How to remove DMSO effectively? _Industrial additives

DMSO: Dimethyl sulfoxide is a colorless and odorless transparent liquid with strong hygroscopicity, high polarity, high boiling point, good thermal stability, and miscibility with water. It is miscible with most organic substances. , also known as the “universal cyanopyridine-soluble agent”.

In organic synthesis, we often use DMSO as a reaction solvent due to its good solubility. However, it is sometimes difficult to remove it during post-processing due to its high boiling point. Let me talk about my experience.

1. If the reactant is stable and resistant to high temperatures, it will be easy to solve. Use an oil pump and vacuum distillation at around 60 degrees to remove it quickly;

2. If the reactants are not so stable, it is obviously not advisable to use an oil pump to pull. If the solubility of the reactant is not good, slowly add a large amount of water. The reactant may precipitate. Filter to remove DMSO. If it does not precipitate, add ethyl acetate and wash with 10 times the amount of water. Can remove DMSO from ethyl acetate (DCM is not recommended because DCM has too good solubility and DMSO is not easy to completely wash off);

3. If the reactant is water-soluble and soluble in water, then volatile solvents such as chloroform, methanol, etc. can be added, evaporate to dryness on a water bath, repeat several times, and DMSO can also be removed; if the laboratory has conditions, you can use For freezing in a freeze dryer, propyl carbonate can also be used to completely remove DMSO. However, one thing to note is that freeze-dried samples containing DMSO are easier to freeze and you can add a little more water when freezing;

4. If none of the above methods work, you can pass it through a normal-phase column, but be careful. DMSO is equivalent to a highly polar solvent in it, so the column should be installed higher. You can also pass it through a reversed-phase column, first flush with water to remove DMSO. , then rinse with methanol, so that the sample is in the methanol phase, collect the methanol and concentrate to dryness to obtain the sample;

5. Especially when we have relatively few samples and use deuterated DMSO to send NMR and need to recover the samples, the freeze dryer is very easy to use; if the laboratory does not have this condition, then find a clean glass dish , pour the deuterated DMSO, cover it with filter paper, and it will evaporate naturally in a few days.

Source: Roaming Medicine