Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Ammonium Acetate, what went wrong
Hazard to Self

Posts: 91
Registered: 30-10-2014
Member Is Offline

Mood: No Mood

[*] posted on 1-5-2021 at 15:32
Ammonium Acetate, what went wrong

Made some ammonium acetate by naturalizing 10% ammonia with white vinegar. Boiled from 1000ml to around 50ml it turned a golden brown. It's been sitting in a beaker to finish evaporating but shows no sign of crystallization. For such a simple reaction, what went wrong?

View user's profile View All Posts By User
International Hazard

Posts: 564
Registered: 26-11-2019
Location: under the sycamore tree
Member Is Online

Mood: ambivalent

[*] posted on 1-5-2021 at 16:26

Ammonium acetate is notoriously difficult to dry (deliquescent even) and I expect you will have to continue to heat it to get it out. The brown color is probably from an impurity in the vinegar either becoming more concentrated or decomposing, although it could be the product decomposing. Another way would be to add acetone and cool the solution as low as possible.

Reflux condenser?? I barely know her!
View user's profile View All Posts By User
International Hazard

Posts: 1306
Registered: 25-3-2014
Location: Yes
Member Is Offline

Mood: No

[*] posted on 1-5-2021 at 17:14

A lot of people are under the impression that white vinegar is just acetic acid and water, but it also contains all sorts of yeast waste products. The golden brown color is perfectly normal, so no worries. You’ve got ammonium acetate, just try boiling it down to a more syrupy consistency and then chill it. It’s 5 times more soluble at 80C than at 0C, so do this correctly and you should get a massive crop of crystals.
View user's profile View All Posts By User
S.C. Wack

Posts: 2276
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 2-5-2021 at 13:41

It would surprise me if any solid can ever be obtained by boiling off water from pure solutions of ammonia and the acid...the pH of such a distillate could be interesting to follow.

"You're going to be all right, kid...Everything's under control." Yossarian, to Snowden
View user's profile Visit user's homepage View All Posts By User
International Hazard

Posts: 1015
Registered: 12-7-2020
Location: Not in USA
Member Is Offline

[*] posted on 2-5-2021 at 14:01

Some vinegar products contain only diluted acetic acid, while some contain a significant residue. I've faced both.

Ammonium acetate and ammonium formate cannot be effectively dried simply by boiling. They need to be vacuum distilled with high vacuum and low heat to prevent decomposition, and/or dried finally with vacuum desiccator. Heating too much will decompose them to acetamide and formamide.

One method is to bubble ammonia gas into pure acetic or formic acid, with inverted funnel and very effective cooling and stirring, because the reaction will generate enough heat to evaporate the acid. It will form a solid sludge, and it could possibly be diluted with anhydrous inert solvent to keep them workable, and evaporating the solvent to obtain powder form. If the intended use does not warrant anhydrous reagent, it can be used wet, just determining the approximate content, or as a limiting reagent in excess.
View user's profile View All Posts By User

  Go To Top