In organic chemistry, a dicarboxylic acid is an organic compound containing two carboxyl groups . The general molecular formula for dicarboxylic acids can be written as, where R can be aliphatic or aromatic. In general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids.
Dicarboxylic acids are used in the preparation of copolymers such as polyamides and polyesters. 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.
The general formula for acyclic dicarboxylic acid is .[1] The PubChem links gives access to more information on the compounds, including other names, ids, toxicity and safety.
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!'.
| C2 | 0 | ethanedioic acid | 1.27 | 4.27 | 971 | |||
| C3 | 1 | propanedioic acid | 2.85 | 5.05 | 867 | |||
| C4 | 2 | butanedioic acid | 4.21 | 5.41 | 1110 | |||
| C5 | 3 | pentanedioic acid | 4.34 | 5.41 | 743 | |||
| C6 | 4 | hexanedioic acid | 4.41 | 5.41 | 196 | |||
| C7 | 5 | heptanedioic acid | 4.50 | 5.43 | 385 | |||
| C8 | 6 | octanedioic acid | 4.526 | 5.498 | 10457 | |||
| C8 | 6 | 14106 | ||||||
| C9 | 7 | nonanedioic acid | 4.550 | 5.498 | 2266 | |||
| C10 | 8 | decanedioic acid | 4.720 | 5.450 | 5192 | |||
| C11 | 9 | undecanedioic acid | 15816 | |||||
| C12 | 10 | 12736 | ||||||
| C13 | 11 | tridecanedioic acid | 10458 | |||||
| C16 | 14 | hexadecanedioic acid | 10459 | |||||
| C21 | 19 | heneicosanedioic acid | 9543668 | |||||
| C22 | 20 | Phellogenic acid | 244872 | |||||
| C30 | 28 | triacontanedioic acid | 5322010 |
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.[6] 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%.[7]
It was shown that hyperthermophilic microorganisms specifically contained a large variety of dicarboxylic acids.[8] 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.[9]
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.[10] 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.[11]
Long-chain dicarboxylic acids containing 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.[12] 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 springs, deep-sea marine hydrothermal systems and high-temperature marine and continental oil fields.[13] 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.[14]
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.[15] The most abundant diacid was the C30 acid.
Biphytanic diacids are present in geological sediments and are considered as tracers of past anaerobic oxidation of methane.[16] 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.
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.[17]
See main article: Maleic acid and Fumaric acid.
See also: Cis–trans isomerism and E-Z notation.
| Type | Common name | IUPAC name | Isomer | Structural formula | PubChem |
|---|---|---|---|---|---|
| Monounsaturated | (Z)-Butenedioic acid | cis | 444266 | ||
| (E)-Butenedioic acid | trans | 444972 | |||
| But-2-ynedioic acid | not applicable | 371 | |||
| (Z)-Pent-2-enedioic acid | cis | 5370328 | |||
| (E)-Pent-2-enedioic acid | trans | 5280498 | |||
| trans | 6442613 | ||||
| Dodec-2-enedioic acid | trans | 5283028 | |||
| Diunsaturated | (2E,4E)-Hexa-2,4-dienedioic acid | trans,trans | 5356793 | ||
| (2Z,4E)-Hexa-2,4-dienedioic acid | cis,trans | 280518 | |||
| (2Z,4Z)-Hexa-2,4-dienedioic acid | cis,cis | 5280518 | |||
| Glutinic acid (Allene-1,3-dicarboxylic acid) | HO2CCH=C=CHCO2H | 5242834 | |||
| Branched | (2Z)-2-Methylbut-2-enedioic acid | cis | 643798 | ||
| (2E)-2-Methyl-2-butenedioic acid | trans | 638129 | |||
| 2-Methylidenebutanedioic acid | – | 811 |
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.[19] [20]
Glutinic acid, a substituted allene, was isolated from Alnus glutinosa (Betulaceae).[21]
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,, a derivative of linoleic acid, is present in Arabidopsis and Brassica napus cuticle.[22]
Several dicarboxylic acids having an alkyl side chain and an itaconate core have been isolated from lichens 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.[23]
A series of alkyl- and alkenyl-itaconates, known as ceriporic acids (Pub Chem 52921868), were found in cultures of a selective lignin-degrading fungus (white rot fungus), Ceriporiopsis subvermispora.[24] [25] The absolute configuration of ceriporic acids, their stereoselective biosynthetic pathway and the diversity of their metabolites have been discussed in detail.[26]
| Common name | IUPAC name | Structural formula | PubChem | |
|---|---|---|---|---|
| 2-Hydroxypropanedioic acid | 45 | |||
| Oxopropanedioic acid | 10132 | |||
| Hydroxybutanedioic acid | 525 | |||
| 2,3-Dihydroxybutanedioic acid | 875 | |||
| Oxobutanedioic acid | 970 | |||
| 2-Aminobutanedioic acid | 5960 | |||
| dioxobutanedioic acid | 82062 | |||
| 2-hydroxypentanedioic acid | 43 | |||
| 2,3,4-Trihydroxypentanedioic acid | 109475 | |||
| 3-Oxopentanedioic acid | 68328 | |||
| 2-Oxopentanedioic acid | 51 | |||
| 2-Aminopentanedioic acid | 611 | |||
| (2R,6S)-2,6-Diaminoheptanedioic acid | 865 | |||
| (2S,3S,4S,5R)-2,3,4,5-Tetrahydroxyhexanedioic acid | 33037 |
| PubChem | ||||
| Phthalic acid o-phthalic acid | Benzene-1,2-dicarboxylic acid | 1017 | ||
| Isophthalic acid m-phthalic acid | Benzene-1,3-dicarboxylic acid | 8496 | ||
| Terephthalic acid p-phthalic acid | Benzene-1,4-dicarboxylic acid | 7489 | ||
| Diphenic acid Biphenyl-2,2′-dicarboxylic acid | 2-(2-Carboxyphenyl)benzoic acid | 10210 | ||
| 2,6-Naphthalenedicarboxylic acid | 14357 |
Dicarboxylic acids are 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.[27] These compounds are weak dibasic acids with pKa 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.[28] 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.
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.
As for monofunctional carboxylic acids, derivatives of the same types exist. However, there is the added complication that either one or two of the carboxylic groups could be altered. If only one is changed then the derivative is termed "acid", and if both ends are altered it is called "normal". These derivatives include salts, chlorides, esters, amides, and anhydrides. In the case of anhydrides or amides, two of the carboxyl groups can come together to form a cyclic compound, for example succinimide.[29]