Sciencemadness Discussion Board - diethyl ether

diethyl ether

brew - 24-5-2008 at 21:00

I have checked out numerous procedures to make this compound, and found one that stated quiet clearly, that denatured ethanol(methylated spirits) could be used. I decided instead to distill methylated spirits and collect gaseous products(methanol) in the range between 60 - 75 deg celcius, where only about 10 or so ml came over in the period of a good 2 hours. Total pot contained 500ml.
Rather than go ahead with the reaction, I decided to test the addition of 98% sulphuric acid to 50ml of distillate and slowly - cautiously- added 10ml of the sulphuric acid. The solution slowly turned redish brown and evolved a fair bit of heat.
I have found various procedures for the preparation of diethyl ether, but none of them described the colour of the pot when sulphuric acid is added to ethanol. I am relatively new at practical chemistry and was surprised by the color change. I understand the mechanism of the reaction and have a good clear preparation etc, but thought I should discuss the color change and question whether it could of been brought about by the use of methylated spirits and perhaps some sort of additive that I have not removed by my initial distillation. Perhaps the color change is what just actually occurs in this reaction - any thoughts, or answers to my questioning would be appreciated.

woelen - 25-5-2008 at 03:48

The color change even occurs with pure ethanol. It seems that there is a side reaction, in which sulphuric acid dehydrates the ethanol and subsequently some polymeric compound is formed. Many times, such polymeric compounds are brown or black and in very low concentrations they tend to be yellow, orange, red.

I have similar results with acetone.

brew - 25-5-2008 at 12:58

Thanks. I just want to be careful with things and when something unexepected occurs I want to know what is happening.

bmc

Klute - 25-5-2008 at 13:07

the pot will end up BLACK after heating anyway.. i your sulfuric acid clear, or colored? In any case I don't think this can cause a problem for the recation your product will be distuille doff in any case, and you should fractionnate it afetr washing and drying. All the junk will stay in the initial pot.

I suppose you have read Len1's excellent piece of work on the subject in prepublication?

evil_lurker - 25-5-2008 at 13:18

One other thing, since your product is methylated spirits, your looking at anywhere from 6-50% by weight methanol.

That means your going to get a bend of dimethyl, methyl ethyl, and ethyl ethers. The problem with this is methyl ether has a boiling point of like 9 degrees, methyl ethyl somewhere in between that and ethyl ether.

Yields are going to suck unless you have one hell of a chiller.

Jor - 25-5-2008 at 13:24

Are you sure methylated spirit is that much methanol?
I have a 2.5L ethanol from Fisher, and the label says:

Methylated spirit industrial , 99% v/v , (74 O.P, alcohol content about 99%), pure

Seems like 99% ethanol to me. Or does the 99% actually mean alcohol as both ethanol and methanol? If yes, what does the O.P mean?

woelen - 25-5-2008 at 13:45

Usually, 99% is indeed the sum of both alcohols, but I do not expect more than a few percent of methanol in the methylated spirit. I think it is exaggerated to say that this can contain up to 50% of methanol.

DJF90 - 25-5-2008 at 14:00

I agree with woelen. In the UK...

"in the case of industrial methylated spirits, with every 95 parts by volume of spirits there shall be mixed 5 parts by volume of wood naphtha.

in the case of mineralised methylated spirits, with every 90 parts by volume of spirits there shall be mixed 9.5 parts by volume of wood naphtha and 0.5 parts by volume of crude pyridine, and to the resulting mixture there shall be added mineral naphtha (petroleum oil) in the proportion 7.5 litres to every 2,000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion 3.0 grammes to every 2,000 litres of the mixture."

...according to a government website. Wood naptha is an alternative name for methanol. It goes on to say...

"Water may be mixed with spirits before methylation or with methylated spirits, but the quantity of water added must not reduce the proportion or quantity of denaturants in the resulting mixture below the proportions or quantities given above for the appropriate class of methylated spirits."

This implies that a simple distillation may not yeild absolute ethanol, even with an efficient column, as any water present will produce an azeotrope. However methylated spirits is a cheap and easily accessible source of ethanol.

brew - 25-5-2008 at 14:34

Quote:

Originally posted by Klute
the pot will end up BLACK after heating anyway.. i your sulfuric acid clear, or colored? In any case I don't think this can cause a problem for the recation your product will be distuille doff in any case, and you should fractionnate it afetr washing and drying. All the junk will stay in the initial pot.

I suppose you have read Len1's excellent piece of work on the subject in prepublication?

The sulfuric acid is clear and no I had not looked at the prepublication work done by Len 1. I have now and I am pleased you pointed this out. Thanks.

pantone159 - 25-5-2008 at 14:51

Quote:

Originally posted by woelen
I think it is exaggerated to say that this can contain up to 50% of methanol.

I think it may depend. I have some OTC 'Denatured alcohol' that according to the MSDS is 65-75% MeOH. This doesn't really claim to approximate ethanol though.

not_important - 25-5-2008 at 20:59

what the labeling means will depend where you are, but for the UK:

methylated_spirits_UK.png - 17kB

MagicJigPipe - 25-5-2008 at 23:58

Don't buy OTC denatured alcohol. In most major cities there will be someone that supplies solvents. There is a solvent called "Synasol, Anhydrous" which (most of the time) consists of 95% EtOH and 5% MeOH, IPA or some other denaturant (most of the time it's MeOH). That is the minimum allowable denaturant percentage (for MeOH) that is allowed while avoiding the liquor tax.

It's VERY cheap, too. Cheaper than buying it at the hardware store, that's for sure.

evil_lurker - 26-5-2008 at 13:42

Honestly, who the heck wants to use a product laced with methanol, MIBK, and gasoline in it as a feedstock for high purity ether production?

Its fucking ridiculous how hard it is to get pure alcohol in the USA at a decent price... the closest OTC thing to pure EtOH is Everclear and that costs $85-90 a gallon which is bullshit IMO... IIRC almost $50 of that is taxes.

JohnWW - 26-5-2008 at 14:50

Denatured alcohol here in New Zealand is called "methylated spirits", $old in supermarkets and hardware stores, avoiding the large excise duty on pure ethanol (which could be used as booze). It has a blue dye, which I presume is methyl violet, but the labels on the 1L and 5L plastic bottles that it comes in do not say what the denaturants in it are. I will have to write to the chemical firms that produce it to find out. Ethanol is made here by fermentation and distillation of sugar (sucrose), whey (lactose), and wheat (starches); and methanol is mostly made from the methane in natural gas in the Fischer-Tropsh process either for export or subsequent catalytic processing into synthetic gasoline (and can also be made by destructive distillation of wood waste or straw).

brew - 26-5-2008 at 19:48

Quote:

Originally posted by evil_lurker
Honestly, who the heck wants to use a product laced with methanol, MIBK, and gasoline in it as a feedstock for high purity ether production?

Its fucking ridiculous how hard it is to get pure alcohol in the USA at a decent price... the closest OTC thing to pure EtOH is Everclear and that costs $85-90 a gallon which is bullshit IMO... IIRC almost $50 of that is taxes.

I dare say you have exhaused all avenues for a cheap 100% but just in case you or another, haven't thought of this, I'd at least mention it. French polishing requires this product and do not require great amounts. In AUS this product at 4L (aqua label methylated spirits 1000mL/L 100% ethanol) can be obtained, but not easily, as most places do not stock- nor do they advertise for obvious reasons. It is around $20 for 4L. I chose to do the diethyl preparation not because I cant obtain pure EtH but because the usual methylated spirits is a lot cheaper.

MagicJigPipe - 26-5-2008 at 20:46

So, making Et2O via "methylated spirits" (for some reason I have never seen it called that before) is cheaper than just buying or distilling Et2O (EtH is ethane, BTW) in your area? That's crazy.

There is a source (in the US) of 80% Et2O (with the other 20% being propane, butane and carbon dioxide and a viscous oil, all of which are much more easily removed than heptane or hexane). In fact, this product can sometimes just be used as is. Noone ever seems to be interested in it's existence, though. I mean, you don't even have to fractionate this stuff, just distill and you're done.

I hope I'll never have to use the H2SO4 + EtOH method because it seems like a royal pain in the ass. Good luck, though.

brew - 26-5-2008 at 21:33

I haven't given it a thorough search to obtain Et2O but it doesn't seem to be common OTC in AUS. As I stated, I am learning practical chem so I thought preparing this compound is a good start. I have just begun simple distillation and have not yet ventured to using a fractional column. You got to start somewhere ha!

bmc

woelen - 26-5-2008 at 22:57

If you want to obtain some practical experience with chemistry, then making diethyl ether is not the thing to start with for the following reasons:
1) The reaction, making the stuff, is not clean at all. There are many side-reactions.
2) Diethyl ether has a very low boiling point. You need really good cooling, plain tap water at room temperature may be insufficient.
3) Diethyl ether is EXTREMELY flammable. If you don't have practical experience, then there is a big chance of getting a major accident. A simple electrostatic spark may cause a big explosion and subsequent fire. You need to take very good safety measures when dealing with this highly volatile and flammable compound.

If you want to get experience and you also want to make some useful reagents, then you could try to make nice colorless pure HCl from OTC muriatic acid, or from table salt and dilute sulphuric acid. Another nice thing to do is making pure aqueous ammonia at a decent concentration from NaOH and ammonium sulfate fertilizer (or ammonium nitrate, or ammonium chloride). Both of these can be done nicely with a distillation setup. In the case of ammonia, you put some water in the collector flask.

brew - 27-5-2008 at 01:02

Thanks woelen, When I say I am learning prac chem, I do have a year worth of a Diploma level lab tech course and from that I am really safety conscious. I am currently an undergraduate in Biomedical Science but lack distallation experience. I have understood your post and will be mindful and not be in too much of a hurry in this area. So far I have made a shit load of salts via reactions including electrolysis. My initial distillation was ethanol I prepared from yeast and sugar which fermented, which went well. I didn't get as much as I thought and will look at improved yields. I did do the ether prep and placed the reciever flask in ice water that included salt which brought the temp down enough. I have a good column but need another stand and do not want to make things do as I do see the importance of being set up right. Getting the distillation glassware was a buz and I suppose Ive been in abit of a hurry to try these things out. I love doing this stuff. It is insanely good. I will also do your suggestion of concentrating ammonia in di water.

bmc

Maya - 10-6-2008 at 03:29

I'm pretty sure when I made Et2O you had to add the EtOH to the conc sulphuric acid @ 125 C and not the acid to the EtOH

Also you need many long distillation columns filled with ice cold water

much easier to get it in other ways, and yes, colored products in the rxn flask are inevitable

undead_alchemist - 11-6-2008 at 00:46

Pure EtOH is even harder to find here in Canada,
Have yet to find any place that sells it.
Most of what you can get is only 40%, and that is over priced
Even the Lab Suppliers don't have it, well at least listed in their catalogs.

It costs me less to buy ether then to make it.
$195 for 18L Lab Grade.
Well helps to be able to buy though my work too.

MagicJigPipe - 12-6-2008 at 09:47

Quote:

dare say you have exhaused all avenues for a cheap 100% but just in case you or another, haven't thought of this, I'd at least mention it. French polishing requires this product and do not require great amounts. In AUS this product at 4L (aqua label methylated spirits 1000mL/L 100% ethanol) can be obtained, but not easily, as most places do not stock- nor do they advertise for obvious reasons. It is around $20 for 4L. I chose to do the diethyl preparation not because I cant obtain pure EtH but because the usual methylated spirits is a lot cheaper.

If Australia's liquor laws are in any way similar to the US's then this cannot be "100% pure EtOH". It wouldn't be called "methylated spirits" if it were just EtOH. Also, if it says "100% ethanol" that usually does not mean pure ethanol. They mean it is anhydrous but still contains MeOH or some other denaturant. I know this for a fact as the EtOH I buy claims to be "100% EtOH, Anhydrous". At best this is misleading and at worst a flat-out lie. It should say, "95% EtOH, 5% MeOH, Anhydrous".

ALMOST NOTHING that is pure EtOH can be sold without a liquor tax. There are VERY FEW exceptions and those can only be had by pharmaceutical companies, some industry and some specialized labs. There will certainly not be any pure EtOH sold to individuals without a high liquor tax (at least in the US).

In fact, I did some research a while back on the subject and apparently the ONLY way even pharm companies can buy it tax free is when they use it in medicine. For some reason they still use denatured for synthesis. The conclusion I drew from that is that the govt. is so restrictive that the ONLY way they allow EtOH to be untaxed is if it shows up in a drug end product. Another reason could be that denatured is cheaper and most syntheses will not be hurt by 5% MeOH.

Either way it's bullshit, IMO. These laws date back at least a hundred years and are out of date, IMO.

Although I'm sure a decent chunk of our govt's money comes from taxation of liquor. It's a double edged sword. Perhaps... Nevermind, don't want to get into that!

Siddy - 12-6-2008 at 17:20

Thats true MagicJigPipe, even people in industry, such as cleaners pay over $80USD for anhydrous EtOH -its only labs that get it for $2/L, and yes sometimes even labs will used denatured just so there lab report has one less potential drug listed that week.

I don't have any issues with the high taxes, in countries like USA, AUS etc where drinking is so big, the govt makes a lot of money which means they don't need to tax other things so much - works out for the non-drinker (or atleast non-alcoholic). Although it doesn't stop the govt from becoming greedy and just taxing everything like crazy...

Just thought id add, a lot of "methylated spirits" no longer contain methanol, they use less toxic (but worst tasting) denaturing agents, such as acetates. These usually cost a dollar or 2 more than the methanol ones. 2 out of 3 local brands have done this where i live.

Brew, i think you can make it out of Ethylene glycol, found in car coolant (antifreeze), but EtOH is the easiest. Also, i doubt its illegal for you to import 10 odd bottles of Methylated spirits.

[Edited on 12-6-2008 by Siddy]

brew - 13-6-2008 at 16:18

I was somewhat shocked to find this product and was told that it is free of methanol or other denaturants, as the process of shellacking requires 100% purity. I showed the person my Uni card -photo Id, and said I am doing various experiments at home associated with my degree, and need to know whether they felt confident with this 100% purity status of this product and do they have total confidence with the producers claim etc. Once again they stated that they did. I am not drinking the stuff, nor am I breathing in its fumes and at this stage have not needed ethanol at such purity. I stumbled upon this outlet, that mainly deals with tradesman and did so as I was looking to buy toluene. I have never seen this aqua labeled methylated spirits before, nor have I seen it in other shops. It is quite a well known brand name in Aus. I will check its b.p. My scales are not good enough to distinguish between ethanol and methanol if this is the case- specific gravity etc. I will also contact the producers and state that one of my shellacking buddies has said that it does contain a denaturing compound etc, and see what they say. I am interested now that you have questioned this. I will post what I find.

evil_lurker - 13-6-2008 at 16:41

Get some sugar, 48hour turbo yeast, and build yourself one of these:

Then stick a column on top of it and a reflux dildo:

Presto cadabra, 90% pure EtOH after 2 distillations. Run the EtOH again thru a column with molecular sieves, then redistill... there is your EtOH... not that much work (just a lot of babysitting) and still less than $25 per gallon.

Formatik - 13-6-2008 at 17:37

How long do you ferment your mixture, evil_lurker? I've left a sugar and yeast mixture to sit for over 1 week, is that too much?

evil_lurker - 13-6-2008 at 19:42

With turbos, 3 or 4 days tops... they are usually done by then. Personally I ferment about 30-32lbs of sugar in one lick with a total volume of 15 gallons at a time using two packs of turbo. Not supposed to do this but it works. It helps immensly to put a mag stirrer under the fermenter and a fan blowing on the outside as a lot of heat is generated by the yeast.

Another equally effective method is to run a partial corn/sugar wash. Over on homedistiller.org they have a method called UJSM (Uncle Jesse's Simple Mash) which basically the corn provides the nutrients for the yeast and a bit of flavor while sugar is used for the alcohol production. Unfortunately most of the corn is not used due to the starches not being converted so to counter that if one were to convert the starches using enzymes, say maybe 10lbs worth of cracked grain and 20lbs of sugar per 15 gallons, it should be possible to do a whole batch very little cash as the corn would provide the vast majority of nutrients for the yeast... one could just use plain old distillers yeast (500g for $15) and just add a little bit of DAP in there for energy and phosphates.

Yeast will not ferment a plain old sugar water mixture as there are no nutrients. Bakers yeast will also not ferment to more than 8-10% alcohol content before crapping out. One must also adjust the initial specific gravity below about 1.10 otherwise the yeast will die from osmotic pressure in tiny little explosions.

There is a whole lot to alcohol production, but once one gets the gist of things its not to difficult. I've pretty much gotten things worked out, just don't have a very good reflux column... once you get into the 90%+ range EtOH is very hard to fractionate to the azeotrope since the alcohol content in the pot is constantly dropping and the reflux ratio must constantly be increased.

Formatik - 14-6-2008 at 21:02

Thanks for the response. I had used a mixture of 25 g sugar and 25 g Brewer's yeast in 250 mL H2O, and let it sit in a jar (not airtight) for over 1 week. I then later attempted to distill at 80 deg. and didn't get any EtOH. So, nutrients is what it was missing then. It looks like 90%+ alcohol still will likley not work for anhydrous ether (at least not directly especially if ether is volatile with water vapors), but I guess there you have to ask yourself if water or the other contaminants are more preferable.

[Edited on 14-6-2008 by Schockwave]

evil_lurker - 15-6-2008 at 13:40

Keep in mind that the conversion of sugar to EtOH is only 42% or effective at best... the rest goes out as CO2.

If you want ether, you reallyneed 98% sulfuric and 96%+ EtOH. Mix 50-50 by volume to approx 1/2 the volume of the reaction flask. Be sure to mix sloooowly due to heat formation... if your not careful the mixing alone with form some Et2O. Once its mixed continue heating. Et2O will start to come off when the EtOH/H2SO4 mixture hits around 115ºC since your dealing with very dry reagents to begin with. At that point start adding in more EtOH.

The trick is to use a packed hempel columm at least 300mm (preferably a little bit longer), magnetic stirrer, and add in the EtOH at a rate where the top of the column stays warm (around the boiling point of ether).

What'll happen is most of the unreacted EtOH will reflux back down into the flask where it gets dehydrated, while the Et2O vapors will come right on over due to Et2O's high partial vapor pressure.

The procedure scales up nicely with multi-liter quantities possible provided the apparatus is large enough and sufficiant cooling is available.

Its really a good procedure, even for a beginner IMO as long as the vapors are contained.

Picric-A - 20-7-2008 at 13:19

as a source of EtOH i buy surgical spirits wich is available readily where i live.
It costs about £4 a litre though but the label says 89%EtOH and the rest is bits ad bobbs like glycerine menthol ect... they are not allowed to sell it to under 18's wich is a good thing.
most of all my tests suggest no methanol- perfect for distilling nearly pure EtOH

497 - 29-3-2009 at 18:47

I have recently found that diethyl ether is highly soluble in concentrated hydrochloric acid. According to this up to 150ml ether per 100ml of cold 32% HCl. It so happens that I was just contemplating the cheap/easy purification of OTC starting fluid..

Why couldn't you simply mix the starting fluid (~30% ether in heptane) with cold hardware store muriatic acid to extract most of the ether? Then pour off the heptane. To get the ether out of the the acid, you could warm it, dilute it, and/or neutralize it. This method seems to be much easier that fractional distillation.. and it should give a product free of heptane?

HydroCarbon - 29-3-2009 at 20:12

On the note of ethanol distillation: this experiment walkthrough may be helpful. It has a nice standard curve of density vs. mass% ethanol, which can be helpful in determining the concentration of your product (assuming little to no contamination).

http://www.cerlabs.com/experiments/10875407404.pdf

We did this in my organic lab for school not too long ago and got to 87.5% ethanol by mass easily.

If you need the ethanol you could always make it according to that method in small batches with standard lab equipment. I'm sure there are countless substitutes for the energy/nutrient requirement other than disodium hydrogen phosphate, if you cant obtain that. Carbon filtration will also be necessary as our product had a yeasty aroma, indicating some volatile contamination from the yeast.

As evil_lurker already noted you probably want as pure ethanol as you can get for this reaction due to the fact you make 3 different ethers with a me/etOh mixture.

You may already know, but don't let the ether sit around for too long. I'm not sure if these warnings are over stated or not; but ethers can auto-oxidize in air to form explosive shock sensitive hydroperoxides. This also goes with warning about the extreme flammability and volatility of ether. When using ether even at room temperature you can see vapors mixing in air when pouring. These could easily be set off by a spark from a nearby electrical device such as a hot plate.

starman - 20-4-2009 at 23:55

Quote: Originally posted by 497

I have recently found that diethyl ether is highly soluble in concentrated hydrochloric acid. According to this up to 150ml ether per 100ml of cold 32% HCl. It so happens that I was just contemplating the cheap/easy purification of OTC starting fluid..

Why couldn't you simply mix the starting fluid (~30% ether in heptane) with cold hardware store muriatic acid to extract most of the ether? Then pour off the heptane. To get the ether out of the the acid, you could warm it, dilute it, and/or neutralize it. This method seems to be much easier that fractional distillation.. and it should give a product free of heptane?

497 all I could get from that reference was useless 'snippet views'.
Did you go ahead and test your theroy?I would be interested in results.

not_important - 21-4-2009 at 06:40

The source, Seidal's Solubilities, is public domain and can be downloaded from the Internet Archives.

Note that 20% hydrochloric acid is nearly the constant boiling composition, the highest boiling point mixture. Anything more concentrated than that will give off HCl gas when heated. You might extract with hardware store grade 36% and add water to dilute it to 20%, then distill the Et2O out of that, and finish by distilling the 20.2% acid for lab use.

peach - 28-8-2010 at 03:34

I've been trolling through the old ether posts for some inspiration and information on the finer details.

D9 is correct that, in the UK, there is a very specific set of rules regarding the composition of methylated spirits.

Quote:

Completely denatured alcohol must be made in accordance with the following formulation: with every 90 parts by volume of alcohol mix 9.5 parts by volume of wood naphtha or a substitute for wood naphtha and 0.5 parts by volume of crude pyridine, and to the resulting mixture add mineral naphtha (petroleum oil) in the proportion of 3.75 litres to every 1000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion of 1.5 grams to every 1000 litres of the mixture.

Lurker, I absolutely loved your brew it at home attitude and method, particularly the reflux dildo and keg. I also love the fact you're using turbo. If anyone is ever planning to do some brewing for distillation, forget the wine shops and supermarket, buy a pack of distillers turbo (partyman.se sells it online). No questions askable, it's incredible. Massive alcohol yield by comparison and it runs so fast it looks like it's going to kill it's self within a day or two.

I have a 10l flask of it brewing now. I could just buy alcohol off the shelf, but that's no fun. I find it really interesting, the idea of going from sugar and yeast to glassware synthesis.

The water / ethanol azeotrope breaks somewhere around 75mBar I believe, meaning you can yield 100% pure alcohol under vacuum.

I certainly don't want any explosive rubbish forming when I'm doing it. I think I may piranha bang all of the glass with 35% H2O2 first, and I have about a kilo of hydroquinone lying around, waiting for a job, which (from my quick read thus far) would do well for the hot flask in terms of keeping it unexploded.

[Edited on 28-8-2010 by peach]