Adipic acid
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Names | |
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Preferred IUPAC name
Hexanedioic acid | |
Other names
Adipic acid
Butane-1,4-dicarboxylic acid Hexane-1,6-dioic acid 1,4-butanedicarboxylic acid | |
Identifiers | |
3D model (JSmol)
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1209788 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.004.250 ![]() |
EC Number |
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E number | E355 (antioxidants, ...) |
3166 | |
KEGG | |
PubChem CID
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RTECS number |
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UNII | |
UN number | 3077 |
CompTox Dashboard (EPA)
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Properties | |
C6H10O4 | |
Molar mass | 146.142 g·mol−1 |
Appearance | White crystals[1] Monoclinic prisms[2] |
Odor | Odorless |
Density | 1.360 g/cm3 |
Melting point | 152.1 °C (305.8 °F; 425.2 K) |
Boiling point | 337.5 °C (639.5 °F; 610.6 K) |
14 g/L (10 °C) 24 g/L (25 °C) 1600 g/L (100 °C) | |
Solubility | Very soluble in methanol, ethanol soluble in acetone, acetic acid slightly soluble in cyclohexane negligible in benzene, petroleum ether |
log P | 0.08 |
Vapor pressure | 0.097 hPa (18.5 °C) = 0.073 mmHg |
Acidity (pKa) | 4.43, 5.41 |
Conjugate base | Adipate |
Viscosity | 4.54 cP (160 °C) |
Structure | |
Monoclinic | |
Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
−994.3 kJ/mol[3] |
Hazards | |
Safety data sheet | External MSDS |
GHS pictograms | ![]() |
GHS Signal word | Warning |
GHS hazard statements
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H319 |
P264, P280, P305+351+338, P337+313 | |
NFPA 704 (fire diamond) | ![]()
2
1
0 |
Flash point | 196 °C (385 °F; 469 K) |
422 °C (792 °F; 695 K) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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3600 mg/kg (rat) |
Related compounds | |
Related dicarboxylic acids
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glutaric acid pimelic acid |
Related compounds
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hexanoic acid adipic acid dihydrazide hexanedioyl dichloride hexanedinitrile hexanediamide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Infobox references | |
Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon. Adipic acid otherwise rarely occurs in nature,[4] but it is known as manufactured E number food additive E355.
Preparation and reactivity[]
Adipic acid is produced from a mixture of cyclohexanone and cyclohexanol called KA oil, the abbreviation of ketone-alcohol oil. The KA oil is oxidized with nitric acid to give adipic acid, via a multistep pathway. Early in the reaction, the cyclohexanol is converted to the ketone, releasing nitrous acid:
- HOC6H11 + HNO3 → OC(CH2)5 + HNO2 + H2O
Among its many reactions, the cyclohexanone is nitrosated, setting the stage for the scission of the C-C bond:
- HNO2 + HNO3 → NO+NO3− + H2O
- OC6H10 + NO+ → OC6H9-2-NO + H+
Side products of the method include glutaric and succinic acids. Nitrous oxide is produced in about one to one mole ratio to the adipic acid,[5] as well, via the intermediacy of a nitrolic acid.[4]
Related processes start from cyclohexanol, which is obtained from the hydrogenation of phenol.[4][6]
Alternative methods of production[]
Several methods have been developed by carbonylation of butadiene. For example, the hydrocarboxylation proceeds as follows:[4]
- CH2=CH−CH=CH2 + 2 CO + 2 H2O → HO2C(CH2)4CO2H
Another method is oxidative cleavage of cyclohexene using hydrogen peroxide.[7] The waste product is water.
Historically, adipic acid was prepared by oxidation of various fats,[8] thus the name (ultimately from Latin adeps, adipis – "animal fat"; cf. adipose tissue).
Reactions[]
Adipic acid is a dibasic acid (it has two acidic groups). The pKa values for their successive deprotonations are 4.41 and 5.41.[9]
With the carboxylate groups separated by four methylene groups, adipic acid is suited for intramolecular condensation reactions. Upon treatment with barium hydroxide at elevated temperatures, it undergoes ketonization to give cyclopentanone.[10]
Uses[]
About 60% of the 2.5 billion kg of adipic acid produced annually is used as monomer for the production of nylon[11] by a polycondensation reaction with hexamethylene diamine forming nylon 66. Other major applications also involve polymers; it is a monomer for production of polyurethane and its esters are plasticizers, especially in PVC.
In medicine[]
Adipic acid has been incorporated into controlled-release formulation matrix tablets to obtain pH-independent release for both weakly basic and weakly acidic drugs. It has also been incorporated into the polymeric coating of hydrophilic monolithic systems to modulate the intragel pH, resulting in zero-order release of a hydrophilic drug. The disintegration at intestinal pH of the enteric polymer shellac has been reported to improve when adipic acid was used as a pore-forming agent without affecting release in the acidic media. Other controlled-release formulations have included adipic acid with the intention of obtaining a late-burst release profile.[12]
In foods[]
Small but significant amounts of adipic acid are used as a food ingredient as a flavorant and gelling aid.[13] It is used in some calcium carbonate antacids to make them tart. As an acidulant in baking powders, it avoids the undesirable hygroscopic properties of tartaric acid.[2] Adipic acid, rare in nature, does occur naturally in beets, but this is not an economical source for commerce compared to industrial synthesis.[14]
Safety[]
Adipic acid, like most carboxylic acids, is a mild skin irritant. It is mildly toxic, with a median lethal dose of 3600 mg/kg for oral ingestion by rats.[4]
Environmental[]
The production of adipic acid is linked to emissions of N
2O,[15] a potent greenhouse gas and cause of stratospheric ozone depletion. At adipic acid producers DuPont and Rhodia (now Invista and Solvay, respectively), processes have been implemented to catalytically convert the nitrous oxide to innocuous products:[16]
- 2 N2O → 2 N2 + O2
References[]
- ^ Mac Gillavry, C. H. (2010). "The crystal structure of adipic acid". Recueil des Travaux Chimiques des Pays-Bas. 60 (8): 605–617. doi:10.1002/recl.19410600805.
- ^ Jump up to: a b "Adipic Acid". The Merck Index. Royal Society of Chemistry. 2013. Retrieved 2 March 2017.
- ^ Haynes, W. M., ed. (2013). CRC Handbook of Chemistry and Physics (94th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4665-7114-3.
- ^ Jump up to: a b c d e Musser, M. T. (2005). "Adipic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_269. ISBN 3527306730.
- ^ Parmon, V. N.; Panov, G. I.; Uriarte, A.; Noskov, A. S. (2005). "Nitrous oxide in oxidation chemistry and catalysis application and production". Catalysis Today. 100 (2005): 115–131. doi:10.1016/j.cattod.2004.12.012.
- ^ Ellis, B. A. (1925). "Adipic Acid". Organic Syntheses. 5: 9.; Collective Volume, 1, p. 560
- ^ Sato, K.; Aoki, M.; Noyori, R. (1998). "A "Green" route to adipic acid: direct oxidation of cyclohexenes with 30 percent hydrogen peroxide". Science. 281 (5383): 1646–47. Bibcode:1998Sci...281.1646S. doi:10.1126/science.281.5383.1646. PMID 9733504.
- ^ Ince, Walter (1895). "Preparation of adipic acid and some of its derivatives". Journal of the Chemical Society, Transactions. 67: 155–159. doi:10.1039/CT8956700155.
- ^ Cornils, Boy; Lappe, Peter (2000). "Dicarboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_523.
- ^ Thorpe, J. F.; Kon, G. A. R. (1925). "Cyclopentanone". Organic Syntheses. 5: 37.; Collective Volume, 1, p. 192
- ^ "Archived copy". Archived from the original on 2015-05-18. Retrieved 2015-05-09.CS1 maint: archived copy as title (link) PCI abstract for adipic acid
- ^ Roew, Raymond (2009), "Adipic Acid", Handbook of Pharmaceutical Excipients, pp. 11–12
- ^ "Cherry Jell-O Nutrition Facts". Kraft Foods. Archived from the original on 24 September 2019. Retrieved 21 Mar 2012.
- ^ American Chemical Society (9 February 2015). "Molecule of the Week: Adipic Acid".
- ^ US EPA. "U.S. Greenhouse Gas Inventory Report, Chapter 4. Industrial Processes" (PDF). Retrieved 2013-11-29.
- ^ Reimer, R. A.; Slaten, C. S.; Seapan, M.; Koch, T. A.; Triner, V. G. (2000). "Adipic Acid Industry — N2O Abatement". Non-CO2 Greenhouse Gases: Scientific Understanding, Control and Implementation. Netherlands: Springer. pp. 347–358. doi:10.1007/978-94-015-9343-4_56. ISBN 978-94-015-9343-4.
Appendix[]
- U.S. FDA citations – GRAS (21 CFR 184.1009), Indirect additive (21 CFR 175.300, 21 CFR 175.320, 21 CFR 176.170, 21 CFR 176.180, 21 CFR 177.1200, 21 CFR 177.1390, 21 CFR 177.1500, 21 CFR 177.1630, 21 CFR 177.1680, 21 CFR 177.2420, 21 CFR 177.2600)
- European Union Citations – Decision 1999/217/EC – Flavoing Substance; Directive 95/2/EC, Annex IV – Permitted Food Additive; 2002/72/EC, Annex A – Authorized monomer for Food Contact Plastics
External links[]
- International Chemical Safety Card 0369
- SIDS Initial Assessment Report for Adipic acid from the Organisation for Economic Co-operation and Development (OECD)
- adipic acid on chemicalland
- Commodity chemicals
- Dicarboxylic acids
- Food acidity regulators
- Monomers
- E-number additives