Previously I've mentioned triethylammonium acetate, and ammonium carbonate. These are salts formed by mixtures of volatile stuff - triethylamine, acetic acid, ammonia, and carbon dioxide. Awhile ago I made one I hadn't ever made before.
This one was triethylammonium bicarbonate, which is weird. You take triethylamine (about 100g), water (about 500mL), and a bunch of dry ice or a tank of CO2, and set something up to bubble gas in while it stirs. Oddly, the triethylamine won't go in at first (since when it's not charged, it's pretty nonpolar), so as you bubble in the carbon dioxide, you make carbonic acid; H2CO3, which reacts with the triethylamine, making triethylammonium and bicarbonate ion. Once you get it all protonated, you get a clear solution.
It's one of the few alchemical feeling things you do in a biochemistry lab - an organic lab has comparatively exotic glassware, and an inorganic lab has that plus myriad brightly colored compounds, more often than not. And both have the rotavap, which always inspires puzzlement on first viewing. Working in a hybrid lab, I get to play with both, but I'm usually working on the bio side of things these days.
If anyone can point me towards any quantitative work on which buffers are most volatile, I'm very interested. I know it would seem like ammonium carbonate would win, but I'm not sure here, since I've read reports that ammonium acetate actually loses acetate first - something funny goes on in the ion-pairs.
And one more thing: as you are laboring to produce hydrogen from apple cores or fully characterize every intermediate in your autocatalytic, ten-step, cascading, protecting-group-free-except-for-acetyl one-pot total synthesis of superduperdifficilin, consider that a note about our humble semivolatile friends was once enough to get you in Nature.
Time marches on.
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Well, there's a lot to be said for being first.
Jug with water and crushed ice. Stir and bubble in CO2. Commercial Dry Ice is contains oil. Vaporize in a separate whatever with a loose glass wool plug (also commercially oily) to entrain mist. Add cold Et3N. Uncatalyzed CO2 hydration is slow, 0.15/sec. Is a speck of carbonic anhydrase, 10^6/sec, indicated? As a transmembrane protein it might also be a phase transfer catalyst.
Et3N does reversible oxygen binding then crudification. Run it neat through a short column of Activity 0 basic alumina right out of the can. A thin yellow line appears at the top of the column.
Im my experience ammonium bicarb is much more volatile than ammonium acetate. Ive done a bunch of ion exchange chromatography with both, and no matter how many times I resolvate and lyophilise the ammonium acetate solutions of my product, they still smell like vinegar.