174 °C (at 0.2 torr)
|Solubility in water||CHCl3, CH2Cl2, Benzene, CH3OH, CH3CH2OH|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Vanadyl acetylacetonate is the chemical compound with the formula VO(C5H7O2)2. This blue-green coordination complex consists of the vanadyl group, VO2+, bound to two acetylacetonate anions, acac−. Like other charge-neutral acetylacetonates, this complex is soluble in organic solvents.
The complex is prepared from vanadium(IV), e.g. vanadyl sulfate, or vanadium(V) precursors, such as vanadium pentoxide. The equation for the redox reaction starting from the pentoxide can be described by this approximate equation:
- 2 V2O5 + 9 C5H8O2 → 4 VO(C5H7O2)2 + (CH3CO)2CO + 5 H2O
The compound is recrystallized from chloroform.
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.
It is used in organic chemistry as a reagent in the epoxidation of allylic alcohols in combination with tert-butyl hydroperoxide (TBHP). The VO(acac)2-TBHP system exclusively epoxidizes geraniol at the allylic alcohol position. For comparison, another epoxidizing agent m-CPBA, reacts with both groups, creating the products in a two to one ratio, favoring the allylic position away from the alcohol. TBHP oxidizes VO(acac)2 to a vanadium(V) species which coordinates the alcohol of the substrate and the hydroperoxide.
Vanadyl(acac) exhibits insulin mimetic properties, in that in can stimulate the phosphorylation of protein kinase B (PKB/Akt) and glycogen synthase kinase-3 (GSK3). It has also been shown inhibit tyrosine phosphatase(PTPase), PTPases such as PTP1B, which dephosphorylates insulin receptor beta subunit, thus increasing its phosphorylation, allowing for a prolonged activation of IRS-1, PKB, and GSK3, allowing them to exert their anti-diabetic properties.
- Richard A. Rowe, Mark M. Jones (1957). "Vanadium(IV) Oxy(acetylacetonate)". Inorg. Synth. Inorganic Syntheses 5: 113–116. doi:10.1002/9780470132364.ch30. ISBN 978-0-470-13236-4.
- Takashi Itoh, Koichiro Jitsukawa, Kiyotomi Kaneda, Shiichiro Teranishi (1979). "Vanadium-catalyzed epoxidation of cyclic allylic alcohols. Stereoselectivity and stereocontrol mechanism". J. Am. Chem. Soc. 101 (1): 159–169. doi:10.1021/ja00495a027.
- Bryant E. Rossiter, Hsyueh-Liang Wu, Toshikazu Hirao “Vanadyl Bis(acetylacetonate)” in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, 2007. doi:10.1002/047084289X.rv003m.pub2. Article Online Posting Date: March 15, 2007
- Mohamad Z. Mehdi and Ashok K. Srivastava (2005). "Organo-vanadium compounds are potent activators of the protein kinase B signaling pathway and protein tyrosine phosphorylation: Mechanism of insulinomimesis". ABB 440 (2): 158–164. doi:10.1016/j.abb.2005.06.008. PMID 16055077.