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KMID : 1059519840280050328
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Journal of the Korean Chemical Society
1984 Volume.28 No. 5 p.328 ~ p.334
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Kinetics and Mechanism of the Hydrolysis of Phenyl N-Benzenesulfonylchloroformimidate Derivatives
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Sung Nack-Do
Kwon Ki-Sung
Kim Tae-Rin
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Abstract
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A series of phenyl N-benzenesulfonylchloroformimidate derivatives (p-H, p-Cl, p-CH3 & p-OCH3) were prepared and the hydrolysis of these compounds were studied kinetically at various pH by UV spectrophotometry in 1 ; 4 dioxane-water at 25℃. Hammett ρ values measured at pH 5.0 (ρ = -0.45) and pH 10.0 (ρ = 0.40) indicate that the reaction proceeds via an azocarbonium ion intermediate in the acidic medium, whereas, it involves direct attack by hydroxide ion on the azomethine carbon atom occurs under the basic medium. The formation of stabilized azocarbonium ion species at pH 5.0 is also consistent with the large solvent effect(m = 1.3-1.5 & n = 5.0-5.5). On the basis of these findings, we may concluded that the hydrolysis of phenyl N-benzenesulfonylchloroformimidate derivatives proceeds by SN1 below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through SN2 and in the range of pH 8.0-10.0, these two reactions occur competitively.
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