Flip
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Preparation of Peracetic acid
I have found a discrepancy in the online literature that needs to be accounted for, concerning the preparation of peracetic acid.
The Rhodium archive lists two different preparations, with wholly different ratios in the preparation of the peracid:
http://www.erowid.org/archive/rhodium/chemistry/peracid.html
* lists 1500 mL GAA to 325 mL 30% H2O2 ratio
http://www.erowid.org/archive/rhodium/chemistry/peracetic.ch...
* lists 29.0 g GAA and 30.2g 35% hydrogen peroxide ratio
Now, even after factoring in the densities here, these two methods are obviously substantially different. So my question is this... which method is
superior for the epoxidation of alkenes? What ratios are supported by the literature? Could one of these methods in truth be imaginative whimsy?
I am also curious about the shelf life of peracetic after it's been prepared, if anyone here has any idea.
Thanks all,
Flip
[Edited on 10/3/06 by Flip]
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panziandi
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Hi Flip, usually you use PAA as a ca 40% solution in acetic acid, so if making it use an excess of GAA (commercially it contains a little sulphuric
acid too). its a more stable organic peroxide and can be stored at 2-8*C although im unsure about solutions greater than 40%. i don't know if thats
any help! 
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The_Davster
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I needed some peracetic at one point for prep of some iodoxy compounds. The ref(lit, not rhodium) I had at the time stated that I would not get
greater than 10% peracetic with 35% peroxide.
PS: The stuff reeks something horrible.
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Nicodem
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Flip, those are not methods of peracetic acid preparation, they are methods for preparing a solution of peracetic acid formed in situ. This
makes a big difference and I guess your confusion arises from the lack of acknowledging this fact. Since peracetic acid in such a mixture will be
bound to the reaction equilibrium, you can regulate its concentration as well as the speed of formation with various factors derived from the reaction
equilibrium and reaction speed theory. For example, by increasing the concentration of acetic acid (1st method), you force the equilibrium toward more
peracetic acid formation. Thus the first method provides a higher concentration of peracetic acid. The reaction speed of AcOOH formation is actually
very slow, so acid catalysis (by adding a little H2SO4) speeds up the time required in reaching the equilibrium point (but it has no influence on the
equilibrium point itself).
Therefore, which method is better, strictly depends on the specific reaction where such a peroxidazing mixture is to be used. Some very reactive
substrates might give better results if a peroxidazing mixture has a low peracetic acid equilibrium concentration (slower reaction with less heat
formation and thus less side reactions). Others, like the above mentioned aryl iodide oxidation, will only work well with high enough peracetic acid
concentration.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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phase_dancer
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Peracetic acid produced via the above method (GAA + H2SO4 + 35% H2O2, stand for 5 days) kept well in the fridge for 4 months and resulted in no
noticable change in yields.
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