Hydrates of the disodium salt or dipotassium salt of 4,4'-bis(2-sulfostyryl)biphenyl

摘要

The invention relates to novel hydrates of the disodium or dipotassium salt of 4,4'-bis(2-sulphostyryl)biphenyl which are characterised by their water of hydration content, to associated crystal forms characterised by their X-ray diffraction diagram, to processes for preparing same, and to the use thereof for preparing concentrated formulations of optical brighteners.