Acridinium ions hydride acceptors

The reactivity of 2- and 3-methoxy-NMAHs towards -acceptors and the cobalt(III) reagent have also been compared (Colter et al., 1984). The 3-methoxy substituent better stabilizes the acridinium ion, while 2-methoxy-NMAH is the better one-electron donor. With a series of quinones in acetonitrile, the 3-methoxy-NMAH is between 4 and 10 times more reactive than its isomer although absolute rates vary by more than 105. With the cobalt(III) oxidant, the 2-methoxy-NMAH is more than 50 times more reactive, suggesting that the quinones react with these acridans uniformly by one-step hydride transfer. 

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