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Author: Subject: “Dried over”

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[*] posted on 14-12-2020 at 09:51
“Dried over”

I’ve seen “dried over” used to mean drying in a desiccator with the desiccant kept separate from/under the substance, as well as to mean directly in contact with the substance.

For instance, I’ve seen “dried over H₂SO₄” mean the former and “dried over 3a molecular sieves” mean the latter. Those were pretty clear, but what about the times where it isn’t so obvious and either way seems reasonable?

Is there a simple way to tell or is it just generally extrapolated from the context?
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[*] posted on 14-12-2020 at 09:57

What do you mean? Give the example of some phrase, where "dried over" isn't obvious.
When you have a solution in some organic solvent, it's obvious, you're not gonna mess around and put it into desiccator. You just dump the hygroscopic substance straight into the liquid. Although when you have some wet solid, you rather put it in desiccator.

[Edited on 14-12-2020 by mackolol]
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[*] posted on 14-12-2020 at 10:44

I believe it's extrapolated from the context. There aren't many ways to dry stuff. Solids, either in an oven or in a closed vessel near (or, over, like a desiccator) a desiccant. Liquids are usually shaken with the desiccant and decanted, or stored with the desiccant still on the bottom of the bottle. Gases, you make them flow through a series of rubes packed with the desiccant.

I don't recall any instance in which a solid is dried in contact with some desiccant. Special cases such as an oily product that is forced to solidify by grinding it with a water-thirsty solvent are mentioned in another way, such as "the oily mass was ground with acetone, and the solid collected".

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