Kinetic studies on the reactions of electrogenerated 9,10-diphenyl-anthracene cation radical with water and alcohols by means of column-electrolytic stopped-flow method

Article abstract of DOI:10.1246/bcsj.63.33

The reactions of 9,10-diphenylanthracene cation radical (DPA^+.) with water and alcohols in acetonitrile (AN) were studied using a novel column-electrolytic stopped-flow spectrophotometric method. The reaction was first-order with respect to DPA^+. in all reactions. The reaction orders of other reactants were determined by plotting the logarithms of the apparent first-order rate constants (k(app)'s) against the logarithms of the concentration of reactants. The plot of log k(app) vs. log [alcohols] was linear, and hence the reaction was clearly determined to be second-order. On the other hand, the log k(app) vs. log [water] plot did not show a linear relationship. Similar results were obtained in the reactions of 9,10-dimethylanthracene cation radical with water and methanol. Comparing the results obtained with water and alcohols, and considering the changes in the physicochemical properties of the AN-water medium, it was concluded that the reaction of water was second-order, though it had been believed previously to be first-order. Products of the reactions are trans- and cis-9,10-dialkoxy-9,10-diphenyl-9,10-dihydroanthracene in many cases.