KINETIC-BEHAVIOR OF DIAZENE IN AQUEOUS-SOLUTION

The acid-catalyzed hydrolysis of azodiformate ((NCO2)2(2-), which has diazene (N2H2) as an intermediate, has been studied by stopped-flow spectrophotometry. When the hydrolysis is conducted at sufficiently low pH (almost-equal-to-6), the second-order dismutation of diazene occurs on a time scale longer than that of its generation. The reduction of azobenzene-4,4'-disulfonate (ABDS) by diazene provides a convenient indicator of these reactions. The consumption of ABDS give the relative rate constants of dismutation and reduction, and the kinetics study gives the absolute rate constants. At 25-degrees-C these rate constants are 2.0 x 10(4) M-1 s-1 and 1.4 x 10(3) M-1 s-1, respectively. A mechanism is proposed in which cis-diazene reduces ABDS and diazene competitively, both reactions proceeding by way of concerted dihydrogen transfer.