Vanadyl acetylacetonate

Vanadyl acetylacetonate
Names
IUPAC name
oxobis(2,4-pentanedionato)vanadium(IV)
Other names
VO(acac)2, VO(pd)2
Identifiers
3153-26-2 YesY
ECHA InfoCard 100.019.628
PubChem 16217092
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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Infobox references

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.

Synthesis

The complex is prepared from vanadium(IV), e.g. vanadyl sulfate, or vanadium(V) precursors, such as vanadium pentoxide.[1] The equation for the preparation of vanadyl acetylacetonate through the prior reduction of the vanadyl pentoxide to vanadyl sulfate may be written using the following equations:[2]

V2O5 + 2 H2SO4 + C2H5OH → 2 VOSO4 + 3 H2O +CH3CHO

VOSO4 + 2 C5H8O2 + Na2CO3 → VO(C5H7O2)2 + Na2SO4+CO2 + H2O

The equation for the direct preparation of vanadyl acetylacetonate starting from the pentoxide may also be described by the following redox equation:[3]

2 V2O5 + 9 C5H8O2 → 4 VO(C5H7O2)2 + (CH3CO)2CO + 5 H2O

The compound is recrystallized from chloroform.[2]

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.[1]

Applications

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.[4][5]

Biomedical aspects

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).[6] 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.[6]

References

  1. 1 2 Rowe, Richard A.; Jones, Mark M. (1957). "Vanadium(IV) Oxy(acetylacetonate)". Inorg. Synth. 5: 113–116. doi:10.1002/9780470132364.ch30. ISBN 978-0-470-13236-4.
  2. 1 2 Rowe, Richard A.; Jones, Mark M. (1957). "Vanadium(IV) Oxy(acetylacetonate)". Inorg. Synth. 5: 113–116. doi:10.1002/9780470132364.ch30. ISBN 978-0-470-13236-4.
  3. ↑ Rowe, Richard A.; Jones, Mark M. (1957). "Vanadium(IV) Oxy(acetylacetonate)". Inorg. Synth. 5: 113–116. doi:10.1002/9780470132364.ch30. ISBN 978-0-470-13236-4
  4. ↑ Itoh, Takashi; Jitsukawa, Koichiro; Kaneda, Kiyotomi; Teranishi, Shiichiro (1979). "Vanadium-catalyzed epoxidation of cyclic allylic alcohols. Stereoselectivity and stereocontrol mechanism". J. Am. Chem. Soc. 101 (1): 159–169. doi:10.1021/ja00495a027.
  5. ↑ 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.
  6. 1 2 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". ABB. 440 (2): 158–164. doi:10.1016/j.abb.2005.06.008. PMID 16055077.
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