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.
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| Names | |
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| IUPAC name
oxobis(2,4-pentanedionato)vanadium(IV)
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| Other names
VO(acac)2, VO(pd)2
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.019.628 |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C10H14O5V | |
| Molar mass | 265.157 g/mol |
| Appearance | blue-green |
| Density | 1.50 g/cm3 |
| Melting point | 258 °C (496 °F; 531 K) |
| Boiling point | 174 °C (345 °F; 447 K) at 0.2 torrs (27 Pa) |
| CHCl3, CH2Cl2, Benzene, CH3OH, CH3CH2OH | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
editThe complex is generally prepared from vanadium(IV), e.g. vanadyl sulfate:[1]
- 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.[1]
Structure and properties
editThe 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.[1]
Applications
editIt 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.[2][3]
Biomedical aspects
editVanadyl 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).[4] It has also been shown inhibit tyrosine phosphatase (PTPase), PTPases[clarification needed] such as PTP1B, which dephosphorylates insulin receptor beta subunit, thus increasing its[clarification needed] phosphorylation, allowing for a prolonged activation of IRS-1, PKB, and GSK-3, allowing them to exert their anti-diabetic properties.[4]
External links
editReferences
edit- ^ a b c Rowe, Richard A.; Jones, Mark M. (1957). "Vanadium(IV) Oxy(acetylacetonate)". Inorganic Syntheses. Inorganic Syntheses. Vol. 5. pp. 113–116. doi:10.1002/9780470132364.ch30. ISBN 978-0-470-13236-4.
- ^ Itoh, Takashi; Jitsukawa, Koichiro; Kaneda, Kiyotomi; Teranishi, Shiichiro (1979). "Vanadium-catalyzed epoxidation of cyclic allylic alcohols. Stereoselectivity and stereocontrol mechanism". Journal of the American Chemical Society. 101 (1): 159–169. doi:10.1021/ja00495a027.
- ^ Rossiter, Bryant E.; Wu, Hsyueh-Liang; Hirao, Toshikazu (2007-03-15). "Vanadyl Bis(acetylacetonate)". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rv003m.pub2. ISBN 978-0-471-93623-7.
- ^ a b Mehdi, Mohamad Z.; Srivastava, Ashok K. (2005). "Organo-vanadium compounds are potent activators of the protein kinase B signaling pathway and protein tyrosine phosphorylation: Mechanism of insulinomimesis". Archives of Biochemistry and Biophysics. 440 (2): 158–164. doi:10.1016/j.abb.2005.06.008. PMID 16055077.