zenosx
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Di-ethyl Ether Gas Scrubbing
This might have been covered but I have had little luck in searching for an effective Diethyl Ether gas scrubber.
I am about to perform a Di-Ether purification from Heptane using fractional distilling in a Vigreux column (20cm) on a 1.5L scale (6x250mL per my
glassware).
My problem is that even though this is being performed in a decent fume hood, I have always had significant ether gas drop down out of the hood. This
is a homemade hood mind you, however, if possible, I would like to run the sealed apparatus through several gas washing bottles to eliminate ether to
air exposure.
My first bottle is 700mL with around 200~g of drierite to prevent water uptake into the distillation apparatus on vacuum uptake of atm. on cool-down
that I use as a general assembly for anhydrous (or close) distillations.
I have two additional 150mL gas washing bottles that can be filled with most common lab reagents except mercury as I do not have enough to fill even a
small wash bottle.
The water uptake of ether is too small as I have already tried this, and yes, I will continue my own research and DO NOT expect to be spoon fed,
however, if anyone has done this before and has a ready answer to the best absorbent for ether fumes it would help. I have spent at least a few hours
researching this issue but other than long articles, or my own ineptitude I have not found much that would (in at least 2 washes, 3 tops) scrub the
ether vapors to at least 80% efficiency.
Thanks to anyone with help, while the vapors aren't an issue for explosive content for the most part for spark proof equipment, fire is always an
issue when distilling ether, and I do have all the safety equipment available for a full blown lab fire, as well as personal safety equipment.
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Magpie
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Simple Green is composed of an aqueous solution of 2-butoxyethanol (5%) and ethoxylated ethanol (5%) according to its MSDS. I wonder if it has much
capacity to absorb diethyl ether? It would be interesting to test it.
Activated charcoal is another possibility. I'm sure it would work in solid form...but I don't know if an aqueous slurry would work.
Then there's the question of how to dispose the ether loaded solvent/absorbent...or how to regenerate the solvent/absorbent for recovery while venting
off the ether in an acceptable manner.
The single most important condition for a successful synthesis is good mixing - Nicodem
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zenosx
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Well, as far as the "loaded" either solvent, if the B.P.'s were far enough apart it would be rudimentary to reload them into the fractionating column
and distill off the collected ether, which isn't a problem but a result IMHO.
Going by what you posted though, I am thinking an initial scrub of activated charcoal followed by a bubble scrub of Simple-green, I would be willing
to test it.
If no one has any better idea's, I'll pick up some of the simple green tomorrow and post back the results of initial starting material (unknown
solution of ether to heptane), to recovered ether from charcoal and (would have to research B.P's of simple-green's components), ether recovery from
that flask.
Any idea's?
(After consideration, the ether recovery from the "simple-green" may in fact be harder than just a simple distillation".. However, the loss of initial
product should be small being that the condenser and recovery flask would be chilled to at minimum of -9Deg C. So even if no recovered ether were
available at least I wouldn't have flammable fumes in the lab.)
[Edited on 15-8-2012 by zenosx]
[Edited on 15-8-2012 by zenosx]
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Magpie
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Of course the obvious solvent for ether would be heptane as that's what is used in starting fluids. Then, as you say the ether could be distilled out
and efficiently recovered. Although I have done this a few times it is indeed risky as you are heating a highly flammable liquid. Even though I have
a highly efficient fume hood the lab does end up smelling a bit like ether for a day or so. Also, the exhausted ether is likely smellable just
outside the lab during the distillation. Doing this on a windy day is therefore advised.
Actually one could probably use a much less volatile hydrocarbon like mineral oil. Maybe even vegetable oil would work. I haven't looked up
solubilities here - I'm just speculating.
[Edited on 15-8-2012 by Magpie]
[Edited on 15-8-2012 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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zenosx
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Well, you have correctly guessed my starting material magpie 
If I already had the heptane, this of course would be the most obvious recoverable solvent, however, the amount of lost ether I will (hope) be rather
negligible.
Unless I find a better method by tomorrow afternoon, I think I will try a vegetable + mineral oil = atmo. scrubber system, or possibly reverse order
as previous if I can find any benefit of switching them based on solubility.
As you say, I have never had any luck scrubbing these vapors, and am trying the starting fluid (heptane+ether+co2 propellant) ether + heptane recovery
method as I have used the H2SO4 + Ethanol = Ether synthesis with usable (but more expensive) yields IMO.
My hope here is to have (after at least two fractional distillations), rather pure Di-Ether on the right (recovered) (@34.5C if I remember), and
heptane left on the other end (99-100C but not sure here unless looking it back up). I will of course then perform at least 2 fractional distills of
the heptane to purify it ending up with fairly good separation since both solvents are more than 20deg C apart.
I could probably speed things up doing a few simple distillations then fractionally distilling but I have never found using the fractionating column
that much slower, and anytime I'm working with ether the less times it's in vapor form in my lab the better
Thanks so far guys!
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Organikum
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Stuff your Vigreux with copper scrubbing pads, not too tight though, this will provide you better separation if you don´t have and are not willing to
build a better column. Helps also against peroxide formation.
Regarding the fumes I am at a loss as I cannot see where and why the ether escapes your setup. Ether is not scrubbed but condensed, thats what I do
and it works. A decent condensor running with icewater and slow distillation (whats essential for separation anyways), the ether collected into a
icecooled flask and a closed setup with a vacuum-adaptor for pressure equalisation. On the vacuum adaptor fit a plastic box stuffed with cotton.
Alternativly collect in a two-neck flask and put a drying tube stuffed with cotton on the second neck.
Ether is not soooo volantile anymore at zero degrees C° or below.
I distilled ether by the liter this way, without a fumehood, in the kitchen and had never problems with fumes nor even smell during distillation.
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zenosx
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My setup uses greased 19/22 glassware, with ice cold condenser bath and salt-chilled ice bath on collection vessel. I seem to always have some either
vapor escaping at the Vac take-off.
I will try packing the column more, and distilling MUCH slower, I usually do the (one drop a second) rule, but I will try going even slower if I have
vapor escape.
I have my vacuum takeoff running into a drying bottle with calcium chloride for above mentioned reasons, I'll stuff some cotton in that as well, if i
STILL have vapor escape on the take-off, I'll try using the above mentioned bubbling fluids.
For those curious my basement runs high on humidity even though I have a de-humidifier running 24/7 about 10' from the lab bench, I extract around 2
gal per DAY of humidity, so I have found the drying bottles mandatory for anything that grabs moisture (just woke up can't remember sp (hydrospcopic?)
Thanks Everyone!
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watson.fawkes
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The product
"Bestine Solvent & Thinner" is technical grade heptane, available retail, very much OTC. See the MSDS.
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Magpie
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Yes, Watson, I have seen heptane sold by the pint at Michael's craft store.
Once you have recovered your 1.5L of ether from the starting fluid you will be flush with heptane. I was accumulating enough of it that it was a
waste disposal issue. I poured it into the gas tank of my car just to get rid of it.
The single most important condition for a successful synthesis is good mixing - Nicodem
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zenosx
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Well I haven't had time to do the distillation / separation yet, and after inspecting my setup today I have a crack straight through the top joint of
my fractionating column. I hope to try tomorrow and give it a go, and ordered another column today as this one will have to be replaced fast, I
apparently cracked it with a shoddy homemade lab stand that was not straight and after sitting overnight...sigh. ( this was not where I had gas leaks,
it was a new fracture from too much sideways pull on the joint. Newb mistake!! And an expensive one!)
If the joint holds I will post back for reference hopefully tommorow night. I appreciate all the input for a newb question.
(Note: I did pack the column with copper for better frac. Squeezing it into 19/22 virgreux column however wasn't fun. And no just a bit. I know not to
over-pack a column).
Thanks again!!
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chemrox
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I have never been able to completely contain ether. Maybe it's because the vapor is so heavy. Maybe the odor strength is a factor. It seems like
ngs of the stuff call out like a bell. Maybe it's because I use lots at a time. I run ether stills with the receiver in ice and a drying tube on the
adapter. I had one good condenser for refluxing ether made for me. It had a coiled coldfinger and a jacket on the outside. It contained 10+ L of
refluxing ether without too much odor provided an exhaust fan was running all the time. Even an opened can of ether smells if not stored in well
ventilated area. It boils at 95F so big surprise. Half the US is over that right now thanks to Chinese coal and US oil consumption.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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zenosx
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Well, my virgreux column didn't hold up, So until my replacement gets here I packed a clasien adapter for at least some fractionating from the
heptane. I ran the rig up very slowly, and had NO ether odor at all. Had the take-off running into a drying bottle with some cotton balls as someone
above suggested, and from there into 2 empty washing bottles.
So far so good, going down to finish up the other batches, then will have to redistil when my column arrives if I want really pure solvents, which atm
I don't need that purity but might as well get it done while I have everything out.
Thanks everyone
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