Using ethyl acetate to dry HCl salts is a very old trick - it is nice to see it reinvented! I learned this from some old hands when I was a bench
chemist a very long time ago. In fact, one of the best ways to make HCl salts is to dissolve the amine in cold ethyl acetate and pass dry HCl gas into
the solution. The resulting solid-liquid mixture is concentrated and the solid salt taken up in ethyl acetate and reconcentrated one or two more
times. In order to avoid having to use HCl gas for every reaction we kept a stock solution of 4M HCl in ethyl acetate stored in the refrigerator. This
is a very stable solution unless it is allowed to absorb too much moisture.
If you have a wet solid or gummy hydrochloride salt, acetonitrile works equally well to remove moisture. It actually works quite well for a variety of
amine salts.