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Solvent distillation

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aimsiú fhírinne
Hey guys, its been a couple years since I've been on here and its really great to be back. I'd like to start off with a few questions about distillation if anyone can help me out. I was wondering if I have to worry about condensation building up on the inside of the coil causing h2o to drip down and mix with whatever I'm collecting. I do sometimes see with some limonine and heptane distillations that there was a layer of water in the collection flask. At first i thought it was a leek but im pretty sure its condensation. Its not too big of a problem as I can just use my separation funnel to separate them but I worry of the purity of my distillate. Should I do a wash with Ca(OH)2 or add molecular sieves? Am I just being paranoid? They are non polar solvents and wont mix with the water very much, maybe 0.0017% solubility or something minuscule but I'm worried about them causing future pulls to be cloudy or effect the boiling temperatures. Maybe I should start runs without chilling the coil until the solvent starts boiling so that way less condensation forms. Thanks everyone, glad to be back.
What's your set up?

A simple distillation set up is three parts, distillation head, condenser, and receiver adapter (usually with vacuum adapter)

The receiver end is important since it prevents water condensed on the outside of the condenser from dripping into your collection flask.

With a RBF collection flask, the entire system is contained, no chance of outside water getting in. Sometimes I distill right into the bottle, and do not have a problem with water getting in.

I have also distilled without the receiver, in this case i place a rag over the end of the condenser where it sits on top of the solvent bottle, and a bit of Aluminum foil. to prevent water from dripping down. So its possible without.


Another possibility is the limo that you are distilling is wet, so when you distill the first thing to come over is the water... Limo does form a lower boiling azeotrope, but not with very much water.
Its a standard glass distillation apparatus with round bottom flasks and clamps. I dont think that its getting in from the outside, i believe there is condensation forming on the inner tube on the liebig condenser, just like how its forming on the outside. If its not normal it might be because of my temperatures or because of a crack on the inside of the condenser. It just seems like I'm always getting a very small amount of water in my collection flask.
if the set up is sealed its highly unlikely that you'll have water from the air condensing INSIDE the condensor.. unless you live in an area with 100% humidity, in that case maybe... Where I live it is quite dry in the winter time..

You can place your glassware in the oven at 150-200F for 10-15min, that will dry the air inside.... This oven drying is adequate for highly water sensitive reactions.

If you're still getting water after this, then its whatever you're distilling thats wet.
Limonene boils at 178°C, so if there's any water in your distillation flask it would also get condensed along with the limonene, since water boils at 100°C, and end up in your collection flask. Heptane has a BP of about 98°C, so even if you're very precise with your temperature control and keep everything below 100°C, you might still have water in your distillate if there was any moisture in the distillation flask. Any water in your collection flask can be removed with Mg(OH)2 or Ca(OH)2 if you really want to be sure your solvent is anhydrous.
I got a new condenser and everything seems fine, i think there was a tiny crack that was leaking water in from the pump. Thanks guys
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