washing ipph

[Doclad]

Goodnight.

If you wanted to purify a batch of isopropylphenidate hcl contaminated with ritalinic acid, how would you do it?
I do not find the solubilities of either of the two substances, and apparently the water is not adequate to dissolve the isopropylphenidate.

Any ideas?


DocLad

 

[sekio]

Basify it to pH 8-10, extract the freebase isopropylphenidate into DCM/chloroform, the sodium ritalinate stays in the water, then convert the DCM solution of freebase back to salt with HCl.

Or just reflux the mixture in isopropyl alcohol w/ a drop of catalytic strong acid, you'd re-form the isopropyl ester, converting ritalinic acid to IPPH.

 

[Doclad]

Strong catalytic acid? Hcl would not work? I think it is the strongest acid I have at my disposal.


DocLad

 

[Limpet_Chicken]

Sulfuric? pretty easily available, ebay if you have standards, bog cleaner if you don't (in all chance, there probably isn't going to be much in the way of any hideously noxious organics in acid drain cleaner anyway, I only use it for generating or drying gases, or for keeping moisture out of things in a desiccator, but in the UK, concentrations I've seen have ranged from 96% at the low end up to 98% H2SO4, its dyed, but for concentrated sulfuric acid anything more than a visual warning is rather besides the point, it isn't as if anyone is going to get desperate and try drinking it, like a gutter bum might with denatured alcohol, it isn't what you'd call reinforcing, from an ingestion point of view, assuming one survived to try it more than once, that is. And organics have to be fairly tough to begin with to survive being pickled in concentrated H2SO4. I've often wondered what that dye IS, to avoid being charred to a crisp in-situ.

Another option might be binding the water as formed during the esterification, either using an anhydrous lewis acid salt, or molecular sieves. Sieves would have the advantage of being available in pelleted form that could be filtered out by more or less anything that the solvent won't melt.

 

[Doclad]

If I do reflux with hcl what happens? or directly without a catalytic acid? Nothing would happen?


DocLad

 

[Pomzazed]

Is reforming ipph a synthetic question? Up to mod then, but...

Reflux without acid will not work.
Reflux with HCl will work but your HCl is continuously lost as HCl gas, leaving more and more hot water inside for hydrolysis reaction.
Reflux with H2SO4 works well as it wont evap and has very few water inside, but risky for burning product, as sulfuric tends to be strong oxidant if too concentrate or too hot. Resulting in yellow, orange black color and loss of product. Just use 1drop per 1Litre of solvent, dont go as high as 0.5%...

Still recommend things like p-toluenesulfonic acid, has like 11% strength of sulfuric acid and very less likely to burn product, if any at all.

 

[Doclad]

Still recommend things like p-toluenesulfonic acid, has like 11% strength of sulfuric acid and very less likely to burn product, if any at all.

No, it is not an option. Finally, should I expect ipph hcl to be soluble in acetone or some type of alcohol? Maybe I can separate ipph from other contaminants.


DocLad