Microreactor-controlled selectivity in organic photochemical reactions

Molecular-sieve zeolites, Nafion membranes, low-density polyethylene films, and mixed surfactant vesicles have been used as microreactors to carry out organic photochemical reactions. The photo-cycloadditions of diaryl compou nds with long flexible chains included in NaY zeolite or low-density polyet hylene films yield intramolecular photocyclomers to the exclusion of interm olecular products. The photosensitized oxidation of alkenes included in pen tasil zeolites or Nafion membranes or vesicles can be directed selectively toward either the singlet oxygen-mediated or the superoxide radical anion-m ediated products by controlling the status: and location of the substrate a nd sensitizer molecules in the reaction media. The photo-Fries rearrangemen t of phenyl phenylacetates included within NaY and pentasil zeolites or Naf ion membranes gives either ortho-hydroxyphenones or decarbonylation product s depending on the size/shape of the microreactors and the substrate molecu les. All these results demonstrate the utility of microreactors to control the product selectivity in organic photochemical reactions.