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YT2095
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| Quote: | Originally posted by not_important
Note that in Forensic Investigation of Clandestine Laboratories (Donnell R. Christian) acetic acid is tagged with "No legitimate home or
hobby use". |
well that`s just Pathetic! I use mine for my chili sauce (and could prove it), in fact I bought it Specificaly for that purpose.
so That shoots That arg right up the a$$.
damn these "know it all, know not a lot" do gooders
\"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)
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Magpie
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| Quote: |
Note that in Forensic Investigation of Clandestine Laboratories (Donnell R. Christian) acetic acid is tagged with "No legitimate home or hobby use".
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I don't see how Christian can say this. Isn't black & white photography a legitimate hobby? Then again if you are being paid by the Feds to
publish a study you will say whatever they want you to say.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Nicodem
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| Quote: | Originally posted by Furch
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. |
You really should have a talk with your supplier, since I'm quite sure he mixed up something. Where I live one needs to sign all kind of stupid forms
when ordering SOCl2 and then wait for a couple of months for the papers being processed and the chemical delivered. This is because SOCl2 is put on
several lists of regulation due to atmospheric and environmental hazards it posses. Acetic acid is one of the commonest solvents in chemistry and it
takes only a couple of days for delivery and no paper work whatsover. Actually, one can even buy it in pharmacies.
Anyway, it is simply stupid to use SOCl2, not only because of the price difference and self poisoning risks, but like I already said, also because it
is impossible to get dry acetic acid by it. You would always get a pretty concentrated solution of HCl in acetic acid contaminated also with acetic
anhydride and SO2. The anhydride can be removed by distillation, but the HCl not. It would even be way more wise to use phosphorous(V) oxide.
…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!
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bio2
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...."No legitimate home or hobby use".........
LOL, guess this lead acetate is illegitimate then.
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Furch
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Alright folks... Thanks for contributing. This thread is closed for my part.
- Furch
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not_important
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| Quote: | Originally posted by Magpie
I don't see how Christian can say this. Isn't black & white photography a legitimate hobby? Then again if you are being paid by the Feds to
publish a study you will say whatever they want you to say. |
There you have it - a government picks an enemy to overcome, one where emotional response will be easy to elicit in some of the public, then produces
documentation as to how evil the enemy is and why it must be fought. Anything contradicting the (forgone) conclusions will be ignored, discredited, or
those expressing the views will be described as mislead and out of touch with current situation. Questionable to bogus statistics will be given as the
fight 'progresses'.
I have an aquaIntance in the US who does B&W prints, often using older chemistries. It became difficult to get pyrogall but they found a
work-around to obtain it. But their local photosupply store stopped carrying acetic acid, only had pre-mixed stuff. When she tried to order GAA, she
was informed that she as an individual or small business could not buy it for reasons very much like those in FICL; the supplier didn't want the
trouble of tracking to keep the Federal government happy and local or regional laws were even more trouble.
So that is one reason people try to make GAA from vinegar or air oxidation of home brewed ethanol.
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bio2
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So what is the best way to remove water from Acetic Acid that is near concentrated.
Ullmans mentions urea but no further info or references are given.
Carbamide doesn't form a hydrate but forms an acetyl among many other compounds. Anyone familiar with this?
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jack-sparrow
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Actualy I am distilling 6 kg of little wet acetic acid (1-2 % water). I distill the crude over 6 feet fractionating column filled with glass helices.
The water come out first. You distill until the temperature at the still head is not 115 degC. I assume one can make such a distillation column with a
PVC pipe filled with broken glass (or glass beads).
Anyway, my column contains approx. 30-40 theoretical plates. I think you need ca. 20 theoretical plates to separates two component with a 15 degC
difference.
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gsd
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| Quote: | Originally posted by bio2
So what is the best way to remove water from Acetic Acid that is near concentrated.
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I think the best way to remove water from 95+ pure AA is to add Acetic Anhydride to it. ( 100 % Acetic Anhydride = 117 % AA)
This may not be feasible for home/hobby chemist due to lack of availability of AAn. However industrially it is the best option.
gsd
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jack-sparrow
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gsd : you are right !
I just proposed the distillation method because that is the one that I use. I am preparing 6 kg of acetic acid-d4 (deuterated) and acetic anhydride-d6
is just too expensive.
Newbies :
DO NOT prepare glacial acetic acid from scratch with pure acetic anhydride (which is a controlled substance) and water because :
1- You start with 2 phases
2- The reaction is exothermic
3- when the reaction starts, the produced aa increase the solubility at the phases interface and cause with the ongoing exotherm a drastic rise in the
reaction rate.
4- boom
Use acetic anhydride to remove a LITTLE (5-10 % max) water in acetic acid.
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bio2
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This is the excerpt from Ullmans I mentioned.
"A way to obtain pure acid is to add urea or potassium acetate to the acid. Then, glacial acetic acid can be distilled."
The Na or K acetate method is well known however the use of urea deosn;t seem well documented. At least I have been unable to find any further
information or details of the process.
Urea being readily available infor cheap in a pure state may have some advantages depending on how much water can be feasibily removed.
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S.C. Wack
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*bangs head against wall*
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bio2
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You may stop banging now, LOL.
Search and yea shall find.
......Abstract of GB312173
"312,173. I. G. Farbenindustrie Akt.- Ges. May 18, 1928, [Convention date]. Right to Patent relinquished. Acetic acid is obtained from its aqueous
solutions by first partially concentrating (to about 60 per cent) and then adding a substance, such as urea or other amide, p-toluidine, or an alkali
acetate, which forms an addition compound with acetic acid, removing the remaining water by distillation or crystallization, and then decomposing the
addition compound by heating to obtain the acid. The preliminary concentration is effected by cooling to -26 C. while stirring, precautions being
taken to avoid supercooling, for which purpose ice crystals may be added. The ice crystals are separated, and may be washed or pressed to recover
adhering acid. In the examples, (1) acetic acid of 20 per cent is run into acetic acid of 60 per cent, with stirring, at -26 C., the ice crystals
being washed with 20 per cent acid; the 60 per cent acid thus obtained is treated with urea and cooled, with stirring, to about 0 C. and below: the
addition compound is separated centrifugally at -17 C. and the acid is recovered by heating in a vacuum, the urea being then dissolved in the
mother-liquor, concentrated until the solution contains acetic acid of 60 per cent, and used in the next operation; (2) acetic is concentrated to 60
per cent as above, the ice crystals being pressed to recover the adhering acid, leaving a solid block of ice; anhydrous potassium acetate is added to
the 60 per cent acid and the mixture is cooled to -24 C. with stirring; potassium acid acetate with 2 molecules of acetic acid separates, and is
heated in a vacuum to recover the acid; the mother-liguor contains potassium acetate and 38 per cent acid, and is returned to the process for the
production of 60 per cent acid."...........
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bio2
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OK, here is the jist of it leaving out all the freezing eutectics etc
which are not really necessary as I see it. Think I've found my way to convert the fractionated 80-90% acid that is piling up
into GAA simply. The unreacted portionwhich is now dilute can then be refractionated.
The K Acetate method is similar except less user friendly as requires cooling to -24 to crystallize out the addition compound.
This is my paraphrased excerpt from the pertinent part of the experimental. Starting with 60% minimum acid.
>>>>>>>> 150 parts urea added to 500 parts 60% acetic acid. On cooling to 0deg CO(HN2)2.2CH3COOH precipitates.
271 parts salt are obtained which when distilled in vauum yield 177 parts GAA. .>>>>>>>>>>>>>>>>
Well boys, what do you think??
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Magpie
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It's easy enough to make 60% acetic with H2SO4 or even HCl. I think what you have paraphrased is worth a try. I'm a little concerned with the need
for centrifugation to isolate the crystals. I do have a small centrifuge, however. 
The single most important condition for a successful synthesis is good mixing - Nicodem
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bio2
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Vacuum filtering quickly at 0 deg then placing a rubber glove or plastic bag over the buchner and letting it press down with the pump running at full
vacuum for a while should work just fine.
If more drying is needed the crystals can be washed on the filter with a dry solvent that is miscible with water then placed in a vac dessicator with
the pump running till they are dry.
Centrifuging would be faster and easier if available.
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not_important
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You may want to use a plastic bottle or jug to make an ice jacket for the Buchner, seeing as the method says -17 C and lower. Good one to run out of
doors in winter.
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garage chemist
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In industry they centrifuge a lot of things which can be filtered on a buchner funnel when working in laboratory scale.
Generally, a buchner funnel (or sintered glass filter) can be used nearly always when a centrifuge is called for. You just have to squeeze out the
crystals with e.g. the bottom of a beaker in order to remove the mother liquor.
Of course you need a filtering flask and a vacuum source (aspirator works fine).
[Edited on 16-10-2006 by garage chemist]
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bio2
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....method says -17 C and lower.....
It also says at 0 deg "nice crystals are obtained.. Based on this the eutectic point should not be required with perhaps some yield decrease. Just
have to try it who will be the first?
Will be some weeks before I have the time
The eutectic point is -17 which is not obtainable by simple (ice/salt) bath and complicates the whole procedure. The jacket idea is a good one with
the ice salt about -5 to -10 is practically obtained.
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Magpie
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My kitchen freezer comes down to -26C when turned up to max cooling. But keeping everything cold once you remove it is another matter.
I have some 60% acetic acid but no urea. And I don't want to have to buy a 50lb bag to get some. So it will be awhile also for me before trying
this.
The single most important condition for a successful synthesis is good mixing - Nicodem
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bio2
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... I don't want to have to buy a 50lb bag to get some. ........
The agricultural grade might be only $10 for
this much. Then recrystalize it.
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