Sciencemadness Discussion Board

Ethyl ether distillation and synthesis

karaffa - 4-5-2004 at 09:38

Hey, I just found this:

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 - 4-5-2004 at 10:02

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 :P

Just keep flame sources away from the place during ether synthesis/handling.

vulture - 4-5-2004 at 10:03

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.

thunderfvck - 4-5-2004 at 10:53

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 know what happens next.

Organikum - 4-5-2004 at 11:27

- 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.


Mendeleev - 13-6-2004 at 17:44

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]

thunderfvck - 13-6-2004 at 19:34

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 - 13-6-2004 at 21:28

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]

thunderfvck - 13-6-2004 at 23:36

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.


Boy, I wish I could find some dry ice like that...I haven't looked, but to know where it is...

Mendeleev - 14-6-2004 at 11:51

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]

Mendeleev - 27-6-2004 at 18:55

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.

thunderfvck - 27-6-2004 at 21:56


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 - 28-6-2004 at 06:06

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.


Mendeleev - 28-6-2004 at 19:36

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?

Organikum - 29-6-2004 at 10:22

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 - 29-6-2004 at 13:29

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 :o. Oh, and I have a picture of my still.

[Edited on 29-6-2004 by Mendeleev]

Ether Still.jpg - 54kB

BromicAcid - 29-6-2004 at 14:16

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.

Picture of Still

HRH_Prince_Charles - 29-6-2004 at 14:27

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?

Mendeleev - 29-6-2004 at 17:49

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]

PVC condenser.jpg - 42kB

Organikum - 30-6-2004 at 02:07

NaOH or better KOH for drying ether for a Grignard.And enough time. Period.

Some guys tried this out long time ago and published the results.

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 - 30-6-2004 at 12:22

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?

Mendeleev - 3-7-2004 at 10:16

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]

bogus poster - 3-7-2004 at 10:37

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!

[Edited on 3-7-2004 by bogus poster]

unionised - 4-7-2004 at 13:17

The only 2 litre coke bottles I have seen are made from PET and they dissolve in strong alkalies. :o
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 - 4-7-2004 at 13:57

Depends, what type of conditions are you storing it at? Light, air, moisture, etc, etc..?

BromicAcid - 4-7-2004 at 14:32

Living in the USA, and possibly elsewhere, Capri Sun "Island Refreshers" are a newly available drink. The bottle is aluminum with a stainless steel bottom along with a cap that screws on with a nice tight seal. Aside from seal integrity, these are almost identicle to the bottles used to store ether in at professional institutes. They also work good for storing other solvents ;)

[Edited on 7/4/2004 by BromicAcid]

ether storage bottle

Magpie - 4-7-2004 at 20:01

Organikum has warned us to place a copper wire in the ether receiver and storage container. Does anyone know if the commercial metal ether containers have copper or other peroxide preventer built in? Or, how do they deal with this problem?

Organikum - 5-7-2004 at 08:11

Commercial ether contains liquid peroxide inhibitors admixed alone for the reason if someone fills other containers with the ether.....

Which depends on the manufacturer and the intended use of the ether. I cannot imagine that any ether is shipped without protection against peroxides.

Mendeleev - 6-7-2004 at 08:03

Those preservatives won't mess up grignard reactions, will they? I have found two great deals on anhydrous ether, and they both have preservatives. One is from Mallinckrodt Chemicals, 14L anhydrous ether for $110.10 US, which contains no preservative, and one from VWR, 20 L anhydrous ether for $170.38 US. this contains 2,6-diterbutylcresole. These are usually inert preservatives that don't interfere with the ethers chemical value as a grignard solvert, no?

Cyrus - 9-7-2004 at 10:15

Mendeleev, you love to have lots of a chemical. :)

How many tons of chemicals do you have?:o

[Edited on 9-7-2004 by Cyrus]

Mendeleev - 14-7-2004 at 14:37

No tons. Yet... ;). I am interested in drying my ether with sodium, as it is much faster. Usually commercial sodium is packaged in kerosene to prvent reacton with the air or water vapor in the air. So how do you go about preparing commercial sodium for drying ether, or is the kerosene not a significant contaminant in Griganrds? Also how much sodium should be used per liter of ether?

[Edited on 14-7-2004 by Mendeleev]

The_Davster - 14-7-2004 at 16:52

I remember that sodium wire is used for drying ether. The book I got this info from also gave instructions for a "sodium press" which would force lumps of Na through a tiny hole thus making wire. The press was suposedly have been able to have been constructed from OTC pipes and fittings.
I think this was a library book that I no longer have unfortunatly.:(

S.C. Wack - 14-7-2004 at 18:02

A type of press is illustrated on page 164 of the Vogel 3rd ed., for this purpose. Just a reminder, because I know everyone here has downloaded and read this of course.

JohnWW - 28-8-2004 at 12:06

Another route to the preparation of ethyl ether: electrophilic heavy-metal cations that form halides insoluble in ethanol, e.g. Ag+ (as ethanol-soluble salts like nitrate, nitrite, perchlorate, fluoride) react with alkyl halides in ethanol to form alkyl ethyl ethers. Hg++ and Pb++ salts may also work.

It produces AgCl as a white precipitate, and, with ethyl chloride as the alkyl halide, diethyl ether, with an acid left in the ethanol solution, in a "SN1" reaction. (any soluble silver salt will also do - heat is required):

C2H5Cl + Ag+ + C2H5OH -> C2H5-O-C2H5 + AgCl + H+

The first of two steps is:

C2H5-Cl + Ag+ -> C2H5-Cl+-Ag -> C2H5+ + AgCl

and the second step is:

C2H5+ + C2H5-OH -> C2H5-OH2+ + C2H5-O-C2H5 + H+

The Ag+, as a Lewis acid, coordinately with an electron pair on the Cl. This weakens the C-Cl bond, the AgCl covalent bond being stronger.

Reference: Organic Chemistry, T.W.G. Solomons (Wiley - 3rd ed. 1984), page 200, and other comprehensive organic texts.

The reaction is driven by the greater affinity (enthalpy of reaction) of AgCl over the ethyl chloride, Ag+ being an electrophile or Lewis acid; and in the second step by the electrophilic affinity of the carbonium ion produced in the first step for the unused electrons on the O in
C2H5OH, which is greater than that for the anion of the Ag+ salt ion, although the
possibility of trace amounts of an ethyl ester being formed cannot be discounted.

The acid produced may form an ester with the ethanol, if any H2SO4 is present, which tends to rule out using Ag2SO4.

John W.

Hermes_Trismegistus - 28-8-2004 at 12:46

Originally posted by rogue chemist
I remember that sodium wire is used for drying ether. The book I got this info from also gave instructions for a "sodium press" which would force lumps of Na through a tiny hole thus making wire. The press was suposedly have been able to have been constructed from OTC pipes and fittings..:(

You could just invest in a garlic press..

The_Davster - 28-8-2004 at 13:27

Yes but a garlic press has many holes, not just a single one. But I gues one could solder closed the other holes, that would probally work.
Neat idea Hermes.

Perhaps not.

Hermes_Trismegistus - 28-8-2004 at 14:08

The sodium was to be utilized for the drying of ether, it's easier to have a bunch of small wire bits of sodium than to have a single long thread of sodium that would have to be chopped into peices anyway.

If a person was to run a knife edge back and forth across the front of the press while extruding the sodium, you would have a reasonable facsimile of sodium sand.


The_Davster - 28-8-2004 at 17:47

Ah, that makes sense. Whenever I have heard the phrase "dry the ____ with sodium wire", I had always thought that one would stirr the substance with a single strand of sodium wire, untill it stopped reacting. This clears things up a bit.

mick - 30-8-2004 at 08:40

I think the idea of the sodium press is you put the bottle or solvent right under it and the clean sodium falls straight into the solvent + solvent vapours without any oxidation.

I have used a sharp knife to take very thin slices that fall straight into the solvent, pre-dried MgSO4 or something.

[Edited on 30-8-2004 by mick]

Esplosivo - 30-8-2004 at 11:55

Originally posted by Mendeleev
Those preservatives won't mess up grignard reactions, will they? I have found two great deals on anhydrous ether, and they both have preservatives. One is from Mallinckrodt Chemicals, 14L anhydrous ether for $110.10 US, which contains no preservative, and one from VWR, 20 L anhydrous ether for $170.38 US. this contains 2,6-diterbutylcresole. These are usually inert preservatives that don't interfere with the ethers chemical value as a grignard solvert, no?

In my case the diethyl ether available from my supplier contains 2,4-Di-tert-butyl-4-methylphenol (BHT) which is in very small quantities, approximately 5 - 10 ppm. I seriously doubt that such small quantities could interefere with any reaction. At such a conc the worst which could happen is a very small decrease in the yield, but nothing to worry about I think :)

Mendeleev - 21-11-2004 at 13:11

Vogel calls for a tube to extend from the addition funnel into the sulfuric acid solution, when adding more ethanol in the synthesis of ether. Is this really necessary? Is it done to prevent splashing inside the flask. I was thinking maybe the ethanol would evaporate before getting a chance to react when it hits a liquid which is at a temperature 50 degrees higher than its boiling point. If this were the case, the tube extending into the reaction mixture would help prevent this.

Grignard Reactions in "Wet" Ether

Eclectic - 21-11-2004 at 16:09

David H. Smith
Department of Chemistry, Doane College, Crete, NE 68333-2496

A small laboratory ultrasonic bath can be used to initiate the Grignard reaction of alkyl or aryl bromides in regular laboratory-quality, undried, diethyl ether and in simple undried test tubes. The reaction typically starts within 30 to 45 seconds and is self-sustaining. Yields and products are the same as obtained with carefully dried ether and equipment. We normally run this reaction at the 1.5-gram scale, but the procedure can be scaled up to at least 10 g of the bromide.

Weird Results

Mendeleev - 30-12-2004 at 16:48

So I tried to do vintage ether synthesis a la Vogel. I did everything by the book: equal volumes of "rectified spirit", that is denatured alcohol from the hardware store, was mixed with sulfuric acid that I concentrated myself and confirmed by a density check to be 96-97%. 250 mL of ethanol was added to the flask followed by 250 mL of the sulfuric acid which was added very slowly to prevent excessive heating.

When the two substances were well mixed well. I configured an apparatus consiting of a 1L flask with a three-hole stopper, bearing a thermomter, a long glass tube, and a short bent tube. The short bent tube was connected to a 300 mm liebig condenser which was connected to a flask in an ice bath. The long tube was connected by tubing to an addition funnel with ethanol. Vogel says the tube must extend to within a cm of the bottom of the flask which I did.

Next he says heat to 140 and maintain between 140 and 145 while adding the ethanol in the funnel at the same rate that liquid distills. This I did, taking 5 hours to add 500 mL ethanol, the temperature staying at 140 give or take a couple of degrees the whole time. I believe the volume of ethanol added is twice that which is mixed with the acid.

Here's the weird part. About 180 mL of distillate was obtained but it was apparently not ether. It did not smell too much like ether more like fruity odor. What is this ethylene? When I proceeded to wash it with water, I only added about 5 mL to a test tube first to check. It would not separate from the 5% NaOH soluiton :mad:. When shook(without NaOH solution) it gives bubbles like mad! I held my thumb over the test tube and very lightly shook it. This caused so much pressure to build up, it nearly shot out, and it was ice cold too.

I have no clue as to what the hell happened. Either I have a solution of ethylene in water or the laws of physics cease to exist on my hotplate :(.

[Edited on 31-12-2004 by Mendeleev]

S.C. Wack - 30-12-2004 at 17:12

And what brand of denatured alcohol did you use? Do you know its actual content?

Mendeleev - 30-12-2004 at 17:52

Crown brand. It comes in a blue can with an orange box on the front labeled "Denatured Alcohol". Two other things about this reaction: After mixing and heating, as the heat rose the mix darkened turning from having a very light tinge of yellow to a deep amber color. As alcohol addition continued it turned completely black. Also now that I've had a chance to clean the glassware, I noticed the condenser was streaked with some sort of white polymer goop :o.

[Edited on 31-12-2004 by Mendeleev]

HNO3 - 30-12-2004 at 18:30

I know PE can be decomposed by H2SO4 in the presence of ethyl alcohol. PE can be made by bubbling C2H4 through a NaOH solution. In fact, I think that's the industrial procedure.

BromicAcid - 30-12-2004 at 18:43

It's solvent grade denatured alcohol, the description of the reaction mixture darkening and the streaks in the vessle clench it in my mind as dissolved organic matter, there is no rigid standard as to purity, the company that made the denatured alcohol probably just collected the excess alcohol from some other industrial process, no telling what's dissolved in it, try evaporating 10 ml or so slowly and see what you're left with, if you get a film then I wouldn't use if for this reaction.

S.C. Wack - 30-12-2004 at 18:48

I've yet to find a hardware brand that was more "alcohol" than "denatured". I buy the cheap vodka when it is on sale but even then it doesn't cost much less than 95% EtOH ($14/750 ml), going by alcohol content. Every hardware brand I've run into is loaded with MeOH and/or ethyl acetate.

Well, here is the MSDS for your product. No surprise.

Mendeleev - 30-12-2004 at 18:48

Yeah I guess you're right. I actually have a pint of 200 proof, but I was saving it for a special occasion(it's not denatured :D). I guess you guys are right, the alcohol is the only variable. Drat. But why would the reaction turn black, is that supposed to happen? Can anyone make a good guess as to what's in the distillate? It smells very fruity, like acetaldehyde or something, I think I've heard that ethylene and several esters smell that way.

EDIT: Just saw S.C. Wack's post, it must be the ethyl acetate that smells fruity, that or a combination of ethyl acetate and ethylene.

EDIT2: Another thing I remembered, at the start of the reactin when the temperature hit 135ish, lots of white fumes were generated. I cautiously smelled the end of the hose that was connected to the receiving flask, and the white fumes billowing out also smelled very fruity.

EDIT 3: What the hell :o! I just read the msds for the crown denatured ethanol! It's 65-75% METHANOL! No wonder there were so many fumes produced that was probably dimethyl ether, which boils at 0 C if I remember correctly. And the black color could have been anything with all the IPA and ketones in there.

EDIT 4: On the other hand at least we have found a very large source of OTC methanol, those damn HEET cans only contain 300 mL.

EDIT5: Thanks a lot S.C. Wack, that Crown page helps a lot as I buy many of their products.

[Edited on 31-12-2004 by Mendeleev]

[Edited on 31-12-2004 by Mendeleev]

[Edited on 31-12-2004 by Mendeleev]

[Edited on 31-12-2004 by Mendeleev]

[Edited on 31-12-2004 by Mendeleev]

trilobite - 30-12-2004 at 19:10

It could also be the denaturants, which are often ketones such as acetone, MEK or methyl isobutyl ketone, that can undergo various condensation reactions (aldol with dehydration which releases water btw, michael addition) under acidic conditions giving products that can have a floral smell. I don't know if this would explain your distillate, but it could explain its smell. Could it be that most of the solution is still ether?

I have some ethanol denatured with MEK (Bp. 79,6' ) and MIBK (strong taste and smell). Some time ago I put some of this alcohol in a flask, poured in a smallish amount of sodium hydroxide, and refluxed it. The colour change was from yellow to orange, red and eventually quite dark. This took from 6 to 8 hours, after which I decided there were enough signs of polymerizing the ketones and distilled it. The distillate was clear and not alkaline at all. It smelled mostly of ethanol, but it's taste told that there were still some denaturants left. I didn't try refluxing the distillate with NaOH to see if it would change colour. All this left me an impression that I had gotten rid of most of the denaturants.

Of course, there are other denaturants too... maybe you should try distilling the "ether" you got, check it's boiling point etc?

Edit: Oh, that explains something.

[Edited on 31-12-2004 by trilobite]

garage chemist - 31-12-2004 at 07:05

Trilobite, the process you outlined is very interesting.
In Germany, "Brennspiritus" actually contains 94% Ethanol (it says so on the bottle) and NO Methanol.
It is denatured with ketones and Bitrex.
Bitrex is nonvolatile I think, and can be removed by distilling the ethanol.
The ketone (usually MEK) is much more difficult to remove though.
Your Method with NaOH seems highly promising!

Do you know which reaction happens when a ketone is heated with NaOH? Polymerization? When yes, which products form?

Mendeleev - 31-12-2004 at 08:48

NaOH causes an aldol condensation in ketones. I think the alpha carbon is deprotonated forming a carbocation which attaches to another molecule of ketone. The carbocation is negatively charged so it adds to the alpha carbon(I think) of the other ketone molecule, forming an aldol. In this complex the oxygen becomes single bonded because of the extra electrons brought by the carbocation, but it is not very stable this way and so forms OH.

Mendeleev - 31-12-2004 at 20:08

I tried this exact experiment with 200 proof non-denatured alcohol, and using about 150 mL acid to 150 mL alcohol and 300 mL in the funnel, I got 150 mL of ether after washing. Very happy now :D.

para toluene sulfonic acid as catalyst ?

xxxxx - 1-1-2005 at 08:03

i once read that if benzene sulfonic acid was used as the catalyst this catalyst would not lose its effectiveness as does sulfuric acid. also if aluminum sulfate was added to the reaction mixture the reaction temperature would be lowered to 120 C. maybe someone could check this with ptsa?

trilobite - 1-1-2005 at 20:59

Yes, aldol condensation. In the case of acetone condensing with itself the reaction is: CH3-CO-CH3 + CH3-CO-CH3 ---> CH3-CO-CH2-C(OH)-(CH3)2

The products of condensation of this type always has a carbonyl group so they too can react in the same way. Eventually you will have mostly large molecules. I'm sure there are other reactions taking place too, this doesn't explain the color change.

Mendeleev - 3-1-2005 at 16:50

Okay now that I'm finally done with everything, final yield after dryign was 148 mL, using 150 mL 200 proof ethanol mixed with 150 mL H2SO4, and 300 mL ethanol in the funnel. Vogel has a star next to this synthesis saying it is not for beginners. I don't know why, he is a liar :P. This synthesis is very easy, temperature control is easy and allows as much as 20 degrees of travel, and all you have to do is steadily drip in alcohol. The reaction isn't too violent, but it does bubble, sometimes a lot, as you drip in alcohol, so don't drip in too much at one time. The mix turned a little darker this time but still clear, and this time no fruity smell. After washing with water I knew I had ether when I saw fumes coming off like crazy when I poured it. :D

[Edited on 4-1-2005 by Mendeleev]

Organikum - 3-1-2005 at 19:13

Very good!

I remember lugh posted an article at the-hive about making ether by passing ethanol over pumice soaked with 75% H2SO4 at 130°-140°C.
It was told this setup was run by the authors for 8 days without problems.

Sounds good too.


tom haggen - 1-2-2005 at 17:58

In regards to using a copper condenser. Could this synthesis be done with just a regular glass distillation setup with out having to worry about the formation of explosive peroxides? If I store my ether should I store it with copper shavings in it?

Organikum - 1-2-2005 at 18:07


tom haggen - 1-2-2005 at 20:33

Thanks a lot man.

Caffinehog - 3-3-2005 at 21:50

Ethyl ether should be quite easy to make.
Reflux ethanol with sulfuric acid and sodium or potassium bromide. Use some kind of dean-stark trap, (or similar.) This should produce and trap bromoethane, a low boiling point liquid (37-40C.) Then react this with ethanol and a nonnucleophilic base. (Sodium carbonate, maybe?) Simple Sn2 reactions! As soon as I get some equipment, I'll try this.

sparkgap - 3-3-2005 at 22:04

That was elaborate, but IIRC, just boiling concentrated sulfuric acid and ethanol should give some ether as a product.

well, that's what the ones who posted before did. why go through all the trouble of being roundabout?

sparky (ºoº)

[Edited on 4-3-2005 by sparkgap]

Caffinehog - 3-3-2005 at 22:11

Originally posted by garage chemistDo you know which reaction happens when a ketone is heated with NaOH? Polymerization? When yes, which products form?

The aldol reaction occurs... but the aldol reaction is very reversible in the presence of acid or base. BUT: The Claisen-Schmidt product can form. This happens when the enolate forms again on the side where the second acetone molecule was added. The ketone reforms, kicking out a hydroxyl group. (a poor leaving group, but conjugation drives it foreward.) This would make 2-methylpent-2-ene-4-one. The other side could react, too. This conjugated pi system would absorb light quite nicely.

Caffinehog - 3-3-2005 at 22:16

Originally posted by sparkgap
That was elaborate, but IIRC, just boiling concentrated sulfuric acid and ethanol should give some ether as a product.

well, that's what the ones who posted before did. why go through all the trouble of being roundabout?

sparky (ºoº)

[Edited on 4-3-2005 by sparkgap]

Bromine is a much better nucleophile than ethanol's oxygen. This should occur at more manageable temperatures. It's also a better leaving group. Iodide might even be better! The second step is a bit iffy.... if only I could get my hands on some sodium metal, I could make the ethoxide, and the reaction with the bromide would definately go!

sparkgap - 3-3-2005 at 22:29

Yes, Br would be a better leaving group than OH, but I'm not exactly keen on how to handle vapors of HBr wafting above my reflux setup save connecting a bottle of bicarb on the top. What exactly would those "more mangeable temperatures" be?

Your second step? You mention Na<sub>2</sub>CO<sub>3</sub> in your first post, and Na in the second. What gives?

As to making sodium ethoxide, this thread
may be of interest.

sparky (^_^)

Caffinehog - 3-3-2005 at 23:03

WOOT! Thanks for the link!

Sodium ethoxide would be best! The carbonate was just an idea to generate the ethoxide without the risk of converting the bromide back to ethanol.

As far as HBr goes, you'll be fine. I had a whole lab full of students reacting butanol with NaBr in H2SO4, to make bromobutane, not in fume hoods, and it worked fine.
The rest should be a Williamson ether synthesis.
As far as what "more manageable temperatures" means, well, I'm not sure. But reading the actual paper Williamson wrote, it doesn't seem like it's too hot.
Link: (Warning... Written in the language of 1850!)

Note: Ethyl Iodide, boils at 78C, so making it should be even easier than the bromide... and it should work better.

[Edited on 4-3-2005 by Caffinehog]

Organikum - 4-3-2005 at 02:48

Comptes Rendus 192(22), 93-95 (1931)

The article is in french but easily to decipher, nevertheless a translation of the experimental details would be appreciated.

What I think it says: Pumice is impragnated with 65% H2SO4, put in a tube and heated to 135°C. Ethanol is vented through the tube and a mixture of ether, water and ethanol is produced, the yields are told to be good. The catalyst is stable for a long time.
(50° to 52° Baume is equal to 63-65%

Article courtesy lugh.

Attachment: ether_französisch.djvu (33kB)
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sparkgap - 5-3-2005 at 00:00

I now have something to add on the issue of leaving groups.

When ethanol and sulfuric acid is mixed and heated together, the ester ethyl hydrogensulfate is formed:

C<sub>2</sub>H<sub>5</sub>OH + H<sub>2</sub>SO<sub>4</sub> --heat--> C<sub>2</sub>H<sub>5</sub>OSO<sub>2</sub>OH + H<sub>2</sub>O

The hydrogen sulfate moiety thus introduced is quite a respectable leaving group, comparable to tosylate. Ethanol should be a good enough nucleophile to attack the sulfate ester.

That is why, IMHO, there might not be a need for halides. :D

sparky (^_^)

ordenblitz - 6-7-2005 at 20:27

Just for the fun of it… I decided to try the ether synthesis using the H2SO4 impregnated pumice method as first introduced in this thread by Organikum.

I began by crushing some pumice stone to what I thought would be a good useable size, -20+40 mesh. This seemed to be a good fit for my glass tube. I diluted some 98% H2SO4 down to the suggested 65% strength. This was then added to the pumice, until it could hold no more and became visibly wet. A small amount more pumice was added to take up excess acid. It worked out to roughly 50/50 by weight.

This was then added to a glass cloth plugged borosilicate tube to a column length of ~12 inches. Lead sheet was cut and rolled so that it made a slip over the tube.

A plate with a socket for a thermometer was fashioned to cover and contain the rolled heat sink for placement on the hotplate.

This was brought up to 140º while 100 ml ethanol (grain alcohol) was brought to boil and the transfer tube heated up so as not to convey any liquid.

An initial temperature spike was observed as the ethanol began to flow through the catalyst bed. This was cooled by misting water from a spray bottle. The temperature was held with this method between 135º and 150º. All the ethanol was allowed to react. This took ~1 hour.

The product this obtained was distilled for a total of .86 grams of the fraction coming over at 36º-38º

I set up the same system again but this time used 98% H2SO4 instead of the 65% as suggested. The final product was again distilled and the fraction coming over at 36º-38 weighed 15.45 grams. Obviously a much better yield. One note however the initial temp spike as the etoh first entered the tube was far greater. It was difficult to control the heat spraying copious amounts of water mist. You can see the difference in the tubes after the runs. The lighter one is the 65%

TubeAfter.JPG - 9kB

flyingbanana - 17-7-2005 at 12:20

The concentrated, hot sulfuric acid burned my stir bar! It is black now =\
My only comment is if you try this synthesis, invest in some dry ice or something because I lost almost half yield from evaporation.

S.C. Wack - 17-7-2005 at 20:13

Here is a JACS article where Et2O or ethylene (depending on whether the temp is 250 or 350) is made by dropping EtOH on hot alumina, for the H2SO4-challenged.

Remembered seeing it while I was looking at something else in the same issue, so I got it at the library today after the above posts jarred my memory. Mentioned in another thread that the hundred or so library computers do not allow the Adobe email function to work, nor the save to CD or zip drive. Apparently someone (not me) did find a way to make the computers save, because now all of the CD and zip drives have been removed.

Attachment: 46_390_1924.pdf (882kB)
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Magpie - 14-4-2006 at 16:42

This is an old thread and I haven't anything new to contribute. But I made some ether today using the old school method of dehydration of ethanol with sulfuric acid at 140-145C, and thought it might be of interest to some.

I didn't have a proper dropping funnel so jury-rigged a 6mm glass tube to the bottom of a 125mL sep funnel using a piece of 3/8"OD Tygon tube as a sleeve.

My ethanol was 96% made from cheap vodka and the H2SO4 was 86%, Rooto brand. First, 46mL of Rooto acid was added to 94mL of alcohol in 5mL increments with cooling in a 500mL 3-neck RBF.

The RBF was then equipped with thermometer, dropping funnel, and ice-water cooled condenser. Receiving flask was also in ice/water. (See picture attached) . The RBF was then brought up to and maintained at 140-145C.

I found this synthesis a little hairy in that even though I added the 104mL of additional alcohol very slowly, it immediately flashed causing violent eruptions. I was never quite sure something wasn't going to break and was glad to have 2 panes of tempered glass between me and the apparatus.

After some time I was able to add all of the alcohol. Crude distillate looks like about 125mL. I'll redistill later and report the final yield.

[Edited on 15-4-2006 by Magpie]

ether production.JPG - 564kB

Magpie - 19-4-2006 at 21:09

I cleaned up the crude ether distillate using the procedure in Vogel's 3rd edition. Final distillate was 40 mL, or 0.38 moles. Since I started with 3.15 moles of ethanol the yield is

% yield = [(2)0.38/3.15]100% = 24%.

I don't think the purity is all that great as the boiling point ranged from 36-41C. But it looks, smells, and acts like ether.

I made up some fresh 10% KI and tested for peroxides in the distillate and the pot residue. Both tested negative. I added 1000 ppm BHT to prevent peroxide formation and stored it in the freezer, double contained.

Having ether around makes me uneasy. I had the crude ether in a 250mL erlenmeyer flask over CaCl2 to remove water and alcohol. Since I didn't have a cork of the right size I used a rubber stopper even though I knew it would likely swell. When I got around to removing it 2 days later it had swollen quite a bit and was a little tough to remove. If it had swollen enough I imagine it could have broken the flask. Then I would have an ether spill in the catch pan of my hood. This would have evaporated, flowed down to the floor and in a worse case scenario traveled across the room to my gas hot water heater. :o

worst case scenario wanted?

stoichiometric_steve - 21-4-2006 at 06:04

i know this is off topic, but it might be a good illustration of how something can go incredibly wrong if no planning is done in advance.

during a 2mol run of my famous "steve reduction", i used a funnel to add borohydride in portions, which clogged up from time to time. a glass rod unclogged the funnel nicely, but this very glass rod was used before to unclog another funnel from the nitropropene substrate, of which some tiny remainder stuck to the glass rod. now imagine borohydride touch dry substrate without solvent in between - first, there was a little glow where the substrate was (massive amounts of hydrogen were evolved from the flask the borohydride was added to), i got so scared i blew some air at the glow and WHOOSH the whole rod started to light up and burn! nothing bad happened, tho. this was my lesson in hydride reagents....

Boomer - 21-4-2006 at 07:11

Now that the thread is alive again... a riddle for you all:

Does anyone know how much of what is in the starter fluid? It says "contains diethyl ether, n- pentane and propane/butane propellant.
Spraying in a bottle, then distilling on a 50C water bath only gave 10% of volume in ether. Even boiling at 107C (saltwater) half of the
liquid remained, and stopped bubbling. Ether smell mostly gone though.

It *does* evaporate in the open, but leaves a residue. I assume there's *some* oil in it to lubricate the motor, but what are those
nearly 50% which boil much too high for ether or pentane?

Fleaker - 21-4-2006 at 10:49

It contains pentane? How then do you get an efficient separation between the pentane and the ether then if ether's boiling point is 34.6 and pentane's is 36.1*C? I can tell you if you sprayed in a bottle and distilled haphazardly on a 50*C water bath, you probably have ether and pentane in there.