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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 22, Number 7
BKCSDE 22(7)
July 20, 2001 

 
Title
The Catalytic Effect of Alkali Metal Ions on Reactions of 8-(5-Nitroquinolyl) 2-Furoate with Alkali Metal Ethoxides in Anhydrous Ethanol
Author
Ik-Hwan Um, Seung-Eun Lee, Ji-Sook Min
Keywords
Alalki metal ion catalysis, Ion pair, Acyl-transfer reaction, kinetics.
Abstract
Pseudo-first-order rate constants have been measured spectrophotometrically for the title reactions. The plot of kobs vs the concentration of alkali metal ethoxides is linear for the reactions performed in the presence of complexing agent, 18-crown-6 ether, but curved upwardly for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions studied in this study behave as a catalyst. The catalytic effect was found to increase in the order Li+ << K+ ≤ Na+. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M+ ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M+/kEtO-) was found to be 2.3, 9.5 and 8.7 for the reaction of 8-(5-nitroquinolyl) 2-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, indicating that the catalytic effect is larger in the reaction of the former substrate than in that of the latter one. The larger catalytic effect was attributed to two possible complexing sites with alkali metal ions in the former substrate.
Page
669 - 672
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