The procedure I used to make the acetic acid ester was to heat ephedrine with acetic acid plus some sulfuric acid, and that was the ruination of the method...along with using sulfuric acid as the electrolyte for the catalytic hydrogenation. That guaranteed that ALL of the ephedrine would be in the form of the sulfate salt. The patent does clear up this matter, and gives good directions for making the ester from acetic anhydride, along with a few methods of hydrogenation. The one using ammonium formate as the hydrogen donor to the Palladium is especially interesting. It is well known that attmpting to hydrogenate sulfate esters is a losing deal, but the info that the sulfate salt of the ephedrine only gives 14% conversion is very useful news.