The Hive > Methods Discourse
Benzaldehyde + MEK acid catalyzed aldol
twodogs:
Viki,yes that would work. Have a look at all the patents under Baeyer-Villager and you will see all the different oxidisers used. Boesken used peracetic.
bio:
Yea, twodogs the peracetic makes sense. I bought some 30% H2O2 intending to try it or even regenerate the Na Perborate. Can the peracetic or performic be made insitu? and would the same molar ratios be used. Also I have the perborate tetrahydrate a monohydrate is also available, the 4 hydrate which is NaBO3.H2O2.3H20 is ca. 10% O2. What is the actual mole ratio needed of O2 for the Baeyer Villiger?
Again thanks for your assistance as the library here is in the wrong language and only goes to the 10th grade (sic).
twodogs:
Bio
I am sorry but this was a while ago and I don't have any notes. I would have thought that you would need at least 50% H2O2 to make a strong enough peracetic. Performic pretty much has to be made on the spot as it deteriorates quite quickly. Peracetic needs a catalyst like H2SO4 to form and that may need to be neutralised before use. I had alot of difficulty in figuring out the percentage of peracetic formed by combining H2O2 and acetic acid. A lot of posts on the topic here at the Hive I think are wrong in that they assume too high a percentage of peracetic in the final product. It is one of those reactions where 1+1 doesn't equal 2. I couldn't buy peracetic and this is the main reason why I went with the perborate as the quantities needed are easier to work out. Have a look at US Patent 4988825 where I got the idea of using perborate.
Rhodium:
See J. Am. Chem. Soc. 907 (1946) (https://www.thevespiary.org/rhodium/Rhodium/pdf/peracid.pdf)
twodogs:
Thanks Rhodium. That is what I had read.. if you use 90% H2O2 with acetic acid you can get the high concentrations of peracetic but 30% H2O2 only gives about 8%. I don't believe that you can buy 90% H2O2 any more. 35% peracetic seems to be the reaction grade.
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