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Solvent-free oxidation of cumene by molecular oxygen catalyzed by cobalt salen-type complexes

Ghanbari, B ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1007/s11164-011-0425-5
  3. Abstract:
  4. Co(salen)-type [where salen = di-(salicylal)-ethylenediimine] complexes were shown to be efficient catalysts in the oxidation of 2-phenylpropane (cumene) by dioxygen primarily to 2-phenyl-2-propanol (cumyl alcohol), 2-phe-nylpropene (a-methylstyrene), and 1-phenylethanone (acetophenone) applying 1H NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The effect of substitution on the ligand was also monitored in both oxygen-absorption and the catalytic reaction. Based on these results, the trend observed for the production of a-methylstyrene and cumyl alcohol were parallel to dioxygen uptake by the catalyst in neat cumene, while acetophenone productions obeyed a non-linear trend. The best selectivity for the reaction in terms of acetophenone production was observed for the complex with the least oxygen-absorption feature. The intermediate of the reaction, LCo(III)-OOcumyl (where L = salen) complex, was synthesized and characterized by IR, 1H NMR spectroscopy as well as elemental analysis, and its reactivity in the present catalytic reaction was also studied. A series of experiments were performed to propose a mechanism for the reaction on the basis of the product distributions in the reaction mixture
  5. Keywords:
  6. Catalyst ; Cobalt(II) ; Dioxygen ; Schiff base ; a-Methylstyrene ; Acetophenones ; Catalytic reactions ; Cumene ; Dioxygens ; Effect of substitution ; Efficient catalysts ; Gas chromatography-mass spectrometry ; H NMR spectroscopy ; Non-linear trends ; Product distributions ; Reaction mixture ; Solvent-free oxidation ; Catalysis ; Catalysts ; Cobalt ; Functional groups ; Gas chromatography ; Ketones ; Oxidation ; Oxygen ; Reaction intermediates ; Aromatic hydrocarbons
  7. Source: Research on Chemical Intermediates ; Volume 38, Issue 3-5 , 2012 , Pages 871-883 ; 09226168 (ISSN)
  8. URL: http://link.springer.com/article/10.1007%2Fs11164-011-0425-5