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1999
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September
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In the Laboratory
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Photochemistry without Light: Oxidation of Rubrene in a Microemulsion with a Chemical Source of Singlet Molecular Oxygen (1O2, 1Dg)
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Véronique Nardello, Marie-Josée Marti, Christel Pierlot, and Jean-Marie Aubry*
ENSCL, Equipe de Recherches "Oxydation et Formulation", BP 108, F-59 652 Villeneuve d'Ascq cedex, France
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September 1999
Vol. 76 No. 9
p. 1285
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| Abstract |
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This simple experiment illustrates the main features of excited oxygen in the singlet state 1O2 (1Dg): (i) its high oxidizing power and its selectivity towards unsaturated organic compounds, (ii) its low excitation energy which allows its access by various chemical processes and (iii) its long lifetime compared to the other usual excited molecules. In the laboratory experiment presented here, 1O2 is generated through the disproportionation of hydrogen peroxide catalyzed by molybdate ions and is used to carry out the oxidation of a polycyclic aromatic compound, rubrene. As the formation of 1O2 proceeds efficiently only in water, a microemulsion is used as solvent to oxidize this highly hydrophobic substrate. Actually, the microemulsion, which consists of aqueous microdroplets surrounded by a continuous organic phase, allows considerable amounts of hydrophilic reactants (H2O2 and MoO42-) and hydrophobic organic substrates to dissolve simultaneously. The typical size of the microdroplets (» 10-50 nm) is much smaller than the mean travel distance of 1O2 in water (» 200 nm). Therefore, 1O2 can diffuse, before deactivation by water, into the organic phase where the oxidation of the substrate can take place.
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| More Information |
 Citation |
Nardello, VŽronique; Marti, Marie-JosŽe; Pierlot, Christel; Aubry, Jean-Marie. J. Chem. Educ. 1999 76 1285.
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Keywords |
Organic Chemistry; Oxygen; Colloids; Photochemistry; Organic Synthesis; Laboratory Instruction
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History |
Created:
Last Updated: |
July 30, 1999
June 23, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
1999
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September
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1285
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