Quote Originally Posted by Gerald C Koch View Post
This is just not true you misunderstand the meaning of catalysis. Ascorbate ion reduces oxidized Phenidone/Dimezone back to the parent compound. However this is a moleculae for molecule process not the massive oxidation of the ascorbate that your statement implies.
But in the end it has the effect of a catalyst. Ascorbate, which would reduce silver very slowly on its own if at all (especially at pH of 8), does it rapidly in the presence of trace amounts of Phenidone or Dimezone S. During regular film development, a lot more Ascorbate is oxidized than Phenidone. Curious why this wouldn't count as a catalytic reaction.