Process for preparing boscalid

摘要

A process of preparing the crystalline modification II of the anhydrate of boscalid comprising: providing a solution of boscalid in an organic solvent system; heating the solution to an elevated temperature; and precipitating solid boscalid from the solution. The elevated temperature is sufficient to preferentially form the crystalline modification II of the anhydrate of boscalid. The organic solvent may be selected from polar organic solvents such as alcohols, ketones, ethers, esters and amides, or from aromatic hydrocarbons. Preferably the elevated temperature is between 55-85°C and seed crystals of the crystalline modification II of the anhydrate of boscalid is added to the solution to aid precipitation. Also claimed is a fungicidal formulation comprising the crystalline modification II of the anhydrate of boscalid.