Kinetics of protonation of the acridine radical anion in DMF by water and alcohols

Rate constants kH for the proton transfer from water, ethanol, n-propanol and t-butanol to the radical anion of acridine in DMF was measured by the voltammetric method. The Brönsted plot of log kH against pKa with a slope of α=−0.5 was observed. The acidity of the conjugate acid of acridine radical anion was estimated to be in the range of 41≫pKa>24.3. It is supported that the reaction under study is the true proton transfer contrariwise to the protonation of anthracene radical anion forming –CH acid.