So I'm trying to crystallize a sample of an amine ketone to a hydrochloride salt. The product is extracted with ethyl acetate (which I'm using as a substitute for diethyl ether), back extracted with dilute (10%) sulfuric acid, basified then extracted with DCM. This is then evaporated to yield a yellow/amber oil.
At this point I dissolved it in isopropanol, added concentrated HCl and was supposed to get crystals, but even after evaporation of solvent I get a yellow oil. I've tried filtering, washing and even using sulfuric acid to yield a sulfate but I ALWAYS end up with an oil regardless of whether it evaporates to dryness with heat or I cool the solution in the freezer then let evaporate at room temperature.
I left a solution of the freebase in ethyl acetate on a tray and this half evaporated to a crystal slurry. Both the freebase and acid should have a boiling point of 170-180°C.
Something worth mentioning is that in the original synthesis the base was distilled bulb to bulb after the DCM extraction, but this particular ketone is prone to dimerizing to a pyrazine, so I was cautious of this.
Can someone help me troubleshoot this? Every step until this point has seemed correct.