# Is it possible to vacuum distill citric acid?

I'm wondering if

1. it is at all possible to vacuum distill citric acid without the slightest decomposition;
2. it is something that can easily be done in a small lab with widely available equipment.

I've looked on internet and found the following data:

• ~154 °C melting point (anhydrous citric acid)
• ~175 °C starts decomposing
• ~310 °C boiling point
• ~$$10^{-8}$$ mmHg vapor pressure at 25 °C
• If you have enough to do a real distillation (not say Kugelrohr), you should have enough for a recrystallization, and I suspect you'll get better results.
– Zhe
Nov 4 '20 at 16:57
• Itaconic acid is formed by the distillation of citric acid. en.wikipedia.org/wiki/Itaconic_acid Nov 4 '20 at 17:28
• Given that the citric acid has an appreciable vapor pressure at 25 °C, I'd look into purification using vacuum sublimation.
– MaxW
Nov 4 '20 at 20:10
• @MaxW Good point, but I don't trust that number. 10mmHg vapour pressure should give a well notiveabele acidic smell, which citric acid doesn't have.
– Karl
Nov 4 '20 at 20:16
• The thermal conversion of citric acid is a decarboxylative dehydration to form the double bond of itaconic acid. Nov 4 '20 at 20:44