Microreactor-controlled selectivity in organic photochemical reactions*
Chen-Ho Tung**, Li-Zhu Wu, Li-Ping Zhang, Hong-Ru Li, Xiu-Yu Yi, Kai
Song, Ming Xu, Zhen-Yu Yuan, Jing-Qu Guan, Hong-Wei Wang, Yun-Ming Ying,
and Xiao-He Xu
Institute of Photographic Chemistry, Chinese Academy
of Sciences, Beijing 100101, China
Abstract: 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 compounds with long flexible chains included in NaY zeolite
or low-density polyethylene films yield intramolecular photocyclomers
to the exclusion of intermolecular products. The photosensitized oxidation
of alkenes included in pentasil zeolites or Nafion membranes or vesicles
can be directed selectively toward either the singlet oxygen-mediated
or the superoxide radical anion-mediated products by controlling the
status and location of the substrate and sensitizer molecules in the
reaction media. The photo-Fries rearrangement of phenyl phenylacetates
included within NaY and pentasil zeolites or Nafion membranes gives
either ortho-hydroxyphenones or decarbonylation products depending
on the size/shape of the microreactors and the substrate molecules.
All these results demonstrate the utility of microreactors to control
the product selectivity in organic photochemical reactions.
*Plenary lecture presented at the 15th
International Conference on Physical Organic Chemistry (ICPOC 15), Göteborg,
Sweden, 8 13 July 2000. Other presentations are published in this
issue, pp. 2219 2358.
**Corresponding author
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