:Vanadyl acetylacetonate
{{chembox
| Watchedfields = changed
| verifiedrevid = 451182907
| ImageFile1 = Vo(acac)2.png
| ImageFile2 = Vanadyl-acetylacetonate-from-xtal-3D-balls.png
| ImageSize =
| IUPACName = oxobis(2,4-pentanedionato)vanadium(IV)
| OtherNames = VO(acac)2, VO(pd)2
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 3153-26-2
| ChemSpiderID = 17344686
| EC_number = 221-590-8
| PubChem = 16217092
| SMILES = CC(=[O+]1)C=C(C)O[V-3]12(#[O+])OC(C)=CC(C)=[O+]2
}}
|Section2={{Chembox Properties
| Formula = C10H14O5V
| MolarMass = 265.157 g/mol
| Appearance = blue-green
| Density = 1.50 g/cm3
| MeltingPtC = 258
| BoilingPtC = 174
| BoilingPt_notes = at {{convert|0.2|Torr|Pa}}
| Solubility = CHCl3, CH2Cl2, Benzene, CH3OH, CH3CH2OH
}}
}}
Vanadyl acetylacetonate is the chemical compound with the formula VO(acac)2, where acac– is the conjugate base of acetylacetone. It is a blue-green solid that dissolves in polar organic solvents. The coordination complex consists of the vanadyl group, VO2+, bound to two acac– ligands via the two oxygen atoms on each. Like other charge-neutral acetylacetonate complexes, it is not soluble in water.
Synthesis
The complex is generally prepared from vanadium(IV), e.g. vanadyl sulfate:{{cite book | first1= Richard A. |last1=Rowe |first2=Mark M. |last2=Jones |chapter=Vanadium(IV) Oxy(acetylacetonate) | title = Inorganic Syntheses | series = Inorganic Syntheses | year = 1957 | volume = 5 | pages = 113–116 | doi = 10.1002/9780470132364.ch30 | isbn = 978-0-470-13236-4}}
:VOSO4 + 2 Hacac → VO(acac)2 + H2SO4
It can also be prepared by a redox reaction starting with vanadium pentoxide. In this reaction, some acetylacetone is oxidized to 2,3,4-Pentanetrione.
Structure and properties
The complex has a square pyramidal structure with a short V=O bond. This d1 compound is paramagnetic. Its optical spectrum exhibits two transitions. It is a weak Lewis acid, forming adducts with pyridine and methylamine.
Applications
It is used in organic chemistry as a catalyst for the epoxidation of allylic alcohols by tert-butyl hydroperoxide (TBHP). The VO(acac)2–TBHP system exclusively epoxidizes geraniol at the allylic alcohol position, leaving the other alkene of geraniol untouched. By comparison, m-CPBA, another epoxidizing agent, reacts with both alkenes, creating the products in a two to one ratio favoring reaction at the alkene away from the hydroxyl group. TBHP oxidizes VO(acac)2 to a vanadium(V) species which coordinates the alcohol of the substrate and the hydroperoxide, directing the epoxidation to occur at the alkene close to this coordination site.{{cite journal | first1= Takashi |last1=Itoh |first2=Koichiro |last2=Jitsukawa |first3=Kiyotomi |last3=Kaneda |first4=Shiichiro |last4=Teranishi | title = Vanadium-catalyzed epoxidation of cyclic allylic alcohols. Stereoselectivity and stereocontrol mechanism | journal = Journal of the American Chemical Society | year = 1979 | volume = 101 | issue = 1 | pages = 159–169 | doi = 10.1021/ja00495a027|bibcode=1979JAChS.101..159I }}{{cite encyclopedia|first1=Bryant E. |last1=Rossiter |first2=Hsyueh-Liang |last2=Wu |first3=Toshikazu |last3=Hirao |title= Vanadyl Bis(acetylacetonate) |encyclopedia= Encyclopedia of Reagents for Organic Synthesis |publisher=John Wiley & Sons |date=2007-03-15 |doi=10.1002/047084289X.rv003m.pub2|isbn=978-0-471-93623-7 }}
Biomedical aspects
Vanadyl acetylacetonate exhibits insulin mimetic properties, in that it can stimulate the phosphorylation of protein kinase B (PKB/Akt) and glycogen synthase kinase 3 (GSK-3).{{cite journal | first1= Mohamad Z. |last1=Mehdi |first2=Ashok K. |last2=Srivastava | title = Organo-vanadium compounds are potent activators of the protein kinase B signaling pathway and protein tyrosine phosphorylation: Mechanism of insulinomimesis | journal = Archives of Biochemistry and Biophysics | year = 2005 | volume = 440 | pages = 158–164 | doi = 10.1016/j.abb.2005.06.008 | pmid = 16055077 | issue = 2}} It has also been shown inhibit tyrosine phosphatase (PTPase), PTPases{{huh|date=February 2017}} such as PTP1B, which dephosphorylates insulin receptor beta subunit, thus increasing its{{clarify|date=February 2017}} phosphorylation, allowing for a prolonged activation of IRS-1, PKB, and GSK-3, allowing them to exert their anti-diabetic properties.
External links
- [https://web.archive.org/web/20211215204420/http://www-oc.chemie.uni-regensburg.de/OCP/ch/chb/oc5/Oxidation_reactions-08.pdf Oxidations tutorial]
References
{{Vanadium compounds}}
{{Acetylacetonate complexes}}
{{DEFAULTSORT:Vanadyl Acetylacetonate}}
Category:Vanadium(IV) compounds