Hello everyone,
I'm trying to get rid of this small impurity present in my final compound. This hydrochloride salt was obtained after a N-Boc deprotection using acetyl chloride and ethanol. According to this chromatogram what do you suggest to purify this compound assuming that I need at least 95% of purity.
PS. It is very water soluble, and has both acidic and basic groups, so dealing with any kind of water for eventual workup is useless.
Try to crystallize the salt in organic solvent.
One thing more at HPLC where your impurity comes if it is non polar than give non polar solvent wash and if it is polar then give polar organic solvent wash.
as your hplc chromatogram shows it is non polar than product.But it is too close to product.
you can also check mass (LCMS) try to identify ,can control during reaction also.
Do you have any idea at all as to the nature of the impurity? All of the above suggestions are good ones depending on the impurity.
The nature and molecular weight are important given that you may employ gel filtration technique to purify your product. Recrystallization also depends on the nature. The other option would be a pH-based separation where you selectively isolate your product as a major one (some of the impurities may come along, especially the near RT value's) depending on its nature (physico-chemical). Lesser the impurity, more easy, pure and high-yielding the recrystallization will be; for that matter any purification.
Thanks for your replies. I actually tried something very simple before any chromatographic procedure. I simply washed the salt with some organic solvents, such as Ethyl Acetate and Hexane and the HPLC shows 94,78% of the main peak now. Well, assuming that the NMR did not showed me extra signals, I think it worked for me. Maybe when I scale up the procedure I would try your suggestions.
Thanks for your time helping me.
Best wishes from Brazil =)
We were trying to help you achieve ~100% purity of your salt. No problem, you are happy with 94.78%. Good Luck!
I take it that you are generating anhydrous HCl in EtOH for the deprotection step and simultaneously quaternizing the freed amine with the HCl. A large number of hydrochloride salts are too soluble in abs. EtOH for this solvent to be of general use to recrystalize HCl salts. 2-Propanol is prefered and sometimes Et2O can be added to precipitate the salt. Acetone has a much more limited use here but may be helpful as a wash in removing your impurity. A quick treatment of the dissolved material with activated charcoal may be useful also.
I would expect the hydrochloride salt to be a solid which is insoluble in diethylether. Try to wash the hydrochloride salt in ether first and then perform a recrystallisation.
Hi Ramon,
You can try extraction using organic solvents such as DCM or ethyl acetate.
Best wishes,
Ramin
Consider Acetyl as reason for your Impurity. Maybe Acetamid formation
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