I was wondering if i was to use a fractionating column and distill 80% acetic acid and then dry the resulting distilate with MgSO4, would i get close
enough to GAA that a second fractional distillation would drive off the last remaining waster?
It seems plausible. .
Thxaga - 9-8-2015 at 07:58
Depends how close you need to be.
Easiest way is to react it with bicarb to make sodium acetate, then distill with conc sulphuric to give very nearly 100% water free GAA.
Breaking these azeotropes is really not easy at all.blogfast25 - 9-8-2015 at 08:32
I was wondering if i was to use a fractionating column and distill 80% acetic acid and then dry the resulting distilate with MgSO4, would i get close
enough to GAA that a second fractional distillation would drive off the last remaining waster?
It seems plausible. .
Thx
I'm not sure MgSO4 would be suitable here...
[Edited on 9-8-2015 by blogfast25]DrWhooo - 9-8-2015 at 09:02
I read somewhere that megalomania's method to GAA was through "drying" 80% acetic acid with h2so4 dripping in to it and then fractionally distilling
to close to GAA and repeating the process to get to 99%!
I just cant seem to find the reference and the way to do it...dowloaded it from the web but any reference to Acetic acid comes down to sodium
acetate...
Yes, may as well use up a load of conc sulphuric acid i guess, and distill it with that.
Edit:
I just checked, and it appears that sodium acetate doesn't form a hydrate when it crystallises, so can be completely dried.
That way you got less water to get rid of = less concentrated H2SO4 required, and baking soda is cheap.
You also get sodium sulphate left in the boiling pot as a by-product.
Oh ! Boiling concentrated sulphuric acid can be dangerous.
[Edited on 9-8-2015 by aga]DrWhooo - 9-8-2015 at 11:49
So let see if i got this straight...
I can get GAA from sodium acetate that i make with 80% acetic acid and baking soda, and i can "boil" this to dryness , and then put that in a RBF and
have concetrated h2so4 drip on it and then distill that to get GAA?
Breaking these azeotropes is really not easy at all.
My understanding is that the acetic acid/water system has no azeotrope and is merely extremely difficult to separate by distillation. This system is
actually quite interesting, as the two components have a moderately large difference in boiling point (18°) and yet are almost impossible to separate
via fractional distillation.
I just checked, and it appears that sodium acetate doesn't form a hydrate when it crystallises, so can be completely dried.
Where did you get that idea? I had a quick look around and I'm pretty sure that sodium acetate crystallises as the trihydrate, even from a hot saturated solution. It CAN be dried out prior to distillation with H2SO4, which as you said is recommended
as it reduces the amount of acid needed.
It is worth noting however that the sodium acetate turns into a mass of rigid foam during drying, which is very annoying to stuff down the neck of a
flask prior to distillation
Sodium acetat
DrWhooo - 10-8-2015 at 05:12
Thx guys for all the good info..really appreciated! ☺
Iv decided that i will make Sodium Acetate from the 80% acetic acid and dry it in an oven to 150c for about 2 h untill it is anhydrous and then i a
RBF add Sodium hydrogen sulphate with the dried Sodium acetate and then distill that...
Want to stay away from H2SO4 as much as possible...
By the way, apart from probably stinking the house down...is GAA a dangerous substance in terms of inhaling and maybe dripping on clothes or skin?
Thx again..Metacelsus - 10-8-2015 at 05:55
Inhaling vapors is very unpleasant, and somewhat dangerous. If you get it on your skin, immediately wash it off. Otherwise, it can burn you.chornedsnorkack - 10-8-2015 at 23:31
Is remaining water easy to separate by freezing?Sulaiman - 11-8-2015 at 00:01
A lot of us live in a country where ordering acetic anhydride has unwanted side reactions involving hand cuffs and extended stays in less than
welcoming places with bars on the windows.
Although it is a list 2 chemical in the US, anyone willing to sell
to individuals is likely a DEA sting operation (some exceptions in suppliers that regularly sell to individuals and allow special order chemicals).
This is more highly restricted in some countries due to its use in making heroin (not just methamphetamines).
PS. if you can order acetic anhydride you can order GAA cheaper. The supplier I previously mentioned has it for a quarter of the price that acetic
anhydride sells for.
