mycotheologist
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The importance of the size of your fractionating column
I ordered an air condenser so I can upgrade my distillation kit (which can only do simple distillations) so I can start getting proper separations.
Problem is I could only find a 19/26 air condenser on ebay and my condenser has something like B41 (EDIT: I had it wrong, its actually only B29). My
intended use it to distill solvents and sometimes I need to distill litre volumes of it so will this air condenser only be useful for distilling
smaller volumes (i.e. 100mL at a time)?
[Edited on 19-4-2012 by mycotheologist]
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bahamuth
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The limiting factor is speed (will explain downwards), lower dist. speeds the smaller column, you can distill for days and recover 50 L with a 14/20,
no problem..
Same with condensers, they tend to overheat if the speed is to high.
When I say speed I refer to the amount of gas produced by the boiling liquid in you boiling flask, and this is proportional to the volume of your
flask.
14/20 glassware is useful op to a 500 ml flask, perhaps up to 1000 ml but have not tried it myself.
19/22 glassware I have no idea but perhaps up to 2000 ml or more?
24/29 would easy do 5000-6000 flasks IMO.
29/32-42 is up to the 10000 ml range atleast.
34/45 i guess would do nicely up to 22000 ml flasks
40/50 I have seen used on 50 L reactor heads.
All this is relative to what you are distilling, how fast you are distilling, if you have a tight packed column , no column, airtight setup and so on
and my projections might be totally off.
I distill easily and as fast as possible chloroform from a 4000 ml flask in a 29/32 system with a 60 cm Vigreux column and a coldfinger to "recycle"
some of the solvent down the Vigreux and is does so nicely. Mind you that I usually just add 2.7 L in the 4000 ml flask.. But I can easily see a 22000
ml flask at the bottom and rather adjusting the coldfinger and the heating mantle to a gentle boil.
But then I have to ask you, are you talking about a column or a condenser as your title suggests a column while your post suggests a condenser..
Any sufficiently advanced technology is indistinguishable from magic.
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mycotheologist
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Whoa, sorry I made a mistake there lol. I checked my condenser and its B29, not B40 lol. I've been using it with 500mL flasks, I didn't know it could
be used for such huge volumes. If everything you said there is correct, then the kit I have should be fine for distilling solvents. Thanks for
providing all that info there, I learned a lot from your post.
Quote: Originally posted by bahamuth  |
But then I have to ask you, are you talking about a column or a condenser as your title suggests a column while your post suggests a condenser..
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Sorry, I'm new to fractional distillation. By column I mean either a condenser held vertically for refluxing or fractionating or a piece of glassware
designed specifically for that such as a Vigreux column. So the difference between a condenser and column is that a column can be packed, is that it?
I hope this "air condenser" I ordered can be packed.
[Edited on 19-4-2012 by mycotheologist]
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bahamuth
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What you describe may be a Hempel column, and those may be packed since they have indentations at the male joint.
Some columns don't have these indentations and as such may or may not be packable but if there is a "narrowness" to the taper part they may also be
packed. Some "culumns are just air condensers used for very high boiling point compounds where a water condenser of sorts would just clog or even
brake because of the strain caused by the heat on the glass "welds".
On the other hand I have some strange Quickfit columns about 40 cm long 24/29 with a coarse glassfrit in the male end (not in the joint but in the
lowest part of the "column", got these dirt cheap from ebay and I uses them as Hempel columns with packing.
By the way, 29/32-42 tapered glassware is just to big for 500 ml (300 ml filling in the flasks) IMO, due to mechanical losses, though it largly
depends on what you are distilling..
PS. Look up the different columns and condensers that are around and read up on how they are used and what for. It is good to know which glassware to
keep an eye out for and what is useless for ones purpose atm.
Any sufficiently advanced technology is indistinguishable from magic.
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Magpie
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I think that even if you don't have those handy indentations at the bottom of your column you may be able to pack it. If you can use just ss scrub
pad, which is an excellent packing, there willl be enough wall friction to hold it in place.
If you want to use broken glass or glass beads you might have to pack the lower end with an inch or so of scrub pad to act as a support.
The single most important condition for a successful synthesis is good mixing - Nicodem
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