CaptainPike
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can DCM be used as a refrigerant?
I remember learning that methylene chloride had a lot of heat capacity, back when I was a little kid – one of those drinking bird things was
interesting to me.
So it has a lot of capacity to transfer energy around, kind of thing. Or maybe it's density changes a lot (relatively) with a mild change in
temperature? Maybe that makes it a bad refrigerant, I don't know – and I could definitely UTFSE, to be sure. Maybe it will make a good topic.
Could it be used in a cold finger to trap volatiles suspected in essential oil distillation? My wife has a thriving wreath business and lots of
balsam fir needles fall my way. I have distilled off some interesting looking light oil with a very short Liebig condenser. There is ever so faint a
smell, a wonderful, coniferous delightful-walk-in-the-woods smell that tells me something is getting away, right?
More later…
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Galinstan
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For a cold finger your better off using ice water or dry ice if needed than DCM. the reason DCM removes heat is due to it's high vapour pressure
rather than it's specific heat capacity which is quite small anyway. the smell from your distillation could either be your not using a long enough
condenser or more likely your products are very volatile.
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CaptainPike
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Right Okay – but circulate what? Ethylene glycol :-),?
I have plenty of more efficient condensers. The thing is, I have investigated this on a small-scale at first. I probably have only about 3 mL light
oil floating on top of a nearly full pea funnel which I have used to collect this distillate via a steam distillation set up (I may figure our how to
include a photo).
I let the addition funnel fill up so it will be easier to pipette off the supernatant.
You see, I have some physical difficulties and make use of assistants. Sometimes, I can't get a thing done as quickly as I'd like. More or less
arbitrary segments of time often interrupt my devilry. I'm using small-scale equipment so as to lose as little "product" on the surfaces of the
glassware, hence the short Liebig.
I had the crazy notion of adding another pea funnel up above the Liebig with a super-efficient condenser, possibly cooled was something especially
cold – colder than ice water even. I could do this. I have an extra pump. I even have one of those cold plates – a stirring cold plate, made by
a little outfit in the middle of this country – a father and son team. Anyway, this esoteric bit of laboratory equipment makes use of the Peltier
effect (the opposite of the Seebeck effect, I think) and will give you a -30° temperature differential. Okay, so this is crazy, but when does one
get a chance to be crazy in the exercise of scientific hobby? (Okay, all the time, I know)
So I could put the ice water through the Liebig condenser and through this cold plate apparatus (that's right, one must rid the instrument of waste
heat). And then, cool and small beaker of, say, ethylene glycol) on the cold plate and circulate that through the highly efficient condenser on the
top of the apparatus. This latter stuff would probably need to be wrapped in insulation.
This is the stuff my mind comes up with the middle of the night while I lie awake. And if this were some unknown research endeavor, it might be worth
all this messing around. But, they pretty much know what is in the balsam fir needles already – it's just a handful of terpenes, but it smells
wonderfully distinctive.
[IMG]
http://i175.photobucket.com/albums/w128/Captain_Pike_photos/...
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Galinstan
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The only problem i can see with using a very cold liquid in your condenser is when the 100 degree steam touches the -30 degree glass it will cause
thermal stress whether this will be large enough to do your glass any damage i don't know but it' something to be wary of.
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