| Pages:
1
2
3
4 |
karaffa
Harmless
Posts: 2
Registered: 2-5-2004
Member Is Offline
Mood: No Mood
|
|
Ethyl ether distillation and synthesis
Hey, I just found this:
http://roguesci.org/megalomania/synth/synthesis2.html#ether
And now I'm wondering if it's realy necessesary (enable spell check) to distill at 130-140 C ? Since the boiling point for diethyl ether is
34C.
Isn't 140 C just like asking for an explosion ?
|
|
|
Esplosivo
Hazard to Others
Posts: 491
Registered: 7-2-2004
Location: Mediterranean
Member Is Offline
Mood: Quantized
|
|
The synthesis of ethyl ether does not only depend on its boiling point. The reactions between two ethanol molecules, catalyzed by H+ ions, occurs at
temperatures around 140 deg Celcius. Synthesis of ethyl ether is surely dangerous, but if the appropriate precautions are taken the ether will be
formed without any problems, and neither explosions 
Just keep flame sources away from the place during ether synthesis/handling.
Theory guides, experiment decides.
|
|
|
vulture
Forum Gatekeeper
Posts: 3330
Registered: 25-5-2002
Location: France
Member Is Offline
Mood: No Mood
|
|
Note that this is the temperature required for the reaction to proceed. The temperature at the top of the fractionating column will be the same as the
boiling point of the ether.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
So I guess a two-neck flask would be optimal here? What happens if you don't have one of these, can you just ASSUME a temperature, ie. 4th
setting on my 7 setting hotplate, for example...Or is the temperature really important here? Alternatively I guess I could could just forget about
measuring the temperature of the distillate and just plunge it into the vessel. Ah. Anyways, I don't plan on doing this, sounds scary.
I'd make sure the joints are nicely sealed too, no leaks! Use vaseline or joint grease to effectively shut them up to prevent any possibilities
of gas escaping and...you know what happens next.
|
|
|
Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
thunderfuck:
- first use an oilbath or at least a sandbath - dont place your flask directly on the hotplate.
- second use your brain. You can very well check what setting on your hotplate correspondends to what temperature of the H2SO4 in the flask by plain
trying it out without column.
- third, you can measure the temperature of the oilbath - by a rule of thumb this temperature is about 20°C higher than the temperature of whats in
the flask.
The alcohol has to be run slowly into the conc. H2SO4 or youll get some not so pleasurable experiences. It is very favorable to use an
copper-condensor here which is very wasy to buildt from common plumbing parts and to place some copper (metal, filings, wire) in the receiving flask
as this will suppress peroxide formation.
But get yourself an "Claisen" threeneck adapter - thats a piece needed over and over again.
ORG
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
Ether can also be bought as engine starting fluid. It's about 60-70% ethyl ether, 5% CO2 and the rest is heptane, so the CO2 will bubble off and
the ether can be distilled, but condensing the ether is a problem considering it boils at room temperature. I don't think cold water will be very
effcient, I was thinking of making a copper coil condenser in a paint can full of dry ice. Does anyone think this will work?
[Edited on 14-6-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
If its worked for others using the synthesis approach (boiling off the newly formed ether and condensing it), I don't see why it wouldn't
work using the spray can. Just spray it all out and boil it to collect the condensing liquid. This of course assumes you have a distillation setup..
I think the dry ice would be unecessary..Maybe improve yields, but, meh.
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
I have some flasks, rubber stoppers, plastic hosing, and a liebig condenser, so I do have a distillation rig although not a ground glass one. However
like I said I'm not going to use my condenser. I plan to buy a length of soft copper tubing and molding it into a coil, which will be inside a
3" thick, 40 cm long piece of pvc full of dry ice, sealed at both ends. This will in effect be a dry ice, graham condenser. The whole setup
will be made air tight by rubber stoppers. You may be right, thunderfvck, perhaps it is redundant, but with dry ice a $1 a pound at my local Food
Lion I feel better than using cold tap water and a liebig to condense ether. Out of curiosity, how many members here have experience distilling or
condensing low boiling point liquids, such as ethyl ether bp 21 C, acetaldehyde bp 20 C (I think), or methylene chloride bp 39 C? If so, could they
please relate their experiences/results/tricks of the trade? Much thanks  . The
last two especially, I would want to condense very effectively as they are nasty carcinogens.
[Edited on 14-6-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
Ether has a bp of about 35 or 36...It's late and I'm NOT opening a new page to check precisely which it was.
I think it was 35.4.
Chemfinder!
Boy, I wish I could find some dry ice like that...I haven't looked, but to know where it is...
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
Hooray, it was 35, that's high enough to make me feel comfortable. Do you not have dry ice in Canada? In the United States every town has at
least one dry ice factory, and almost every supermarket sells it at $1/pound? You could probably find it if you looked in the right place. I looked
up ether in the merck index and it says not to shake dry ether as the static electricity could build up enough to start a fire. The anhydrous product
forms peroxides in the presence of air or light. I will probably fill the copper tube with a section of calcium chloride so as the ether vapors pass
through they are dried, and also paint the flask black so no light gets through.
[Edited on 14-6-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
I distilled some ether from starting fluid today, with good results. Two cans were emptied into a 1 L erlenmeyer flask, coming to a volume of around
800-900 mL. The flask was sealed with a rubber stopper, and the rubber stopper was linked by plastic hose to a condenser. The condenser consisted of
a copper coil inside a 3" diameter piece of PVC pipe filled with regular ice. I didn't feel like buying 5 pounds of dry ice for $5, when
the same $5 bought me 35 pounds of regular ice. I didn't use it all however, only about 10 pounds or so for both cooling the receiving flask and
the condenser. The flask was heated on an hoil bath at 50-60 C for 4 hours at which point bubbles stopped forming. 150-200 mL of distillate was
obtained, which made me a little dizzy when I caught a whiff. The operation appears to be a succes. 200 mL of ether for a grand total of $2.50
isn't bad! I will proceed to dry it with calcium chloride later, but even now it appears to be quite pure.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
Appears!
Dry it and distill is again would be a good idea for perfectly clean top of the line ether!
That's pretty crazy. You only got like 200 ml's from 800 ml's of starting fluid? Cheap bastards.
|
|
|
Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
Add a piece of copperwire to the flask where you store the ether in, this prvents peroxide formation. This does not destroy already formed peroxides
though. To destroy peroxides redistill but add a dash of ferrous sulfate before starting the distillation.
So you have now 200ml of ether. A easy way to get it pure is to collect about 10ml at start of the distillation change receiving flask, collect about
150ml and change back again. The 150ml "middle fraction" resembles the pure stuff (as long there is not a lot of azeotropic shit in it what
is unprobable in starter fluid).
Usual ice/water mixture is absolutely ok for condensing ether. Dont forget to cool your receiving vessel and put the copper wire in from start.
Store in a dark (brown) bottle away from air and at a cool place.
Ether and chloroform are great solvents - to be handled with care thats understood, but as they have been the favorite solvents in the lab for a long
time I would like to say that it is very well possible to work with them.
ORG
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
If I don't redistill the ether, but simply mix with calcium chloride and filter, will I get a product of sufficient purity for making grignard
reagents? Or will it be contaminated with heptane, the only other constituent of the starting fluid besides CO2?
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
1. No.
Dry your product with lots of NaOH - this takes some weeks (yes weeks) but is the only way to get the ether dry enough for a Grignard without using
Na-wire or such.
After drying you have to distill the ether preferable directly before use. Discard the first ml´s which come over because they will carry the
moisture of the air in the system.
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
Why sodium hydroxide? Why not calcium chloride? I thought calcium chloride was more hygroscopic, and for me it's a lot cheaper too. I looked
in Vogel's 3rd and the preparation of ether did not involve weeks of drying. How realistic is it to prepare anhydrous ether fit for grignards
under household conditions? I heard it is done in a nitrogen atmosphere  .
Oh, and I have a picture of my still.
[Edited on 29-6-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
BromicAcid
International Hazard
Posts: 3246
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
I myself would use sodium hydroxide in preference to calcium chloride as my drying agent mainly because of the presence of dissolved CO2 in the
resulting ether. Most starter fluid is pressurized with CO2 and it is not much of a stretch to say some of it may have worked its way into the
collection flask. Noting that in Grignards CO2 will lead to a carboxylic acid the NaOH would lead to the extra benefit not present in CaCl2, and that
is taking the CO2 from the resulting ether. Also, NaOH holds water better then CaCl2.
|
|
|
HRH_Prince_Charles
Hazard to Self
Posts: 92
Registered: 29-6-2004
Location: Clarence House, London
Member Is Offline
Mood: Bombastic
|
|
Picture of Still
Is the distillation closed circuit?
I take it the large diameter white pipe is filled with cold water - I can't see any recirculation pipes?
Loather of monstrous carbuncles, lover of organic melons and servant girls.
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
The large white pipe has a copper coil inside, and is filled with ice, which cools the coil during the distillation. The top cap is kept loosely
screwed so ice can be replenished during the distillation. There is no seal where the vinyl tubing leaves the bottom of the PVC jacket, so the water
just leaks out. It's primitive but it works. Here's an inside pic. I distilled another 180 mL from two more cans of starting fluid today.
This time it only took 2 hours because I had the temperature of the oil bath at a constant 65 C. It might be a little less pure, but I am
redistilling it anyway for grignards. Seriously can I prepare grignards at home without a fancy and expensive ground glass closed system purged with
nitrogen? Are rubber stoppers obsolete even in home labs  ? I'm sure Victor
Grignard didn't use ground glass back in 1907, as Vogel's third edition, which was written in the 50's, describes ground glass as
having just begun to take over due to it becoming much less expensive. Oh and how much NaOH/1 L of ether would you recommend using and does it need
to be renewed?
[Edited on 30-6-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
NaOH or better KOH for drying ether for a Grignard.And enough time. Period.
Why?
Some guys tried this out long time ago and published the results.
Ok?
Rubberstopper are a nono in Grignards as they inhibit the formation of the Grignard-reagent. Nitrogen is not needed as the evaporating ether shields
the reaction already. Actually it is possible to run a Grignard (not too big of course) without fancy glassware. VERY good ventilation is a must
though. You understand, the ether shielding says of course you have ether vapours around and quite a lot. Doing it on a open window with a fan blowing
out is told to do the job. The fan should be placed BEHIND you and not between window and reaction - blowing not sucking!
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
Why would the rubber stopper inhibit the formation of the grignard if it doesn't contanct it? It's just sealing the flask so nothing else
can get it. Also once the grignard is formed, will the stopper destroy it if it does touch, like in a distillation?
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
Mendeleev
Hazard to Others
Posts: 237
Registered: 25-12-2003
Location: USA
Member Is Offline
Mood: stoned
|
|
Okay I have about 1.2 liters of not very pure ethyl ether distilled form car starting fluid. I distilled the second half of those 1.2 liters using a
standard 30 cm liebig condenser, so I guess my copper coil apparatus was a bit redundant. Here's what I'm going to do. I will add about
200 grams of CaCl2 and mix for 5 minutes, then let sit for 15 minutes and then filter. I will then add another 300 grams of CaCl2 mix 5 minutes, let
sit for half an hour, then distill at 33-38 C through a calcium chloride drying tube. Prior to this my glassware will be rinsed with acetone and
dried for 1-2 hours with a blow drier set to max. Following the distillation with calcium chloride, I will toss the distilled product into a 2L coke
bottle which has been dried in the same manner as the glassware, acetone/blow drier. Into this I will also chuck 510 grams of sodium hydroxide, then
mix them well and let them sit for 2 weeks. After two weeks I will distill the product at 33-38 C through a calcium chloride tube and will hopefully
have anhydrous ether. In all these apparati, all the holes/air exits will be guarded with calcium chloride tubes and all glassware will be dried
using acetone/hair drier. Does this sound good enough for grignards? Would anyone like to point out any flaws, mistakes in my grand scheme?
[Edited on 3-7-2004 by Mendeleev]
[Edited on 4-7-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
|
|
|
bogus poster
Harmless
Posts: 7
Registered: 13-1-2004
Location: locus
Member Is Offline
Mood: bogus
|
|
You wont need to distill through CaCl2 after drying with NaOH. But you for sure should have a moisture protection tube with CaCl2 at your receiving
flask and to dry your glassware before. Discard the first 10 percent of the distillate and the last 20. The middle fraction should be what you wanted.
Swirl the flask with the ether/NaOH from time to time during the 2 weeks - this is favorable.
Good work up to now!
bogus
[Edited on 3-7-2004 by bogus poster]
|
|
|
unionised
International Hazard
Posts: 5126
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
The only 2 litre coke bottles I have seen are made from PET and they dissolve in strong alkalies.
I'm also not sure about the general merits of plastic as a container for solvents.
If coke bottles are glass where you are then please ignore these warnings.
Does anyone know if 2 weeks is long enough to get peroxides at hazardous levels?
|
|
|
The_Davster
A pnictogen
Posts: 2861
Registered: 18-11-2003
Member Is Offline
Mood: .
|
|
Depends, what type of conditions are you storing it at? Light, air, moisture, etc, etc..?
|
|
|
| Pages:
1
2
3
4 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
