Crystalline N-acetyl neuraminic acid derivatives and process for their preparation

摘要

Two useful crystal hydrates of 5-acetamido-2,3,4,5-tetradeoxy-4-guanidino-D-glycero-D-galacto-non-2-enopyranosonic acid have either a low or high aspect ratio. These crystalline N-acetyl neurominic acid derivatives are favored for pharmaceutical formulation because of their physical properties. For example, the low aspect ratio crystal has good flow properties, and the high aspect ratio crystal has a stable water content over time.