Article

The efficient liquid‐phase oxidation of aromatic hydrocarbons by molecular oxygen in the presence of MnCO3

State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Graduate School of the Chinese Academy of Sciences, Liaoning 116023, PR China
Journal of Chemical Technology & Biotechnology (Impact Factor: 2.49). 07/2007; 82(7):620 - 625. DOI: 10.1002/jctb.1717

ABSTRACT BACKGROUND: The liquid-phase catalytic oxidation of aromatic hydrocarbons by molecular oxygen is a commercially important process. We consider the MnCO3-promoted oxidation of toluene to produce benzaldehyde and benzoic acid. In this investigation, toluene was oxidized with 25.0% conversion and 80.8% selectivity with respect to benzoic acid in the presence of MnCO3 under 1.0 MPa of oxygen at 190 °C for 2 h.RESULTS: Moreover, the oxidation of other aromatic hydrocarbons, such as ethylbenzene, p-xylene, m-xylene, o-xylene, and p-chlorotoluene, were also efficiently promoted by MnCO3.CONCLUSION: It is concluded that an efficient oxidation of aromatic hydrocarbons can be achieved in the presence of MnCO3 under solvent-free conditions. The catalytically active species are high-valence Mn generated via the action of MnCO3 with oxygen. Copyright © 2007 Society of Chemical Industry

Full-text

Available from: Xinli Tong, Jun 10, 2014
0 Followers
 · 
137 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It is very difficult to selectively oxidise stable compounds such as toluene and xylenes to useful chemicals with molecular oxygen (O2) under moderate conditions. To achieve high conversion and less over-oxidised products, a new class of photocatalysts, metal hydroxide nanoparticles grafted with alcohols, is devised. They can efficiently oxidise alkyl aromatic compounds with O2 using visible or ultraviolet light or even sunlight to generate the corresponding aldehydes, alcohols and acids at ambient temperatures and give very little over-oxidation. For example toluene can be oxidised with a 23% conversion after a 48-hour exposure to sunlight with 85% of the product being benzaldehyde, and only a trace of CO2.The surface complexes grafted onto metal hydroxides can absorb light, generating free radicals on the surface, which then initiate aerobic oxidation of the stable alkyl aromatic molecules with high product selectivity. This mechanism is distinctly different from those of any known catalysts. The use of the new photocatalysts as a controlled means to generate surface radicals through light excitation allows us to drive the production of fine organic chemicals at ambient temperatures with sunlight. The process with the new photocatalysts is especially valuable for temperature-sensitive syntheses and a greener process than many conventional thermal reactions.
    Chemical Science 05/2012; 3(6):2138-2146. DOI:10.1039/C2SC20114C · 8.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tandem processes involving catalysts can offer unique and powerful strategies for converting simple starting materials into more complex products in a single reaction vessel. Imines were synthesized directly from alcohols via a tandem catalytic process using manganese octahedral molecular sieves (OMS-2) as catalyst. The synthesis proceeds through two steps: an oxidation of the alcohols to carbonyls followed by the nucleophilic attack by an amine on the carbonyl to form the imine. OMS-2 acts as a bifunctional catalyst and catalyzes two mechanistically distinct processes in a single reaction vessel under the same conditions. Conversions up to 100% were obtained for benzylic alcohols with this efficient, environmentally friendly catalytic reaction. The advantages of this process are that the intermediates need not be isolated and the catalysts can be reused upon simple filtration without loss of activity.
    Journal of Catalysis 01/2008; 253(2):269-277. DOI:10.1016/j.jcat.2007.11.006 · 6.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Oxidation is one of the fundamental transformations in organic synthesis. The selective oxidation of inert substrates is interesting and important. In this review, the transition metal-catalyzed oxidation of methylarenes is discussed. Benzaldehyde, benzoic acid, benzyl alcohol, etc., were produced as the target products. Copyright © 2014 John Wiley & Sons, Ltd.
    Applied Organometallic Chemistry 12/2014; 46(14). DOI:10.1002/aoc.3244 · 2.02 Impact Factor