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garage chemist
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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?
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Mendeleev
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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.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Mendeleev
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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  .
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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xxxxx
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para toluene sulfonic acid as catalyst ?
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?
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trilobite
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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.
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Mendeleev
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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  . 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.
[Edited on 4-1-2005 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Organikum
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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.
/ORG
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tom haggen
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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?
N/A
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Organikum
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Yes.
Yes.
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tom haggen
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Thanks a lot man.
N/A
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Caffinehog
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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.
I don\'t understand what you are saying, but I agree with every word of it!
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sparkgap
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That was elaborate, but IIRC, just boiling concentrated sulfuric acid and ethanol should give some ether as a product.
edit:
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]
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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Caffinehog
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| Quote: | | 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.
I don\'t understand what you are saying, but I agree with every word of it!
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Caffinehog
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| Quote: | Originally posted by sparkgap
That was elaborate, but IIRC, just boiling concentrated sulfuric acid and ethanol should give some ether as a product.
edit:
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!
I don\'t understand what you are saying, but I agree with every word of it!
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sparkgap
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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 (^_^)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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Caffinehog
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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: http://web.lemoyne.edu/~giunta/williamson.html (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]
I don\'t understand what you are saying, but I agree with every word of it!
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Organikum
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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%
H2SO4)
Article courtesy lugh.
Attachment: ether_französisch.djvu (33kB)
This file has been downloaded 846 times
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sparkgap
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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.
sparky (^_^)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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ordenblitz
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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.
http://img40.imageshack.us/img40/5746/imppumice1sn.jpg
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.
http://img40.imageshack.us/img40/9991/pbsheet9ue.jpg
http://img40.imageshack.us/img40/6919/rollheatsink5qc.jpg
A plate with a socket for a thermometer was fashioned to cover and contain the rolled heat sink for placement on the hotplate.
http://img40.imageshack.us/img40/5525/coverplate5nm.jpg
http://img40.imageshack.us/img40/9333/hotplate8rx.jpg
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.
http://img40.imageshack.us/img40/1209/boiletoh2op.jpg
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.
http://img40.imageshack.us/img40/8572/setup7vb.jpg
The product this obtained was distilled for a total of .86 grams of the fraction coming over at 36º-38º
http://img40.imageshack.us/img40/2042/distprod5xh.jpg
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%
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flyingbanana
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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.
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S.C. Wack
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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)
This file has been downloaded 1084 times
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Magpie
lab constructor
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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]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Magpie
lab constructor
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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. 
The single most important condition for a successful synthesis is good mixing - Nicodem
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stoichiometric_steve
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worst case scenario wanted?
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....
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Boomer
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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?
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