Abstract: In the previous paper the equilibrium constants Keq for protonation of substituted pyridine bases in aqueous solution have been determined. In this paper the equilibrium constants Keq of various substituted quinolines hare been determined with the same method.
The experimental results showed that the equilibrium constants of quinol-ine bases were decreased or increased,when certain hydrogen on thfe quinoline ring was substituted with electron-attracting groups or electron-donating groups respectively. Thus, the electronic effect of substituents can be deduced from the Keq values.