ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
ACID-CATALYZED ESTER FORMATION
I want to ask about the ideal method for ester formation from benzoic acid
the problem that I use abolute ethanol and sulfuric acid and make reflux for 7 hr but only small amount of acid converted to ester i leave reaction
for secod day crystals formed perhaps it is of ester
i do not know whether to continue reflux or make separation between acid and ester and how i will make such separation and how to deal with acid after
that
|
|
|
bbartlog
International Hazard
Posts: 1139
Registered: 27-8-2009
Location: Unmoored in time
Member Is Offline
Mood: No Mood
|
|
Ethyl benzoate ester is liquid at room temperature. Whatever your crystals are, they aren't the ester you're after. BTW, how do you know that only a
small amount of acid was converted to the ester?
More generally, it would be nice to know things like the temperature you tried to do this at, the concentration of your sulfuric acid, and the amounts
of the reagents.
|
|
|
crazyboy
Hazard to Others
Posts: 436
Registered: 31-1-2008
Member Is Offline
Mood: Marginally insane
|
|
What were your proportions? I usually use about 5g of carboxylic acid, 50ml of alcohol and 6ml of sulfuric acid, plus a few boiling stones and a water
cooled reflux cndesor. Then I just let it reflux occasionally adding ice cubes to keep the water cool. For Fischer esterfication I find near 100%
conversion in 4 hours.
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
Sorry dr BTW---what does it mean
I use 1ml conc sulfuric acid and 24 ml absolute ethanol for esterificaiton of 4 gm of 4-chloro-3-nitro benzoic acid
but i want to ask can i use methanol and is it nessecary to be absolute thanks alot
|
|
|
Sedit
International Hazard
Posts: 1939
Registered: 23-11-2008
Member Is Offline
Mood: Manic Expressive
|
|
It means By The Way(BTW).
What do you mean can you use MeOH? If thats the Ester you want then you can. You do understand how this reaction takes place don't you? The mechanics
of the reaction are fairly simple.
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
|
|
|
medchem
Harmless
Posts: 41
Registered: 12-12-2009
Member Is Offline
Mood: No Mood
|
|
@andlos, electron-withdrawing groups, like nitro group, on the aromatic ring of benzoic acid hinder esterification. May be because of that you are
getting low yield while putting for short time. (though for nonsubstituted it will be completed within few hr). So its better you put more time.
You can get precipitate on cooling which can be separated by filtration.
Reference below has done the esterification of the compound you have mentioned. Please refer the following article.
http://pubs.acs.org/doi/abs/10.1021/cc0499486 (for method)
http://www2.heidelberg.edu/depts/chm/fischer.html (good for general understanding)
|
|
|
Nicodem
|
Thread Moved
19-12-2009 at 02:23 |
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
ANDLOS, please learn to UTFSE. There are some examples of methyl and ethyl benzoate synthesis on this forum, as well as many more in the literature.
Fischer esterification in general is often discussed here.
Also, you seem to have not even bothered to read anything about what you are doing. Such an attitude can be dangerous when what you are doing is
chemistry related. At least read the Esterification chapter in Kirk-Othmer. That is a good review on the subject for a beginner.
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Nicodem  | ANDLOS, please learn to UTFSE. There are some examples of methyl and ethyl benzoate synthesis on this forum, as well as many more in the literature.
Fischer esterification in general is often discussed here.
Also, you seem to have not even bothered to read anything about what you are doing. Such an attitude can be dangerous when what you are doing is
chemistry related. At least read the Esterification chapter in Kirk-Othmer. That is a good review on the subject for a beginner.
|
why dr you say that i didnot read thing i read too much but i am realy beginnter and try to learn ,
hope not to bother you
and realy i need help from you and all member
sorry dr what is meant by UTFSE
thanks dr
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by crazyboy | | What were your proportions? I usually use about 5g of carboxylic acid, 50ml of alcohol and 6ml of sulfuric acid, plus a few boiling stones and a water
cooled reflux cndesor. Then I just let it reflux occasionally adding ice cubes to keep the water cool. For Fischer esterfication I find near 100%
conversion in 4 hours. |
thanks alot dr
|
|
|
medchem
Harmless
Posts: 41
Registered: 12-12-2009
Member Is Offline
Mood: No Mood
|
|
this shows you are not a search engine-philic. Just type the word in google, bing or yahoo search engine, you will get the meaning.
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by medchem | | this shows you are not a search engine-philic. Just type the word in google, bing or yahoo search engine, you will get the meaning. |
UTFSE = using the freeking search engine
is that right
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Nicodem | ANDLOS, please learn to UTFSE. There are some examples of methyl and ethyl benzoate synthesis on this forum, as well as many more in the literature.
Fischer esterification in general is often discussed here.
Also, you seem to have not even bothered to read anything about what you are doing. Such an attitude can be dangerous when what you are doing is
chemistry related. At least read the Esterification chapter in Kirk-Othmer. That is a good review on the subject for a beginner.
|
please dr I try to search Esterification chapter Kirk-Othmer
but i dont have access to wiley if you can help me and give me this chapter certainley
realy thanks alot
|
|
|
hissingnoise
International Hazard
Posts: 3940
Registered: 26-12-2002
Member Is Offline
Mood: Pulverulescent!
|
|
Just to be clear---it means Use the Forum (Fucking) Search Engine.
'Freaking' or 'freeking' is for wimin when they're shoppin'. . .
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by ANDLOS |
please dr I try to search Esterification chapter Kirk-Othmer
but i dont have access to wiley if you can help me and give me this chapter certainley |
I thought you said you read too much?
Attachment: Esterification & Esters (Kirk-Othmer).pdf (767kB)
This file has been downloaded 11743 times
|
|
|
ANDLOS
Harmless
Posts: 30
Registered: 13-12-2009
Member Is Offline
Mood: No Mood
|
|
Realy I am so thankful to you
|
|
|
Vogelzang
Banned
Posts: 662
Registered: 26-4-2008
Member Is Offline
Mood: No Mood
|
|
This might work if you substituted benzoic acid for acetic acid. Click to enlarge picture.
http://www.sciencemadness.org/talk/viewthread.php?tid=11828#...
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
