The stabilities of Meisenheimer complexes. Part 18. Proton transfer and σ-complex formation in the reactions of N-substituted 2,4,6-trinitroanilines (picramides) with sodium methoxide in methanol

Abstract

The 1:1 interactions of picramide, N-substituted picramides, and NN-dimethylpicramide with sodium methoxide in methanol have been investigated by stopped-flow and T-jump spectrophotometry. Picramide and its N-substituted derivatives give rise to a very rapid process which is attributed to proton transfer to give the conjugate base, and to a slower process (measurable by stopped-flow) attributed to methoxide addition at the unsubstituted 3-position. The variation of rate and equilibrium constants with substituent are discussed.