Adipic acid

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Adipic acid
Adipic acid
IUPAC name hexanedioic acid
Other names butane-1,4-dicarboxylic acid
Identifiers
CAS number 124-04-9
SMILES
 
ChemSpider ID 191
Properties
Molecular formula C6H10O4
Molar mass 146.14 g mol−1
Appearance White crystals
Density 1.36 g/cm³
Melting point

152 °C (425 K)
Boiling point

337 °C (610 K)
Solubility in water slightly soluble
Acidity (pKa) 4.43, 5.41
Hazards
Main hazards flammable
R-phrases R: R36
Flash point 232 °C
Related compounds
Related dicarboxylic acids glutaric acid
pimelic acid
Related compounds hexanoic acid
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox references

Adipic acid (IUPAC systematic name: hexanedioic acid) is a dicarboxylic acid. It is a white crystalline powder. Due to its long aliphatic chain, it is not very soluble in water.

Contents

[edit] Preparation

Historically, adipic acid was prepared from various fats using oxidation. Current commercial adipic acid is produced from cyclohexane by two oxidation steps.

  1. Cyclohexane + O2 → cyclohexanol and cyclohexanone+byproducts
  2. cyclohexanol/cyclohexanone + nitric acid + air → adipic acid + nitrous oxide

(The mixture of cyclohexanol and cyclohexanone produced from cyclohexane is commercially called "KA oil", the abbreviation of "Ketone-Alcohol oil".)

Other patented processes include those using phenol as feedstock. For example, phenol can be hydrogenated to KA oil, which is further processed to give adipic acid.[1]

Utilizing principles of green chemistry, a new method of synthesis has been developed, which involves oxidizing cyclohexene with hydrogen peroxide via a tungsten catalyst and a phase transfer catalyst to produce adipic acid.[2] The waste product is water.

[edit] Uses

By far the main use of adipic acid is as monomer for the production of nylon by a polycondensation reaction with hexamethylene diamine forming 6,6-nylon. Other uses include:

  • reactant to form plasticizers and lubricant components
  • Food Ingredient as a flavorant and gelling aid.E-number E355.
  • 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

[edit] References

  1. ^ U.S. Patent 7,250,537 
  2. ^ 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): 1646–7. doi:10.1126/science. (inactive 22 June 2008). 

[edit] External links

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