Isolation and comparative action of ephedrine pseudo-ephedrine from ma-huang. (Ephedra vulgaris,var. helvetica).

Abstract

The alkaloids ephedrine and pseudo-ephedrine were isolated by Nagai 1 and Merck, 2 respectively, from Ephedra vulgaris. The Chinese drug Ma-huang, variously identified as Ephedra vulgaris, Rich. var. helvetica, Hk. et Thoms., 3 Ephedra equisetina, Bge., 4 has been recently studied by K. K. Chen and Carl F. Schmidt. 5 , 6 From this they isolated the alkaloid ephedrine and conducted various physiological experiments. They gave the following physical constants for ephedrine and its salts:

It has been found that the basic substance isolated from Ma-huang, contains about 20 per cent of pseudo-ephedrine as well as ephedrine, the former being identical in all respects with that obtained by the action of HC1 upon ephedrine. The ephedrine, having a melting point of 43°, and being considered to be laevo-rotatory up to now, is found to be dextro-rotatory in water and laevo-rotatory in alcohol. Its specific rotation suffers no change towards the action of dilute HC1, Na₂CO₃ and pepsin in acid solution. Some difference in optical activity has, however, been observed by the introduction of trypsin into its alkaline solution.

Salts of both ephedrine and pseudo-epKedrine were prepared and studied. Generally speaking the salts of ephedrine are better crystallized and less soluble in water and alcohol than those of pseudo-ephedrine. The remarkable diference in solubility of their oxalates in cold water affords a good means of separating ephedrine from pseudo-ephedrine, whenever a mixture of these two isomers has to be dealt with.

SALTS OF EPHEDRINE.

Hydrochloride. C₁₀H₁₅ON.HC1. prismatic needles, m.p. 216° C. [α] 22/D −32.5°. Easily soluble in alcohol and water. Its aqueous solution is stable at boiling temperature.