Glacial Acetic Acid synthesis wo sulfuric

Once/if I add acetic anhydride to the distilled acetic solution (which is really coming at 106, I had to stand on my tippy toes to read it correctly), how long and how much heat will it take to hydrolyse it into acetic? I don't want to acetylate the amine!

Does anyone have access to a table that indicates the %h20 of an acetic solutions boiling at 106 C at sea level?

Ok, so I add a less than stoiciometric amount of acetic anhydride to the distilled solution, reflux to hydrolyse most of the water, add some drying agent, and distil?

Edit: it looks like copper sulfate is root killer at stores here so that will be the drying agent. I might be able to omit the acetic anhydride hydrolysis, although it sounds fun

Would the azeotropic distilation with ethyl acetate be easier? Acetic anhydride is not expensive compared to retail prices for anything!

[Edited on 17-12-2009 by maozim]

The CuSO4 I've seen in hardware stores definitely needs to be recrystallized before use as a reagent. The bottle I have says "95% CuSO4"... who knows what the other 5% is! Still, crystallizing copper sulfate is easy and the crystals are pretty I don't have references handy so this may be entirely wrong, but for many salts, if one recrystallized once or twice then dissolved the purified crystals in distilled water, some organic solvent like an alcohol or acetone mixed into the solution would probably bring it down as small crystals suitable for heating to an anhydrous state. Large crystals will eventually dehydrate but take a long time. CuSO4 anhydrous is a moderately strong dehydrating agent in acidic environments. My experience is that it's stronger than MgSO4 (which is more nearly neutral pH) and can be used where some of the more common agents (CaO, NaOH, etc) are inappropriate.

Here is my experience with trying to make a small amount of glacial acetic acid from sodium acetate and NaHSO₄.

5 x 50ml sodium acetate handwarmers were obtained and their contents dried for 10h at (200 C) on a frypan. The fluffy salt was collected, ground in a mortar and pestle, and then stored in an airtight container. 28.8g per 50g handwarmer, or 57.6% was recoverable. (price: $1 per 29g).

40g of this dried NaCH₃COO was added to 68g of NaHSO₄.H₂O (pHDown pool acidifier), and the two powders were ground together for 5 minutes in a mortar and pestle to achieve intimate mixing.

The whole mass was transferred to a 500ml RBF, then heated on reflux (setting =7, temp data not available but just below the point of baby oil fuming) in an oilbath for 1.5h.

After 1h, the reaction was cooled, and the rbf was connected to a West condenser, and the mixture heated to distill the product.

Product started coming off at around 100 degrees, rising to 105 degrees. (thermometer is rated to 110).

26ml of product, with a measured density of 1.037 was obtained. CRC/Wikipedia tables reported this to be between 20% and 30%, and by interpolation between these two values was found to be 28.9% w/w acetic acid.

The actual yield of acetic acid was calulated as 26ml x 1.03 x 0.289 = 7.79g

The percentage yield was calculated as Actual/ moles NaCH₃COO x Mr Acetic acid x 100%

which equals 26.5%.

I thought that this sucked, so I tried to see if I could chase out some more by adding 50ml H₂SO₄ to the spent residue in the 500mlRBF and distilling that. The still temp never rose above 100 degrees and there was almost no smell of acetic acid in the second distillation. There was a distinct smell of burnt matches to that second distillation, but not at high concentration.

Conclusion: dry distilling off acetic acid from NaHSO₄/NaCH₃COO is not viable - a large amount of reagent is used for a terrible yield. More yield might be achieved by reacting the two as solutions and then double distilling, and I may try this later, if I have time.
It would be interesting to know what happened to the remaining sodium acetate.


Puzzling.

Quote: Originally posted by Nicodem

I'm puzzled by the lack of the thinking process among certain members! Why on earth do you need to dry a 90% acetic acid if all you need it for is just a solvent for an electrophilic bromination? You could even use water as solvent, so why do you care about those 10% water?

Quote: Originally posted by Melgar

Judging from the substrate, OP clearly just wants to make some 2C-B amphetamine derivative, which he does NOT need GAA for.

Quote: Originally posted by Melgar

Quote: Originally posted by Nicodem   I'm puzzled by the lack of the thinking process among certain members! Why on earth do you need to dry a 90% acetic acid if all you need it for is just a solvent for an electrophilic bromination? You could even use water as solvent, so why do you care about those 10% water? Did nobody read this? And has nobody here learned that Nicodem rarely shows up anymore unless someone is saying something incredibly dumb? Judging from the substrate, OP clearly just wants to make some 2C-B amphetamine derivative, which he does NOT need GAA for. I mean, I guess if someone finds this thread in the future, some of these suggestions might be helpful (although some of them are way more complicated than necessary) but OP is probably long gone, on a trip to who knows where.