EXTRACTION OF EPHEDRINE FROM EPHEDRA SINICA STAFF LEACH LIQUOR I.——Selection of Solvents and Determination of Distribution Data
Among common industrial solvents, toluene, mixed xylenes and chloro-benzene have been considered as the most suitable extractants. Data of distribution of l-ephedrine between the above mentioned solvents and pure water (and aqueous sodium hydroxide solution) at different temperatures were obtained. The distribution coefficient, m=(concentration in solvent)/(concentration in aqueous solution), for each solvent is practically constant over the concentration range investigated, increasing with rising temperature from 20 to 60℃. The coefficient is also increased with the addition of sodium hydroxide in the aqueous phase. 
The relationship between the pll value of the leach liquor and the percentage of alkaloids present in free form was also investigated. It shows that only at pH≥ll.5 practically all alkaloids can be set free and therefore extractable. 
For the system toluene-leach liquor (with the addition of NaOH to pH=12)-mixed alkaloids present in Ephedra Sinica Stapf, the values of m at 20°,40° and 60° were found to be 2.1, 2.6 and 4.4; and at 60 when chlorobenzene was used m = 5.2. These values of m are smaller than those for the corresponding pure systems. Using mixed xylenes as solvent m at 60° was found to be 5.4, which is somewhat greater than that for the pure system. 
Alkaloids in the organic solvents can be easily and completely re-extracted into aqueous solution to form hydrochlorides by hydrochloric acid. Thus the solvents can be recovered and returned to the cycle for extraction of leach liquor.