Sciencemadness Discussion Board - replacement of diethyl ether

replacement of diethyl ether

pbmineral - 11-8-2007 at 14:18

Hi,
Today in France & quite everywhere it's difficult to get diethyl ether from suppliers.
I just wondered if others sovents could be used.

What I used to do with ether was extraction of amines from aqueous solutions.

I have THF at home but it's not suitable to extract amines from water because of it's high solubility in water ?

Some people told me I could use MTBE (if anyone uses it please let me know) but also DCM (methylene chloride)
or ethyl acetate.

What to use to extract amines ?

jon - 11-8-2007 at 15:47

mbte, or isopropyl ether depending on the amine, toulene, xylene, benzene to name a few dcm will work, also chloroform if the solution is'nt made basic with NaOH due to dichlorocarbene formation. ethylacetate will work it will have to be dried because it pulls water. i've even used isopropanol this was handy you can saturate the solution with table salt and the isopropanol will come out as a separate phase and relatively dry too.

Sergei_Eisenstein - 11-8-2007 at 16:19

I thought that diisopropyl ether formed peroxides rather easily, so take the necessary precautions when using it. Though I don't think you'll be able to get it if you can't get your hands on diethyl ether.

pantone159 - 11-8-2007 at 17:32

According to Williamson, Macroscale and Microscale Organic Experiments, 2nd ed, MTBE is an excellent replacement for diethyl ether for extractions, and they specify it for most workups. It is considerably less peroxide prone than Et2O, and less volatile also so overall much less fire hazard. Not necessarily easier to get.

smuv - 11-8-2007 at 20:53

I usually obtain my ether through fractional distillation of engine starting fluid. Some brands contain >50% ether (mixed with propellents lubricants and usually heptane). The separation is quite easy, and for quantities less than a liter, it is fairly practical.

For said extraction though, starting fluid on its own, without distillation should be acceptable.

stoichiometric_steve - 11-8-2007 at 23:21

MTBE is the thing you want if you can get it cheap (it is produced in large quantities as a fuel additive).

otherwise, i have always used toluene due to its excellent properties for extraction. MTBE is partially water-miscible and you will thus always have losses.

bio2 - 12-8-2007 at 20:27

Hexanes or 30-60deg petroleum ether make a good low boiling substitutes for Et2O.

It takes a larger amount than benzene or toluene or
aromatics in general.

Klute - 13-8-2007 at 11:39

At work we generally use pentane (bp ~30) instead of hexanes as thoses are considered more dangerous.. I'm not sure how bad hexanes are compared to hydrocarbons in general though.
But pentane's volatility is somethimes a real pain in the ass, for colum chromatography for example.
DCM and Ethyl Acetate are my favourites.

bio2 - 13-8-2007 at 11:52

The standard industrial grade Hexanes are referred to as 3 deg because the boiling range is 68-71 degrees IIRC. It's
a good trade off between ease of removal by evaporation
and vapor pressure.

In a warm climate pentane is as bad as Et2O, vapor pressure
wise, making it difficult to use especially in a separatory funnel.

MTBE can be had from distilling unleaded gas which is up to 20%

[Edited on by bio2]

Methyl.Magic - 21-8-2007 at 12:00

oula !

Le MTBE je ne pense pas que tu en trouveras si tu ne trouve deja pas d'ether !!!

Si ta besoin de prod pour les extract, je te conseille l'essence F qu'on achete chez monsieur Bricolage. Certes c'est pas du pur pur mais ca va tres bien !

Si t'as du DCM ou du chloroform alors vas-y ! par contre fais gaffe, c'est narcotique ! Sinon le toluene, le naphte, xylene, hexane, acetate d'ethyle ou de butyle, etc...

dedalus - 22-8-2007 at 03:45

I've frequently used DCM instead of diethyl ether, which I hate a lot because it ignites if you look at it wrong.

It does have a tendency to form emulsions, more so than ether, in my experience. But it's more polar than toluene, if you're doing amine chemistry that might be a consideration.

basement - 8-7-2018 at 00:30

I'm sorry to dig this thread out but it's kind of related and I don't want to open a new thread for this small question.

A warming hello to ya all first as this seems to be my first post on this forum.

So my question is regarding ethers, especially THF and Et2O. What I know so far is that THF is miscible with water (which Et2O is not) and that Et2O has a higher vapor pressure thus lower boiling point. In which cases can Et2O be replaced by THF and in which not? Right now I'm thinking particularly about Grignard reactions.

Thank you, this forum is an enormous help!

unionised - 8-7-2018 at 02:23

If my memory serves me correctly, THF is often a better solvent for making grignard reagents than diethyl ether.
It does a better job of complexing the magnesium ion.

basement - 8-7-2018 at 03:07

That's what I read too. That's why I was wondering if there is a case or a thing you need to watch out for when replacing it with THF (which is just cheaper for me to acquire, but is it easier/safer/better to work with in your experience? First time grignard here^^)

[Edited on 8-7-2018 by basement]

neddy17 - 8-7-2018 at 09:03

Depending on the scale at which you are attempting your Grignard the exotherm of formation could give you problems. You'd definitely want a condenser if using Et2O. As said above, the coordinative ability of THF helps the formation/solubilization of the reagent, but that shouldn't be a big problem if it is your first time anyway.

wildfyr - 9-7-2018 at 05:10

Methyl THF is an interesting replacement. Its a bit expensive, but unreactive and bio-sourced so its a little easier on the environment. It is immiscible with water.

basement - 9-7-2018 at 05:16

I really do care about the environment, however 2-Methyl-THF is no option for me in this scenario.
You confirmed my thoughts about THF usage, thanks guys for your time!

Dr.Bob - 10-7-2018 at 10:57

THF works pretty well in most cases, and using salt (brine) can lower its solubility in water. A mix of THF and hexanes also works somewhat. MTBE would be great, but not used now as much since the state of California knows it to cause cancer (as does coffee, french fries, and almost everything on earth).

basement - 11-7-2018 at 06:15

Who would drink MTBE? Sometimes laws and regulation make unreasonable decissions.. MTBE is a great alternative imho.

Thanks to further confirm the usage of THF

Melgar - 20-7-2018 at 07:45

Quote: Originally posted by Dr.Bob

THF works pretty well in most cases, and using salt (brine) can lower its solubility in water. A mix of THF and hexanes also works somewhat. MTBE would be great, but not used now as much since the state of California knows it to cause cancer (as does coffee, french fries, and almost everything on earth).

I love how California specifically exempts all chemicals that occur naturally in food from this requirement. In essence, they turn a blind eye to anything that doesn't confirm their ideological biases, and require labeling for anything that gives rats cancer when they eat and breathe nothing but that. I think we'd all be better off if those labels were just changed to "warning: consuming too much of just about any chemical will have a good chance of giving you cancer."

I bet I could sell aflatoxin-laced kombucha in a California farmer's market, labeled as "all-natural", and their state regulatory boards wouldn't bat an eye.

happyfooddance - 20-7-2018 at 09:30

Quote: Originally posted by Melgar

I bet I could sell aflatoxin-laced kombucha in a California farmer's market, labeled as "all-natural", and their state regulatory boards wouldn't bat an eye.

I doubt your lab/kitchen/whatever would come close to meeting the standards for producing anything, least of all kombucha, that could be sold in a California farmer's market.

But I get your point.

Melgar - 20-7-2018 at 09:40

Quote: Originally posted by happyfooddance

I doubt your lab/kitchen/whatever would come close to meeting the standards for producing anything, least of all kombucha, that could be sold in a California farmer's market.

But I get your point.

Heh. While it's true that I just threw that out as an example to make a point, I always thought kombucha was made in hippies' basements. Am I not sufficiently in agreement with hippie philosophy to produce and sell it?

happyfooddance - 20-7-2018 at 11:02

Quote: Originally posted by Melgar

I bet you could make great kombucha, and could sell it to your hippie friends, too; just not at a farmer's market in Ca... As much of a hippie item kombucha is, an inspector is going to want to see that you keep everything sterile, have your cultures perfectly isolated, have hepa filters on your aerator, etc... Not that that is impossible or even difficult for someone skilled as yourself... But man, that is a lot of work. The biggest disqualifier would be that mixing a lab space and a food preparation space is a huge no-no... Having say, half a gram of a mercury salt in a locked cabinet in the same building will get your operation shut down.

But yeah, diethyl ether...