Quote Originally Posted by Alan Johnson View Post
Patrick,

The rate of aerobic oxidation of ascorbic acid has maxima at pH 5 and 11.5 (google ascorbic acid oxidation pH lester packer).
If that is true the ascorbate version at pH 14 will probably not be as resistant to oxidation as Rodinal.
However it may show considerable increase in film speed.
Is there a formula to test yet?
I wasn't thinking of such a high pH. I want to stay below the point where ascorbates alone are active. Ascorbate will still serve to regenerate oxidized Metol at pH = 8.7, at which pH it produces results like those of sulfite. This is the reason it works in place of sulfite in the Pyrocat developers that are dissolved in glycol. Its function there is to allow Phenidone or p-aminophenol or Metol to interact synergistically with the catechol when water is added to the glycol stock as sulfite does in the water stock.
We think of Metol-hydroquinone as a superadditive pair, but the superadditivity does not work without sulfite or ascorbate.
The developing agent in Rodinal is potassium aminophenolate with sulfite preservative. It is more an analog of D-23 than anything else, if you choose to look at it that way. If we could buy (maybe we can) potassium p-aminophenolate, we could probably get the same result as Rodinal by putting it in a solution with sulfite, and not worry about how the phenolate was manufactured. Now substitute potassium ascorbate for the sulfite and see what happens.