| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Since crown ethers are known to hold metal cations tightly intramolecular anion capping, the catalytic activity of the functionalized crown ethers having catalytic groups would be enhanced by a metal cation if the metal cation bound in the crown cavity could attract an anionic substrate by electrostatic interaction into the vicinity of the catalytic site. To test this possibility, we synthesized the following functionalized crown ethers, and the following are examined; (a)relationship of alkali metal ions and rate acceleration, (b)relationship between the crown cavity and the catalytic group, and (c)possibility of two points-recognition by employing bis-crown ethers. For the thiazolium salts, the effect of Alkali metal ions on the oxidative decarboxylation of alpha-keto acids, oxidation of carboxybenz- aldehydes, and cleavage of the Ellman reagent was examined kinetically in EtOH containing DBU as a base. For the crown thiols, thiolysis of p- nitrophenylhydrogen terephthalate was examined in EtOH (DBU). The results showed that the electrostatic field of the metal cation bound in the crown cavity is able to attract the anionic substrate to bring about rate- acceleration. It was also found that the distance between the crown cavity and the catalytic site is one of the important factors, and the biscrown thiazolium ion exhibits larger rate-enhancement for bis- anionic substrate. The present systems involve the nucleophilic attack of the catalytic groups to the reaction sites of the substrates. Other systems such as electron- transfer must be examined to generalize this concept.
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