A pulse radiolysis study on the reactions of hydroxyl radical and sulfate radical anion with guanidine derivatives in aqueous solution

The reactions of hydroxyl radical (OH) with guanidine, 1,1-dimethylguanidine, and 1-ethylguanidine have been investigated by the method of pulse radiolysis. The characteristic absorption observed in the OH reaction with guanidine under basic conditions was assigned to a nitrogen-centered radical. On the other hand, reducing carbon-centered radicals were generated in the OH reaction with 1,1-dimethylguanidine and 1-ethylguanidine over a pH range of 7–13, which may suggest that the primarily formed nitrogen-centered radicals at a high pH are converted into carbon-centered radicals by hydrogen atom shift. Similar transient species were also observed in the reaction of sulfate radical anion with the guanidine derivatives.