Aztreonam beta polymorph with very low residual solvent content

摘要

The invention relates to the beta polymorph of Aztreonam, which contains less than 2.5% by weight residual solvent and to a process of making said polymorph. In the process of the invention, a polymorph of Aztreonam is dissolved in an absolute C_1-6 alcohol in the presence of a base to form a solution, an acid is added to the solution, and the solution is stirred efficiently.