I couldn't get a very clear answer on this. some used it but most advised against it, saying Molceular sieves are best.

I read that metallic Magnesium can cause explosion with chlorohydrocarbons, would MgSO4 do this. (I wanna know because its most available to me.

thanks.

ADD ON.

With DCM being non polar it shouldn't absorb any water from the air like Acetone or IPA, correct? just when directly mixing both together.

Yes, anhydrous MgSO4 is fine for drying DCM.

Also, if your DCM has methanol as an impurity (furniture stripper) , then you can use CaCl2 to dry it both of water, and of trace methanol. Anhydrous CaCl2 will complex with methanol similarly that it does with water.

For most purposes, MgSO4 will work fine - certainly for kitchen extraction chemistry. I used it all the time when I was working in a synthetic orgo chem lab for exactly this, drying DCM.

There are times when a molecular sieve would be preferable, but you're unlikely to encounter them outside laboratory setting. If you were asking around on a board for chemists, it makes sense they might suggest the sieve, since they are technically more effective, but your instincts are right. MgSO4 is fine.

Blessings
~ND

thank you very much

Hygroscopic was the word I was looking for.

DCM is not hygroscopic, but that doesn't mean you can't end up with water contamination. If you used some kind of liquid-liquid extraction set-up like a sep funnel, it's not uncommon to get tiny 'beads' of water in your DCM. They don't mix, but if you're doing a reaction that's water-sensitive, or using a compound that is reactive to water (which many are, water is highly reactive), you still need to dehydrate your solution.

Also, there is some small solubility of water in DCM. Not much, of course, but basically anything is soluble in anything else if you try hard enough. I've definitely had experiences where I've had an Erlenmeyer flask full of DCM that I would swear was pure, but when I add MgSO4, it clumps up, indicated the presence of water.

Blessings
~ND

zeolite 4A is readily available from e.bay

Yes, but take care which ones you choose, some of the cheap chinese ones can be of very low quality. Lots of dust/particulate, and poor water absorption. Sometimes you get what you pay for.

Good activated sieves will heat up a LOT when wet (a thermodynamic effect). So much that if done in the palm of your hand can burn you. Some of the crappy chinese ones I have had barely get warm.