The Vespiary

The Hive => Chemicals & Equipment => Topic started by: claude on September 01, 2004, 09:02:00 AM

Title: GAA from > 75% acetic acid solutions
Post by: claude on September 01, 2004, 09:02:00 AM
GAA is not equally easy to find OTC in all countries. In some places, only the 75% or maybe 80% are available.
So, I've read numerous post concerning the drying of aqueous solutions of acetic acid, particularely for concentration superior to 75%. And the use of a drying agent like MgSO4, or CuSO4 is rarely mentionned. But CuSO4 is said to work for formic acid, when concentration superior to 77% (which is the azeotrope water/formic acid) is needed. So, maybe it can work for acetic acid too ? But, that's right, a big quantity of drying agent is needed :

For exemple for 1L of 75% solution of acetic acid : the quantity of water is approximately 250g i.e. 250/18 = 13,9 mol.
Each mole of CuSO4 crystallize with 5 moles of H2O. So, too absorb all the water, we need a minimum of 13,9/5 = 2,78 mol of CuSO4 i.e. 2,78 X 159,6 = 443,7 g of CuSO4.

It's big, but it's possible, what's your opinion ? Informations that prove that doesn't work ?
Title: You can azeotropicaly dry acetic acid
Post by: Nicodem on September 02, 2004, 01:55:00 AM
You can azeotropicaly dry acetic acid: (

You can make some n-butyl acetate from your 75% acetic acid and n-butanol.

Title: Thanks Nicodem
Post by: claude on September 02, 2004, 04:01:00 AM
This process is technically interesting, but unless you have already n-butyl acetate, it involves a new esterification reaction to form it from acetic acid and n-butanol. Followed by the azeotrope drying, including a distillation.
So, if the method of drying agents can work, it's a good point. If it's a dead end, then I will look in the azeotrope drying way.