Camphorquinone
{{Chembox
| ImageFile = Camphorquinone structure.svg
| ImageSize = 150px
| ImageAlt = Structure of camphorquinone
| IUPACName = 2,6-Bornanedione
| OtherNames = Camphorquinone
6-Oxocamphor
CQ
CPQ
| Section1 = {{Chembox Identifiers
| CASNo = 10373-78-1
| CASNo_Ref = {{cascite|correct|CAS}}
| ChEBI = 34607
| ChEMBL = 301431
| ChemSpiderID = 23544
| EC_number = 233-814-1
| Gmelin = 482102
| KEGG = C14515
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = RAL3591W33
| PubChem = 25208
| StdInChI=1S/C10H14O2/c1-9(2)6-4-5-10(9,3)8(12)7(6)11/h6H,4-5H2,1-3H3
| StdInChIKey = VNQXSTWCDUXYEZ-UHFFFAOYSA-N
| SMILES = CC1(C2CCC1(C(=O)C2=O)C)C
}}
| Section2 = {{Chembox Properties
| C=10|H=14|O=2
| Appearance =
| Density =
| MeltingPtC = 197–203
| BoilingPt =
| Solubility =
}}
| Section3 = {{Chembox Hazards
| GHS_ref=[https://pubchem.ncbi.nlm.nih.gov/compound/25208#section=Safety-and-Hazards]
| GHSPictograms = {{GHS07}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|315|319|335}}
| PPhrases = {{P-phrases|261|264|264+265|271|280|302+352|304+340|305+351+338|319|321|332+317|337+317|362+364|403+233|405|501}}
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
Camphorquinone, also known as 2,3-bornanedione, is an organic compound derived from camphor. A yellow solid, it is used as a photoinitiator in curing dental composites.{{cite journal |last1=Jakubiak |first1=J. |last2=Allonas |first2=X. |last3=Fouassier |first3=J.P. |last4=Sionkowska |first4=A. |last5=Andrzejewska |first5=E. |last6=Linden |first6=L.Å. |last7=Rabek |first7=J.F. |title=Camphorquinone–amines photoinitating systems for the initiation of free radical polymerization |journal=Polymer |date=August 2003 |volume=44 |issue=18 |pages=5219–5226 |doi=10.1016/S0032-3861(03)00568-8}} Camphorquinone is produced by the oxidation of camphor with selenium dioxide.{{cite journal |doi=10.15227/orgsyn.079.0125|title=Camphorquinone and Camphorquinone Monoxime |journal=Organic Syntheses |year=2002 |volume=79 |page=125|first1=James D.|last1=White|first2=Duncan J.|last2=Wardrop|first3=Kurt F.|last3=Sundermann }}
Photocuring details
Polymerization is induced very slowly by camphorquinone, so amines such as N,N-dimethyl-p-toluidine, 2-ethyl-dimethylbenzoate, N-phenylglycine are generally added to increase the rate of curing.
It absorbs very weakly at 468 nm (extinction coefficient of 40 M−1·cm−1) giving it a pale yellow color. Photoexcitation results in nearly quantitative formation of its triplet state through intersystem crossing and very faint fluorescence.{{cite journal |last1=Allonas |first1=Xavier |last2=Fouassier |first2=Jean-Pierre |last3=Angiolini |first3=Luigi |last4=Caretti |first4=Daniele |title=Excited-State Properties of Camphorquinone Based Monomeric and Polymeric Photoinitiators |journal=Helvetica Chimica Acta |date=19 September 2001 |volume=84 |issue=9 |pages=2577 |doi=10.1002/1522-2675(20010919)84:9<2577::AID-HLCA2577>3.0.CO;2-Q}}
Reactions
It can be hydrolyzed by the enzyme 6-oxocamphor hydrolase.
Camphorquinone has been examined as a reagent in organic synthesis.{{cite journal |doi=10.1021/ar100050p|title=Synthesis of α-Amino Acids Based on Chiral Tricycloiminolactone Derived from Natural (+)-Camphor |year=2010 |last1=Luo |first1=Yong-Chun |last2=Zhang |first2=Huan-Huan |last3=Wang |first3=Yao |last4=Xu |first4=Peng-Fei |journal=Accounts of Chemical Research |volume=43 |issue=10 |pages=1317–1330 |pmid=20672798 }}