L_jamf (Stranger)
06-23-03 21:40
No 442008
      ammonium acetate preparation  Bookmark   

i'm wondering about how to prepare anhydrous ammonium acetate from non-flagged reagents. i can't find a recipe laying around, so i suppose it's rather easy.

after utfse, i found one post that suggested bubbling ammonia through acetic acid, and then evaporating to recover ammonium acetate. 

however, I have concerns about handling the ammonia gas, and knowing when the acetic acid is used up and the bubbling should be stopped. 

also, would the residue be pure ammonium acetate?

as an alternate method, could ammonium hydroxide solution be reacted with dilute acetic acid and the result evaporated to obtain the ammonium acetate?

and is there a method to make it anhydrous (i am assuming just heat it to drive off the water).

how suspicious / watched is the reagent?  is it safe to order it from a chemical supplier or better to make it?

internal, eternal, exothermal, infernal burning, the present
 
 
 
 
    SPISSHAK
(Hive Addict)
06-23-03 22:05
No 442014
      Ammonium acetate is the stuff they use in...  Bookmark   

Ammonium acetate is the stuff they use in those hotpacks thatyou snap a ring and it cystallizes and gives off heat they are hand warmers.
 
 
 
 
    El_Zorro
(Hive Addict)
06-24-03 07:13
No 442109
      If you want to make ammonium acetate, then all  Bookmark   

If you want to make ammonium acetate, then all you would have to do is mix a solution of ammonium hydroxide and a solution of acetic acid, then evaporate to get the ammonium acetate.  The only problem is, if you need it anhydrous, then that way just won't do.  In order to get rid of the water, then you would have to heat it, but the problem is, when you heat the ammonium acetate up high enough to drive off the water, then it will dehydrate into acetamide.  So you have to use anhydrous ammonia and glacial acetic acid.  So just bubble your ammonia gas into your glacial acetic acid.  I don't know how soluble ammonium acetate is in GAA, so it might even immediately precipitate from the solution.  But even if it doesn't you won't use up all of the GAA because if you did, then you would end up with a solid chunk of ammonium acetate.  So just bubble it until it becomes really viscous, or until it becomes too thick with precipitate to work with, then just evap off the excess GAA.

Oh and don't forget, the GAA+NH3 reaction might get a little hot, so you might use an ice bath.

It is seductive, way too seductive.             -Eleusis
 
 
 
 
    josef_k
(Hive Bee)
06-24-03 15:14
No 442161
      If you wan't to use the ammonium acetate as a...  Bookmark   

If you wan't to use the ammonium acetate as a catalyst for the knoevegel (sp?) reaction, you don't strictly need anhydrous, but it is ofcourse better. I've gotten away with just mixing undistilled oil of bitter almonds, nitroethane, 98% acetic acid and 24,5% ammonium hydroxide, and still got a reasonable yield  (40g p2np from 50ml oil of bitter almond).
 
 
 
 
    karl
(Hive Bee)
06-24-03 15:16
No 442162
      The problem with just bubbling the GAA is that  Bookmark   

The problem with just bubbling the GAA is that its all going to get blocked with solids unless you intend to use this as a catalyst in GAA solvent in the first place.
The decomposition into Acetamide isn't all that significant until you reach a temperature of ~180'C and then the decomposition isn't what you would call high yield. I would guess it would be fine if you gently heated under reduced pressure to dehydrate it. Then again I could be wrong.
 
 
 
 
    hypo
(Hive Addict)
06-24-03 18:46
No 442203
      hmmm...  Bookmark   

what about this:

NH4OAc(s) ---> AcOH(l) + NH3(g)

i imagine this could be a problem, since NH3(g) is constantly
removed from the equilibrum. if this is not a problem, then
why?
 
 
 
 
    cthulhujr
(Hive Bee)
06-25-03 05:10
No 442319
      read an acetimide synth someplace where the...  Bookmark   

read an acetimide synth someplace where the first step was heating ammonium carbonate with GAA 90C until it becomes acidic.??..wouldn't the resulting compound be ammonium acetate...sounds like it 
From there to produce acetimide required several hours at 200+C under pressure or something.
If that is actually the case perhaps the acetate could simply be melted at 115C, and recrystalized...similarly to drying sodium acetate, with no fear of acetimide by-products. 

take this with a grain of salt...swim is a dumbshit for the most part and may be way out there on this...

not to mention how hard is ammonium carbonate to come by...plus it sounds like it's rather a vile thing to handle.

Spissak...sodium acetate is definitly in hand warmers...not sure on ammonium acetate.

Iń-R'lyeh! Cthulhu fhtagn! Iń Iń!
 
 
 
 
    El_Zorro
(Hive Addict)
06-25-03 07:32
No 442344
      Re: NH4OAc(s) ---> AcOH(l) + NH3(g) i ...  Bookmark   


NH4OAc(s) ---> AcOH(l) + NH3(g)

i imagine this could be a problem, since NH3(g) is constantly
removed from the equilibrum. if this is not a problem, then
why?





Because the reaction between acetic acid and ammonia is exothermic.  For the reaction to go the other way, it would require added energy to do so.

But that kinda makes me think, because all I really know is that the reaction between an ammonium salt and an acid is exothermic.  And one reason for that is most definately the formation of water in the reaction.  So if the ammonia atom isn't protonated, and there's no water to be formed, then will the reaction be exothermic, or will it happen at all?  I'd bet it will, but now it's just got me thinking.crazy


It is seductive, way too seductive.             -Eleusis
 
 
 
 
    lugh
(Moderator)
06-25-03 13:22
No 442415
      Answer is in the Search Engine  Bookmark   

You need to learn to use the search engine better, the answer to your question has been here for years in Post 71294 (lugh: "Re: Anhydrous or not....", Methods Discourse)



Chemistry is our Covalent Bond
 
 
 
 
    L_jamf
(Stranger)
06-25-03 17:25
No 442450
      does this imply...  Bookmark   

does this imply that i can prepare the ammonium acetate a la the ammonium hydroxide and acetic acid method then dessicate it via addition of silica gel (as per lugh's referenced post) ? or should this only be done when i have ammonium acetate that was previously anhydrous?

lugh: apologies for poor usage of TSFE.

internal, eternal, exothermal, infernal burning, the present
 
 
 
 
    hypo
(Hive Addict)
06-25-03 18:16
No 442462
      heh...  Bookmark   

sorry blush
 
 
 
 
    lugh
(Moderator)
06-25-03 23:04
No 442522
      Dehydration  Bookmark   

Hydrated ammonium acetate can bee prepared by a number of methods, the search engine should reveal several if one uses it wink According to the referenced Talanta paper, decomposition doesn't begin until the temperature exceeds 60░ C, thus vacuum dessication as suggested would dehydrate it within a reasonable amount of time smile The silica gel dessicant is used in a separate container in the dessicator, just like any other dessicant, as is explained in any good lab manual such as the ones on Rhodium's website and several posts here that can be found using the search engine wink

Chemistry is our Covalent Bond
 
 
 
 
    L_jamf
(Stranger)
06-26-03 04:18
No 442582
      thanks lugh  Bookmark   

thanx lugh, i'll work on using the tools available. redundancy is painful, especially when repeated.

internal, eternal, exothermal, infernal burning, the present