Methyl viologen reactions. 5. Rates and mechanism of cation-radical formation in aqueous base

Initial rates for methyl viologen cation-radical (MV/sup center dot +/) formation from methyl viologen (MV/sup 2 +/) in aqueous base has been obtained by spectrophotometry at 604 nm and 24/degrees/C. From rate runs at various reactant concentrations, the order in MV/sup 2 +/ was found to be 2 and the order in base was 1 (or in a few sets of runs somewhat larger). The rate constant k/sub 0/ based on third-order rate law is 1.46 /times/ 10/sup -4/M/sup -2/ s/sup -1/ in H/sub 2/O; in D/sub 2/O the constant is 2.48 /times/ 10/sup -3/ M/sup -2/ s/sup -1/. 20 references, 2 figures, 1 table.