The stabilities of Meisenheimer complexes. Part 28. The reactions of 2,2′,4,4′,6,6′-hexanitrobibenzyl with alkoxides

Abstract

¹ H N.m.r. and visible spectral measurements indicate that in the presence of alkoxide ions 2,2′,4,4′,6,6′-hexanitrobibenzyl forms σ-adducts by base addition. Attack at the 3-(3′-) positions precedes attack at the 1-(1′-) positions but gives thermodynamically less stable adducts. Kinetic and equilibrium data are reported for the formation in ethanolic sodium ethoxide of 1 : 1 adducts by attack at the 3- or 1-position and for the formation of a 1 : 2 adduct by addition at the 1 - and 1′-positions. Data are also reported for the formation in methanolic sodium methoxide of a 1 : 1 adduct formed by attack at the 1-position. These results are compared with values obtained for σ-adduct formation of related substrates.