Dimorphism of Ergometrine

Abstract

ERGOMETRINE as described by the late H. W. Dudley¹ is a white crystalline substance, which melts at 162°–163° (decomp.). During the process of preparing ergometrine, we have isolated in addition to this form a modification which crystallises from acetone in long needles, m.p. 212° (decomp.). We also find that the low melting point form tends to pass into the high melting point form on keeping, and that the transformation of the former into the latter can be effected rapidly by crystallisation in the presence of a crystal of the form m.p. 212°. The more stable form is also the less soluble. Both modifications have the same specific rotation, (c in dehydrated alcohol 1.7) for the solvent free substance.