Caprolactone

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Caprolactone
Caprolactone.png
Identifiers
CAS number 502-44-3 YesY
PubChem 10401
ChemSpider 9972 YesY
KEGG C01880 YesY
ChEBI CHEBI:17915 YesY
ChEMBL CHEMBL373123 YesY
Jmol-3D images Image 1
Properties
Molecular formula C6H10O2
Molar mass 114.14 g/mol
Density 1.030 g/cm3
Melting point −1 °C (30 °F; 272 K)
Boiling point 253 °C (487 °F; 526 K)[2]
Solubility in water Miscible [1]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

ε-Caprolactone or simply caprolactone is a cyclic ester, a member of the lactone family, with a seven-membered ring with the formula (CH2)5CO2. This colorless liquid is miscible with most organic solvents. It is produced on a very large scale as a precursor to caprolactam.

Production and uses[edit]

The great majority of caprolactone is consumed, often in situ, as a precursor to caprolactam.[3] It is also a monomer used in the manufacture of highly specialised polymers. Ring-opening polymerization, for example, gives polycaprolactone.[4] Another polymer is polyglecaprone, used as suture material in surgery.[5]

Caprolactone is prepared industrially by Baeyer-Villiger oxidation of cyclohexanone with peracetic acid. The three main manufacturers are BASF in the USA, Daicel in Japan and the largest Perstorp in the UK.

Reactions[edit]

The dominant reaction for caprolactone is its conversion to caprolactam, billions of kilograms of which are produced annually. Caprolactone is treated with ammonia at elevated temperatures to give the lactam:

(CH2)5CO2 + NH3 → (CH2)5C(O)NH + H2O

Carbonylation of caprolactone gives, after hydrolysis, pimelic acid. The lactone ring is easily opened with nucleophiles including alcohols and water to give polylactones and eventually the 6-hydroxyadipic acid.

Related compounds[edit]

Several other caprolactones are known, although none approaches the technological importance of ε-caprolactone. These isomers include alpha-, beta-, gamma-, delta-caprolactones. All are chiral. Gamma-caprolactone is component of flower aromas and an insect pheromone.[6] delta-Caprolactone is found in heated milk fat.[7]

Safety[edit]

Caprolactone hydrolyses rapidly and the resulting hydroxycarboxylic acid displays unexceptional toxicity, as is common for the other hydroxycarboxylic acids.[8] It is known to cause severe eye irritation. Exposure may result in corneal injury.

References[edit]

  1. ^ OECD SIDS [www.chem.unep.ch/irptc/sids/OECDSIDS/502443.pdf 502443 - epsilon-caprolactone]
  2. ^ OECD SIDS [www.chem.unep.ch/irptc/sids/OECDSIDS/502443.pdf 502443 - epsilon-caprolactone]
  3. ^ Josef Ritz, Hugo Fuchs, Heinz Kieczka, William C. Moran "Caprolactam" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_031
  4. ^ Horst Köpnick, Manfred Schmidt, Wilhelm Brügging, Jörn Rüter, Walter Kaminsky "Polyesters" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a21_227
  5. ^ http://www.curehunter.com/public/keywordSummaryC095495-glycolide-E-caprolactone-copolymer.do
  6. ^ Leading reference: M. Teresa Nunez, Victor S. Martin (1990), Efficient oxidation of phenyl groups to carboxylic acids with ruthenium tetraoxide. A simple synthesis of (R)-gamma-caprolactone, the pheromone of Trogoderma granarium. Journal of Organic Chemistry, 1990, Volume 55, Issue 6, pp 1928–1932. doi:10.1021/jo00293a044
  7. ^ Thomas H. Parliament, Wassef W. Nawar and Irving S. Fagerson (1965), Delta-Caprolactone in Heated Milk Fat Journal of Dairy Science Vol. 48 No. 5 pages 615-616.
  8. ^ Karlheinz Miltenberger "Hydroxycarboxylic Acids, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a13_507