Catalytic Way of Transforming 2,3-Dimethylphenol to para-Quinone with the Use of Vanadium-Containing Heteropoly Acids
Science article
| Общее |
Language:
Английский,
Genre:
Full article,
Status:
Published,
Source type:
Original
|
| Journal |
Applied Catalysis A: General
ISSN: 0926-860X
, E-ISSN: 1873-3875
|
| Output data |
Year: 2018,
Volume: 549,
Pages: 216-224
Pages count
: 9
DOI:
10.1016/j.apcata.2017.09.022
|
| Tags |
Benzoquinone, Biphasic system, Heteropoly acid, Homogeneous catalysis, Selective oxidation |
| Authors |
Rodikova Yulia A.
1
,
Zhizhina Elena G.
1
,
Pai Zinaida P.
1
|
| Affiliations |
| 1 |
Boreskov Institute of Catalysis SB RAS, prosp. Akad. Lavrentieva 5, 630090 Novosibirsk, Russia
|
|
Funding (1)
|
1
|
Federal Agency for Scientific Organizations
|
V.44.2.4.
|
2,3-Dimethyl-p-benzoquinone (2,3-Me2BQ) is a valuable chemical that is applied as a soft oxidizing and dehydrogenating agent and also as a synthon in preparing different complex products including pharmaceutical and biochemical substances. Keggin- and modified-type aqueous solutions of Mo-V-phosphoric heteropoly acids (Mo-V-P HPAs) with the gross compositions H3+xPMo12-xVxO40 (HPA-x) and HaPzMoyVx’Ob (HPA-x’), respectively, possessing high oxidation potential and simplicity of regeneration can serve as effective soft oxidants for obtaining such para-quinone from 2,3-dimethylphenol (2,3-Me2P). The synthesized HPA catalysts with different vanadium content were characterized by a number of analysis techniques, such as 31P and 51V NMR spectroscopy, potentiometry, titrimetry, and pH measurement. It was found that the predominant formation of 2,3-Me2BQ instead of corresponding diphenoquinone (DPQ) at one-electron oxidation is achieved by a consecutive optimization of reaction conditions, the most important among them being organic solvent and molar ratio of vanadium(V) to substrate. As was shown, the substitution of HPA-x by HPA-x’ allows one to increase the quinone selectivity and to decrease the optimal molar ratio of vanadium(V) to substrate. The highest yield of the desired quinone (97%) at total substrate conversion was obtained by using the biphasic water-benzene system at molar vanadium(V) to substrate ratio of 12. The temperature of 50 °C and an inert atmosphere were established to be the optimal reaction conditions. The aqueous HPA-10’ solution including the highest content of VO2+ ions proved to be the most efficient catalyst among investigated HPAs. Carrying out catalyst regeneration at a separate stage provides the preservation of its activity and selectivity at the initial level for at least ten cycles.