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Photoreactions in hydrophobic pockets

  • S Devanathan
  • M S Syamala
  • V Ramamurthy
Article
  • 14 Downloads

Abstract

Organic chemists have long recognized the important role that reaction media play in controlling rates, product distributions and stereochemistry. Recently, much effort has been directed towards the use of organized media to modify reactivity as compared to that in isotropic liquids. Judicious selection of a given organized system for a given application requires sufficient understanding of the properties of the organized media themselves and those of the substrate interactions therein. The multimolecular aggregation of hydrophobic solutes in water could prove to be of immense value to the organic chemist. The aggregation of simple olefinic systems in water, would enable photocycloaddition to compete efficiently with the various other modes of dacay of the short-lived excited state. Investigations of a few systems (dimerization of coumarins, stilbenes and alkylcinnamates), in our laboratory have been successful and they bring to light the significance of the hydrophobic effect. One of the most accepted manifestations of the hydrophobic interactions is probably the formation of micellar aggregates in aqueous solutions. Micelles provide a unique interface between aqueous and non-aqueous phases at which the non-polar solute can orient itself. While intermolecular orientation at micellar interfaces can provide selectivity in dimerization reactions, intramolecular orientation can be utilized to bring about selectivity in unimolecular photo-transformations. Such examples are presented.

Keywords

Photoreactions association in aqueous media micellar effect selectivity in reactions hydrophobic effect 

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References

  1. Abraham M H 1982J. Am. Chem. Soc. 104 2085CrossRefGoogle Scholar
  2. Ben-Naim A 1980Hydrophobic interactions (New York:Plenum Press)Google Scholar
  3. Berenjian N, de Mayo P, Sturgeon M, Sydnes L K and Weedon A C 1982Can. J. Chem. 60 426CrossRefGoogle Scholar
  4. Breslow R, Maitra U and Rideout D C 1983Tetrahedron Letts. 24 1901CrossRefGoogle Scholar
  5. Frank H S and Evans M W 1945J. Chem. Phys. 13 507CrossRefGoogle Scholar
  6. Grieco P A, Garner P and Zhen-min He 1983aTetrahedron Letts. 24 1897CrossRefGoogle Scholar
  7. Grieco P A, Garner P, Yoshida K and Huffman J C 1983bTetrahedron Letts. 24 3807CrossRefGoogle Scholar
  8. Grieco P A, Yoshida K and Garner P 1983cJ. Org. Chem. 48 3139CrossRefGoogle Scholar
  9. Kleopfer R and Morrison H 1972J. Am. Chem. Soc. 94 255CrossRefGoogle Scholar
  10. Lee K H and de Mayo P 1979J. Chem. Soc., Chem. Commun. 493Google Scholar
  11. Muthuramu K and Ramamurthy V 1982J. Org. Chem. 47 3976CrossRefGoogle Scholar
  12. Muthuramu K and Ramamurthy V 1984Indian J. Chem. B25 502Google Scholar
  13. Muthuramu K, Ramnath N and Ramamurthy V 1983J. Org. Chem. 48 1872CrossRefGoogle Scholar
  14. Otten J G, Yeh C S, Byrn S and Morrison H 1977J. Am. Chem. Soc. 99 6353CrossRefGoogle Scholar
  15. Ramesh V and Ramamurthy V 1984aJ. Org. Chem. 49 536CrossRefGoogle Scholar
  16. Ramesh V and Ramamurthy V 1984bJ. Photochem. 24 395CrossRefGoogle Scholar
  17. Ramnath N and Ramamurthy V 1984J. Org. Chem. 49 2827CrossRefGoogle Scholar
  18. Ramnath N, Ramesh V and Ramamurthy V 1985J. Photochem. 31 73CrossRefGoogle Scholar
  19. Ramamurthy V 1986Tetrahedron (in press)Google Scholar
  20. Rideout D C and Breslow R 1980J. Am. Chem. Soc. 102 7816CrossRefGoogle Scholar
  21. Syamala M S and Ramamurthy V 1986J. Org. Chem. (in press)Google Scholar
  22. Turro N J, Gratzel M and Braun A M 1980Angew. Chem., Int. Ed. Engl. 19 675CrossRefGoogle Scholar
  23. von Hippel P H and Schleich T 1969Acc. Chem. Res. 2 257CrossRefGoogle Scholar
  24. Wertz D H 1980J. Am. Chem. Soc. 102 5316CrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 1987

Authors and Affiliations

  • S Devanathan
    • 1
  • M S Syamala
    • 1
  • V Ramamurthy
    • 1
  1. 1.Department of Organic ChemistryIndian Institute of ScienceBangaloreIndia

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