Vanadium pentoxide, Vanadium compounds
Vanadium pentoxide is used in different, industrial processes as catalyst: In the contact process it serves for the oxidation of SO2 to SO3 with oxygen at 440°C. Besides it is used in the oxidation of ethanol to ethanale and in the production of phthalic anydride, polyamide, oxalic acid and further products.
contact process
Vanadium pentoxide melts at 690°C and decomposes at 1750°C. V3+ is a strong reducing agent, which sets hydrogen free with water. This shows that Vanadium pentoxide may only rarely be applicable as sole oxidizing agent. Of interest are its abilities to form polyoxides. In the following process the oxidation number of the vanadium remains constant for example, but the polarization of the peroxide group increases:
Vanadium-catalyzed reaction by
the example of an oxidative esterification (R. Gopinath, B. Patel,
Org. Lett., 2000, 2, 577-579.)
As primary oxidizing agents e.g. oxygen and hydrogen peroxide are applicable in such processes.
Recent Literature
Aldehydes undergo oxidative transformation to the methyl esters in methanol
as solvent upon treatment with catalytic amounts of vanadium pentoxide in
combination with hydrogen peroxide. This method features mild reaction conditions,
short reaction times, high efficiencies, cost-effectiveness, and facile
isolation of the desired products.
R. Gopinath, B. Patel, Org. Lett., 2000,
2, 577-579.
Oxidation of alcohols to aldehydes and ketones were performed under
atmospheric oxygen with a catalytic amount of V2O5
in toluene at 100°C. Secondary alcohols can be chemoselectively
converted into ketones in the presence of primary hydroxy groups.
S. Velusamy, T. Punniyamurthy, Org. Lett., 2004,
6, 217-219.
S. Velusamy, T. Punniyamurthy, Org. Lett., 2004,
6, 217-219.
Optimized selective aerobic oxidations in ionic liquids convert various
activated primary alcohols into their corresponding acids or aldehydes in good
to excellent yields. The newly developed catalytic systems could also be
recycled and reused for three runs without any significant loss of catalytic
activity.
N. Jiang, A. J. Ragauskas, J. Org. Chem.,
2007,
72, 7030-7033.
N. Jiang, A. J. Ragauskas, J. Org. Chem.,
2007,
72, 7030-7033.
VO(acac)2 catalyzes the oxidation of aromatic and aliphatic aldehydes
to the corresponding acids efficiently and selectively in the presence of
hydrogen peroxide as an oxidant. This method offers functional-group
compatibility, easy workup procedure, and a short reaction time. The performance
of titania-supported VO(acac)2 in the oxidation of aldehydes was also
investigated.
D. Talukdar, K. Sharma, S. K. Bharadwaj, A. J. Thakur, Synlett, 2013, 24,
963-966.
Aromatic aldehydes and benzylic alcohols are rapidly converted into esters
derived from methanol, ethanol, iso-propanol, n-butanol, sec-butyl
alcohol, and propargylic alcohol without additives in a one-pot manner using a
bench-stable V-catalyst and H2O2 as a green oxidant. The
developed method is compatible with a broad range of functional groups.
G. Mali, I. Verma, H. Arora, A. Rajput, A. Kumar, R. D. Erande, J. Org. Chem., 2023, 88,
5696-5703.
A new catalytic system for the asymmetric epoxidation of allylic alcohols
has been developed featuring high enantioselectivity for Z olefins,
catalyst loading of less than 1 mol%, reaction temperatures of 0°C to room
temperature over a shorter time, and simple workup procedures for small
expoxy alcohols.
W. Zhang, A. Basak, Y. Kosugi, Y. Hoshino, H. Yamamoto, Angew. Chem. Int. Ed.,
2005,
44, 4389-4391.
Chiral amino acid-based hydroxamic acids can be effective asymmetric catalysts
for the epoxidation of allylic alcohols, especially disubstituted allylic
alcohols. The mild reaction conditions, e.g., reasonable temperature, low degree
of catalyst loading, and halogen-free solvent, extend the scope of this process.
Y. Hoshino, H. Yamamoto, J. Am. Chem. Soc., 2000,
122, 10452-10453.
Chiral bishydroxamic acid ligands provided good yields and high
enantioselectivities in the vanadium-catalyzed asymmetric epoxidation of
homoallylic alcohols.
W. Zhang, H. Yamamoto, J. Am. Chem. Soc., 2007,
129, 286-287.
The combination of very high ee values with high yield, the consequence of
an efficient initial asymmetric oxidation followed by an efficient kinetic
resolution, makes the reported system very practical for the asymmetric
oxidation of simple akyl aryl sulfides.
C. Drago, L. Caggiano, R. F. W. Jackson, Angew. Chem. Int. Ed., 2005,
44, 7221-7223.
The asymmetric oxidation of sulfides to chiral sulfoxides with hydrogen
peroxide in good yield and high enantioselectivity has been catalyzed very
effectively by a chiral vanadium-salan complex. The efficient kinetic
resolution of racemic sulfoxides catalyzed by the vanadium-salan system is
also described.
J. Sun, C. Zhu, Z. Dai, M. Xang, Y. Pan, H. Hu, J. Org. Chem.,
2004, 69, 8500-8503.
Vanadium pentoxide very effectively promotes the bromination of organic
substrates, including selective bromination of some aromatics, by
tetrabutylammonium bromide in the presence of hydrogen peroxide. The reaction
offers mild conditions, high selectivity, yield, and reaction rate, and
redundancy of bromine and hydrobromic acid.
U. Bora, G. Bose, M. K. Chaudhuri, S. S. Dhar, R. Gopinath, A. T. Khan, B. K.
Patel,
Org. Lett., 2000, 2, 247-249.
