:Caprolactone
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443497647
| Name = Caprolactone
| ImageFileL1 = Caprolactone.svg
| ImageSizeL1 = 100px
| ImageAltL1 = Skeletal formula of caprolactone
| ImageFileR1 = Caprolactone-from-xtal-2007-3D-balls.png
| ImageSizeR1 = 150
| ImageAltR1 = Ball-and-stick model of the caprolactone molecule
| PIN= Oxepan-2-one
| OtherNames = Caprolactone
ε-Caprolactone
Hexano-6-lactone
6-Hexanolactone
Hexan-6-olide
1-Oxa-2-oxocycloheptane
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 9972
| PubChem = 10401
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C01880
| InChI = 1/C6H10O2/c7-6-4-2-1-3-5-8-6/h1-5H2
| InChIKey = PAPBSGBWRJIAAV-UHFFFAOYAG
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 373123
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C6H10O2/c7-6-4-2-1-3-5-8-6/h1-5H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = PAPBSGBWRJIAAV-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 502-44-3
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 56RE988L1R
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 17915
| SMILES = C1CCC(=O)OCC1
}}
|Section2={{Chembox Properties
| Formula = C6H10O2
| MolarMass = 114.14 g/mol
| Density = 1.030 g/cm3
| MeltingPtC = -1
| BoilingPtC = 241
}}
}}
ε-Caprolactone or simply caprolactone is a lactone (a cyclic ester) 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.
Production and uses
Caprolactone is prepared industrially by Baeyer-Villiger oxidation of cyclohexanone with peracetic acid.
Caprolactone is a monomer used in the production of highly specialised polymers. Ring-opening polymerization, for example, gives polycaprolactone.{{cite encyclopedia|last1=Köpnick|first1=Horst|last2=Schmidt|first2=Manfred|last3=Brügging|first3=Wilhelm|last4=Rüter|first4=Jörn|last5=Kaminsky|first5=Walter|title=Polyesters|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|edition=6th|date=2002|publisher=Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a21_227}} Another polymer is polyglecaprone, used as suture material in surgery.{{cite web|url=http://www.curehunter.com/public/keywordSummaryC095495-glycolide-E-caprolactone-copolymer.do|title=glycolide E-caprolactone copolymer Summary Report|publisher=CureHunter|access-date=2017-10-11}}
Reactions
Although no longer economical, caprolactone was once produced as a precursor to caprolactam. 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==
Several other caprolactones are known, including α-, β-, γ-, and δ-caprolactones. All are chiral. (R)-γ-caprolactone is a component of floral scents and of the aromas of some fruits and vegetables,{{cite journal|last1=Mosandl|first1=A.|last2=Günther|first2=C.|title=Stereoisomeric flavor compounds: structure and properties of gamma-lactone enantiomers|journal=Journal of Agricultural and Food Chemistry|volume=37|pages=413–418|date=1989|doi=10.1021/jf00086a031}} and is also produced by the Khapra beetle as a pheromone.{{cite journal|last1=Nunez|first1=M. Teresa|last2=Martin|first2=Victor S.|date=1990|title=Efficient oxidation of phenyl groups to carboxylic acids with ruthenium tetraoxide. A simple synthesis of (R)-gamma-caprolactone, the pheromone of Trogoderma granarium|journal=Journal of Organic Chemistry|volume=55|issue=6|pages=1928–1932|doi=10.1021/jo00293a044}} δ-caprolactone is found in heated milk fat.{{cite journal|last1=Parliament|first1=Thomas H.|last2=Nawar|first2=Wassef W.|last3=Fagerson|first3=Irving S.|date=1965|title=Delta-Caprolactone in Heated Milk Fat|journal=Journal of Dairy Science|volume=48|number=5|pages=615–616|doi=10.3168/jds.S0022-0302(65)88298-4|doi-access=free}}
An ether of caprolactone is used as a binder for AP/AN/Al rocket propellant HTCE: Hydroxy-Terminated Caprolactone Ether [https://www.acronymfinder.com/Hydroxy_Terminated-Caprolactone-Ether-(solid-rocket-propellant)-(HTCE).html HTCE]
Safety
Caprolactone hydrolyses rapidly and the resulting hydroxycarboxylic acid displays unexceptional toxicity, as is common for the other hydroxycarboxylic acids.
{{cite encyclopedia|last=Miltenberger|first=Karlheinz|title=Hydroxycarboxylic Acids, Aliphatic|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|edition=6th|date=2002|publisher=Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a13_507}} It is known to cause severe eye irritation. Exposure may result in corneal injury.