Priest
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Ester hydrolysis
Hi!
SWIM got some Phenylacetic acid ethyl ester this week and asked me if he could break the ester up with a strong lye...
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vulture
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How about UTFSE and typing "ester hydrolysis" into google?
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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chemrox
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@vulture et al., what is "UTFSE?" I've always wanted to know (for six months or so anyway).
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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12AX7
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Dur, UTFSE!!!! :rolleyes:
http://www.google.com/search?q=utfse
A tip: www.acronymfinder.com and www.urbandictionary.com are your two most important language resources on the 'net.
Tim
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chemrox
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Indeed! Thanks.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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solo
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I have a question ...on the hydrolysis of phenyl ethyl acetate....the product would be an acid and an alcohol....as in all hydrolysis of esters, some
claim that it would yield phenylacetic acid and an alcohol.....how can that be.....once the salt is treated with the acid ...
C6H5CH2-CH2-O-C(O)-CH3 +NaOH------> CH3-C(O)-ONa + C6H5-CH2-CH2-OH---->RX--H2SO4----->
CH3-C(O)-OH + C6H5-CH2-CH2-OH
.............I see no Phenylacetic acid....what did I miss? (puzzled)....solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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MagicJigPipe
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Because I think they mean the following:
C6H5-CH2-C(O)-O-CH2-CH2 + NaOH
That should technically be called "ethyl 2-phenylacetate".
Yours would be called "2-phenylethyl acetate" which, as you stated, should produce 2-phenylethanol and sodium acetate.
Technically, only one of these should be of much use to a certain group of individuals. Guess which one...
I woudn't mind having some phenylacetic acid to mess around with, though, if it weren't so damn risky to possess.
[Edited on 6-7-2008 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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solo
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Ok right, I missed the CH3...so it should read not as you suggest,
C6H5CH2-CH2-O-C(O)-CH2-CH3 +NaOH------> CH3-C(O)-ONa + C6H5-CH2-CH2-OH---->RX--H2SO4----->
CH3-C(O)-OH + C6H5-CH2-CH2-OH
........let's deal with the question at hand, not with your intuitive insights of precursors....solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Klute
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You've still got sodium acetate and 2-phenylethanol there..
C6H5-CH2-C(O)-O-CH2CH3 --NaOH--> C6H5-CH2-COO-Na+ + CH3-CH2-OH
I think a hour or two reflux with 10% excess base in ethanol/H2O mixture would be just fine... The recation could be folowed by TLC, and the formed
phenylacetate should be too sensitive to excess base, even with heating.
Is phenylaectic acid a solid? If it isn't too soluble in water, you could even distill off EtOH/water until reaching H2O's bp, and then cool and
acidify with conc. acid to precipiatte the phenylacetic acid..
If your ester is pur enough, there wiouldn't much needed is recrystallizing the phneylacetate,a s any trapped abse would be neutralized by the acid,
and even after acidifying a recrysatllized phenylacetate, you will still have sodium/potassium sulfate/chloride to remove, so you would better be off
purifying the acid if it is more practical (distn?).
I guess the ester must smell nice, I'ev heard the acid itself is pretty bad smelling!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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solo
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---Is phenylaectic acid a solid?
.........yes
my bad...I read it wrong ....the ester is Ethyl 2-phenylacetate (ethyl phenyl acetate) not phenylethylacetate no wonder it didn't make
sense......thanks Klute, Edit and MagicJigPipe I thought I was loosing it....and it seems after
being exposed to the NaOH in excess, to make sure all the ester is used up, it does make the the phenylacetic salt which later RX with H2SO4 will
precipitate the phenylacetic acid , which is then filtered and washed several times with clean water and put to dry.....yields are usually in the
high 90%, I think the sulfate and potassium salts remain in the water , so no need to purify, is there any concern about moisture and the sensitivity
of the carbonium in the phenylacetic acid when RX with the other elements in the Dakin West Reaction (i.e. acetic anhydride, sodium acetate) ? so that
the phenylacetic acid should be completely dry before using?.......solo
[Edited on 7-6-2008 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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MagicJigPipe
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The issue at hand is which chemical someone is more likely to be talking about. It is relative to note that it would be the ethyl ester of
phenylacetic acid.
Actually, you are incorrect. "C6H5CH2-CH2-O-C(O)-CH2-CH3" would be 2-phenylethyl propanoate which would yield sodium propanoate and PhEtOH. THIS IS
IN RESPONSE TO YOUR RESPONSE TO ME. YOU (ACCIDENTLY?) PUT AN ESTER OF PROPIONIC ACID.
EDIT
This was to be posted 2 posts up. Apparently 2 people posted before I was done typing this. Solo, I basically said the same thing yet you say,
"Thanks Klute". That is very disrespectful. Is there a problem?
....
Okay, I was wondering what solo's problem was (I tried to settle this through PM but for some reason he has me blocked) but I figured it out. Damn,
these Willy Daisies hold on to anger and grudges as long as women...
[Edited on 6-7-2008 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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solo
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As stated in my last post , I was wrong, ....so let's move on.....solo
Edit
"........let's deal with the question at hand, not with your intuitive insights of precursors"
Sounds sarcastic to me. Anyway, I'm going to have to assume that to be the case if/until I get an answer.
........no you're right it is sarcasm.....solo
[Edited on 7-6-2008 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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solo
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| Quote: | Originally posted by Klute
You've still got sodium acetate and 2-phenylethanol there..
C6H5-CH2-C(O)-O-CH2CH3 --NaOH--> C6H5-CH2-COO-Na+ + CH3-CH2-OH
I think a hour or two reflux with 10% excess base in ethanol/H2O mixture would be just fine... The recation could be folowed by TLC, and the formed
phenylacetate should be too sensitive to excess base, even with heating.
Is phenylaectic acid a solid? If it isn't too soluble in water, you could even distill off EtOH/water until reaching H2O's bp, and then cool and
acidify with conc. acid to precipiatte the phenylacetic acid..
If your ester is pur enough, there wiouldn't much needed is recrystallizing the phneylacetate,a s any trapped abse would be neutralized by the acid,
and even after acidifying a recrysatllized phenylacetate, you will still have sodium/potassium sulfate/chloride to remove, so you would better be off
purifying the acid if it is more practical (distn?).
I guess the ester must smell nice, I'ev heard the acid itself is pretty bad smelling! |
Actually the phenylacetic acid will precipitate out and the other salts will stay in solution ..... sodium sulfate will be washed off y soaking the
phenylacetic acid in water a couple of times then allowing it to dry well before use.
Note: As a point of interest ...all the esters of acetate , the methyl , ethyl propyl and many more will produce the phenylacetic acid via hydrolysis
and the respective alcohol, be it methyl ethyl propyl....etc.
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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kmno4
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Ethyl phenylacetate hydrolyses quickly (2-3 hours) in excess of 20% NaOH under reflux. No TLC is needed, just layer of ester disappears completely in
the end of reaction.
To reduce time of reaction, small (10%) amount of any alcohol can be added - it increases solubility of ester.
Interesting - isopropyl phenylacetate reacts much slower with NaOH.
Both: ethyl and isopropyl ester possesses honey like smell. Personally, I feel associations of this smell with some kind of candies 
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