PTC for bisulfite-adducts

[Barium]

This is a quite useful method to generate the bisulfite-adduct from impure aldehydes or ketones.

Dissolve the impure carbonyl compound in a equal volume of toluene or DCM and add 1-5 mol% PTC (my choice is aliquat 336). To this solution add 1.5-2 molar equivalents sodium bisulfite [1] as a 25% aqueous solution and stir the crap out of the mixture for 30 minutes at room temp [2]. Filter off the precipitated bisulfite-adduct and continue the stirring for another 30 minutes. Repeat until no more adduct precipitates out. Rinse the adduct once with 70% IPA to remove any remaining toluene. The yields are close to quantitative. 

[1] Carbonyl compounds can be scarce and very expensive while sodium bisulfite is cheap. To get high yields of the adduct use excess of bisulfite.
[2] If the precipitation doesn't start within 30 minutes at room temp, heat the mixture to 50-60°C and continue the stirring.

Edit: It looks like this method has been patented already.

Patent US4162269

[fierceness]

Wow!  Excellent find!  So, does this render vacuum distillation of MDP2P optional?

1)  Atmospheric Distillation of safrole
2)  Isomerization of Safrole
3)  Performic/Peracetic oxidation of isosafrole
4)  Workup to MDP2P
5)  Using the above method to purify MDP2P
6)  Al/Hg reductive amination of above to get product
EDIT:  7) Recrystallization from IPA

If so, then this would greatly help bees without a good vacuum source!

[runne]

So if the test crystallizes in the freezer, then disappear at room temperature, that probably means too much IPA/water?

[Barium]

As far as I know most bisulfite adducts aren't soluble in either water, alcohols or non-polar solvents. Once you've got the adduct you will have to decompose it by alkaline or acidic hydrolysis. I don't know what you got but it doesn't sound like a bisulfite adduct.

[Antoncho]

As far as know, they DO dissolve in water, but not in sat. NaHSO₃ solutions, hence the isolation technique.

Non-soluble in non-polars, certainly.

[sYnThOmAtIc]

Can sodium bisulfate NaHSO4 be used to make the adduct or no?

It's the stuff at the pool chem place and haven't found BISULFITE  OTC anywhere yet. Just online canning sites.

[Antoncho]

Synthomatic , do you really identify yourself with that profile picture of yours? I noticed that i try to avoid your posts as much as possible: the picture scares me.

[sYnThOmAtIc]

Everybody avoids my posts! What else is new?

Scares you? How?

Man and that is the best picture of me I have. If you think that is scary you should see me for real!

--Edit: The phrase or the picture? It's just a joke it's supposed to be funny not scary. I have been thinking abut changing it with a new pic of me jsut haven't figured out what with yet.

[GOD]

bump.

swim reiterates fiercness's question:

Wow!  Excellent find!  So, does this render vacuum distillation of MDP2P optional?

[Rhodium]

Not completely, especially not if you use the wacker oxidation to make your MDP2P. A common byproduct is MD-Phenylpropanal (also called "MDP3P"), and as this also will form a bisulfite adduct, you cannot remove that with this procedure. All impurities with a carbonyl function (aldehydes/ketones) will form bisulfite adducts (piperonal and MD-Phenylacetaldehyde are other examples).