The stabilities of Meisenheimer complexes. Part 16. Kinetic and equilibrium data for sodium isopropoxide addition to some aromatic nitro compounds in propan-2-ol

Abstract

Equilibrium and kinetic data are reported for reaction of sodium isopropoxide in propan-2-ol with 1,3,5-trinitrobenzene and a series of 1-isopropoxy-2,4-dinitro-6-X-benzenes (X = NO₂, Cl, CO₂Prⁱ, or H). Three types of reaction can be distinguished; addition of base at unsubstituted ring positions, addition at alkoxy-substituted positions, and S_N2 dealkylation. Complexes formed by base addition at unsubstituted ring positions show little tendency to associate with sodium ions and the rate constants for isopropoxide addition are considerably reduced by ion-pairing. However, the 1,1-di-isopropoxy complexes and the transition states leading to them are strongly stabilised by association with sodium ions.