Adipic acid

Last updated
Adipic acid
Adipic acid 200.svg
Adipic acid molecule ball from xtal.png
Names
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)
1209788
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.250 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 204-673-3
E number E355 (antioxidants, ...)
3166
KEGG
PubChem CID
RTECS number
  • AU8400000
UNII
UN number 3077
  • InChI=1S/C6H10O4/c7-5(8)3-1-2-4-6(9)10/h1-4H2,(H,7,8)(H,9,10) Yes check.svgY
    Key: WNLRTRBMVRJNCN-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H10O4/c7-5(8)3-1-2-4-6(9)10/h1-4H2,(H,7,8)(H,9,10)
    Key: WNLRTRBMVRJNCN-UHFFFAOYAY
  • O=C(O)CCCCC(=O)O
  • C(CCC(=O)O)CC(=O)O
Properties
C6H10O4
Molar mass 146.142 g·mol−1
AppearanceWhite 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
−994.3 kJ/mol [3]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H319
P264, P280, P305+P351+P338, P337+P313
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Flash point 196 °C (385 °F; 469 K)
422 °C (792 °F; 695 K)
Lethal dose or concentration (LD, LC):
3600 mg/kg (rat)
Safety data sheet (SDS) External MSDS
Related compounds
glutaric acid
pimelic acid
Related compounds
 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).

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. Salts and esters of adipic acid are known as adipates.

Contents

Preparation and reactivity

Adipic acid is produced by oxidation of a mixture of cyclohexanone and cyclohexanol, which is called KA oil, an abbreviation of ketone-alcohol oil. Nitric acid is the oxidant. The pathway is multistep. Early in the reaction, the cyclohexanol is converted to the ketone, releasing nitrous acid:

HOCH(CH2)5 + HNO3 → O=C(CH2)5 + HNO2 + H2O

The cyclohexanone is then nitrosated, setting the stage for the scission of the C-C bond:

HNO2 + HNO3 → [NO+]NO3]− + H2O
O=C(CH2)5 + NO+ → O=C(CHNO)(CH2)4 + 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.

Auguste Laurent discovered adipic acid in 1837 [8] [9] by oxidation of various fats with nitric acid via sebacic acid [10] and gave it the current name because of that (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. [11]

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. [12]

Uses

About 60% of the 2.5 billion kg of adipic acid produced annually is used as monomer for the production of nylon [13] 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. [14]

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. [15]

In foods

Small but significant amounts of adipic acid are used as a food ingredient as a flavorant and gelling aid. [16] 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. [17]

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, [18] 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: [19]

2 N2O → 2 N2 + O2

Adipate salts and esters

Structural formula of the adipate dianion Adipate.svg
Structural formula of the adipate dianion

The anionic (HO2C(CH2)4CO2−) and dianionic (−O2C(CH2)4CO2−) forms of adipic acid are referred to as adipates. An adipate compound is a carboxylate salt or ester of the acid.

Some adipate salts are used as acidity regulators, including:

Some adipate esters are used as plasticizers, including:

Related Research Articles

<span class="mw-page-title-main">Condensation polymer</span> Polymer produced via a condensation reaction

In polymer chemistry, condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction. Natural proteins as well as some common plastics such as nylon and PETE are formed in this way. Condensation polymers are formed by polycondensation, when the polymer is formed by condensation reactions between species of all degrees of polymerization, or by condensative chain polymerization, when the polymer is formed by sequential addition of monomers to an active site in a chain reaction. The main alternative forms of polymerization are chain polymerization and polyaddition, both of which give addition polymers.

<span class="mw-page-title-main">Ketone</span> Organic compounds of the form >C=O

In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.

<span class="mw-page-title-main">Hydroxylamine</span> Inorganic compound

Hydroxylamine is an inorganic compound with the chemical formula NH2OH. The compound is in a form of a white hygroscopic crystals. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. The oxidation of NH3 to hydroxylamine is a step in biological nitrification.

<span class="mw-page-title-main">Nitrous acid</span> Chemical compound

Nitrous acid is a weak and monoprotic acid known only in solution, in the gas phase, and in the form of nitrite salts. It was discovered by Carl Wilhelm Scheele, who called it "phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.

Cyclohexene is a hydrocarbon with the formula (CH2)4C2H2. It is an example of a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an intermediate in the commercial synthesis of nylon.

<span class="mw-page-title-main">Cyclohexanol</span> Chemical compound

Cyclohexanol is the organic compound with the formula HOCH(CH2)5. The molecule is related to cyclohexane by replacement of one hydrogen atom by a hydroxyl group. This compound exists as a deliquescent colorless solid with a camphor-like odor, which, when very pure, melts near room temperature. Millions of tonnes are produced annually, mainly as a precursor to nylon.

<span class="mw-page-title-main">Sebacic acid</span> Chemical compound

Sebacic acid is a naturally occurring dicarboxylic acid with the chemical formula HO2C(CH2)8CO2H. It is a white flake or powdered solid. Sebaceus is Latin for tallow candle, sebum is Latin for tallow, and refers to its use in the manufacture of candles. Sebacic acid is a derivative of castor oil.

<span class="mw-page-title-main">Caprolactam</span> Chemical compound

Caprolactam (CPL) is an organic compound with the formula (CH2)5C(O)NH. This colourless solid is a lactam (a cyclic amide) of caproic acid. Global demand for this compound is approximately five million tons per year, and the vast majority is used to make Nylon 6 filament, fiber, and plastics.

In chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction.

<span class="mw-page-title-main">Cyclopentanone</span> Chemical compound

Cyclopentanone is the organic compound with the formula (CH2)4CO. This cyclic ketone is a colorless volatile liquid.

<span class="mw-page-title-main">Cyclohexanone</span> Chemical compound

Cyclohexanone is the organic compound with the formula (CH2)5CO. The molecule consists of six-carbon cyclic molecule with a ketone functional group. This colorless oily liquid has a sweet odor reminiscent of benzaldehyde. Over time, samples of cyclohexanone assume a pale yellow color. Cyclohexanone is slightly soluble in water and miscible with common organic solvents. Millions of tonnes are produced annually, mainly as a precursor to nylon.

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 HO2C−R−CO2H, where R can be aliphatic or aromatic. In general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids.

<span class="mw-page-title-main">Pimelic acid</span> Chemical compound

Pimelic acid is the organic compound with the formula HO2C(CH2)5CO2H. Pimelic acid is one CH
2 unit longer than a related dicarboxylic acid, adipic acid, a precursor to many polyesters and polyamides. However compared to adipic acid, pimelic acid is relatively small in importance industrially. Derivatives of pimelic acid are involved in the biosynthesis of the amino acid lysine and the vitamin biotin.

Autoxidation refers to oxidations brought about by reactions with oxygen at normal temperatures, without the intervention of flame or electric spark. The term is usually used to describe the gradual degradation of organic compounds in air at ambient temperatures. Many common phenomena can be attributed to autoxidation, such as food going rancid, the 'drying' of varnishes and paints, and the perishing of rubber. It is also an important concept in both industrial chemistry and biology. Autoxidation is therefore a fairly broad term and can encompass examples of photooxygenation and catalytic oxidation.

<span class="mw-page-title-main">Hydroperoxide</span> Class of chemical compounds

Hydroperoxides or peroxols are compounds of the form ROOH, where R stands for any group, typically organic, which contain the hydroperoxy functional group. Hydroperoxide also refers to the hydroperoxide anion and its salts, and the neutral hydroperoxyl radical (•OOH) consist of an unbond hydroperoxy group. When R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have the formula ROOR. Organic hydroperoxides can either intentionally or unintentionally initiate explosive polymerisation in materials with unsaturated chemical bonds.

<span class="mw-page-title-main">Caprolactone</span> Chemical compound

ε-Caprolactone or simply caprolactone is a lactone possessing a seven-membered ring. Its name is derived from caproic acid. This colorless liquid is miscible with most organic solvents and water. It was once produced on a large scale as a precursor to caprolactam.

<span class="mw-page-title-main">Cyclohexenone</span> Chemical compound

Cyclohexenone is an organic compound which is a versatile intermediate used in the synthesis of a variety of chemical products such as pharmaceuticals and fragrances. It is colorless liquid, but commercial samples are often yellow.

<span class="mw-page-title-main">Hydroxylammonium sulfate</span> Chemical compound

Hydroxylammonium sulfate [NH3OH]2SO4, is the sulfuric acid salt of hydroxylamine. It is primarily used as an easily handled form of hydroxylamine, which is explosive when pure.

Cycloheptanone, (CH2)6CO, is a cyclic ketone also referred to as suberone. It is a colourless volatile liquid. Cycloheptanone is used as a precursor for the synthesis of pharmaceuticals.

<span class="mw-page-title-main">Nitrolic acid</span>

Nitrolic acids are organic compounds with the functional group RC(NO2)=NOH. They are prepared by the reaction of nitroalkanes with base and nitrite sources:

References

  1. ↑ 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.
  2. 1 2 "Adipic Acid" . The Merck Index . Royal Society of Chemistry. 2013. Retrieved 2 March 2017.
  3. ↑ Haynes, W. M., ed. (2013). CRC Handbook of Chemistry and Physics (94th ed.). Boca Raton, Florida: CRC Press. ISBN   978-1-4665-7114-3.
  4. 1 2 3 4 5 Musser, M. T. (2005). "Adipic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_269. ISBN   3527306730.
  5. ↑ 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.
  6. ↑ Ellis, B. A. (1925). "Adipic Acid". Organic Syntheses . 5: 9; Collected Volumes, vol. 1, p. 560.
  7. ↑ 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.
  8. ↑ Roscoe, Henry Enfield; Schorlemmer, Carl (1890). A Treatise on Chemistry: The chemistry of the hydrocarbons and their derivatives, or Organic chemistry. Appleton.
  9. ↑ Laurent, Aug. (1837). "Recherches diverses de Chimie organique". Annales de chimie et de physique. 66.
  10. ↑ 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.
  11. ↑ Cornils, Boy; Lappe, Peter (2000). "Dicarboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_523. ISBN   3527306730.
  12. ↑ Thorpe, J. F.; Kon, G. A. R. (1925). "Cyclopentanone". Organic Syntheses . 5: 37; Collected Volumes, vol. 1, p. 192.
  13. ↑ "Adipic Acid". Archived from the original on 2015-05-18. Retrieved 2015-05-09. PCI abstract for adipic acid
  14. ↑ "Polyvinylchloride - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2023-11-10.
  15. ↑ Roew, Raymond (2009), "Adipic Acid", Handbook of Pharmaceutical Excipients, pp. 11–12
  16. ↑ "Cherry Jell-O Nutrition Facts". Kraft Foods. Archived from the original on 24 September 2019. Retrieved 21 Mar 2012.
  17. ↑ American Chemical Society (9 February 2015). "Molecule of the Week: Adipic Acid".
  18. ↑ US EPA (12 August 2013). "U.S. Greenhouse Gas Inventory Report, Chapter 4. Industrial Processes" (PDF). Retrieved 2013-11-29.
  19. ↑ 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.

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