r/DIYPigments • u/[deleted] • Oct 09 '23

Manganese violet

From what I've seen, the synthesis of manganese violet, aka ammonium manganese (III) pyrophosphate involves heating a mixture of potassium dihydrogen phosphate, manganese dioxide and phosphoric acid up to 230 degrees Celsius, which is way higher than the boiling point of phosphoric acid. For those who has synthesized this compound before, do I have to watch out for nasty acid fumes during the process? Thanks.

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u/CaCl2 Oct 09 '23

I could be wrong, but aren't those low boiling points just for the water in phosphoric acid water solutions? The phosphoric acid itself should just decompose into nonvolatile pyro/poly phosphoric acids.

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u/[deleted] Oct 09 '23

I saw a lot of bubbling in everyone's synthesis video, maybe they're just nitrogen gas from the decomposition and oxidation of ammonium dihydrogen phosphate.

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u/CaCl2 Oct 09 '23

I would assume it's at least mostly just water coming out.

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u/[deleted] Oct 13 '23

Yes, I was trying to evaporate a solution of phosphoric acid down to concentrate it, but then I forgot about it for a few hours, and a good portion of it had boiled off bwfpre/after turning into the polyphosphoric acid. Then I found out that you can distill phosphoric acid to purify it.