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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 18, Number 8
BKCSDE 18(8)
August 20, 1997 

A Mechanistic Study for Aminolysis of p-Nitrophenyl Phenylacetate
Ik-Hwan Um*, E-Suk Yeom, Hye-Jin Kwon, Dong-Sook Kwon
Second-order rate constants have been measured spectrophotometrically for the reactions of p-nitrophenyl phenylacetate (1) and benzoate (2) with a series of alicyclic amines in H2O containing 20 mole % DMSO at 25.0 ℃. 1 appears to be more reactive than 2 toward all the amines studied, although phenylacetic acid is a weaker acid than benzoic acid. The higher reactivity of 1 can be attributed to resonance and/or steric effect, since the ground state of 2 can be stabilized by resonance and 1 would experience less steric hindrance due to the presence of CH2 group between phenyl and C=O group. The reactivity of the amines increases with increasing their basicity. The Bronsted-type plots for aminolysis of 1 and 2 show good linearity with βnuc values of 0.81 and 0.85, respectively, indicating that the TS structures of the aminolyses of 1 and 2 are similar. Besides, the linear Bronsted plots obtained in the present system clearly suggest that there is no mechanism change for the given series of the amines and the reactions of 1 and 2 proceed in a same mechanism.
865 - 868
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