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Magpie
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ethyl acetate
ethyl alcohol + acetic acid = ethyl acetate + water
(with H2SO4 as catalyst)
This compound isn't too exciting but I thought I'd share the results of my synthesis. I used my old school procedure, with the exception that I
didn't have glacial acetic acid, but 92.5% acid. As not_important had predicted this worked out well anyway. My yield was 53%, just as indicated in
the procedure. Although this is just a basic Fischer esterification, the work-up on it is fairly complex. First there is distillation to remove the
H2SO4. Then neutralization with Na2CO3, washing with CaCl2 solution, and a final dewatering with MgSO4. Then fractional distillations to obtain the
product boiling at 75-78C.
[Edited on 10-10-2006 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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bio2
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And the old school procedure would be?
What do you think about using HCl (gas) in lieu the sulfuric?
Heard it works better although never did it, yet.
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Tacho
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I disagree about ethyl acetate not being exciting! Since I bought a bottle of it, it became my favorite solvent. It's almost harmless healthwise (if
someone knows better, please post), dissolves lots of things (good to clean fingers and tools), evaporates easily and smells good. Great for
extractions too. I wonder why it's not more popular with amateurs. Is it hard to find in other countries? Some health concern I don't know about?
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woelen
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Where I live, it is much more expensive than acetone. Acetone can be purchased everywhere in liter quantities at remarkable purity for just a few
euros. Ethyl acetate is hard to find as a pure chem and it is expensive.
Easiliy available pure solvent chemicals (really plentyful and cheap) over here are:
1) acetone
2) ligroin (bp ranges 100 .. 140, and 40 ... 60)
3) diethylether
4) ethanol 95%, denatured with traces of MEK (spiritus ketonatus).
5) toluene
Other pure solvent chemicals are not available here as OTC sources and you need to search for them and be prepared to pay a lot for them. There are
more, but these are mixes with all kinds of stuff.
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Magpie
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Bio2, my old school procedures are taken from:
'UNITIZED EXPERIMENTS IN ORGANIC CHEMISTRY," by Brewster, Vanderwerf & McEwen, reprinted June 1962.
I think the idea behind using HCl gas would be that it is a technique for not adding any additional water. Anhydrous ethanol should help also. As
you know this is an equilibrium reaction and typical yields for Fischer esterifications do not exceed 67% because of that, according to my procedure.
The single most important condition for a successful synthesis is good mixing - Nicodem
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bio2
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Doing exhaustive steam distillation during hydrolysis often ups yields so maybe this could work in reverse also.
Equilibrium shifts as water and/or product is removed. Takes forever though.
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garage chemist
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Ethyl acetate WAS once very cheap and easy to get here, until the suppler (Kremer) turned away from the hobby chemists and decided to sell no more
chemicals to individuals.
I still have nearly a liter which was cheap and is of good purity.
Of course it can still be got, there are other suppliers which sell to individuals, and you can always order stuff at the pharmacy. But it is not
cheap.
Yes, ethyl acetate is a nice solvent, and not more toxic than ethanol. It is good for extractions and for dissolving some plastics (e.g.
acetylcellulose).
It is also useful for making acetamide by reacting it with conc. ammonia solution (see frogfots page). From acetamide, methylamine can be made by
reaction with bleach+NaOH.
The synthesis of acetamide from ethyl acetate is interesting, I have done it myself. The product is purified by distillation, but the condenser must
not be cooled with water as the product solidifies at about 50°C.
Magpie, I don't like that you have to make such basic compounds as acetic acid yourself. Can't you print out an order list for a known scientific
supplier, go to the next pharmacy with it and tell them to order the things for you? I'm sure this is the easiest way to get non-OTC chemicals (for me
it is). This is also your chance to get some thionyl chloride.
I know that there will at some time be no chemical suppliers left which sell to individuals. The importance of pharmacies will therefore grow a lot.
Just remember to print out an order list. If you just got to the pharmacy and say "I want some glacial acetic acid" they most likely won't give you
any.
[Edited on 10-10-2006 by garage chemist]
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Magpie
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Garage chemist, don't worry about me making basic chemicals just yet. I'm still not bored with this as there are some interesting challenges. And I
feel like I'm more in tune with the basic functional groups than if I was synthesizing some complex compound.
I think it is wonderful (and a bit incredible) that you have established such a good relationship with a pharmacist. I'm not sure that that is
possible in the US today. Although Germany certainly has had its share of terrorists, and going way back too, I sense that people in the US are more
paranoid and irrational than in your country.
I said before that I know a pharmacist. I was reminiscing with her one day saying that when I was a child I could get ether and chloroform OTC for
use in my hobby of lepidoptery. She said "you can still do that you know." Then when I asked her if she would sell me some chloroform (casually,
not when she was at work) she said "Oh, you should just order that from a chemical supplier." So I gave up on her. But eventually I will try this
again, only I will go to a pharmacy with a written order to a chemical supplier, as you suggest.
The single most important condition for a successful synthesis is good mixing - Nicodem
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woelen
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Garage chemist, do pharmacies in Germany still use chemicals? Over here, recently (last 5 years) all pharmacies changed from places where they made
medicines themselves to just outlets of pharmacy industry. I see pharmacies dismantled at a high rate around me. All the glass bottles and other fancy
stuff they have are disappearing and what remains is a small counter, where you can order medicines and then they take these medicines from the
backoffice, prepackaged. This also means that no knowledgeable people remain in the pharmacies, they usually are young girls, who only type the name
of the medicine in their computer and the computer tells them where the stuff is in the backoffice (which drawer, etc.). You only get anything from
them, if it is a confirmed order from a doctor. Usually the confirmation is sent to them by electronic means and if you go there after visiting a
doctor, they already have the confirmation. So, effectively, our "pharmacies" are just distribution outlets, nothing more.
Real pharmacies are in the larger hospitals, but these are not accessible for people who have no business with them.
So, effectively, the source of chems through pharmacies is gone in the Netherlands  . Even a compound like pure KCl is not present anymore at these outlets. I tried it, just out of curiousity. Also empty little glass bottles and
that kind of stuff is not present anymore. They stare at you as if you are coming from another planet if you ask for KCl or glass bottles.
[Edited on 11-10-06 by woelen]
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chromium
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| Quote: | Originally posted by Tacho
It's almost harmless healthwise (if someone knows better, please post) |
Some books claim that butyl acetate is even less toxic.
When all think alike, then no one is thinking. - Walter Lippmann
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Magpie
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Once you have made ethyl acetate it is easy to make acetamide from it as discussed above. I did that a few days ago. Today I recrystalized some of
it from chloroform to determine its melting point. The fine needle crystals are so beautiful that thought I should post a picture of them to the
forum. So here it is. Unfortunately everything is so blinding white that it is hard to see the crystals except around the edges.
EbC: reduced picture size.
[Edited on 26-1-2007 by chemoleo]
The single most important condition for a successful synthesis is good mixing - Nicodem
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garage chemist
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Wow, that looks very good.
I haven't recrystallized mine, I just distilled it at atmospheric pressure (it was a wet mass before, acetamide is very hygroscopic but it boils so
high that distillation gets it very dry). The product solidified in the receiver and formed long needles. I melted it and poured it into a storage
bottle.
However, it acquires a strange smell upon distillation. The original wet product obtanied from evaporating the volatile compounds from the ethyl
acetate/ammonia reaction was nearly odorless, but after distillation it had a distinct smell of mice excrement.
I have not tried to obtain methylamine from this, but if you try, remember that the product might be mixed with ammonia by hydrolysis of the amide by
the NaOH (side reaction). You should purify it by extraction of the hydrochlorides with absolute ethanol (or maybe isopropanol, I'm not the expert on
methylamine purification, like some other members here are).
From methylamine it is possible to make nitrosomethylurea by reaction with urea and sodium nitrite. Nitrosomethylurea is the classic precursor to the
special methylation reagent diazomethane (I have never tried this, but I might try in the future since I now have some methylamine solution).
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Magpie
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Yes, I had to heavily insulate my distillation flask, stillhead, and half of my air condenser to get the acetamide to stay liquid before reaching the
receiving flask. I completely melted one of my new Keck clamps (good for only 150C, I've got to get some stainless steel clamps).
My old school procedure says that acetamide is odorless and that the smell is due to an impurity. It smells like amine to me and I would suspect it's
ethylamine. The recrystalized material on the filter paper has no odor.
I will be making methylamine by the Hoffman hypobromite rearrangement using 15g of the 22 grams that I estimate I made. Thanks for your notes on
this.
The single most important condition for a successful synthesis is good mixing - Nicodem
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UnintentionalChaos
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If you're intentionally trying to make acetamide (and ethyl acetate happens to be not so cheap for you), couldn't you just use the ammonia and acetic
acid route? Ammonium Acetate should decompose fairly easily into acetamide and water (Just going by wikipedia on this one, though I am about to go do
this anyway). I suppose that route is less feasible if you happen to be working with heavily diluted OTC stuff whereas ethyl acetate would be one 100%
starting component.
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pantone159
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| Quote: | Originally posted by garage chemist
after distillation it had a distinct smell of mice excrement.
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I have a document titled 'The Methylamine FAQ v. 2.0' which comments under its acetic acid and urea prep for acetamide, which states:
"If the product smells strongly of mice (as in the rodents), then recrystallization from warm methanol is in order."
It goes on to describe what I think is a mixed solvent MeOH/Et2O recrystallization. Sounds like chloroform works too, from Magpie's results.
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Magpie
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@JEANBERGIAN: These Fischer esterifications are reversible and reach equilibrium with considerable unreacted reactants. That is why the initial
reactants should be as water-free as possible and an excess of the cheaper reactant is usually specified.
Also, one could improve yield by removing one or both of the products where this is practical.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Klute
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I have had good results by refluxing 50grs of AcOH with 60grs of EtOH and 10ml sulfuric acid (PTSA is a good acid catalyst also) for 1 hours, then
changing to fractionall distillation (400mm vigreux) and dripping a 1 to 2 molar ratio of AcOH and EtOH... this effectively deplaces equilibrium as
stated, by distilling mainly EtOAc formed.. Some EtOH distills too, that's why you add excess with the acetic acid... It's very long though, and you
have to distill slowly with ice cooled water in condenser and ice bath for the receiver because Ethyl Acetate is very volatil.. Often had ~70-75%
yields when done correctly... Placing silica gel and using anhydrous EtOH would surely boost up yields even more... When using denaturated EtOH,
small quantities of methyl acetate is formed also, but that's no hassle.. It's not impossible to obtain a liter in a whole night of work, with adapted
glassware, but it is usefull to add a little more sulfuric now and then as some converts to ethyl sulfate with the EtOH.. Any unreacted AcOH can be
recycled by distilling the still flask contents... won't be glacial except if you used some drying agent.. but 70-75% AcOH is handy too.
And ethyl acetate sure is a great solvent for extraction and washings solids, aswell as for making acetamide.. good setup, BTW Magpie!!
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chemrox
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Et Ac would be the solvent of choice for extracting DMT from Phalaris arundinaceae
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cheeseandbaloney
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Sorry to bump an old topic, but I thought I'd share my revised synthesis of this sweet smelling solvent.
I originally tried this synthesis the normal way by refluxing AcOH, ethanol and sulfuric acid then distilling, but was discouraged with my 45% yield.
I tried a different route by using a drip tube extended below the reaction mixture and experienced a rough yield of ~85% (based on the AcOH). What was
nice is that I didn't have to wait while it refluxed as I simply collected it as it was being made. Although I admit my Ethyl acetate is still
somewhat contaminated with ethanol, here was my procedure:
To a two neck 500ml RBF ~100g (1.67M) of glacial acetic acid and ~8ml of sulfuric acid are added (slowly). A 250ml addition funnel with a home made
drip tube extending below the AcOH (using tygon tubing as the connector to the glass tube and funnel) is charged with ~115g (2.5M) of 95% ethanol and
attached to one neck. The other neck is set up for simple distillation and the flask is immersed in a silicone oil bath which is brought up to a temp
of ~105-110C. (I didn't want my AcOH distilling over so I kept it under 118C). With stirring the ethanol is slowly added. The distillate coming over
originally shoots up to ~82C, but with adjustments steadies around ~77C. (I noticed if the drip rate was too fast or too much ethanol was in the flask
the distillate would steady around ~72C instead). After neutralizing my distillate with Na2CO3 (no bubbles formed) and shaking with copious amounts of
CaCl2 for a few minutes, then finally filtering over some fresh CaCl2, the product was weighed giving ~125g of impure ethyl acetate. Right now it's
sitting over some CaCl2 and I plan on fractionally distilling next chance I get. This was faster and better yielding than my previous attempt so I
thought I'd share the results.
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GreenD
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hey wait - so can this process be reversed in a base bath? KOH + heat to get ethanol and acetic acid?
Guess this wouldn't be extremely helpful though - a mixture of all those three would be annoying to seperate...
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Sedit
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Why would it be hard to separate, sodium acetate and ethanol can be separated thru distilling the EtOH.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Melgar
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I made acetamide once by mixing stochiometric amounts of sodium acetate and ammonium chloride, then heating it to its melting point. Ammonium acetate
forms from the molten salts but at that temperature it's unstable and decomposes to acetamide. I also made it from heating urea and glacial acetic
acid. There are really quite a lot of ways to make it, it's just hard to purify. The urea + gaa seems fairly pure if you use stochiometric
quantities though.
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ParadoxChem126
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I performed this reaction a while ago, and I made a video on it. Click this link to see it.
http://www.youtube.com/watch?nomobile=1&v=cFxZ0NircIk
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Fantasma4500
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so im reading through this, i only find preps using glacial acetic acid, im pretty sure i did this myself years ago using 80% HAc
i did the math, 500mL 80% HAc is 400g, 307g EtOH and 100g/mL water
the reaction then produces 120mL water and 586g EtAC
this would imply i would need almost 1L of 96% H2SO4??? disgusting. now, couldnt just half of that be used so that it only turns the 80% into glacial-
in situ? i think im gonna have a go with it and use just a catalytic amount of H2SO4, like 50mL total
maybe dumping in a load of freshly dehydrated MgCl2 would do something- oh wait, that wouldnt be grand with H2SO4. MgSO4 it is.
we gotta figure out the most effortless way to make EtAc in these disastrous times where DCM is no more
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Dr.Bob
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MgSO4 can also be used to dry ethanol, so drying it and the acetic acid might help the yield. You should be able to dewater acetic acid by either
distillation or freezing, but I have never tried it. If you have some acetyl chloride, that can use used to react with the ethanol to both dry it
and produce some HCl, which acts as the catalyst instead of sulfuric acid. I have used that trick to make acetates before, about 5-10% mol % acetyl
chloride will produce a soln of HCl in your ethanol that can be used to drive the reaction of an alcohol with acetic acid.
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