View source for Dicarboxylic acid

{{short description|Organic compound with two –COOH groups}}

In [[organic chemistry]], a '''dicarboxylic acid''' is an [[organic compound]] containing two [[carboxyl group]]s ({{chem2|\sCOOH}}). The general [[molecular formula]] for dicarboxylic acids can be written as {{chem2|HO2C\sR\sCO2H}}, where R can be [[aliphatic]] or [[Aromatic compound|aromatic]]. In general, dicarboxylic acids show similar chemical behavior and reactivity to [[carboxylic acid|monocarboxylic acids]].

Dicarboxylic acids are used in the preparation of [[copolymer]]s such as [[polyamide]]s and [[polyester]]s. The most widely used dicarboxylic acid in the industry is [[adipic acid]], which is a precursor in the production of [[nylon]]. Other examples of dicarboxylic acids include [[aspartic acid]] and [[glutamic acid]], two [[amino acids]] in the human body. The name can be abbreviated to '''diacid'''; long chain aliphatic dicarboxylic acids are known as '''fatty diacids'''.

== Linear and cyclic saturated dicarboxylic acids ==
{{expert needed|Chemistry|reason = to reconcile the fact that the physicochemical and other data and information appearing is unsourced, and not that appearing at the linked PubChem page, thus creating discrepancy between source and WP article content|date=September 2024}}
The general formula for acyclic dicarboxylic acid is {{chem|HO|2|C(CH|2|)|n|CO|2|H}}.<ref name="Ullmanns">Boy Cornils, Peter Lappe "Dicarboxylic Acids, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry 2014, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a08_523.pub3}}</ref> The [[PubChem]] links gives access to more information on the compounds, including other names, IDs, toxicity and safety.{{cn|date = September 2024}}

Acids from the two-carbon oxalic acid to the ten-member sebacic acid may be remembered using the [[mnemonic]] 'Oh My Son, Go And Pray Softly And Silently', and also 'Oh my! Such great Apple Pie, sweet as sugar!'.{{says who|date = September 2024}}<!--THIS IS NOT A PLACE TO POST PERSONALLY APPROVED/EXPERIENCED EDUCATIONAL MNEMONICS. DRAW IT FROM A SOURCE, SO IT IS NOT WP:OR.-->

:{| class="wikitable"
|+
!C
! n !! Common name !! Systematic IUPAC name !! Structure !! pK<sub>a</sub>1 !! pK<sub>a</sub>2 !! PubChem
|-
|C2
| 0 || [[Oxalic acid]] || ethanedioic acid || [[File:Oxalsäure2.svg|60px]] || 1.27 || 4.27 || [https://pubchem.ncbi.nlm.nih.gov/compound/971 971]
|-
|C3
| 1 || [[Malonic acid]] || propanedioic acid || [[File:Malonic acid structure.png|80px]] || 2.85 || 5.05 || [https://pubchem.ncbi.nlm.nih.gov/compound/867 867]
|-
|C4
| 2 || [[Succinic acid]] || butanedioic acid || [[File:Succinic acid.png|100px]] || 4.21 || 5.41 || [https://pubchem.ncbi.nlm.nih.gov/compound/1110 1110]
|-
|C5
| 3 || [[Glutaric acid]] || pentanedioic acid || [[File:Glutaric acid.png|120px]] || 4.34 || 5.41 || [https://pubchem.ncbi.nlm.nih.gov/compound/743 743]
|-
|C6
| 4 || [[Adipic acid]] || hexanedioic acid || [[File:Adipic acid structure.png|140px]] || 4.41 || 5.41 || [https://pubchem.ncbi.nlm.nih.gov/compound/196 196]
|-
|C7
| 5 || [[Pimelic acid]] || heptanedioic acid || [[File:Pimelic acid.png|160px]] || 4.50 || 5.43 || [https://pubchem.ncbi.nlm.nih.gov/compound/385 385]
|-
|C8
| 6 || [[Suberic acid]] || octanedioic acid || [[File:Suberic acid.png|180px]] || 4.526 || 5.498 || [https://pubchem.ncbi.nlm.nih.gov/compound/10457 10457]
|-
|C8
| 6 ||  || [[1,4-Cyclohexanedicarboxylic acid]] || [[File:1,4-cyclohexanedicarboxylicAcid.svg|180px]] ||  ||  ||[https://pubchem.ncbi.nlm.nih.gov/compound/14106 14106]
|-
|C9
| 7 || [[Azelaic acid]] || nonanedioic acid || [[File:Azelaic acid.svg|200px]] || 4.550 || 5.498 || [https://pubchem.ncbi.nlm.nih.gov/compound/2266 2266]
|-
|C10
| 8 || [[Sebacic acid]] || decanedioic acid || [[File:Sebacic acid.png|220px]] || 4.720 || 5.450 || [https://pubchem.ncbi.nlm.nih.gov/compound/5192 5192]
|-
|C11
| 9 || || undecanedioic acid || [[File:Undecanedioic acid.svg|240px]] || || || [https://pubchem.ncbi.nlm.nih.gov/compound/15816 15816]
|-
|C12
| 10 || || [[dodecanedioic acid]] || [[File:Dodecanedioic acid structure.svg|260px]]
| || || [https://pubchem.ncbi.nlm.nih.gov/compound/12736 12736]
|-
|C13
| 11 || [[Brassylic acid]] || tridecanedioic acid || [[File:Brassylic acid.svg|280px]] || || || [https://pubchem.ncbi.nlm.nih.gov/compound/10458 10458]
|-
|C16
| 14 || [[Thapsic acid]] || hexadecanedioic acid || [[File:Thapsic acid.png|300px]] || || || [https://pubchem.ncbi.nlm.nih.gov/compound/10459 10459]
|-
|C21
| 19 || [[Japanic acid]] || heneicosanedioic acid || || || || [https://pubchem.ncbi.nlm.nih.gov/compound/9543668 9543668]
|-
|C22
| 20 || Phellogenic acid || [[docosanedioic acid]] || [[File:Docosanedioic acid.svg|280px]] || || || [https://pubchem.ncbi.nlm.nih.gov/compound/244872 244872]
|-
|C30
| 28 || [[Equisetolic acid]] || triacontanedioic acid || || || || [https://pubchem.ncbi.nlm.nih.gov/compound/5322010 5322010]
|}

== Occurrence ==
* Adipic acid, despite its name (in Latin, adipis means fat), is not a normal constituent of natural lipids but is a product of [[lipid peroxidation|oxidative rancidity]]. It was first obtained by oxidation of [[castor oil]] ([[ricinoleic acid]]) with nitric acid. It is now produced industrially by oxidation of [[cyclohexanol]] or [[cyclohexane]], mainly for the production of [[Nylon 6-6]]. It has several other industrial uses in the production of [[adhesive]]s, [[plasticizer]]s, gelatinizing agents, [[hydraulic fluid]]s, [[lubricant]]s, [[emollient]]s, [[polyurethane foam]]s, [[leather tanning]], urethane and also as an [[acidulant]] in foods.
* Pimelic acid (Greek {{transl|grc|pimelh}}, fat) was also first isolated from oxidized oil. Derivatives of pimelic acid are involved in the biosynthesis of [[lysine]].
* Suberic acid was first produced by nitric acid oxidation of cork (Latin suber). This acid is also produced when castor oil is oxidised. Suberic acid is used in the manufacture of [[alkyd resin]]s and in the synthesis of [[polyamide]]s ([[nylon]] variants).
* Azelaic acid's name stems from the action of nitric acid (azote, nitrogen, or azotic, nitric) oxidation of [[oleic acid]] or [[elaidic acid]]. It was detected among products of rancid fats.<!--<ref>Nicolet B. H. et al., [http://pubs.acs.org/journal/iecred?cookieSet=1 Journal Industrial Engineering Chemistry] 1916, 8, 416 and Nunn L et al., [http://pubs.acs.org/journal/bichaw Biochemistry Journal] 1938, 32, 1974</ref> --> Its origin explains for its presence in poorly preserved samples of [[linseed oil]] and in specimens of ointment removed from Egyptian tombs 5000 years old.<!--<ref>Banks A et al., Analyst 1933, 58, 265</ref> --> Azelaic acid was prepared by oxidation of oleic acid with [[potassium permanganate]],<!--<ref>Ganttner F et al., Berichte der Deutschen Chemischen Gesellschaft 1881, 14, 1545</ref> --> but now by oxidative cleavage of oleic acid with [[chromic acid]] or by ozonolysis.  Azelaic acid is used, as simple esters or branched-chain esters) in the manufacture of plasticizers (for [[vinyl chloride]] resins, rubber), lubricants and [[Grease (lubricant)|greases]]. Azelaic acid is now used in [[cosmetics]] ([[Acne#Management|treatment of acne]]). It displays [[bacteriostatic]] and [[bactericidal]] properties against a variety of [[aerobic bacteria|aerobic]] and [[anaerobic bacteria|anaerobic micro-organisms]] present on acne-bearing skin. Azelaic acid was identified as a molecule that accumulated at elevated levels in some parts of plants and was shown to be able to enhance the resistance of plants to infections.<ref>{{cite journal |last1=Jung |first1=Ho Won |last2=Tschaplinski |first2=Timothy J. |last3=Wang |first3=Lin |last4=Glazebrook |first4=Jane |last5=Greenberg |first5=Jean T. |title=Priming in Systemic Plant Immunity |journal=Science |date=2009 |volume=324 |issue=3 April 2009 |pages=89–91 |doi=10.1126/science.1170025 |pmid=19342588 |bibcode=2009Sci...324...89W|s2cid=206518245 }}</ref>
* Sebacic acid, named from sebum ([[tallow]]).  Thenard isolated this compound from distillation products of beef tallow in 1802. It is produced industrially by alkali fission of castor oil.<ref name="Kadesch54">{{cite journal |last1=Kadesch |first1=Richard G. |title=Dibasic acids |journal=Journal of the American Oil Chemists' Society |date=November 1954 |volume=31 |issue=11 |pages=568–573 |doi=10.1007/BF02638574|s2cid=189786702 }}</ref> Sebacic acid and its derivatives have a variety of industrial uses as plasticizers, lubricants, [[Oil diffusion pump|diffusion pump oils]], cosmetics, candles, etc. It is also used in the synthesis of polyamide, as nylon, and of alkyd resins.  An isomer, isosebacic acid, has several applications in the manufacture of vinyl resin plasticizers, extrusion plastics, adhesives, ester lubricants, polyesters, polyurethane resins and [[synthetic rubber]].
* Brassylic acid can be produced from [[erucic acid]] by [[ozonolysis]],<ref name="Mascia Scheffran Widholm 2010 p. 231">{{cite book |last1=Mascia |first1=P.N. |last2=Scheffran |first2=J. |last3=Widholm |first3=J.M. |title=Plant Biotechnology for Sustainable Production of Energy and co-products |publisher=Springer Berlin Heidelberg |series=Biotechnology in Agriculture and Forestry |year=2010 |isbn=978-3-642-13440-1 |url=https://books.google.com/books?id=j-ia88HtH1QC&pg=PA231 |access-date=18 May 2021 |page=231}}</ref> but also by microorganisms ([[Candida (genus)|''Candida'' sp.]]) from [[tridecane]]. This diacid is produced on a small commercial scale in Japan for the manufacture of fragrances.<ref name="kk" />
* Dodecanedioic acid is used in the production of nylon (nylon-6,12), polyamides, coatings, adhesives, greases, polyesters, dyestuffs, detergents, flame retardants, and fragrances. It is now produced by fermentation of long-chain alkanes with a specific strain of ''[[Candida tropicalis]]''.<ref name="kk">{{cite journal |title=Industrial biotechnology provides opportunities for commercial production of new long-chain dibasic acids |last1=Kroha |first1=Kyle |journal=Inform |date=September 2004 |volume=15 |pages=568–571}}</ref> Traumatic acid is its monounsaturated counterpart.
* Thapsic acid was isolated from the dried roots of the Mediterranean "deadly carrot", ''[[Thapsia garganica]]'' ([[Apiaceae]]).

[[Japan wax]] is a mixture containing triglycerides of C21, C22 and C23 dicarboxylic acids obtained from the [[sumac]] tree (''Rhus'' sp.).

A large survey of the dicarboxylic acids present in Mediterranean nuts revealed unusual components.<ref name="dem02">{{cite journal |last1=Dembitsky |first1=Valery M |last2=Goldshlag |first2=Paulina |last3=Srebnik |first3=Morris |title=Occurrence of dicarboxylic (dioic) acids in some Mediterranean nuts |journal=Food Chemistry |date=April 2002 |volume=76 |issue=4 |pages=469–473 |doi=10.1016/S0308-8146(01)00308-9}}</ref> A total of 26 minor acids (from 2 in pecan to 8% in peanut) were determined: 8 species derived from [[succinic acid]], likely in relation with [[photosynthesis]], and 18 species with a chain from 5 to 22 carbon atoms. Higher weight acids (>C20) are found in [[suberin]] present at vegetal surfaces (outer bark, root epidermis).  C16 to C26 α,ω-dioic acids are considered as diagnostic for suberin. With C18:1 and C18:2, their content amount from 24 to 45% of whole suberin. They are present at low levels (< 5%) in plant [[cutin]], except in ''[[Arabidopsis thaliana]]'' where their content can be higher than 50%.<ref>{{cite journal |last1=Pollard |first1=Mike |last2=Beisson |first2=Fred |last3=Ohlrogge |first3=John B. |title=Building lipid barriers: biosynthesis of cutin and suberin |journal=Trends in Plant Science |volume=13 |issue=5 |date=3 April 2009 |pages=89–91 |doi=10.1016/j.tplants.2008.03.003|pmid=18440267 }}</ref>

It was shown that [[hyperthermophilic]] microorganisms specifically contained a large variety of dicarboxylic acids.<ref>{{cite journal |last1=Carballeira |first1=N. M. |last2=Reyes |first2=M. |last3=Sostre |first3=A. |last4=Huang |first4=H. |last5=Verhagen |first5=M. F. |last6=Adams |first6=M. W. |title=Unusual fatty acid compositions of the hyperthermophilic archaeon Pyrococcus furiosus and the bacterium Thermotoga maritima |journal=J. Bacteriol. |date=2009 |volume=179 |issue=8 |pages=2766–2768 |doi=10.1128/jb.179.8.2766-2768.1997 |pmc=179030 |pmid=9098079}}</ref>
This is probably the most important difference between these microorganisms and other marine bacteria. Dioic fatty acids from C16 to C22 were found in an hyperthermophilic [[archaeon]], ''[[Pyrococcus furiosus]]''. Short and medium chain (up to 11 carbon atoms) dioic acids have been discovered in [[Cyanobacteria]] of the genus ''[[Aphanizomenon]]''.<ref>{{cite journal |last1=Dembitsky |first1=V. M. |last2=Shkrob |first2=I. |last3=Go |first3=J. V. |title=Dicarboxylic and Fatty Acid Compositions of Cyanobacteria of the Genus Aphanizomenon |journal=Biochemistry (Moscow) |date=2001 |volume=66 |issue=1 |pages=72–76 |doi=10.1023/A:1002837830653 |pmid=11240396|s2cid=34894138 }}</ref>

Dicarboxylic acids may be produced by [[ω-oxidation]] of fatty acids during their [[catabolism]]. It was discovered that these compounds appeared in urine after administration of [[tricaprin]] and triundecylin. Although the significance of their biosynthesis remains poorly understood, it was demonstrated that ω-oxidation occurs in rat liver but at a low rate, needs oxygen, [[NADPH]] and [[cytochrome P450]]. It was later shown that this reaction is more important in starving or diabetic animals where 15% of [[palmitic acid]] is subjected to ω-oxidation and then tob-oxidation, this generates [[malonyl-CoA]] which is further used in saturated fatty acid synthesis.<ref>{{cite journal |last1=Wada |first1=F. |last2=Usami |first2=M. |title=Studies on fatty acid ω-oxidation antiketogenic effect and gluconeogenicity of dicarboxylic acids |journal=Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism |date=1997 |volume=487 |issue=2 |pages=261–268 |doi=10.1016/0005-2760(77)90002-9}}</ref>
The determination of the dicarboxylic acids generated by permanganate-periodate oxidation of monoenoic fatty acids was useful to study the position of the double bond in the carbon chain.<ref>{{cite journal |last1=Longmuir |first1=Kenneth J. |last2=Rossi |first2=Mary E. |last3=Resele-Tiden |first3=Christine |title=Determination of monoenoic fatty acid double bond position by permanganate-periodate oxidation followed by high-performance liquid chromatography of carboxylic acid phenacyl esters |journal=Analytical Biochemistry |date=1987 |volume=167 |issue=2 |pages=213–221 |doi=10.1016/0003-2697(87)90155-2 |pmid=2831753}}</ref>

== Branched-chain dicarboxylic acids ==

Long-chain dicarboxylic acids containing [[vicinal (chemistry)|vicinal]] dimethyl branching near the centre of the carbon chain have been discovered in the genus ''[[Butyrivibrio]]'', bacteria which participate in the digestion of cellulose in the rumen.<ref name="klein79">{{cite journal |last1=Klein |first1=RA |last2=Hazlewood |first2=GP |last3=Kemp |first3=P |last4=Dawson |first4=RM |title=A new series of long-chain dicarboxylic acids with vicinal dimethyl branching found as major components of the lipids of Butyrivibrio spp. |journal=The Biochemical Journal |date=1 December 1979 |volume=183 |issue=3 |pages=691–700 |pmid=540040 |pmc=1161651 |doi=10.1042/bj1830691}}</ref> These fatty acids, named '''diabolic acids''', have a chain length depending on the fatty acid used in the culture medium. The most abundant diabolic acid in ''Butyrivibrio'' had a 32-carbon chain length. Diabolic acids were also detected in the core lipids of the genus ''[[Thermotoga]]'' of the order [[Thermotogales]], bacteria living in [[Solfatara (volcano)|solfatara springs]], deep-sea marine hydrothermal systems and high-temperature marine and continental oil fields.<ref name="Huber86">{{cite journal |last1=Huber |first1=Robert |last2=Langworthy |first2=Thomas A. |last3=König |first3=Helmut |last4=Thomm |first4=Michael |last5=Woese |first5=Carl R. |last6=Sleytr |first6=Uwe B. |last7=Stetter |first7=Karl O. |title=Thermotoga maritima sp. nov. represents a new genus of unique extremely thermophilic eubacteria growing up to 90&nbsp;°C |journal=Archives of Microbiology |date=May 1986 |volume=144 |issue=4 |pages=324–333 |doi=10.1007/BF00409880 |bibcode=1986ArMic.144..324H |s2cid=12709437 }}</ref> It was shown that about 10% of their lipid fraction were symmetrical C30 to C34 diabolic acids. The C30 (13,14-dimethyloctacosanedioic acid) and C32 (15,16-dimethyltriacontanedioic acid) diabolic acids have been described in [[Thermotoga maritima]].<ref name="Carballeira97">{{cite journal |last1=Carballeira |first1=NM |last2=Reyes |first2=M |last3=Sostre |first3=A |last4=Huang |first4=H |last5=Verhagen |first5=MF |last6=Adams |first6=MW |title=Unusual fatty acid compositions of the hyperthermophilic archaeon Pyrococcus furiosus and the bacterium Thermotoga maritima. |journal=Journal of Bacteriology |date=April 1997 |volume=179 |issue=8 |pages=2766–8 |pmid=9098079 |pmc=179030 |doi=10.1128/jb.179.8.2766-2768.1997}}</ref>

Some parent C29 to C32 diacids but with methyl groups on the carbons C-13 and C-16 have been isolated and characterized from the lipids of thermophilic anaerobic bacterium ''[[Thermoanaerobacter ethanolicus]]''.<ref name="Jung94">{{cite journal |last1=Jung |first1=S |last2=Zeikus |first2=JG |last3=Hollingsworth |first3=RI |title=A new family of very long chain alpha,omega-dicarboxylic acids is a major structural fatty acyl component of the membrane lipids of Thermoanaerobacter ethanolicus 39E. |journal=Journal of Lipid Research |date=June 1994 |volume=35 |issue=6 |pages=1057–65 |doi=10.1016/S0022-2275(20)40101-4 |pmid=8077844|doi-access=free }}</ref> The most abundant diacid was the C30 {{Chem name|α,ω-13,16-dimethyloctacosanedioic}} acid.

Biphytanic diacids are present in geological sediments and are considered as tracers of past anaerobic oxidation of methane.<ref name="Birgel08">{{cite journal |last1=Birgel |first1=Daniel |last2=Elvert |first2=Marcus |last3=Han |first3=Xiqiu |last4=Peckmann |first4=Jörn |title=13C-depleted biphytanic diacids as tracers of past anaerobic oxidation of methane |journal=Organic Geochemistry |date=January 2008 |volume=39 |issue=1 |pages=152–156 |doi=10.1016/j.orggeochem.2007.08.013|bibcode=2008OrGeo..39..152B }}</ref> Several forms without or with one or two pentacyclic rings have been detected in Cenozoic seep limestones. These lipids may be unrecognized metabolites from Archaea.

[[File:Crocetin.svg|thumb|Crocetin]]
[[Crocetin]] is the core compound of crocins (crocetin glycosides) which are the main red pigments of the stigmas of saffron (''[[Crocus sativus]]'') and the fruits of gardenia (''[[Gardenia jasminoides]]''). Crocetin is a 20-carbon chain dicarboxylic acid which is a diterpenoid and can be considered as a carotenoid. It was the first plant carotenoid to be recognized as early as 1818 while the history of saffron cultivation reaches back more than 3,000 years.  The major active ingredient of saffron is the yellow pigment [[crocin]] 2 (three other derivatives with different glycosylations are known) containing a [[gentiobiose]] ([[disaccharide]]) group at each end of the molecule. A simple and specific HPLC-UV method has been developed to quantify the five major biologically active ingredients of saffron, namely the four crocins and crocetin.<ref name="Li999">{{cite journal |last1=Li |first1=Na |last2=Lin |first2=Ge |last3=Kwan |first3=Yiu-Wa |last4=Min |first4=Zhi-Da |title=Simultaneous quantification of five major biologically active ingredients of saffron by high-performance liquid chromatography |journal=Journal of Chromatography A |date=July 1999 |volume=849 |issue=2 |pages=349–355 |doi=10.1016/S0021-9673(99)00600-7 |pmid=10457433}}</ref>

== Unsaturated dicarboxylic acids ==
{{Main|Maleic acid|Fumaric acid}}
{{See also|Cis–trans isomerism|E-Z notation}}
:{| class="wikitable"
|+
|-
! Type !! Common name !! IUPAC name !! Isomer !! Structural formula !! PubChem
|-
| rowspan="7" | Monounsaturated || [[Maleic acid]] || (''Z'')-Butenedioic acid || cis || [[File:Maleic-acid-2D-skeletal-A.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/444266 444266]
|-
| [[Fumaric acid]] || (''E'')-Butenedioic acid   || trans || [[File:Fumaric-acid-2D-skeletal.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/444972 444972]
|-
| [[Acetylenedicarboxylic acid]] || But-2-ynedioic acid   || not applicable || [[File:Acetylenedicarboxylic acid.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/371 371]
|-
| rowspan="2" | [[Glutaconic acid]] || (''Z'')-Pent-2-enedioic acid || cis || [[File:Glutaconic acid cis vinyl-H.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5370328 5370328]
|-
|  (''E'')-Pent-2-enedioic acid || trans || [[File:Glutaconic acid trans vinyl-H.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5280498 5280498]
|-
| || [[2-Decenedioic acid]] || trans || [[File:2-Decenedioic acid.svg|200px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/6442613 6442613]
|-
| [[Traumatic acid]]  || Dodec-2-enedioic acid || trans || [[File:Traumatic acid structure.png|200px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5283028 5283028]
|-
| rowspan="4" | Diunsaturated || rowspan=3 | [[Muconic acid]] || (2''E'',4''E'')-Hexa-2,4-dienedioic acid || trans,trans
| [[File:muconic acid EE.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5356793 5356793]
|-
|  (2''Z'',4''E'')-Hexa-2,4-dienedioic acid || cis,trans || [[File:muconic acid EZ.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5280614 280518]
|-
|  (2''Z'',4''Z'')-Hexa-2,4-dienedioic acid || cis,cis || [[File:muconic acid ZZ.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5280518 5280518]
|-
| Glutinic acid<br />(Allene-1,3-dicarboxylic acid) || (''RS'')-[[Penta-2,3-dienedioic acid]] || || HO<sub>2</sub>CCH=C=CHCO<sub>2</sub>H || [https://pubchem.ncbi.nlm.nih.gov/compound/5242834 5242834]
|-
| rowspan="3" | Branched || [[Citraconic acid]] || (2''Z'')-2-Methylbut-2-enedioic acid || cis || [[File:Citraconic acid.svg|100px|alt=HO<sub>2</sub>CCH=C(CH<sub>3</sub>)CO<sub>2</sub>H]] || [https://pubchem.ncbi.nlm.nih.gov/compound/643798 643798]
|-
| [[Mesaconic acid]] || (2''E'')-2-Methyl-2-butenedioic acid || trans || [[File:Mesaconic-acid-2D-skeletal.svg|100px|alt=HO<sub>2</sub>CCH=C(CH<sub>3</sub>)CO<sub>2</sub>H]] || [https://pubchem.ncbi.nlm.nih.gov/compound/638129 638129]
|-
|  [[Itaconic acid]] || 2-Methylidenebutanedioic acid || – || [[File:Itaconic acid.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/811 811]
|}
Traumatic acid, was among the first biologically active molecules isolated from plant tissues. This dicarboxylic acid was shown to be a potent wound healing agent in plant that stimulates cell division near a wound site,<ref>{{cite journal |last1=Farmer |first1=Edward E. |title=Fatty acid signalling in plants and their associated microorganisms |journal=Plant Molecular Biology |date=1994 |volume=26 |issue=5 |pages=1423–1437 |doi=10.1007/BF00016483 |pmid=7858198|s2cid=3712976 }}</ref>
it derives from 18:2 or 18:3 fatty acid [[hydroperoxide]]s after conversion into oxo- [[fatty acid]]s.

''trans,trans''-Muconic acid is a [[metabolite]] of benzene in humans.  The determination of its concentration in urine is therefore used as a [[biomarker]] of occupational or environmental exposure to benzene.<ref>{{cite journal |vauthors=Wiwanitkit V, Soogarun S, Suwansaksri J |title=A correlative study on red blood cell parameters and urine trans, trans-muconic acid in subjects with occupational benzene exposure |journal=Toxicologic Pathology |volume=35 |issue=2 |pages=268–9 |year=2007 |pmid=17366320 |doi=10.1080/01926230601156278|s2cid=6392962 }}</ref><ref>{{cite journal |vauthors=Weaver VM, Davoli CT, Heller PJ |title=Benzene exposure, assessed by urinary trans,trans-muconic acid, in urban children with elevated blood lead levels |journal=Environ. Health Perspect. |volume=104 |issue=3 |pages=318–23 |year=1996 |pmid=8919771 |doi=10.2307/3432891 |pmc=1469300 |jstor=3432891 |display-authors=etal}}</ref>

Glutinic acid, a substituted [[allene]], was isolated from ''[[Alnus glutinosa]]'' (Betulaceae).<ref name="Sati">{{cite journal |author1=Sati, Sushil Chandra |author2=Sati, Nitin |author3=Sati, O. P. |year=2011 |title=Bioactive constituents and medicinal importance of genus ''Alnus'' |journal=Pharmacognosy Reviews |volume=5 |issue=10 |pages=174–183 |doi=10.4103/0973-7847.91115 |pmc=3263052 |pmid=22279375 |doi-access=free }}</ref>

While polyunsaturated fatty acids are unusual in plant cuticles, a diunsaturated dicarboxylic acid has been reported as a component of the surface waxes or polyesters of some plant species. Thus, {{Chem name|octadeca-c6,c9-diene-1,18-dioate}}, a derivative of [[linoleic acid]], is present in Arabidopsis and [[Brassica napus]] cuticle.<ref>{{cite journal |last1=Bonaventure |first1=Gustavo |last2=Ohlrogge |first2=John |last3=Pollard |first3=Mike |title=Analysis of the aliphatic monomer composition of polyesters associated with Arabidopsis epidermis: occurrence of octadeca-cis-6, cis-9-diene-1,18-dioate as the major component |journal=The Plant Journal |date=2004 |volume=40 |issue=6 |pages=920–930 |doi=10.1111/j.1365-313X.2004.02258.x |pmid=15584957 |doi-access=free}}</ref>

=== Alkylitaconates ===
[[File:Itaconic acid.png|thumb|150px|Itaconic acid<br />[https://pubchem.ncbi.nlm.nih.gov/compound/811 PubChem 811]]]
Several dicarboxylic acids having an alkyl side chain and an itaconate core have been isolated from [[lichen]]s and [[fungi]], [[itaconic acid]] (methylenesuccinic acid) being a metabolite produced by filamentous fungi. Among these compounds, several analogues, called chaetomellic acids with different chain lengths and degrees of unsaturation have been isolated from various species of the lichen [[Chaetomella]]. These molecules were shown to be valuable as basis for the development of anticancer drugs due to their strong [[farnesyltransferase]] inhibitory effects.<ref name="singh000">{{cite journal |last1=Singh |first1=Sheo B. |last2=Jayasuriya |first2=Hiranthi |last3=Silverman |first3=Keith C. |last4=Bonfiglio |first4=Cynthia A. |last5=Williamson |first5=Joanne M. |last6=Lingham |first6=Russell B. |title=Efficient syntheses, human and yeast farnesyl-protein transferase inhibitory activities of chaetomellic acids and analogues |journal=Bioorganic & Medicinal Chemistry |date=March 2000 |volume=8 |issue=3 |pages=571–580 |doi=10.1016/s0968-0896(99)00312-0 |pmid=10732974 }}</ref>

A series of alkyl- and alkenyl-itaconates, known as ceriporic acids ([https://pubchem.ncbi.nlm.nih.gov/compound/52921868 Pub Chem 52921868]), were found in cultures of a selective [[lignin]]-degrading fungus ([[Wood-decay fungus#White rot|white rot fungus]]), Ceriporiopsis subvermispora.<ref name="Enoki00">{{cite journal |last1=Enoki |first1=Makiko |last2=Watanabe |first2=Takashi |last3=Honda |first3=Yoichi |last4=Kuwahara |first4=Masaaki |title=A Novel Fluorescent Dicarboxylic Acid, (Z)-1,7-Nonadecadiene-2,3-dicarboxylic Acid, Produced by White-Rot Fungus Ceriporiopsis subvermispora. |journal=Chemistry Letters |volume=29 |date=2000 |issue=1 |pages=54–55 |doi=10.1246/cl.2000.54}}</ref><ref name="Amirta03">{{cite journal |last1=Amirta |first1=Rudianto |last2=Fujimori |first2=Kenya |last3=Shirai |first3=Nobuaki |last4=Honda |first4=Yoichi |last5=Watanabe |first5=Takashi |title=Ceriporic acid C, a hexadecenylitaconate produced by a lignin-degrading fungus, Ceriporiopsis subvermispora |journal=Chemistry and Physics of Lipids |date=December 2003 |volume=126 |issue=2 |pages=121–131 |doi=10.1016/S0009-3084(03)00098-7 |pmid=14623447}}</ref> The absolute configuration of ceriporic acids, their stereoselective biosynthetic pathway and the diversity of their metabolites have been discussed in detail.<ref name="Nishimura009">{{cite journal |last1=Nishimura |first1=Hiroshi |last2=Murayama |first2=Kyoko |last3=Watanabe |first3=Takahito |last4=Honda |first4=Yoichi |last5=Watanabe |first5=Takashi |title=Absolute configuration of ceriporic acids, the iron redox-silencing metabolites produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora |journal=Chemistry and Physics of Lipids |date=June 2009 |volume=159 |issue=2 |pages=77–80 |doi=10.1016/j.chemphyslip.2009.03.006 |pmid=19477313}}</ref>

== Substituted dicarboxylic acids ==
:{| class="wikitable"
|+
|-
! Common name !! IUPAC name !! Structural formula !! PubChem
|-
| [[Tartronic acid]] || 2-Hydroxypropanedioic acid || [[File:Tartronic acid.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/45 45]
|-
| [[Mesoxalic acid]] || Oxopropanedioic acid || [[File:Mesoxalic acid.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/10132 10132]
|-
| [[Malic acid]] || Hydroxybutanedioic acid || [[File:Äpfelsäure3.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/525 525]
|-
| [[Tartaric acid]] || 2,3-Dihydroxybutanedioic acid || [[File:Tartaric acid.svg|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/875 875]
|-
| [[Oxaloacetic acid]] || Oxobutanedioic acid || [[File:Oxaloacetic acid.png|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/970 970]
|-
| [[Aspartic acid]] || 2-Aminobutanedioic acid || [[File:Asparaginsäure - Aspartic acid.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/5960 5960]
|-
| [[dioxosuccinic acid]] || dioxobutanedioic acid || [[File:Dioxosuccinic acid.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/82062 82062]
|-
| [[Alpha-Hydroxyglutaric acid|α-hydroxyGlutaric acid]] || 2-hydroxypentanedioic acid || [[File:Alpha-hydroxyglutaric acid.png|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/2-hydroxyglutaric_acid 43]
|-
| [[Arabinaric acid]] || 2,3,4-Trihydroxypentanedioic acid || || [https://pubchem.ncbi.nlm.nih.gov/compound/109475 109475]
|-
| [[Acetonedicarboxylic acid]] || 3-Oxopentanedioic acid || [[File:Structural formula of acetonedicarboxylic acid.svg|100px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/68328 68328]
|-
| [[α-Ketoglutaric acid]] || 2-Oxopentanedioic acid || [[File:Alpha-ketoglutaric acid.png|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/51 51]
|-
| [[Glutamic acid]] || 2-Aminopentanedioic acid || [[File:Glutaminsäure - Glutamic acid.svg|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/611 611]
|-
| [[Diaminopimelic acid]] || (2R,6S)-2,6-Diaminoheptanedioic acid || [[File:Diaminopimelic acid.svg|150px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/865 865]
|-
| [[Saccharic acid]] || (2S,3S,4S,5R)-2,3,4,5-Tetrahydroxyhexanedioic acid || [[File:Glucaric acid structure.svg|150px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/33037 33037]
|}
<!--
== Simple forms of dicarboxylic acids ==
Hidden: Dubious relevance and un-traceable references -->
<!-- It has been proposed that dicarboxylic acids are alternate lipid substrates in [[parenteral nutrition]]. --><!--<ref>{{cite journal |last1=Mingrone |first1=G. |last2=Greco |first2=A.V. |last3=Benedetti |first3=G. |last4=Capristo |first4=E. |last5=Semeraro |first5=R. |last6=Zoli |first6=G. |last7=Gasbarrini |first7=G. |title=0.68 Evaluation of diet-induced thermogenesisin Crohn's diseased patients |journal=Clinical Nutrition |date=August 1995 |volume=14 |pages=25 |doi=10.1016/S0261-5614(95)80140-5 }}</ref> Can't loacate this reference. PG They are water soluble, undergo b-oxidation, do not induce [[ketogenesis]] but rather promote [[gluconeogenesis]]. They could represent an immediately available form of energy. Thus, inorganic salts of [[sebacic acid|sebacic]] and the monocarboxylic acid [[lauric acid|lauric]] (C12) acids were firstly proposed, but now, triglycerides containing these fatty acids are under investigation.<ref>{{cite journal |last1=Capristo |first1=Esmeralda |last2=Mingrone |first2=Geltrude |last3=De Gaetano |first3=Andrea |last4=Addolorato |first4=Giovanni |last5=Greco |first5=Aldo V. |last6=Gasbarrini |first6=Giovanni |title=A new HPLC method for the direct analysis of triglycerides of dicarboxylic acids in biological samples |journal=Clinica Chimica Acta |date=November 1999 |volume=289 |issue=1-2 |pages=11–21 |doi=10.1016/S0009-8981(99)00145-X }}</ref> and inhibited the development of advanced cardiovascular disease.<ref>{{cite journal |last1=Russell |first1=James C. |last2=Amy |first2=Roger M. |last3=Graham |first3=Sandra E. |last4=Dolphin |first4=Peter J. |last5=Wood |first5=George O. |last6=Bar-Tana |first6=Jacob |title=Inhibition of Atherosclerosis and Myocardial Lesions in the JCR:LA-cp Rat by β,β′-Tetramethylhexadecanedioic Acid (MEDICA 16) |journal=Arteriosclerosis, Thrombosis, and Vascular Biology |date=July 1995 |volume=15 |issue=7 |pages=918–923 |doi=10.1161/01.ATV.15.7.918 }}</ref> -->

== Aromatic dicarboxylic acids ==
:{| class="wikitable"
|+
! Common names !! IUPAC name !! Structure || PubChem
|-
| [[Phthalic acid]]<br />''o''-phthalic acid || Benzene-1,2-dicarboxylic acid || [[File:Phthalic-acid-2D-skeletal.png|80px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/1017 1017]
|-
| [[Isophthalic acid]]<br />''m''-phthalic acid || Benzene-1,3-dicarboxylic acid || [[File:Isophthalic-acid-2D-skeletal.png|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/8496 8496]
|-
| [[Terephthalic acid]]<br />''p''-phthalic acid || Benzene-1,4-dicarboxylic acid || [[File:Terephthalic-acid-2D-skeletal.png|120px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/7489 7489]
|-
| Diphenic acid<br />Biphenyl-2,2′-dicarboxylic acid || 2-(2-Carboxyphenyl)benzoic acid || [[File:Diphenic Acid Structural Formula V.1.svg|110px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/10210 10210]
|-
| [[2,6-Naphthalenedicarboxylic acid]] || 2,6-Naphthalenedicarboxylic acid || [[File:2,6-Naphthalenedicarboxylic acid.svg|150px]] || [https://pubchem.ncbi.nlm.nih.gov/compound/14357 14357]
|}
Terephthalic acid is a [[commodity chemical]] used in the manufacture of the [[polyester]] known by brand names such as [[Terylene|PET, Terylene, Dacron and Lavsan]].

== Properties ==
Dicarboxylic acids are usually crystalline solids.  Solubility in water and melting point of the α,ω- compounds progress in a series as the carbon chains become longer with alternating between odd and even numbers of carbon atoms, so that for even numbers of carbon atoms the melting point is higher than for the next in the series with an odd number.<ref name="jsoc">{{cite book |last1=Schmidt |first1=Julius |title=Organic Chemistry |date=1955 |publisher=Oliver and Boyd |location=London |pages=283–284}}</ref> These compounds are weak dibasic acids with pK<sub>a</sub> tending towards values of ca. 4.5 and 5.5 as the separation between the two carboxylate groups increases. Thus, in an aqueous solution at pH about 7, typical of biological systems, the [[Henderson–Hasselbalch equation]] indicates they exist predominantly as dicarboxylate anions.

The dicarboxylic acids, especially the small and linear ones, can be used as crosslinking reagents.<ref>{{cite journal |last1=Moghadas |first1=Babak |last2=Solouk |first2=Atefeh |last3=Sadeghi |first3=Davoud |title=Development of chitosan membrane using non-toxic crosslinkers for potential wound dressing applications |journal=Polymer Bulletin |date=September 2021 |volume=78 |issue=9 |pages=4919–4929 |doi=10.1007/s00289-020-03352-8 }}</ref> Dicarboxylic acids where the carboxylic groups are separated by none or one carbon atom decompose when they are heated to give off carbon dioxide and leave behind a monocarboxylic acid.<ref name="jsoc" />

Blanc's Rule says that heating a barium salt of a dicarboxylic acid, or dehydrating it with acetic anhydride will yield a cyclic acid anhydride if the carbon atoms bearing acid groups are in position 1 and (4 or 5). So succinic acid will yield [[succinic anhydride]].  For acids with carboxylic groups at position 1 and 6 this dehydration causes loss of carbon dioxide and water to form a cyclic ketone, for example, adipic acid will form [[cyclopentanone]].<ref name="jsoc" />

== Derivatives ==
{{expand section|with=a well sourced, more expansive presentation than that of a 1922 sophomore text | small = no | date = September 2024}}
As for monofunctional carboxylic acids, derivatives of the same types exist;{{what | date = September 2024}}<!--Clear only to a specialist, who knows this already.--> however, there is the added complication that one or both of the carboxylic groups could be altered.{{fact|date = September 2024}} If only one is changed then the derivative is termed "acid", and if both ends are altered it is called "normal".{{what | date = September 2024}}{{update after|2024|9|12}} Derivatives include one or both of the carboxylates being converted to their salts, acid chlorides, esters, amides, and anhydrides.{{fact | date = September 2024}} In the case of anhydrides or amides, two of the carboxyl groups can come together to form a cyclic compound, for example [[succinimide]].<ref name="Bernthsen22">{{cite book |last1=Bernthsen |first1=A. |title=Organic Chemistry |date=1922 |publisher=Blackie & Son |location=London |page=242}}</ref>

== See also ==
* [[Tricarboxylic acid]]

== References ==
{{Reflist|colwidth=30em}}

== External links ==
* [http://www.lipidmaps.org/data/structure/LMSDSearch.php?Mode=ProcessClassSearch&LMID=LMFA0117 Lipidomics gateway Structure Database Dicarboxylic acids]
* {{cite web |last1=Dijkstra |first1=Albert J. |title=Trivial names of fatty acids-Part 1. |url=http://lipidlibrary.aocs.org/resource-material/trivial-names-of-fatty-acids-part-1 |website=lipidlibrary.aocs.org |access-date=24 June 2019}}
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[[Category:Dicarboxylic acids| ]]