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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 20, Number 7
BKCSDE 20(7)
July 20, 1999 

Kinetics and Mechanism for the Reaction of 4-Nitrophenyl 2-Furoate with Secondary Alicyclic Amines
Jong-Pal Lee, Ji-Hui Yoon, Ik-Hwan Um
Second-order-rate constants (kN) have been measured spectrophotometrically for the reactions of 4-nitrophenyl 2-furoate (1) with a series of secondary alicyclic amines in H2O containing 20 mole % DMSO at 25.0℃. 1 is about 5-8 times more reactive than 4-nitrophenyl benzoate (2), although 1 is expected to be less reactive than 2 based on MO calculations and 13 C NMR study. The Brфnsted-type plots for the aminolysis reactions of 1 and 2 are linear with βnuc values of 0.78 and 0.85, respectively. The replacement of the CH=CH group by an O atom in the acyl moiety (2->1) does not cause any mechanism change. The reaction of piperidine with a series of substituted phenyl 2-furoates gives a linear Hammett plot with a large ρ- value (ρ- = 2.88) when σ- constants are used. The linear Brфnsted and Hammett plots with a large ρ- value suggest that the aminolysis reaction of 1 proceeds via rate-determining break-down of the addition intermediate to the porducts.
805 - 808
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