The effect of structure change in bases on their reaction with 2,4-dinitrophenyl arylmethanesulphonate esters in water

Abstract

The reaction of bases with 2,4-dinitrophenyl arylmethanesulphonate in water has been measured over a wide range of base structure for aryl = 3,5-dinitrophenyl, phenyl, and 4-chloro-2-nitrophenyl. Reaction is shown to involve S–O bond cleavage to yield phenol and sulphonate derivative; no SNAr mechanism is observed except to a minor extent for attack of hydroxide. The Bronsted β value for the reaction of bases with the sulphonate esters decreases with an increase in electron-withdrawing power of the substituents on the arylmethane group consistent with a transition state involving little S–O bond fission. The data are consistent with an unsymmetrical E2 mechanism where C–H and S–O cleavage are not equally advanced in the transition state.