The ether is capable of holding a certain limited amount of water but dissolves no HCl salt at all, while the alcohol can hold a certain limited amount of HCl salt, and tends to become water-immiscible when saturated with salts. So the water will slowly migrate to the ethereal solvent part when enough ether was used, and the HCl salt will be pushed into the alcohol, where it slowly precipitates. Acetone can be used instead of ether BTW.
In fact, you
partition the HCl salt/water (derived from neutralizing your freebase) between the ethereal and alcoholic part of your solvent mixture...
But this method is not very good (no flame Os!): you have to use *much* ether, and even then a small amount of HCl salt will remain dissolved in the water/alcohol after filtration. If you use ether anyway, you could try to add 37% HCl to some ether, then add enough NaCl to saturate the water layer, and some of the HCl (not all) will exit the water layer and dissolve in the ether. Separate the acidic ether and add slowly to your fb/IPA solution until slightly acidic, then carefully heat until most of the ether has evapped, and add dry acetone and chill for several hours to precipitate the hydrochloride. Recrystallize from IPA/acetone to get rid of eventual NaCl impurities.
(not tried yet; but it *should* work fine - and it is always better to use as little water as possible when crystallizing hygroscopic salts...
)
Or maybe it would help to evaporate almost all the IPA/water after neutralizing the fb, and then add dried ether? I'm
sure it would work better than leaving those 63% water in there!
Theoretically, the ether could be reused: but unfortunately it forms azeotropes with both water and alcohols, and in this case it contains also the excess HCl from your previous run - thorough purification is advised...
indole_amine