Reading Haist: what is more powerful, hydroquinone or catechol?

Alan Johnson said:

Original idea, Murray, I wonder why the old timers never produced such a formula AFAIK. Presumably HQ would regenerate PPD as maybe does ascorbate in Jay DeFehr's Halcyon developer:
https://www.largeformatphotography....?71010-Halcyon-superfine-grain-film-developer.
This is different to the other old PPD developers where PPD was partly a developer but mainly a solvent and and another developer, metol, glycin etc was added to speed up the process at the expense of grain, not to regenerate PPD.

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In my limited experience, a combination of equimolar PPD with hydroquinone precipitates out of solution at moderate pH (8-9). If more alkali is added, the precipitate dissolves but the resultant developer is rather active and too contrasty. Perhaps this answers a related question why PPD:hydroquinone adduct called "hydramine" never got popular as a "new" developing agent. In contrast, a combination of CD-2 and hydroquinone is used in a current developer Atomal 49 from Adox, which I tested and liked.

bnxvs said:

I don’t have any yet. It just thoughts. It would sometimes be helpful to have a less active hydroquinone alternative.

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Well, hydroquinone monosulfonate is exactly this. If you are not alien to experiments with oxidizing hydroquinone and then reacting it with sulfite, you may arrive at something useful. I am not publishing my experiments because I am not sure they are reproducible elsewhere in the world. I mean, my hydroquinone it "too pure" ;-)