RESUMO
Erythromycin (Er) as a weak base showed some specific properties when dissolved in aqueous solutions. The basic ability of Er had a tendency to become weaker during storage in the room settings and especially at high temperatures. The temperature gradient within the ranges of 10 to 25 degrees C was dpH/dt = -0.03 (for 2 x 10(-3) M Er solution). However, the basic properties of the Er base partly renewed when Lewis' bases such as dimethyl carboxide, dimethylformamide and dimethyl sulfoxide were added to Er aqueous solutions previously stored for days or weeks. In chloroform solutions, either the thermodynamics or the kinetics of Er protonization showed no abnormalities as compared to nitric bases. It was supposed that in aqueous solutions of Er base there was transformation linked with intramolecular or extramolecular interactions which provoked shielding of the tertiary basic atom of nitrogen due to formation of the nitrogen linkage.