trinitrotoluene
Hazard to Others
Posts: 142
Registered: 17-10-2002
Location: California
Member Is Offline
Mood: paranoid
|
|
extraction of acetlysalicylic acid with some strange results
8 days ago I crushed 125 asprain pills and powdered them.Then I dissolved the powder in 500ml of 70% isoproply alcohol. After there dissolved I did
some stirring then let it sit over night. The insoluable filler will sind to the bottom so I can extract the alcohol with the acetlysalicylic acid
dissolved in it. To extracted the stuff and left it on a beaker for 5 days. After 5 days there was 150ml of the alcohol left. But alot of
acetlysalicylic acid crystals had deposited on the edges. So yesterday I boiled it. I had to go somewhere so I wasnt done I had 50ml left. Today an
hour ago I decided to boil away the rest.So I put it onto a hot plate turned it on max then sit tight. For some strange reason the stuff had turned
solid last night but as I boiled the studd liquidified I can smell fumes of isoproply alcohol. Then the stuff turned yellow. And now I smell acetic
acid. Then I grabed some PH paper and it read that its acidic. For some reason it had changed to acetic acid or what I suspect. Any explanations?
Edit: Corrected spelling in title
[Edited on 14-10-2004 by chemoleo]
TNT
|
|
|
kingspaz
Hazard to Self
Posts: 55
Registered: 23-7-2002
Location: UK
Member Is Offline
Mood: No Mood
|
|
ASA is an ester of SA and acetic acid. thats why it smells of vinegar. since you used 70% alcohol you have 30% H2O which can hydrolise this ester back
to SA and acetic acid. it's hydrolised much more readily than aliphatic esters because in the SA-O-CO-CH3 bit the C in the middle is much more
polarised because of the presence of the delocalised system withdrawing electrons. thus the a lone pair on H2O can more easily make an attack. well
thats what i think! any corrections?
|
|
|
Polverone
Now celebrating 21 years of madness
Posts: 3186
Registered: 19-5-2002
Location: The Sunny Pacific Northwest
Member Is Offline
Mood: Waiting for spring
|
|
Yes, it's been hydrolyzed. But I wouldn't say it's more readily hydrolyzed than aliphatic esters. Many simple esters aren't even stable toward cold
water. Next time try extracting with hot acetone instead of 70% IPA.
|
|
|
Microtek
National Hazard
Posts: 872
Registered: 23-9-2002
Member Is Offline
Mood: No Mood
|
|
Also, avoid heating as this tends to promote hydrolysis. The result of using ethanol at the boiling point will often give a non-crystalline solid that
is unsatisfactory for some applications.
|
|
|
Darkfire
Hazard to Others
Posts: 292
Registered: 3-1-2003
Location: California
Member Is Offline
Mood: Wondering
|
|
I also had something similar happen to me exept when i heated it it burn t giving of a very nasty colorless gas, it acted like a mild hcocking agent,
any idea what this could be?
CTR
|
|
|
trinitrotoluene
Hazard to Others
Posts: 142
Registered: 17-10-2002
Location: California
Member Is Offline
Mood: paranoid
|
|
Maybe the nasty colorless gas could be acetic acid. Thats what I got last time.
TNT
|
|
|
Gnown
Harmless
Posts: 1
Registered: 22-8-2003
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Extraction of Acetylsalicylic Acid
I tried the same thing, except I used absolute ethanol to extract the ASA. I too had a real problem with the acetic acid fumes and found it was
extremely difficult to get rid of all the acetic acid present.
I intended to hydrolyse the stuff and when I did so, I found it just made things worse, since it now smells like it contains salicylic acid, acetic
acid AND ETHYL SALICYLATE!! Just great! Oh well...
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
