Patent ID: 7692025

Claim:
A process for purifying Anastrozole of the following formula, comprising the steps of: a. extracting a quenched reaction mixture containing crude anastrazole with a mixture comprising toluene and a linear, branched or cyclic C 5-8 hydrocarbon and water to form an organic phase and an aqueous phase; b. adding water to the aqueous phase; c. extracting the aqueous phase formed in step (b) with toluene to produce an organic phase; d. extracting the organic phase of step (c) with a polar mixture containing a solvent selected from the group consisting of N-methylpyrrolidinone (NMP) and a C 1-3 alcohol mixed with water, and e. adding a linear, branched, or cyclic C 5-8 hydrocarbon to the organic phase of step (d) to precipitate Anastrozole.