Steam distillation

[Pb1]

Would it be feasible to steam distill concentrated nitric acid from a mixture of XNO3 and H2SO4? Not with water, of course, but with an inert, immiscible low-boiling solvent (chloroform, maybe)? The highest temperature required would be the boiling point of the solvent, so there would be little or no decomposition.

[megalomania]

I wouldn't see why not. It does strike me as somewhat wasteful of solvent to try that since final distillation would require extra work in the end. There is a reason the tried and true methods are best: they are tried and true.

[knowledgehungry]

Don't forget fire hazards and poisoning from vaporized solvents.

[tom haggen]

What exactly is steam distillation? I was reading up on isolating safrole from natural products and it said that steam distillation is the only way this can be done. My first thought is why wouldn't you be able to soak the plant matter in the proper solvent to form an emulsion, and then vacuum distill obtaining the pure product.

[Pb1]

Steam distillation is blowing a vaporized solvent (usually steam) which doesn’t mix with what you’re trying to distill into the crude reaction product. The vapor picks up anything volatile, leaving with a small portion of it on its way to the condenser. You condense the vapors and the distillate contains the solvent and your product. As an example, say you want to get some essential oils out of a flower. Pass steam over it and the oils will come over with the steam. Condense the steam and the oils come with it, forming an immiscible layer.

Thinking about this some more, you wouldn’t even need an immiscible solvent if you don’t care about small losses. Just use an inert low-boiling solvent and boil it off, leaving you with nitric acid.

[FrankRizzo]

A date with the search engine will turn up a thread where exactly this is discussed (using methlyene chloride).


Steam distillation is blowing a vaporized solvent (usually steam) which doesn’t mix with what you’re trying to distill into the crude reaction product. The vapor picks up anything volatile, leaving with a small portion of it on its way to the condenser. You condense the vapors and the distillate contains the solvent and your product. As an example, say you want to get some essential oils out of a flower. Pass steam over it and the oils will come over with the steam. Condense the steam and the oils come with it, forming an immiscible layer.

Thinking about this some more, you wouldn’t even need an immiscible solvent if you don’t care about small losses. Just use an inert low-boiling solvent and boil it off, leaving you with nitric acid.

[Pb1]

Thinking back on what I said, it wouldn’t quite work that way. The same principle that gives you the acid would also carry it off. You’d need a fractionating column to keep the acid.

Frank: Are you referring to that last line? I searched the forum without finding anything about steam distillation of nitric acid. I think you’re confusing this idea with the final step in the MeCl2 procedure where the MeCl2 is boiled off. Otherwise, the ideas have nothing in common.