Sciencemadness Discussion Board - Diethyl Ether - Illustrated Practical Guide

Diethyl Ether - Illustrated Practical Guide

len1 - 4-1-2008 at 18:25

This is a series of Illustrated Key Syntheses in Chemistry which I intend to post, with the purposes and guidelines outlined in the thread of the same name in the General Chemistry section.
I shall attampt to ensure that the first post in all syntheses contains all the relevant information. If something needs to be added later on, due to comments further down the thread for instance, I shall edit the first post.

Aim

It is the aim here to present an illustrated demonstration and comparison of two simple methods for generating and purifying diethyl ether suitable for the amateur. The yield of the main product and impurities are analysed using analytical techniques and FTIR. A misconception associated with the role of sulphuric acid in ether generation is illustrated, and this should allow to increase yield.

Motivation

Ether is a key compound in organic synthesis. Arguably the first anaesthetic used, nowadays its major use is as a solvent, a fuel, in extraction and purification, and for anhydrous reactions such as Grignard synethesis. Its synthesis by H2SO4 catallytic dehydration of ethanol is described in many organic practicums, however the yields and reaction rates are rather low - the combined volume of EtOH and H2SO4 produces 1/4 the volume of ether - which brings into question its suitability as a preparative method for volumes required in the laboratory. An alternative source of ether easily accessible to the amateur takes the form of fractioning of starting fluid, whose ether content ranges from 25 - 60%. There is a paucity of data on the efficiency of this method, and the purity of the product so obtained, and this report presents a quantitative evaluation, and comparison to ether obtained via the first method, for the least favourable 25% starter fluid. Some experimentation along these lines has already been presented in this forum in the Making Diethyl Ether and Ethyl Ether Distillation and Synthesis threads. The present is an extention of these, with an improved procedure, analysis, and illustrations.

Findings

The ethanol dehydration reaction is unsteady (non-smooth), time intensive, but is cheap, and can give good yields.

Yield 74% based on theoretical and 40% based on ethanol consumption
Ethanol based yield will tend to theoretical yield for larger runs
Reaction temperature of 140C is way above b.p. of EtOH leading to bumping
Instability, hard to establish correct EtOH drip rate and steady-state conditions
Almost all H2O formed distills with ether - minimum 4 purification steps required
12% EtOH distills unreacted - requiring corresponding amounts of CaCl2 for purification
Clear FTIR spectrum of product

Fractionation of starter fluid, is quick, efficient, product purity is comparable to the above - but it is expensive

76% yield of available ether using 25% ether starting mixture
Fast, single step procedure
H2O contamination evident in FTIR spectrum due to lack of purification - irrelevant for many extractions

Theory

Et-O-Et from dehydration of EtOH

C2H5OH + HHSO4 -> C2H5HSO4 + H2O

This is an acid base reaction in which sulphuric acid forms the ester ethyl bisulphate and generates water. This reaction occurs in the cold immediately when the reagents are mixed, evolving much heat. For this reason its best to start with the reagents near freezing. This step forms the main 'overhead' wastage of alcohol in this synthesis, since the alcohol remains bound and very little ether is generated. Note that H2O is generated in this reaction in a 1:1 ratio to the H2SO4 used. Thus, contrary to what is often stated, one does not require absolute alcohol, or 98% acid for the reaction to work. The main requirement is that the combined initial reagent water should not make the initial H2SO4 concentration less than about 70%, at which point the boiling point of the mixed acid approaches the reaction temperature used in step 2 - and it will start distilling over with the products.
C2H5HSO4 + HOC2H5 -> C2H5OC2H5 + H2SO4

When excess EtOH is added to the mixture in (1) and heated to 140C ether if formed and H2SO4 regenerated - it thereby acts as a catalyst. If no excess ethanol is added, the ethyl bisulphate remains stable to about 160C when it starts eliminating H2SO4 and generating ethylene C2H4. It is therefore imperitive that this temperature is never reached during the reaction. Instead, ethanol is dripped in at the rate at which it is converted to ether - two moles for every mole of ether formed, while the composition of the reagent fluid remains esentially that of (1). The H2SO4 liberated regenerates ethyl bisulphate with the extra alcohol added.

The vapour pressure of water above 75% H2SO4 is about 0.4 atmosphere at the reaction temperature, hence it is distilled over with the ether as soon as it is formed. Its concentration in (1) does not rise substantially during the reaction - the acid acts as a catalyst not as a dehydrating agent as is often quoted. Therefore a little acid can produce quite a lot of ether - the limiting factor coming from oxidation-reduction side reactions, which remove H2SO4 from solution, and result in the contents of the reagent flask becoming tarry.

Method

All reactions were carried out at an ambient temperature of 42C

Formation of crude ether

The first stage is to carry out reaction (1). 20gms of clean sand were placed at the bottom of a 1L 3-neck flask, and 180ml of EtOH (sold as methylated spirit, about 95% EtOH) were poured in through a funnel. Next 160ml of 92% (1.81 sp) H2SO4 technical grade were measured out, and cooled, together with the EtOH, in a freezer. The H2SO4 was then poured into the flask gradually and with frequent mixing - so the mixture attained homogeneity before the next lot was added. This took about 5 mins, during which time the temperature of the mixture rose to about 60C. The flask was fitted with a high-T thermometer, which dipped right to the sand, as well as an adaptor for measuring the exiting vapour temperature and an outlet leading to a cooled-coil condenser. The vertial neck was fitted with a tube for delivering the EtOH right to the bottom of the reagent mixture, Figure 1. This is necessary as the temperature at which ether is generated is well above the bp of EtOH. If dripped onto the surface of the reaction mixture most will vapourise before reacting, introducing it below the surface affords better mixing - as evidenced by only 12% EtOH distilling unreacted in the procedure. However the generation of superheated ethanol vapour is a major source of instability, and leads to difficulty in controlling the reaction.

The receiver end is equiped with a secondary IR condenser, whose outlet dips through a delivery tube into an ice/water mixture, figure 2. The exit from the delivery tube is vented. The secondary condenser is cooled by a small submerged 2.5W motor, circulating the freezing water through its jacket. A secondary condenser is best employed to condense ether - which forms explosive mixtures with air - on hot days. Since the ambient temperature in the lab was 42C (108F) ether would be a gas, and for the same reason tap water (30C) would not be efficient at condensing ether on such a day. However a tap-water cooled condenser was used ahead of the ice-chilled stage to cool the 70C vapour from the reaction and extend the life of the ice bath.

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs1_2.JPG">

Once the equipment had equilibrated, the mixture was heated on a heating mantle to about 140C, when some gas evolution (bubbling) commenced. At this point 200ml EtOH was added to the drop-funnel and the delivery rate adjusted so the flow rate in the delivery tube was about 3mm/sec, at which rate the entire volume is added in about 2 hrs. The delivery is accompanied by some unavoidable bumping due to the superheated ethanol, this periodically shakes the reaction vessel contents, and introduces frothing, figure 3. The bumping can not be eliminated altogether, but it can be adjusted to acceptable levels by keeping the EtOH delivery rate below the above mentioned, the rate can be gauged by bubbles in the delivery tube introduced by the bumping. The temperature of the reaction bath stays at a remarkably steady 140-145C due to the thermal equilibrium introduced by the reaction - the distilling ether and water removes heat which prevents the temperature rising. The temperature of the evolved ether/H2O vapour kept at a fairly steady 60-70C. One can see the ether distilling with the water in the exit tube, figure 4.

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs3_4.JPG">

Reaction analysis

When all the EtOH had dripped into solution (~2hrs) the tap was closed and a temperature of 140C was maintained until the ether flow rate into the receiving flask had curtailed (about 10mins). At this point the appartus was cooled down. The remnants in the reagent flask are seen in figure 5. The black colour is due to oxidative side reactions producing carboneous mater, but there were no solid lumps, and the products of these reactions were more obvious by appearance than by their volume.

The reaction mixture, 240ml, was titrated with NaOH solution and found to be 69% H2SO4 by weight. This represents a loss of 20gms H2SO4 - presumably as SO2 in the oxidative reactions which produced the tar. The density of the reaction mixture was 1.48, compared to 1.46 for ethyl bisulphate and 1.58 for 69% H2SO4. Assuming a linear ethyl bisulphate/water density-concentration curve, we see that the remnant reaction mixture is mainly ethyl bisulphate, with the water present 21gms, being essentially that of the initial acid. In addition the mass concentration of H2SO4 in the initial ethyl bisulphate solution is 98/(98+46) = 68%. We thus come to the conclusion that the reagent mixture remained eseentially unchanged during the reaction except for the loss of 21gms of H2SO4 to oxidation/reduction processes.

The main drawback of this reaction is the need to renew the spent H2SO4/EtOH reaction bath, which forms a waste in the process. The present findings show that the reaction bath being mainly unchanged, is suitable for coninued use. The attrition, 21gms H2SO4 is a fraction of the 240gms H2SO4 still remaining. It is likely the bath can be used for four-fold the volume of EtOH used in the present experiment (indeed this is consistent with the finding of the inventor of the process - a little H2SO4 goes a long way). A further limiting factor is likely to be the build up of tar in the flask, hindering the reaction.

Purification, yield

Figure 6 shows the contents of the receiver flask, 210 ml single layer. The content were poured into a separation funnel, 100ml of 10% NaOH solution added, and shaken, figure 7. The aqueous layer was removed, and the process repeated. This left 182 ml ethereal product in the funnel, while the aqueous layer correspondingly gained 28ml, where the second washing gained only 3ml showing this purification was essentially complete. Ether is 10% soluble in water (presence of EtOH enhances this), and this washing removed mostly H2O (with SO2 and ethanol being minor impurities removed). This result is in accord with the fact that 200ml of EtOH (3.4mol) produce 30gms of water according to reactions (1, 2) (recall that the initial 180ml remained essentially unchanged).

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs5_6.JPG">

Next 26gms fused and crushed CaCl2 were placed in a flask, cooled, the ethereal layer poured in, and let to stand 1hr in the cold. The flask was then placed in a water bath maintained at 60C, and the fraction boiling in the range 35-39C collected, figure 8. This left the flask almost entirely dry - showing most water and ethanol have been removed by the washing and the CaCl2. The latter gained 18gms in the process, which is more than the desired maximum 40% CaCl2 : EtOH ratio, hence we conclude 50gms fused CaCl2 per 200ml crude is the appropriate ratio in this setup. The adduct can be seen in figure 9.

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs7_8.JPG">

The product was analysed on an FTIR machine (see the thread http://www.sciencemadness.org/talk/viewthread.php?tid=7993&a...) in both thick and thin film, and gave very good spectra, figure 10. The presence of traces of H2O and EtOH are evident, and this can be removed with the appropriate amount of CaCl2. The final purified product occupied 130ml (1.26mol), figure 11. The corresponding yields are as follows:

Based on 200ml (3.4mol) EtOH, 74%
Based on total EtOH 380ml (6.4mol) 40%

Clearly continuation of the reaction will get the yield closer to (1).

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs9_11.JPG">
 
<IMG src="http://www.sciencemadness.org/scipics/Len1/ether_17.JPG">

Fractionation of starting fluid

A 493ml pressurised can of starting fluid, with 25% ether, and dimethyl ether as propellant was used. Both the can and a 1L receiver flask were cooled to 0C before the contents of the can were emptied via a tube, while maintaining both containers in a freezing bath. This produced only 390ml of fluid, and it was presumed that most of the ether was lost at this stage due to its co-vapourisation with the dimethyl ether. To overcome this, the arrangement shown in figure 12 was employed. In this way 430ml were gathered - it is assumed the 493ml contents quoted on the can includes the dimethyl ether propelant.

Some boiling chips were dropped into the flask, and fractionation on an insulated hempel collumn with a hot water bath was performed, figure 13. The boiling commenced right away - but it wasnt allowed to be too rapid - a feat which can be accomplished by lowering and raising the water bath - and in about 10 mins the first drops of fluid appeared in the condenser. The fraction boiling in the range 33-39C was gathered, which took about 90mins. The volume of this fraction was 83ml, or 19% of the total liquid volume. This gives a 76% yield in the separation on the 25% total ether content quoted. Figure 14 shows a thick film spectrum for both this fraction, and that of the previous synthsis, showing that a considerable amount of water is still present in the present product, due to lack of a purification step. This can be removed with CaCl2 as before, but for many extraction processes it is acceptable.

<IMG src="http://www.sciencemadness.org/scipics/Len1/Et_figs12_14.JPG">
 
<IMG src="http://www.sciencemadness.org/scipics/Len1/ether_16.JPG">

Conclusion

Acid-catalysed ethanol dehydration is an efficient and cheap method for ether production, giving a maximum yield of about 74% based on ethanol. With the present simple arrangement it is however enherently unstable and time consuming. Fractionation of strater fluid is a much faster simpler method, it is however more expensive.

[Edited on 8-1-2008 by len1]

DeAdFX - 4-1-2008 at 20:04

hmm.. Nicely done on this topic and the chlorine topic. Keep up the good work!

organometallic - 23-3-2008 at 02:25

Yeah, really damn good work. I really enjoy your posts

smuv - 24-3-2008 at 21:09

Regarding the distillation of starting fluid:

I find it is best to use starting fluid which only uses CO2 as a propellant, I have encountered those which used isobutane and propane and noticed the ether distilled contained these dissolved gases. This could be seen by the fact that when this cold distillate was poured onto a paper towel, it fizzed on contact (like soda in a way).

Also if the starting fluid container does not have a spray nozzel tube attachment as yours does (I have never seen starting fluid sold with one) you can easily pull off the spray nozzel from the can, and attach soft plastic tubing to the the valve; and transfer in this way. I have heard of people (although I have never tried it) turning the can upside down and puncturing the bottom, releasing the compressed CO2 (in the head space above the ether) and then simply pouring the mixture out of the can.

I like your idea about chilling the can before sparying, I will try this in the future (although even spraying alone seems to cool the can quite a lot). I also can confirm similar yields, from the distillation of 6 cans of a 35% ether starting fluid I get about 650mL of ether (I collect from room temp to 35c as the forerun seems to be ether).

EDIT: When distilling ether I have noticed that connecting a tube to the vac adapter outlet and routing it out a window, makes the entire process of distilling ether nearly odor free.

[Edited on 24-3-2008 by smuv]

Sophism - 24-3-2008 at 22:20

nice work

Saerynide - 2-5-2008 at 00:33

Great read once again!!! And you own an FTIR??

len1 - 2-5-2008 at 03:17

I think yield would be higher in the procedure I outlined compared to what you did because here ether distilation is accompanied by the flux of an uncondensable gas - this will carry some ether out of the apparatus with it, also makes distillation rate harder to control.

I do not think its so safe due to the higher rate of ether loss to the environment - but if there are no hot surfaces in the vicinity (ie youre using a mantle) and no flames I think you should be alright.

The FTIR is mine - but as Ive said elsewhere on this forum, theres no reason why amatuers shouldnt have one these days, they can be bought for several hundred dollars on eBay. Ive outlined the refurbishment I did on my FTIR elsewhere on the forum. Doing chemistry with compared to what it was like before feels like suddenly being able to see.

Same applies to MS and NMR, but the FTIR is the most useful of these for following reactions.

not_important - 2-5-2008 at 07:25

Nice work again, Len.

When the industrial process was based on this method, they ran it continuously for weeks. Ethanol was added continuously, some water was distilled out as well, keeping the acid strength up, and separated from the ether through fractionation. This indicates that the acid should be reusable to some degree.

Other catalysts that have been used include H3PO4, which would be a mix of condensed phosphoric acids at the reaction temperature, and aromatic sulfonic acids. These cause less side reaction and charing, not oxidising the alcohol and thus releasing SO2; or at least that was claimed.

Magpie - 2-5-2008 at 10:51

Quote:

Is this safe? I was a little paranoid, I'm using an electric single element stove on a dimmer switch

Len, he didn't say a "mantle." Using a bare element in the presence of ether would make me nervous. I would preferably use a steam bath for ether, but have also used a mantle (fiberglass covered element).

Panache - 11-8-2008 at 09:10

The 'start-you bastard' product used in your illustration Len utilises dimethyl ether as the propellant. If the cans are dropped to below -50C, they can be drilled through and decanted into a round bottom. A dry ice condenser will condense the dimethyl ether fraction that comes over at around -25C. This ether is easily re-stored in a small bbq gas cylinder. It is a very useful thing, forming up to 35%solutions with water.
From there the di-ethyl ether can be distilled and so on.
Just additional information nothing else.

In case any are in dispute of this fact, because on the can it actually states the propellant as being CO2, however if you download the MSDS on the product it states the propellant to be dimethyl ether. I have actually performed the reclaimation above and can tell you that dimethyl ether condensed, making the claim on the can incorrect and the claim in the msds correct. Another fine example of australian attention to detail, lol.

[Edited on 26-8-2008 by Panache]

Engager - 4-7-2009 at 02:28

Thanks for this publication, it's very detailed and comprehensive. Good work! I've made two ~200ml batches of ether using your procedure, and yields are exactly as you described. However i have 2 small comments. First is that ether prepared from C2H5OH/H2SO4 and purified as you described contains some small ammount of water, boiling points are evident - final product start to destill at ~34C that corresponds to distillation of azeotropic mixture of ether with water containing 98.74% of ether (boiling point 34.15C). Second is that ether tends to accumulate peroxides durring distillation and they surely present in final product, to get rid of them it is very recomended to store final product above a small batch of KOH, it is insoluble in ether, transforms forming hydroperoxides to insolube products and also acts as good dehydrating agent.

[Edited on 5-7-2009 by Engager]

jmneissa - 17-10-2009 at 10:43

Hey great work however I have a question. You used methylated spirits which contain (most of the time) a mixture of ethanol, methanol, and many other alcohols with ethanol comprising about 90% of the mixture. Do these 10% of impurities cause a problem in the synthesis? For example the boiling point of ethanol is 78C while the boiling point of methanol is lower at 65C and isopropyl alcohol being higher at 82C when you distill of the primary reaction leaving behind the black liquid wouldn't the alcohol distill over with the ethanol? If so do they react with the sulfuric acid forming a separate product? I really would like to replicate your work and I have a can of Denatured Alcohol but I am wondering how these other alcohols present with effect my product.

starman - 17-10-2009 at 15:32

len works in Australia where the denaturant is usually MIBK.If you use a mixture of alcohols,you will get a mixture of ethers.If you have significant methanol you will form significant dimethyl ether,which due to its very low boiling point will probably carry off a good deal of your target.(see Panache a couple of posts above)

white rabbit - 22-12-2009 at 20:35

I liked this "Practical guide" so much that I have duplicated,( as best I could), the entire procedure with the exception of the FTIR results. I used Everclear ~191 proof for my source of EtOH rather than the SDA 200 because of its denaturing. Also I did run 750mL EtOH through the reaction bath confirming that it can convert quite a bit before needing to be replaced. Here I have include some pics.

Ether Synth.JPG - 54kB

This is the first setup.

Raw ether small.JPG - 27kB

This is the raw ether 655mL

Ether wash small.JPG - 41kB

Washing the product.

Ether synth small.JPG - 56kB

Re distilling from the CaCL2

Ether finished.JPG - 27kB

Here it is, 320mL Diethyl Ether!

I really enjoyed the experiment. Thanks to Len1 for the "Illustrated Practical guide" !

White Rabbit

Magpie - 22-12-2009 at 22:53

Nice work, Rabbit - thanks for the pictures. You have a lot of nice equipment. It is of sufficient scale for production of reagents. I'm in the process of acquiring some larger (24/40) scale equipment for that purpose.

Where did you get your equipment? EBay? Do you like the Graham condenser better than a West (Liebig style) condenser?

len1 - 23-12-2009 at 01:33

Very nice, I enjoyed your post. Thank you

Engager - 23-12-2009 at 14:18

Let's make ether picture gallery! My equipment is not so perfect as western, but is much cheaper and works just fine =)

My ether setup:

Reflux flask setup:

Condensing ether vapors:

Crude ether:

Pure ether redestiller setup:

Final product - pure ether:

[Edited on 23-12-2009 by Engager]

JohnWW - 23-12-2009 at 15:35

Very good! But because of its low boiling point, only 30ºC I believe (it gets that warm in my country in summer), and liability to form an explosive peroxide on exposure to air and light, you will have to keep it in a refrigerator, and preferably sealed under argon (or a gas that you are sure it will not react with or adversely affect any reactions in which it is used as a solvent or reagent).

[Edited on 25-12-09 by JohnWW]

len1 - 23-12-2009 at 22:36

ne hueva!

white rabbit - 24-12-2009 at 13:51

Quote: Originally posted by Magpie

Nice work, Rabbit - thanks for the pictures. You have a lot of nice equipment. It is of sufficient scale for production of reagents. I'm in the process of acquiring some larger (24/40) scale equipment for that purpose.

Where did you get your equipment? EBay? Do you like the Graham condenser better than a West (Liebig style) condenser?

Thanks Magpie. Yeah, I do have quite a bit of glassware. Sometimes, I buy a new piece on ebay and when I go to put it away, I find that I already have one. Ooops! I bought some of my glassware on ebay, some I buy direct from Wilmad Labglass, and the rest I get from a glass shop I use for my custom pieces.

The condenser in the pic is not a Graham, it is a jacketed "cool coil". I feel that the Graham has too much flow resistance for a first stage. The cool coil works well and the jacket around it really makes the difference. It is basically a Liebig with a coil inside of it. The Graham may be better for the second stage but I like the effectiveness,(greater surface area), of the Friedrich. I bought the jacketed cool coil from Wilmad Labglass.

I really like to seeing the hands on work all of you guys have posted.

White rabbit

DJF90 - 25-12-2009 at 03:33

JohnWW: bp of ether is a little higher, at ~35C. Storing it in the refrigerator is overkill unless you live somewhere rediculously hot. Peroxides arent that much of a problem if you keep the bottle topped up and store in an amber bottle, preferably stabilised with some BHT. There are many posts on ether peroxides and preventing their formation; copper supposedly does the job nicely, but requires a large surface area (a copper scourer stuffed into the bottle should be sufficiently adeqate. Alternatively you could form a copper mirror on the inside of the bottle, using chemical deposition. This can be done by electrolysis if you store your ether in aluminium bottles).

Argon is definately OTT, especially if you have limited headspace and an inhibitor.

[Edited on 25-12-2009 by DJF90]

sonogashira - 25-12-2009 at 18:40

Wow! I am jealous of all this equipment!

But I wondered: does 'wet' ether form a peroxide also? Well, I suppose it is 'yes,' but I meant that perhaps it is destroyed by water, and so safer to store?... But anyway, copper sounds a very nice idea if it works well... I hadn't heard of that before. I would like to try this one day, so thank you for the details since it will, I hope, be very useful!

aonomus - 25-12-2009 at 19:42

I've seen ampules of hygroscopic liquids from sigma stored over copper shot/powder. I'm not sure how well simply taking a lump of copper or shavings would work, probably too dirty?

Also, doesn't storing over KOH precipitate any intermediate before the peroxide forms?

12AX7 - 26-12-2009 at 01:13

Seems to me a transition metal would catalyze the reaction. Or is that more of an iron thing?

The usual solution is easy enough: the last bottle of ether I used claimed ethanol as a stabilizer. Add back a few drops of the swill you started with and all's well.

Tim

DJF90 - 26-12-2009 at 05:21

I'm not sure why hygroscopic liquids were stored over copper aonomus; the function of the copper with ether is to inhibit the formation of the peroxide.

Tim: I think the role of the copper is to actually catalyse the decomposition of any peroxide that may form. Definately a good thing. I had a paper on it somewhere but cannot find it. I'm familiar with ethanol being used to stabilise chloroform but its use in ether is new to me. Thanks for sharing!

entropy51 - 26-12-2009 at 11:55

Quote:

the last bottle of ether I used claimed ethanol as a stabilizer

Tim, are you sure that wasn't CHCl3? EtOH is added to CHCl3 to prevent formation of COCl2 on storage, but I can't recall hearing that it would prevent peroxide formation in Et2O. But Cu was for sure used as a coating on the inside of ether cans to prevent peroxides.

Science Madness Mission Statement:

You say ether, we say PEROXIDES!

12AX7 - 26-12-2009 at 13:21

Sigma Aldrich claims 2% EtOH and 10ppm BHT in the first ether found on Google. BHT of course is better known for peroxide protection.

As I recall, the bottles were simply aluminum. I don't remember a coppery coating, and I don't remember copper pellets rattling around in the bottom (although I can't say I ever shook the stuff on purpose!).

I don't remember what was in the CHCl3, although I think we used CDCl3 more often, and being for NMR purposes, I don't think it had EtOH.

Tim

[Edited on 12-26-2009 by 12AX7]

DJF90 - 26-12-2009 at 13:25

Aluminium bottles are the standard packaging aside from amber glass winchesters. I wouldnt expect there to be a copper coat, as this was purely my suggestion, and not something I had heard of previously.

aonomus - 1-1-2010 at 22:48

Quote: Originally posted by DJF90

I'm not sure why hygroscopic liquids were stored over copper aonomus; the function of the copper with ether is to inhibit the formation of the peroxide.

Tim: I think the role of the copper is to actually catalyse the decomposition of any peroxide that may form. Definately a good thing. I had a paper on it somewhere but cannot find it. I'm familiar with ethanol being used to stabilise chloroform but its use in ether is new to me. Thanks for sharing!

Not to get off topic, but I recall it was both hygroscopic, and a larynchamator (sp). Something with 1,3-bromo-chloro _____ comes to mind. I don't think it had any peroxide forming ability, perhaps it had another function.

I think also, prior to making ether, it would be a good idea to make some peroxide test strips. You can make them by taking a KI/starch solution and soaking filter paper, followed by careful drying. Once you have the strips cut up, store them away from moisture.

To test, dip the strip in the solution/solvent, and wait for any reaction. A small amount of water may be required to initiate the reaction (atmospheric moisture, or maybe a drop of water). Blue indicates peroxide, light yellow coloration indicates some peroxides (enough to form some iodine, not enough to form the blue starch-iodine complex).

Though, if you have access to commercial suppliers, buying real test strips may be worth it. Why risk your safety on potentially dodgy test strips?

starman - 10-5-2010 at 22:25

Well I ran this reaction a couple of weekends ago with minor modifications. The most important of these was the use of a peristaltic pump to deliver feed ethanol via a capillary (broken thermometer).

The result of this arrangement was a greatly reduced incidence in bump and foam, with the very small droplets hardly disturbing the mixture in the first half hour and virtually no bump at all after the reaction settled down.

From my final yields there was also a slight reduction in the rate of ethanol coming over unreacted in the distillate.

I don’t have Len’s capability to definitively characterise my final product. But the whole of the distillate came over as a very tight fraction 34.5-35C after sitting overnight over CaCl2.

I would like to thank Len for his detailed posting and a bit of inspiration that not everything needs be done according to Vogels! One can actually experiment and look for improvements and adaptions to amateur settings.

I seem to be having problems inserting images so here are links to a couple of photos I took as an afterthought. Please don’t laugh at my current ‘lab‘. I have to fight with the wife as to when I can book the laundry.

photo 1

photo 2

UnintentionalChaos - 10-5-2010 at 23:58

Two condensers? Ritzy. The bomex, not so much.

Bikemaster - 11-5-2010 at 07:45

Weird distillate?

That made already one month that I make a good amount of diethyl ether (2 L). This part of the the distillate is not a mystery, I purified and it is now store at -30 C. But in the bottom of the flask they were and other layer after the first distillation (the reaction distillation)??? That was the first time that I was seeing that. That was also the first time I was using ethanol without water (and a really small amount of isopropanol). Have you any idea of what this layer is made of? If it were isopropyl ether, will it mix with the ethyl ether/water/ethanol layer?
The ethanol use was Ethanol Bio Fuel for ethanol fire place.

I don't have made a lot of tests on this layer, but I have over 300ml of it, so it will be enough to find what it consite of.
I thing the first thing to do is to dry this layer and make a fractional distillation. With the boilling point and the density of each fraction I have good chance to find what it is.
The only test that I have already made is a flame test. This layer is very flammable (less that diethyl ether) and burn with a green flamme.

Hope you can help

chief - 11-5-2010 at 08:08

Di-ethylether: I did this as a kid: Just plainly distilling conc. H2SO4 with C2H5OH ...; no big deal ...
==> cooling with a NaCl-ice-mixture ...
==> ... and I believe the recommended procedure was to add also some water-free Na2SO4 into the boiling-flask for extra-dehydration ...

Mildronate - 11-5-2010 at 08:12

Engager, to my mind soviet ring stands are the best.

slinky - 29-10-2010 at 14:40

This is a great cheap and safe alternative to distilling from cans of startup fluid. Awesome writeup and pics in this thread. Thanks everyone

Regarding the distillation of starting fluid:

A few guys have posted their ideas. I've found it best to flip the can upside down and depress the spray tip which removes all of the propellant. The can will get nice and cold as the propellant leaves which will make the ether less volatile. Then use a manual (not electric) can opener to remove the bottom of the can. The cold ether can then be easily poured into your flask. Using a drill seems like a fire hazard : / [ friction -> heat -> fire + electricity -> sparks -> fire ] This way you get ether without it being vaporized into a difficult to control explosive aerosol.

peach - 16-3-2012 at 14:36

I have been repeating the work in the thread so far, using len's measurements.

I was curious if the work up could be improved to yield more d.ether by instead proceeding to redistil the crude yield immediately after the first distillation (without washing); to reduce the quantity of ethanol / methanol present without loosing ether to washing. Another interest was whether or not the by-products could be recycled back into the process (by avoiding neutralisation and dilution).

I took 25ml aliquots from the crude material, which roughly equated to 145ml of volume.

These were then redistilled and the temperature curves are in the graph below.

YELLOW:

This was done with simple distillation. The line is a continuous progression and features no separation. Not much good to be had there.

ORANGE:

This was with a vigreux column in the way. There are now two distinct plateaus representing the ethereal and alcohol regions.

BLUE:

The transition between the two is important as, ideally, it should be a vertical rise with a temperature drop before it, to show that clean fractioning is occurring. This slight dip is present, but it would be nice if the gradient was even steeper.

I was curious as to why the temperature wasn't rising within a minute or three, instead taking ten or so.

I then realised that ether, methanol and ethanol all form an azeotrope with water and proceeded to dry a 25ml aliquot of the crude ether; electing to use magnesium sulphate (as calcium chloride is incompatible as a drying agent with the alcohols present).

After drying, my volume of crude ether had dropped to just 9ml. Partly due to moisture absorption, but also due to the mechanical losses. I recovered about another 10 by squeezing the filter paper out. Messy.

I redistilled the now dry(er) crude ether through a virgeux and obtained this line. Which still shows two plateaus, but it is, if anything, a softer gradient than the untouched crude ether. Also note the lack of a dip before the climb.

----------------------------------------------

It appears vigreux distillation of the untouched crude ether is the best of the three, and also easier than bothering to dry it.

Why there is a ten minute transition time (with material flowing through the still) I am not entirely sure. But it may be related to this having been done from methylated spirits; there is likely a complex blend of petroleum distillate, ethanol, methanol, dissolved dimethyl ether, diethyl ether, sulphur dioxide, sulphuric and water in the crude material. Starting from drinkable, ala white bunny, could provide an interesting comparison; if it is byproducts from the reaction it's self or the poisoned alcohol Len and I have used.

However, separation can be achieved with a vigreux and would likely be even better with a packed column.

Unfortunately, despite returning my results to the original crude ether, over the coarse of running all these mini experiments, I can see the level in the flask has dropped by what I later determined to be around 50ml. It is likely this is primarily ether that has evaporated off.

I now have around 92 / 93ml of crude material. I distil this, as is, through the virgeux and cut off at 73C.

The results can be seen in the second photo, around 42 / 43ml of aqueous still bottoms, likely full of water, ethanol and they are strongly acidic. This would suggest I have around 45ml of ether in that 100ml funnel in the photo.

I tried washing the ethereal result with 3ml of water and noticed no cloudiness. I split the aqueous off and checked it's pH. Right down around 1.

12g of sodium carbonate were then dissolved in 100ml of water and I begin adding a few mls at a time, shaking and testing. It is reading neutral after 7mls have been added.

I also noticed this. Which is the crude ether immediately before I distilled it all. Upon adding it to a flask with a bit of muck (tar) on it's neck (via a pipette), it split.

Perhaps it'd be more efficient to extract the ether or load the organic phase with something none polar rather than trying to remove the aqueous layer?

I'd have liked to make this more conclusive, but realised I couldn't offer a direct comparison against Len's numbers when the volume in the crude flask had dropped so noticeably.

white rabbit - 17-3-2012 at 19:33

Nice work you've done here.

jmneissa - 28-7-2012 at 18:26

Hey guys I just did this synthesis to the letter of Len's original procedure and re-distilled the washed ether with a vigreux column. I used Home Depot brand Denatured alcohol and hardware store grade sulfuric acid. Upon the second distillation I collected a very small yield of productcollected from room temperature to 70 degrees C. However upon adding anhydrous magnesium sulfate to the distillate in an effort to dry it further it began to boil even though its temperature was only 10 degrees. At this point I realized that clearly my reaction had been contaminated with something. I proceeded to let it boil believing that since the temperature was 10 degrees the ether loss would be minimal. It is still boiling right now. My question is what do you believe is causing this boiling at below room temperature? I am not sure the percentage break down of the denatured alcohol I am using which I know is where the problem is coming from. Do you believe that my product could be mostly methyl ethyl ether which has a BP of 7.4 degrees C? Any advice you have would be much appreciated.

Daedalus - 29-7-2012 at 12:18

Check the MSDS for "Klean-Strip" denatured alcohol. I contains 50-55% methanol.

497 - 29-7-2012 at 17:52

Hah, I had that exact thing happen a couple years ago... "how the hell is my ether boiling below room temp???"

Very confusing at first... Eventually traced it to the Klean-Strip. I'd don't even get how they can get away with calling that "denatured alcohol."

Polverone - 30-7-2012 at 16:12

The "green" Klean-Strip alcohol is more than 90% ethanol and may be worth trying if you don't want to go to the expense of starting from 190 proof grain alcohol.

GammaFunction - 12-3-2013 at 10:45

I couldn't find anyone using a Vigreux or Hempel column during the reaction. Would this not hugely reduce water and ethanol contamination, recycling the ethanol back? Then subsequent washing would be much easier.

Bikemaster - 15-3-2013 at 18:01

Quote: Originally posted by GammaFunction

I couldn't find anyone using a Vigreux or Hempel column during the reaction. Would this not hugely reduce water and ethanol contamination, recycling the ethanol back? Then subsequent washing would be much easier.

I have done this synthesis many times and I never had a lot of unreacted ethanol in my recovery flask. You also want to remove the water from de reaction flask because you want to keep your sulfuric acid over 70%.
Washing the product of this reaction is really easy, so there is no point to keep the water and the ethanol away from it.

[Edited on 16-3-2013 by Bikemaster]

Dr.Q - 28-3-2013 at 11:12

So i tried to make ether too . But the luquid that i get was not smell like ether.
So here is how i did
I used %98 , 40 gram of sulfiric acid and 60 gram ethanol. Fırst i cool them up and then i pour the sulfiric acid drop by drop.
than i pour the mixture to a baloon flask and put a reflux condenser on it. On the top of the condenser i attached a narrow-mouthed U pipe . The other side of the pipe is
connected to a another empty flask.
I heated up at 140 degrees. The volatile ether colelcted in the flask that connected to pipe.
I though it was ether . It should be ... i looked for its boiling point and it was near 36 C degrees. It doesnt disolve in water either. But its had very pungent odor.
Not even near to ethers'sweet sugared smell.

What the hell is this ??? Some oxidated product or what ?

skeletal-clown - 10-7-2013 at 00:38

So I performed this synthesis today (I'm not 100% done yet), and I'd like to share an observation I made. To begin with, I was using anhydrous (distilled over CaO), EtOH (originally Diggers brand methylated spirits). During this time, the reaction mixture didn't turn black at all in the way Len1's did. It was slightly discoloured at best. When I ran out of anhydrous EtOH, I switched to straight, unpurified Diggers brand Methylated spirits (95% EtOH), within 20 minutes the mixture was pitch black. I'm assuming this means that the black colour is due to side-reactions not with the EtOH itself, but with the denaturent used in the methylated spirits.

Organikum - 10-7-2013 at 17:28

Quote: Originally posted by Myeou

So i tried to make ether too . But the luquid that i get was not smell like ether.
So here is how i did
I used %98 , 40 gram of sulfiric acid and 60 gram ethanol. Fırst i cool them up and then i pour the sulfiric acid drop by drop.
than i pour the mixture to a baloon flask and put a reflux condenser on it. On the top of the condenser i attached a narrow-mouthed U pipe . The other side of the pipe is
connected to a another empty flask.
I heated up at 140 degrees. The volatile ether colelcted in the flask that connected to pipe.
I though it was ether . It should be ... i looked for its boiling point and it was near 36 C degrees. It doesnt disolve in water either. But its had very pungent odor.
Not even near to ethers'sweet sugared smell.

What the hell is this ??? Some oxidated product or what ?

Impurities masking the smell.

Check ph, neutralize with bicarb in water (brine), separate and redistill for dentists delight....

/ORG

gravityzero - 22-7-2013 at 06:07

Quote: Originally posted by skeletal-clown

So I performed this synthesis today (I'm not 100% done yet), and I'd like to share an observation I made. To begin with, I was using anhydrous (distilled over CaO), EtOH (originally Diggers brand methylated spirits). During this time, the reaction mixture didn't turn black at all in the way Len1's did. It was slightly discoloured at best. When I ran out of anhydrous EtOH, I switched to straight, unpurified Diggers brand Methylated spirits (95% EtOH), within 20 minutes the mixture was pitch black. I'm assuming this means that the black colour is due to side-reactions not with the EtOH itself, but with the denaturent used in the methylated spirits.

I could be way off here, but I've ran this synth many times and always attributed the color change to using sand. It appears from the photos that grains of sand can be seen at the top of the flask.

Maybe it is a side reaction that would occur without the sand. I would not know, cause I've always used sand as a buffer. Clean sand or silica.

I know it has nothing to do with methylation, cause I've always used grain alcohol.

gravityzero - 22-7-2013 at 07:49

Quote: Originally posted by Organikum

Quote: Originally posted by Myeou

Impurities masking the smell.

Check ph, neutralize with bicarb in water (brine), separate and redistill for dentists delight....

/ORG

So, let me get this straight. In various reactions, usually ones including an acid, as in this case H2SO4, there is acid left in the finished product.

If the final product is acidic, that would mean that some H2SO4 and water is still hanging around. As to my understanding, pure ether as with most solvents can not have a PH.

Knowing this, I assume the brine is being used to neutralize the left over acid. It wouldn't be necessary to be particular on how much brine is added, as it will be separated off.
In other words there is little chance of the ether becoming too basic afterwards.

I've always read this procedure being employed to remove left over acid.
I've never seen a procedure employing the addition of acid to bring back to neutral, but that may be due to my lack of experience.

As with everything I do in life, I over examine to the extreme.
I just like to clarify for myself and others.

BTW, if NaHCO3 and H2O is considered brine, then what is NaCl and H2O? I always thought NaCl and H2O was considered brine. They may both be considered such.

bfesser - 22-7-2013 at 09:34

Organikum had a brain fart. NaHCO3(aq) is used to neutralize the remaining acid. Saturated aqueous sodium chloride, sat. NaCl(aq) aka brine, and is used for initial removal of water before employing better drying agents.

[edit] Outside of chemistry, 'brine' is any old aqueous solution of salt(s), e.g. seawater. In chemistry, it's generally taken to mean sat. NaCl(aq).

[Edited on 7/22/13 by bfesser]

skeletal-clown - 22-7-2013 at 23:53

Quote:

Hmm, this is interesting. I also used sand in my synthesis, and didn't even bother properly cleaning it. (Coarse builders sand heated multiple times in a sand bath to destroy most organics).

You're certainly right about it not being methylation, MeOH has been banned in denatured alcohol in Australia for over 10 years. I couldn't find anything about the denaturant used now on the product's MSDS, but I assume it must have been removed via distillation over Calcium Oxide (My method of drying EtOH).

bfesser - 23-7-2013 at 06:12

If it's not listed in the MSDS, it's likely a denatured with a trace of <a href="http://en.wikipedia.org/wiki/Denatonium" target="_blank">denatonium benzoate</a> <img src="../scipics/_wiki.png" />.

skeletal-clown - 24-7-2013 at 02:02

I thought so, either that or a pyridine. I remember finding a thread somewhere else on this specific brand of denatured alcohol, but I can't seem to find it. Seeing as the EtOH which was first distilled over CaO didn't produce the black tar, what ever the denaturant was, it must have been destroyed by it. (or at least reduced to something with a high boiling point).

Hellafunt - 14-4-2015 at 21:51

anyone who is making their own ether will find this video fascinating.

https://www.youtube.com/watch?v=gyND4M2WrlI

Loptr - 15-4-2015 at 12:15

Where can you get a fractionating column with actual plates, such as the one seem in the video? Is a packed column more efficient?

Funkerman23 - 8-9-2015 at 01:06

If I didn't know any better those look like frits in that column... yikes!

Funkerman23 - 4-11-2015 at 23:58

Question( if I may): would PTFE tubing be acceptable to feed the ethanol under the surface& into the rxn mixture? I am pretty sure that the temperatures aren't too harsh for it but with the boiling ethanol& sulfuric acid mixture I wanted to ask. Finding an a glass adapter to do so is becoming harder and harder.

sulfuric acid is the king - 16-5-2018 at 15:29

Can we add "full" quantities of EtOH and H2SO4 ALL AT ONCE and obtain ether?
I tried right now and i obtained some liquid with the smell of EtSO4,maybe that's actually smell of ether,but when i mixed with water there were no layers...I don't know what's going on...And my oil in the oilbath was little bit overheated,and after some time it was boiling but the flask was cloudy maybe ethylene formed couse oil was more than 180C...
Anyway....I'm litle bit narcotized by fumes..

[Edited on 17-5-2018 by sulfuric acid is the king]

sulfuric acid is the king - 16-5-2018 at 16:22

When i collected that first liquid i was somewhere else,and then writting this message,when i turned back to see,this is what i found...

Carbonized? Inside flask is pure carbon or something else but it looks like when you mix sulfuric acid and sugar...