| Pages:
1
2 |
Furch
Hazard to Others
Posts: 130
Registered: 8-10-2006
Member Is Offline
Mood: No Mood
|
|
Drying wet acetic acid.
Greetings all,
I've got a bottle of presumably wet acetic acid, and I need glacial ditto... I assume it has a concentration of about 90% or higher (I haven't
titrated it yet).
One way to go about the problem is to perform an azeotropic distillation, but I can't do that.
Now, if I would've had some Ac2O, I could've made AcO from the water in the solution... But I don't have any Ac2O, so I can't do that either.
What I do have, on the other hand, is SOCl2 (thionyl chloride). As we all know, SOCl2 reacts more or less violent with water, forming HCl and SO2,
which are poisonous gases... That's not a problem for me however.
The above mentioned method would rid the solution from water, and leave more or less no trace behind, as the products of the reaction are gasses...
However before I start to fuck the whole thing up, I would like someone elses thoughts on the subject. So what do you say? Is this a feasible method
to rid water from water contaminated acetic acid? My worst fear is that the reaction is too violent, and that it can't be done for that reason...
Thanks in advance!
- Furch
|
|
|
evil_lurker
National Hazard
Posts: 767
Registered: 12-3-2005
Location: United States of Elbonia
Member Is Offline
Mood: On the wagon again.
|
|
IIRC if you have 10% water contamination you can distill approx 20% of the volume off and get pure glacial... the azeotrope will come off first
leaving pure glacial behind.
This only works with high concentrations of acid though.
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
Furch...please do not waste SOCl2 on cleaning up acetic acid. If I had SOCl2 I'd probably be having an orgasm right now. You can always buy glacial
at the photo shops.
Secondly, I'm sorry Evil Lurker, but there is no azeotrope. Gmehling's 50 odd citations say so. Please see thread "acetic acid/sodium hydroxide" by
Hermes T.
Furch, also please see the above thread. I struggled like crazy just to get 92.5% acetic acid from 87% acetic acid using 2 fractional distillations.
I did this just to see what was possible with my equipment.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
I heard the azeotrope was 96% H2O, and that it's certainly possible to get the AcOH out by distillation, but the boiling and vapor (analog of solidus
and liquidus respectively) temperatures are so close that it's very impractical.
Tim
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
Furch, why not just do it on a small scale and find out? If we tell you not to, that it will never work, will you believe us and never try it?
It is true that azeotropic distillation is used as a good way to get GAA, but the not-water part of the azeotrope is some added component, not acetic
acid. There is no need to get into not-SOCl2 here, there are many acetic acid threads. I'm not sure how many exactly we need. It's all been gone over
already, see? A Google search of two acetate addition compound patents that I was aware of brought up this thread. I suggest reading leu's patents at espacenet.
|
|
|
YT2095
International Hazard
Posts: 1091
Registered: 31-5-2003
Location: Just left of Europe and down a bit.
Member Is Offline
Mood: within Nominal Parameters
|
|
I`m not certain, but I beleive the addition of P4O10, should lock up the excess water quite nicely.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
|
|
|
Nerro
National Hazard
Posts: 596
Registered: 29-9-2004
Location: Netherlands
Member Is Offline
Mood: Whatever...
|
|
Just curious, would anhydrous CuSO4 or MgSO4 do the job?
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
|
|
|
YT2095
International Hazard
Posts: 1091
Registered: 31-5-2003
Location: Just left of Europe and down a bit.
Member Is Offline
Mood: within Nominal Parameters
|
|
MgSO4.7H2O loses 6 water at roughly 150c the copper salt even lower temp.
so it could be tricky as Ethanoic acid has a BP of 118c.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
|
|
|
Nerro
National Hazard
Posts: 596
Registered: 29-9-2004
Location: Netherlands
Member Is Offline
Mood: Whatever...
|
|
I really don't see why... You heat blue CuSO4.5H2O untill it's white, and then you add it to the glacial-to-be AA.
The salt absorbs the present watermolecules and you filter to remove the hydrate...
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
|
|
|
Furch
Hazard to Others
Posts: 130
Registered: 8-10-2006
Member Is Offline
Mood: No Mood
|
|
Hello again, and thanks for all the replies.
The reason I asked was because I wasn't sure on how SOCl2 will react with water... Sure, it fumes when exposed to the humidity of air, but that
doesn't say much about how it will react when the two liquids are mixed. I thought maybe you could provide me with that information.
Anyway, I will titrate my wet acetic acid and then perform the SOCl2 + H2O reaction and report the results back to you, partly for the sake of closing
this thread (as there seem to be a lot of AA related threads).
Thanks again!
- Furch
|
|
|
scientistfromdarkness
Harmless
Posts: 25
Registered: 26-6-2006
Member Is Offline
Mood: schlenk
|
|
use molecular sieve
|
|
|
YT2095
International Hazard
Posts: 1091
Registered: 31-5-2003
Location: Just left of Europe and down a bit.
Member Is Offline
Mood: within Nominal Parameters
|
|
but isn`t copper sulphate somewhat soluble in AA? I know it is a little in EtOH.
it`s something like the second step in TACC synthing IIRC.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
|
|
|
gsd
National Hazard
Posts: 847
Registered: 18-8-2005
Member Is Offline
Mood: No Mood
|
|
Acetic Acid and Water do not form an azeotrope.
The reason why industrially "Azeotropic Distillation " (with Benzene as an entrainer) is used to separate them is their "relative volatility" is very
low. Which means to make glacial AA you would need large number of contacting stages - i.e. very tall column and very high reflux ratio -i.e. very
high energy input. Hence when an entrainer like benzene is used eventhough it means 2 distillation columns the over-all fixed as well as operating
cost is significantly lower.
gsd
[Edited on 9-10-2006 by gsd]
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Using SOCl2 to dry acetic acid is not only pretty stupid considering how precious SOCl2 is, but is also very difficult. You would first have to
measure the H2O concentration to calculate how much SOCl2 you need. If you add too much you will form acetic anhydride as well. Next, you would have
to remove SO2 and HCl from the so dried acetic acid, which is nearly impossible by easy means. SO2 may be removed to some extent by vacuum, but HCl
will stay in solution. One way would be to use anhydrous AcONa and then distill, but what a waste of time and precious chemicals just to get something
so cheap like acetic acid!
Edit:
And consider that you would need almost 700g of SOCl2 to dry just one liter of 90% acetic acid!
[Edited on 9-10-2006 by Nicodem]
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
|
|
|
unionised
International Hazard
Posts: 5102
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
What?
Nobody mentioned freezing out the bulk of the acid, pouring off the water/ acid mix then re melting the purified acid. (Of course, you can always
distill the wet acid that you pour off).
I'm pretty sure that someone here would gladly swap a litre of GAA for 700 ml of SOCl2.
|
|
|
YT2095
International Hazard
Posts: 1091
Registered: 31-5-2003
Location: Just left of Europe and down a bit.
Member Is Offline
Mood: within Nominal Parameters
|
|
ok, I`ll bite *sigh* What is so special about this SOCl2?
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
|
|
|
Furch
Hazard to Others
Posts: 130
Registered: 8-10-2006
Member Is Offline
Mood: No Mood
|
|
To me SOCl2 isn't that exotic... You see, what I _need_ is GAA, not SOCl2, hence I'm not stupid for that reason. I would've been stupid if I needed
AcOH and somehow spent it to acquire SOCl2, which I don't need. Makes sense, eh?
Moving on: I titrated my presumably wet acetic acid, and came to the conclusion that it's still of high enough concentration (18.5 mol/L) to be used
for my purposes.
Anyway, thanks for the replies folks... You were great.
- Furch
|
|
|
Sandmeyer
National Hazard
Posts: 784
Registered: 9-1-2005
Location: Internet
Member Is Offline
Mood: abbastanza bene
|
|
| Quote: | Originally posted by Furch
To me SOCl2 isn't that exotic... You see, what I _need_ is GAA, not SOCl2, hence I'm not stupid for that reason. I would've been stupid if I needed
AcOH and somehow spent it to acquire SOCl2, which I don't need. Makes sense, eh?
|
Anyone who can obtain thionyl chloride can also get glacial acetic acid, it's strange that you can't, which raises the question how the hell you got
your hands on SOCl2 in the first place. One who thinks that this is a good idea shouldn't mess around with large quantities of chemicals as dangerous
and nasty as thionyl chloride, esp since operations with it easily get out of control.
| Quote: | One way to go about the problem is to perform an azeotropic distillation, but I can't do that.
As we all know, SOCl2 reacts more or less violent with water, forming HCl and SO2, which are poisonous gases... That's not a problem for me however.
|
Let us hope that you won't hurt any innocent people...
[Edited on 10-10-2006 by Sandmeyer]
[Edited on 10-10-2006 by Sandmeyer]
|
|
|
Furch
Hazard to Others
Posts: 130
Registered: 8-10-2006
Member Is Offline
Mood: No Mood
|
|
Hello Sandmeyer.
I got rather offended by your post. Usually I don't bother answering people who actually make an effort trying to insult me (I know, I know, you're
going to claim that it wasn't your intent etc.), however this time I will.
First of all... In case you didn't notice, I brought this topic up for discussion before even considering starting to experiment with it. So I have no
clue as to where you got the idea that I thought of it as a "good idea".
I don't know where you are situated, but in my country thionyl chloride is a lot less restricted than glacial acetic acid. Trust me, I know. You want
to know where I got my SOCl2? I bought it from a chemical supplier. The very same chemical supplier that denied me to purchase glacial acetic acid, on
the grounds that it is restricted for individuals to posess it without a special permit from the authorities.
Stop being an ass just because you haven't got your facts straight, Sandmeyer.
Also, stop hurting innocent people.
- Furch
|
|
|
Sandmeyer
National Hazard
Posts: 784
Registered: 9-1-2005
Location: Internet
Member Is Offline
Mood: abbastanza bene
|
|
Sorry if I insulted you, I'm in a pretty bad mood today due to some personal stuff. I just can't belive that you can buy SOCl2 and not acetic acid, it
sounds too absurd to be true. If you're gonna work with SOCl2 in appartmant and simillar (not reccomended), be prepared that nearby metal objects can
and will rust - it seems inevitable, but trap must be used to prevent this somewhat. Only an asshole will lead these reaction fumes outside -
neighbours will definitly notice. It is enough to simply open the flask briefly to stink up the whole room, doing reaction with such amounts is
something to avoid, and trap is a must.
[Edited on 10-10-2006 by Sandmeyer]
[Edited on 10-10-2006 by Sandmeyer]
|
|
|
Furch
Hazard to Others
Posts: 130
Registered: 8-10-2006
Member Is Offline
Mood: No Mood
|
|
Thanks for the tips, Sandmeyer!
Indeed it is quite odd... I was amazed myself to find AcOH not being OTC here. It's got the same restriction as concentrated sulphuric- and nitric
acid...
I work in a more or less well equipped lab with great ventilation... However that's a good point you're making, about the smell and health hazard
concerning my neighbours.
Anyway, I've got my GAA now, and I didn't have to use SOCl2 on it, fortunately... Though I might give it a try in the future just for the science of
it, on a microscale of course.
You've got my respect, Sandmeyer!
- Furch
|
|
|
bio2
Hazard to Others
Posts: 447
Registered: 15-1-2005
Member Is Offline
Mood: No Mood
|
|
..........One way would be to use anhydrous AcONa and then distill,..............
I can attest to this , however your flask will be severily damaged. Found this out the hard way!
............. but what a waste of time and precious chemicals just to get something so cheap like acetic acid!..............
Last I checked was $5.40/liter by the jug for the RA, ACS, Glacial Acid.
.................. in my country thionyl chloride is a lot less restricted than glacial acetic acid. Trust me, I know..............
Strange laws, I quess, in some countries these days!
................... you can buy SOCl2 and not acetic acid, it sounds too absurd to be true....................
Yes, it does. Even high purity CH3COOH is like water availability in the chemical industry.
|
|
|
day2knight
Harmless
Posts: 1
Registered: 9-10-2006
Member Is Offline
Mood: No Mood
|
|
HI all,
I once left a glass of vinegar in a hot room for 2 months. After that time i got some crystals at the bottom.
|
|
|
KingKarloff
Harmless
Posts: 2
Registered: 26-9-2006
Member Is Offline
Mood: Ghoulish
|
|
| Quote: | Originally posted by scientistfromdarkness
use molecular sieve |
What Molecular sieve will seperate Acetic acid and water?
[Edited on 10-10-2006 by KingKarloff]
[Edited on 10-10-2006 by KingKarloff]
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by bio2
............. but what a waste of time and precious chemicals just to get something so cheap like acetic acid!..............
Last I checked was $5.40/liter by the jug for the RA, ACS, Glacial Acid.
.................. in my country thionyl chloride is a lot less restricted than glacial acetic acid. Trust me, I know..............
Strange laws, I quess, in some countries these days!
................... you can buy SOCl2 and not acetic acid, it sounds too absurd to be true....................
Yes, it does. Even high purity CH3COOH is like water availability in the chemical industry. |
Note that in Forensic Investigation of Clandestine Laboratories (Donnell R. Christian) acetic acid is tagged with "No legitimate home or
hobby use". Given recent changes in laws in the US, and Iraq becoming a double plus ungood War to win voters with, expect the WoD to heat up and do
not be surprised if possesing or attempting to obtain chemicals so flagged will win you a trip to places you'd rather not go.
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
