Editing Carboxylic acid (section)

==Synthesis==

===Industrial routes===
In general, industrial routes to carboxylic acids differ from those used on a smaller scale because they require specialized equipment.
* Carbonylation of alcohols as illustrated by the [[Cativa process]] for the production of acetic acid. Formic acid is prepared by a different carbonylation pathway, also starting from methanol.
* Oxidation of [[aldehyde]]s with air using cobalt and manganese catalysts. The required aldehydes are readily obtained from alkenes by [[hydroformylation]].
* Oxidation of hydrocarbons using air. For simple alkanes, this method is inexpensive but not selective enough to be useful. Allylic and benzylic compounds undergo more selective oxidations. Alkyl groups on a benzene ring are oxidized to the carboxylic acid, regardless of its chain length. [[Benzoic acid]] from [[toluene]], [[terephthalic acid]] from ''para''-[[xylene]], and [[phthalic acid]] from ''ortho''-[[xylene]] are illustrative large-scale conversions. [[Acrylic acid]] is generated from [[propene]].<ref>{{cite book|last1=Riemenschneider|first1=Wilhelm|date=2002|chapter=Carboxylic Acids, Aliphatic|title=Ullmann's Encyclopedia of Industrial Chemistry|publisher=Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a05_235|isbn=3527306730}}.</ref>
* Oxidation of ethene using [[silicotungstic acid]] catalyst.
* Base-catalyzed dehydrogenation of alcohols.
* Carbonylation coupled to the addition of water. This method is effective and versatile for alkenes that generate secondary and tertiary [[carbocation]]s, e.g. [[isobutylene]] to [[pivalic acid]]. In the [[Koch reaction]], the addition of water and carbon monoxide to [[alkenes]] or [[alkynes]] is catalyzed by strong acids. Hydrocarboxylations involve the simultaneous addition of water and [[Carbon monoxide|CO]]. Such reactions are sometimes called "[[Walter Reppe|Reppe chemistry]]."
:{{chem2|[[Acetylene|HC\tCH]] + CO + H2O → [[Acrylic acid|CH2\dCH\sCO2H]]}}
* Hydrolysis of [[triglyceride]]s obtained from plant or animal oils. These methods of synthesizing some long-chain carboxylic acids are related to [[soap making]].
* [[Fermentation (biochemistry)|Fermentation]] of ethanol. This method is used in the production of [[vinegar]].
* The [[Kolbe–Schmitt reaction]] provides a route to [[salicylic acid]], precursor to [[aspirin]].

===Laboratory methods===
Preparative methods for small scale reactions for research or for production of fine chemicals often employ expensive consumable reagents.
* [[Oxidation of primary alcohols to carboxylic acids|Oxidation of primary alcohols]] or [[aldehyde]]s with strong [[Oxidizing agent|oxidants]] such as [[potassium dichromate]], [[Jones reagent]], [[potassium permanganate]], or [[sodium chlorite]]. The method is more suitable for laboratory conditions than the industrial use of air, which is "greener" because it yields less inorganic side products such as chromium or manganese oxides.<ref>{{Cite journal |last1=Mohammadpoor-Baltork |first1=Iraj |last2=Sadeghi |first2=Majid M. |last3=Adibi |first3=Abol-Hassan |date=2001-10-31 |title=Efficient, Solvent-Free Oxidation of Organic Compounds with Potassium Dichromate in the Presence of Lewis Acids |journal=Molecules |language=en |volume=6 |issue=11 |pages=900–908 |doi=10.3390/61100900 |doi-access=free |issn=1420-3049 |pmc=6236395}}</ref>
* Oxidative cleavage of [[olefin]]s by [[ozonolysis]], [[potassium permanganate]], or [[potassium dichromate]].
* Hydrolysis of [[nitrile]]s, [[ester]]s, or [[amide]]s, usually with acid- or base-catalysis.
* Carbonation of a [[Grignard reagent]] and [[organolithium]] reagents:
:{{chem2|RLi + [[Carbon dioxide|CO2]] → RCO2−Li+}}
:{{chem2|RCO2−Li+ + [[Hydrogen chloride|HCl]] → RCO2H + [[Lithium chloride|LiCl]]}}
* [[Halogenation]] followed by hydrolysis of [[methyl ketone]]s in the [[haloform reaction]]
* Base-catalyzed cleavage of non-enolizable ketones, especially [[aryl]] ketones:<ref>{{cite journal|title=Carboxylation of Aromatic Compounds: Ferrocenecarboxylic Acid|author=Perry C. Reeves|journal=Org. Synth.|year=1977|volume=56|page=28|doi=10.15227/orgsyn.056.0028}}</ref>
:{{chem2|R\sC(\dO)\s[[Aryl|Ar]] + H2O → R\sCO2H + ArH}}

===Less-common reactions===
Many reactions produce carboxylic acids but are used only in specific cases or are mainly of academic interest.
* Disproportionation of an [[aldehyde]] in the [[Cannizzaro reaction]]
* Rearrangement of diketones in the [[benzilic acid rearrangement]]
* Involving the generation of benzoic acids are the [[von Richter reaction]] from nitrobenzenes and the [[Kolbe–Schmitt reaction]] from [[phenol]]s.