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smaerd
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Ethyl Acetate?
Totally new here, so if I am doing it wrong let me know! I'm fairly new to chemistry and have a lot to learn. I recently purchased a chromatography
column(liquid) and was thinking about doing some practicing with it. For the eluent I plan on using a Ethyl Acetate as part of a binary solvent
mixture.
I used the search function perhaps I should have looked further but I got three pages of "diethyls" and plenty of other "acetates" hehe.
Buying ethyl acetate won't have the FDA at my door or anything right? Wouldn't be a big deal but I just don't wanna get arrested for buying chemicals
or something stupid.
How do people run columns with this when it costs 5 dollars per 30 mL?
I've looked into 'synthesis' and it seems really easy, however no distillation apparatus is available . I was told it is a main constituent in some non-acetone nail-polish removers, but it appears there are many other
compounds which could dirty up the whole reason of running a column.
Any ideas on how/where to procure relatively cheap, fairly pure ethyl acetate for the at home experimenter?
Thanks so much!
[Edited on 23-1-2010 by smaerd]
[Edited on 23-1-2010 by smaerd]
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entropy51
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The FDA wouldn't care if you filled your swimming pool with EtOAc. I think you have FDA confused with DEA. I doubt DEA would care either. Local
cops, well...
You can find a cheaper source than $5 per ounce, for sure. Many threads here have mentioned companies that sell to individuals, at least sometimes.
Spend some time looking at old threads.
If you want to make it, you will have to distill. Enter the phrase "preparation of ethyl acetate" in google and lots of preps come up. It is a
favorite experiment in college chemistry.
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Magpie
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Quote: Originally posted by smaerd  |
Buying ethyl acetate won't have the FDA at my door or anything right? Wouldn't be a big deal but I just don't wanna get arrested for buying chemicals
or something stupid.
How do people run columns with this when it costs 5 dollars per 30 mL?
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Why whould the FDA care? You need to get your three letter agencies straight.
$5/30mL? That's redickerous! Who sells it for that?
Welcome to ScienceMadness. 
The single most important condition for a successful synthesis is good mixing - Nicodem
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smaerd
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Thank you for such prompt replies! An active community, excellent!
Who sells EtOAc for 5/30mL -> ebay fails.
Ahhh so 'Preparation' is more likely the proper word for what I have been seeking. I knew synthesis didn't sound right. Thanks for the tip!
DEA, FDA, it's all the same to me. A big group of people taking my tax dollars assuming I can't make decisions for myself.
Thanks for the welcome! I have a feeling I will learn a lot here. It feels homely  .
Off to do some research. Zoooom
Namaste.
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entropy51
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| Quote: Originally posted by smaerd |
DEA, FDA, it's all the same to me. A big group of people taking my tax dollars assuming I can't make decisions for myself. |
Well. I sorta think someone who doesn't know how to make EtOAc probably shouldn't presume to decide which medications he should be
allowed to put into his body if he gets sick. Before there was an FDA people died from taking "medicine" sold in the stores.
You seem rather proud of your ignorance. I'm guessing that with that 'tude that you will fit right in here.
[Edited on 24-1-2010 by entropy51]
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smaerd
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Hey hey hey, let's not get super judgemental about someone we don't know anything about. I am not proud of my ignorance, I apologize for making such a
generalized statement.
I never said I didn't know how to make it I said I don't have the equipment at home and was wondering if maybe someone had another way.
But thanks again, much love, I'm here to learn that is all. If I am wrong please correct me, I stand by this.
[Edited on 24-1-2010 by smaerd]
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starman
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Ethyl acetate can be had commercially at fairly reasonable prices.I think I paid about $70-$80 for 5 litres.That was part of a 2 pack system for
bostik rubber adhesive,and was purchased in Australia,where everything seems to be twice the price.
However if you're serious about getting into chromatography,you either need the means to purify commercial grades(distillation apparatus is a must) or
you shell out for analytical grade solvents.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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crazyboy
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http://store.hvchemical.com/browse.cfm/4,90.html
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rrkss
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Ethyl Acetate is easy to prepare but until you know a little about organic chemistry lab technique, I'd stay away from the synthesis since you will be
working with concentrated acids at higher temperatures. To buy it should not be that difficult. Take a look at sources such as ebay and such. Its
not a controlled chemical and has many uses such as nail polish remover and adhesive remover to name a couple. Heck I use it at home to remove the
glue residue from labels I've peeled off of containers.
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rrkss
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In case you are interested and up for the challenge I'm gonna post my preparation of ethyl acetate. I did this reaction small scale today but you can
scale up accordingly.
In a 100 mL roundbottom, I added one boiling stone. Following this I added the following reagents.
30 mL of 95% acetic acid
22 mL of 95% ethanol
1 mL of 96.5% Sulfuric Acid
I proceeded to reflux that for one hour.
After the reflux I let the roundbottom cool. Then added a 300 mm vigruex column and fractionally distilled the product out of the reaction flask.
You get 3 fractions. The first fraction comes over around 74 C depending on your altitude. This fraction is ethyl acetate + any residual unreacted
alcohol. Your second fraction is water which comes over around 100*C and your last fraction is acetic acid.
Obviously you stop the distillation when the second fraction starts to come over.
Then I took the product and did a workup with 10 mL of satuarated Sodium Bicarbonate Solution. As expected, I did not have any residual acetic acid
in the product evidenced by lack of bubbling. Then I did another workup with 10 mL of saturated CaCl2 solution in a seperatory funnel to remove any
residual Ethanol (you can substitute a type 4A molecular sieve for this step). Then I dried my product with anhydrous copper sulfate and put it into
another 100 mL roundbottom with a boiling stone for distillation.
After a second distillation, I had 27 mL of ethyl acetate which is about an 80% yield. My yield probably was higher but I did lose some product in
the workup due to ethyl acetate's slight solubility in water.
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entropy51
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rrkss, what was the boiling range on the second distillation? Thanks.
80% isn't bad on this scale!
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rrkss
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I did not put a thermometer in the simple distillation when I purified the compound after drying so I can't tell you but if I had to guess it would
have come over at around 75 degree Celsius.
[Edited on 30-1-2010 by rrkss]
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MagicJigPipe
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There is a company in my area that sells EtOAc. The only problem is the smallest size is 5 gallons. I have "sold" some (really just acted as a
middle-man) before to a member and it worked out fine. It's been a long time so I can't really remember the price but I know it was pretty cheap
($40-$50 for 5 gallons?)
I'm not sure if I'll do it for someone that is new here but...
If you just look around you will find something. And, if you want I'll give you their phone number. They will ship to other states for a reasonable
fee (but I'm not sure if they can say, take a credit card over the phone; you would need someone to give them the cash).
[Edited on 1-30-2010 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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smaerd
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Thanks so much for the offer. The experiment kind of failed, so this is no longer near urgent. However in the future I may need to ask for that
number! That's a very good price.
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User
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| Quote: |
In a 100 mL roundbottom, I added one boiling stone. Following this I added the following reagents.
30 mL of 95% acetic acid
22 mL of 95% ethanol
1 mL of 96.5% Sulfuric Acid
[Quote]
I proceeded to reflux that for one hour.
After the reflux I let the roundbottom cool. Then added a 300 mm vigruex column and fractionally distilled the product out of the reaction flask.
You get 3 fractions. The first fraction comes over around 74 C depending on your altitude. This fraction is ethyl acetate + any residual unreacted
alcohol. Your second fraction is water which comes over around 100*C and your last fraction is acetic acid.
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Today i did the same synthesis with slight adjustments.
70ml 80% acetic acid.
50ml 96% EtOH (distilled from raw source, not really pure)
2.2ml 98% SA
2.0gr Sodium acetate (anhydrous)
All the reagents where added to a 250 ml erlemeyer.
This was refluxed at boiling point for 30 min under heavy stirring.
Heat turned off.
Next, the reflux condenser was swapped for a vigreux (70cm).
A normal distillation set-up was build.
The heat was turned on and solution brought to boiling.
The first liquid came over at 68 degrees C.
Around 100ml of product was collected.
The heat was turned off when the temp in the head dropped.
100 ml of near saturated NaCl/tap water was prepared.
50 ml of this solution was added to the collected product in a sep. funnel.
The funnel was turned up side down degassed etc.
This was done one more time with the rest of the NaCl solution.
The Ethyl acetate was left over night in a desiccator.
A total of 65ml where obtained.
-The yield isnt bad considering the amount of water present in the reaction.
-The sodium acetate was added as an attempt to suck up moisture.
I might try to saturate the solution with it next time.
Considering this is such a cheap chem it could be used to up the yield where low % acetic is available.
*edit*
Sorry I forgot to mention that it EA did not respond to a test with sodiumbicarbonate.
Lol , somehow I like the smell.
[Edited on 10-2-2010 by User]
What a fine day for chemistry this is.
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bbartlog
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But your sodium acetate will react with the sulfuric acid (yielding sodium sulfate and acetic acid), so you have to add excess acid or else just start
with the sodium sulfate. In the reaction you just did, you would have had ~4g of H2SO4 (~40mmol) and ~25mmol of sodium acetate, so at least you didn't
neutralize all your acid. The sodium sulfate that is produced does take up water, but only below 30C (so it's not an effective way to remove water
from the reaction as it takes place...). If you want to dehydrate I'd go with MgSO4 or CaSO4 instead of sodium acetate / sodium sulfate.
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rrkss
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| Quote: | 100 ml of near saturated NaCl/tap water was prepared.
50 ml of this solution was added to the collected product in a sep. funnel.
The funnel was turned up side down degassed etc.
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This is counterproductive as you loose product unneccessarily washing it with water. I only do a wash with bicarbonate because my reagent in excess
was Acetic Acid.
I dry my product with 4a molecular sieves (absorbs ethanol and water). The sieves can be regenerated in an oven after the organics have first been
evaporated off (to prevent an explosion). You can substitute 3a molecular sieves but you won't remove the ethanol only the water.
I agree with the previous poster, remove the sodium acetate. You are only destroying your catalyst with that and not really removing water. You
still got product which was great. I like the smell of the ester as well.
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entropy51
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| Quote: | | The first liquid came over at 68 degrees C. |
What was the boiling range? EtOAc boils at 77 C. There are
binary and ternary azeotropes with H2O and EtOH at about 70 C. The usual prep is to wash the crude distillate with saturated CaCl2 to remove H2O and
EtOH (as rrkss did) and then redistill, collecting the fraction near 77 C. EtOAc tenaciously holds H2O and yours my still be wet. But maybe that's
OK for your uses.
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User
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Yep thanks for the reply's.
That temp surprised me as well, the ratio of the collected product was +/- 60/40 ethyl acetate/EtOH
Ill take the boiling point as a double check.
I will do a second distillation run and see how much product i will obtain.
This stuff i cheap as dirt for me so.
Plenty of CaCl2 and anhydrous NaCO3 lying around.
Ill dehydrate the ethyl acetate and do some measurements.
*edit*
Can someone tell me why the acetic acid itself doesn't catalyse the reaction?
[Edited on 10-2-2010 by User]
What a fine day for chemistry this is.
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rrkss
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Another thing is to run your reflux a little bit longer. 30 minutes will give you some product but not at its full potential. At least an hour
though the industry standard is 4 hours. This is organic chemistry and organic reactions do tend to run slower than most of their inorganic
counterparts.
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User
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Yes i know that refluxing longer would be good for the yield.
This was just a crude quick and dirty test, it will be scaled up later.
[Edited on 10-2-2010 by User]
What a fine day for chemistry this is.
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rrkss
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Well I just reran my synthesis and upon the second distillation, I did add a thermometer. It came over at exactly 77 degrees Celsius.
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entropy51
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Good Job!
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bbartlog
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| Quote: | | Can someone tell me why the acetic acid itself doesn't catalyse the reaction? |
I'm no expert, but I believe that the problem is that acetic acid just isn't strong enough. In order for the reaction to take place, the ethanol needs
to be protonated to form an oxonium ion. Since the conjugate acid of ethanol C2H5(H2O+) has a pKa of -2, you want an acid that has a pKa lower than
that to protonate ethanol. Acetic acid (a weak acid) has a pKa of 4.8, where sulfuric acid has a pKa of -3.
I expect that HCl is also strong enough but since it's more volatile, possibly results in some volatile products via side reactions (ethyl chloride),
and isn't as hydrophilic as sulfuric acid, it wouldn't be quite as suitable.
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rrkss
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The mechanism involves the carbonyl C=O on the acetic acid being protonated. In order to do that effectively, you need a strong acid like sulfuric
acid. Ethanol can also act like an acid and the reaction will run just extremely slowly hence we add the sulfuric acid to speed things up greatly.
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