Analytical Sciences

Electrochemical Study of the SN2 Reaction of 1-p-Toluenesulfonyl-2,4-dinitronaphthalene with Hydroxide Ions at the Nitrobenzene-Water Interface

Young-Tae KONG, Shin-ichiroIMABAYASHI and TakashiKAKIUCHI *

Department of PhysicalChemistry, Yokohama National University, Tokiwadai, Hodogaya, Yokohama 240, Japan

The rate of the interfacial nucleophilic reaction of1-p-toluenesulfonyl-2,4-dinitronaphthalene (TSDNN) with OH- ions atthe polarized nitrobenzene (NB)-water (W) interface was studied using apolarographic technique. The TSDNNpartitioned into the aqueous phase underwent a displacement of thep-toluenesulfonyl moiety with OH - . The transfer ofone of the products, 2,4-dinitronaphthalate (DNN -), from the W phase to the NB phase was monitored asthe currentacross the interface. The rate constant of the reaction of TSDNN with OH- in the aqueous phase wasestimated to be1.03±0.23 dm 3 mol-1 s -1at 25qŽ¨ which is ten-times higher than the rate constant of the displacement of 2,4-dinitro-fluorobenzenewith OH - in the aqueous phase,1.01±0.13¥10 -1 dm3 mol -1s -1 . Thecontribution from the reactions in theNB phase and at the interface to the formation of DNN -seems to be negligible, suggesting the absence of aninterfacialfacilitation of the reaction. (Keywords: Nucleophilic substitution reaction, SN2 reaction,1-p-toluenesulfonyl-2,4-dinitronaphthalene, polarizednitrobenzene-water interface, polarography)

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