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Offline Aribo

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vac distillation confusion
« on: January 16, 2014, 08:30:31 AM »
Hi All,

I'm having trouble answering/understanding a question I have been asked about distilling petroleum jelly(Vaseline) from chloroform under reduced pressure. reason being is Vaseline is not a liquid but a semi solid!? confusion set in from there.

i would like to try and answer the question and if anyone can assist were I'm right or wrong would be a great help.

the facts I have..

Vaseline is soluble in chloroform

Vaseline B.p 343oC  m.p 37oC

Chloroform b.p 61oC

If I set up for vac distillation with heating the chloroform will come over first (maybe without heat if vac is strong)

the Vaseline will be left in the the boiling flask heating will be continued until the Vaseline boiling point is reached and the Vaseline comes over. what I don't understand is that once it hits the cold condenser it will solidify making a thick gunky mess in my condenser does the fact that its at reduced pressure come into play and lower the melting point also? to below room temp which allows it through the condenser and into the receiving flask as a liquid? until cooled or the vac is disconnected? or am I totally wrong?

thanks in advance  for any help


apologies. seems ive posted in the wrong section


Offline discodermolide

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Re: vac distillation confusion
« Reply #1 on: January 16, 2014, 09:00:44 AM »
If you use a cold water condenser that will happen. Best thing is to drain the water from the condenser after the chloroform has finished distilling.
The air will be sufficient for the vaseline condensation.
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Offline Aribo

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Re: vac distillation confusion
« Reply #2 on: January 16, 2014, 09:30:03 AM »
Great, I will try this tonight and see how it goes.
Ive been pulling my hair out with all sorts of theory's none seemingly right.

thank you

Offline acvkrs

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Re: vac distillation confusion
« Reply #3 on: February 23, 2014, 11:34:53 AM »
Circulate hot water through the condenser and cool the receiver flask in ice or cold water. see how it works. i think it works fine for your task.

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