PROCESS FOR SELECTIVELY CONTROLLING THE CRYSTALLISATION OF MESOTRIONE POLYMORPH FORM 1

摘要

The invention relates to a process for selectively controlling the crystallisation mesotrione [2-(4-methylsulphonyl-2-nitrobenzoyl)cyclohexane-l ,3-dione] from aqueous solution in which the aqueous mesotrione solution is introduced to a crystalliser containing seed crystals predominantly of the thermodynamically stable polymorph ("Form 1") in a semi-continuous or continuous manner. The invention further relates to a process for converting the metastable polymorph ("Form 2") of mesotrione to Form 1 by introducing an aqueous solution containing the former form to a crystalliser containing seed crystals predominantly of the latter form.