Schiff base equilibria. IV. N-Methylimines of m- and p-hydroxybenzaldehydes

Abstract

The formation of Schiff bases between methylamine and m- and p-hydroxybenzaldehydes has been studied by spectrophotometry. Because of overlapping equilibria and ionic strength effects, the formation constants, K_F, of the neutral Schiff bases are determined with less precision than for the ortho compound. In dilute solution they are estimated by extrapolation to be 1.0 x 10³ and 1.0 x 10⁴, respectively. The formation constants, K_A, of the anionic forms of the Schiff bases have been more precisely measured as 1.45 x 10² and 5.52, respectively. The equilibria are compared with those for salicylaldehyde.