View source for Saturated and unsaturated compounds

{{Short description|Classification of organic compounds based on nature of their chemical bonds}}
{{About|chemical bonds|saturation status of solutions|solubility|and|supersaturation}}

A '''saturated compound''' is a [[chemical compound]] (or ion) that resists [[addition reaction]]s, such as [[hydrogenation]], [[oxidative addition]], and the binding of a [[Lewis acids and bases|Lewis base]]. The term is used in many contexts and classes of chemical compounds.  Overall, saturated compounds are less reactive than unsaturated compounds. Saturation is derived from the Latin word ''saturare'', meaning 'to fill'.<ref>''[[Mosby's Medical, Nursing & Allied Health Dictionary]]'', Fourth Edition, Mosby-Year Book Inc., 1994, p. 1394</ref>An unsaturated compound is also a [[chemical compound]] (or ion) that attracts [[reduction reaction]]s, such as [[dehydrogenation]],[[oxidative reduction]]

==Organic chemistry==
Generally distinct types of unsaturated organic compounds are recognized.  
For hydrocarbons:
*[[alkene]] (unsaturated) vs alkane (saturated)
*[[alkyne]] (unsaturated) vs alkane (saturated)
*[[arene]] (unsaturated) vs cycloalkane (saturated)
For organic compounds containing heteroatoms (other than C and H), the list of unsaturated groups is long but some common types are:
*[[carbonyl]], e.g. [[ketone]]s, [[aldehyde]]s, [[ester]]s, [[carboxylic acid]]s (unsaturated) vs alcohol or ether (saturated)
*[[nitrile]] (unsaturated) vs amine (saturated)
*[[Nitro compound|nitro]] (unsaturated) vs amine (saturated)

{| class="wikitable floatleft" style="text-align:center"
! colspan="3" | Saturated compounds
|-
|[[File:Ethan_Lewis.svg|[[File:Ethan_Lewis.svg]]|102x102px]]
[[Ethane]]
|[[File:Propan_Lewis.svg|[[File:Propan_Lewis.svg]]|136x136px]]
[[Propane]]
|[[File:Octan-1-ol_Skelett.svg|[[File:Octan-1-ol_Skelett.svg]]|245x245px]]
[[1-Octanol]]
|}
{| class="wikitable floatcenter" style="text-align:center; font-size:89
! colspan="3" | Unsaturated compounds
|- 
|[[File:Ethene_structural.svg|83x83px]]
[[Ethylene]]
|[[File:Ethyne-2D-flat.png|111x111px]]
[[Acetylene]]
|[[File:Alpha-Linolenic_acid_Structural_Formulae_V.2.svg|183x223px]] 
[[alpha-Linolenic acid|''alpha''-Linolenic acid]], an unsaturated fatty acid
|}
Unsaturated compounds generally carry out typical addition reactions that are not possible with saturated compounds such as alkanes. A saturated organic compound has only single bonds between carbon atoms. An important class of saturated compounds are the [[alkane]]s.  Many saturated compounds have functional groups, e.g., [[alcohols]].

===Unsaturated organic compounds===
The concept of saturation can be described using various naming systems, [[formula]]s, and [[Analytical chemistry|analytical tests]]. For instance, [[IUPAC nomenclature of organic chemistry|IUPAC nomenclature]] is a system of naming conventions used to describe the type and location of unsaturation within organic compounds. The "[[degree of unsaturation]]" is a [[formula]] used to summarize and diagram the amount of hydrogen that a compound can bind. Unsaturation can be determined by [[NMR]], [[mass spectrometry]], and [[IR spectroscopy]], or by determining a compound's [[bromine number]] or [[iodine number]].<ref>{{March6th}}</ref>

===Fatty acids and fats===
[[File:TriglycerideTallow.svg|thumb|340px|The bottom chain of this fat is unsaturated.]]
{{Main|Unsaturated fat}}
{{Further|Hydrogenation#Food industry}}
The terms saturated vs unsaturated are often applied to the [[fatty acid]] constituents of [[fat]]s.  The triglycerides (fats) that comprise [[tallow]] are derived from the saturated [[stearic acid|stearic]] and monounsaturated [[oleic acid]]s.<ref name=Ullmann>{{cite encyclopedia|author=Alfred Thomas |title=Fats and Fatty Oils|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|publisher=Wiley-VCH|place=Weinheim|year=2002|doi=10.1002/14356007.a10_173|isbn=3527306730}}</ref> Many [[vegetable oil]]s contain fatty acids with one (''monounsaturated'') or more (''polyunsaturated'') double bonds in them.

==Saturated and unsaturated compounds beyond organic chemistry==
===Organometallic chemistry===
[[File:Vaska's.svg|thumb|left|220px|[[Vaska's complex|IrCl(CO)(PPh3)2]] is an unsaturated [[coordination complex]].]]
In [[organometallic chemistry]], a coordinatively unsaturated complex has fewer than [[18-electron rule|18 valence electrons]] and thus is susceptible to [[oxidative addition]] or coordination of an additional [[ligand]].  Unsaturation is the characteristic of many [[catalysis|catalysts]]. The opposite of coordinatively unsaturated is coordinatively saturated.  Complexes that are coordinatively saturated rarely exhibit catalytic properties.<ref>Hartwig, J. F. ''Organotransition Metal Chemistry, from Bonding to Catalysis''; University Science Books: New York, 2010. {{ISBN|1-891389-53-X}}</ref><ref>{{cite web|title=IUPAC definition of Coordinatively Unsaturated Complex|doi=10.1351/goldbook.C01334 |url=https://goldbook.iupac.org/html/C/C01334.html|doi-access=free}}</ref>

===Surfaces===
{{Further|Surface science}}
In [[physical chemistry]], when referring to surface processes, saturation denotes the degree at which a binding site is fully occupied.  For example, [[cation-exchange capacity|base saturation]] refers to the fraction of [[cation-exchange capacity|exchangeable cations]] that are base cations.

==References==
{{reflist}}

[[Category:Organic chemistry]]
[[Category:Chemical nomenclature]]