]
* [[Hydrocarbon mixtures]]
* [[Organic nuclear reactor]]
{{Div col end}}
{{clear}}

==References==
{{Reflist}}

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[[Category:Hydrocarbons| ]]