"There is no azeotrope with GAA and water"
- after several databases on azeotropes there is.
"Freezing out pure acetic acid won't work either. Have you tried this? I could not get it to work with 80% acetic acid."
- of course freezing out does not work well with 80% acetic acid. As I told before, you have to distill it before and freezing out is the last step to GAA. Freezing out is a little tricky as it needs patience for not to cool down to fast and to deep and to include water in the crystal lattice of the frozen acetic acid. Vacuum filtration is a "must do".
I used freezing out quite often in the past.
Reposting or linking to this diagram you spoke about would be highly appreciated.
regards
rAg
EDIT: After some deeper investigation onto this I came to the conclusion that "freezing out" is a useful way to concentrate acetic acid with an concentration over 95%.
But it actually seems that although acetic acid forms an azeotrope with water it is not feasible to distill this azeotrope out for what reasons ever, so simple distillation of the named 80% acetic is no way. Azeotropic distillation might be - benzene, chloroform, DCM should work, but after consulting some books of practical wisdom (written before 1900
![Smiley :)](https://thevespiary.org/talk/Smileys/default/smiley.gif)
) I came to the conclusion that Chromic is right on the point when he says that the best way for concentrating the 80% acetic acid to GAA is by forming an acetate followed by distillation with conc. H2SO4.