Tungsten.Chromium
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Working with acetic anhydride
I've been looking into the synthesis of acetylsalicylic acid as an esterification experiment to try lately and would like to give it a go, but am a
little worried about working with acetic anhydride, mainly the vapors.
Is a fume hood absolutely required when handling acetic anhydride or could I use a respirator instead? A good respirator looks like its going to cost
me around 100-150 bucks and would be a much cheaper option for me then buying or building a good fume hood. I know the hood would have much more uses
and I do plan on building one eventually, but I'm a broke college student and don't have a ton to spend lol 
Any other input on the experiment is welcome too 
Prosit!
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byko3y
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AFAIK you can safely work with acetic anhydride until you can't tolerate it's smell. Same problems with neighbours. Your respirator won't last long
and won't really help if you have really high concentration of AA in air.
In case of fume hood you also need a filter to neutralize the AA in outgoing air, otherwise you'll probably end up with cops knocking at your door.
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gdflp
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As long as you work outside and use goggles and gloves, you should be fine working with acetic anhydride. If you get too close to the bottle and get
a strong whiff of it, your respiratory tract may get irritated temporarily, but as long as you don't intentionally inhale large amounts you should be
fine.
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Tungsten.Chromium
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Thank you for the helpful info! I'm planning on either working outside or in my garage right next to a door that opens outside with a fan going,
it'll depend on the weather.
Good to know that that the smell alone won't kill, ever since I read about the dangers when working with H2S I've been pretty careful when dealing
with anything that has nasty fumes. For working with small amounts (5ml in my case), would a respirator still be beneficial? I know it wouldn't help
if you get stuck in a thick cloud of AA, but would it prevent lung damage that could come up later down the road? OSHA lists the ceiling exposure
limit at 21mg/m3, which seems pretty low. I might just being overly cautious though.
For neutralizing it, wouldn't you just run the fumes through water to hydrolyze it to acetic acid?
Sorry if I'm being paranoid, just trying to work safe!
Prosit!
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gdflp
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With such small amounts, you should be fine, a respirator is overkill. If you are worried, have a spray bottle full of dilute sodium bicarbonate
solution, if you start getting overwhelmed by the fumes, simply spray the solution in the air and it should instantly neutralize the acetic anhydride
into sodium acetate. If you closed your garage door, my calculations say that half of your acetic anhydride, ~2.6ml, would have to vaporize to meet
the ceiling exposure limit. If you have a fan going, the concentration will be much lower than that, and acetic anhydride isn't that volatile.
[Edited on 4-24-2015 by gdflp]
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Tungsten.Chromium
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Okay, thanks for the reassurance gdflp. Can't wait to do this experiment and will definitely post back on how it goes!
Prosit!
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