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<br />ε-Caprolactone<br />Hexano-6-lactone<br />6-Hexanolactone<br />Hexan-6-olide<br />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 | Solubility = Miscible <ref name="OECD">{{cite web|title=ε-caprolactone SIDS Initial Assessment Report|publisher=OECD|url=http://www.chem.unep.ch/irptc/sids/OECDSIDS/502443.pdf|archive-url=https://web.archive.org/web/20110815130105/http://www.chem.unep.ch/irptc/sids/OECDSIDS/502443.pdf#|archive-date=2011-08-15|access-date=2017-10-12|url-status=dead}}</ref> | MeltingPtC = -1 | BoilingPtC = 241 | BoilingPt_ref = <ref>{{cite web|url=https://www.perstorp.com/-/media/files/perstorp/pds/capa%20monomer/pds_capa%20monomer_eng-6142.pdf|title=Capa Monomer product data sheet|publisher=Perstorp|date=2015-02-27|access-date=2017-10-11|archive-url=https://web.archive.org/web/20170202061130/https://www.perstorp.com/-/media/files/perstorp/pds/capa%20monomer/pds_capa%20monomer_eng-6142.pdf|archive-date=2017-02-02|url-status=dead}}</ref> }} }} '''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.<ref name="UllmannPolyesters"/>

==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.<ref name="UllmannPolyesters">{{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}}</ref> Another polymer is polyglecaprone, used as suture material in surgery.<ref>{{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}}</ref>

==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,<ref>{{cite journal|last1=Mosandl|first1=A.|last2=Günther|first2=C.|title=Stereoisomeric flavor compounds: structure and properties of γ-lactone enantiomers|journal=Journal of Agricultural and Food Chemistry|volume=37|pages=413–418|date=1989|doi=10.1021/jf00086a031}}</ref> and is also produced by the Khapra beetle as a pheromone.<ref>{{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'')-γ-caprolactone, the pheromone of ''Trogoderma granarium''|journal=Journal of Organic Chemistry|volume=55|issue=6|pages=1928–1932|doi=10.1021/jo00293a044}}</ref> δ-caprolactone is found in heated milk fat.<ref>{{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}}</ref>

An ether of caprolactone is used as a binder for AP/AN/Al rocket propellant HTCE: Hydroxy-Terminated Caprolactone Ether <ref> [https://www.acronymfinder.com/Hydroxy_Terminated-Caprolactone-Ether-(solid-rocket-propellant)-(HTCE).html HTCE]</ref>

==Safety== Caprolactone hydrolyses rapidly and the resulting hydroxycarboxylic acid displays unexceptional toxicity, as is common for the other hydroxycarboxylic acids.<ref name="UllmannHCAAliph"> {{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}}</ref> It is known to cause severe eye irritation. Exposure may result in corneal injury.<ref name="OECD" />

== References == {{reflist}}

{{Authority control}}

Category:Epsilon-lactones Category:Monomers Category:Oxepanes