Formaldehyde → Escitalopram Oxalate

Participants

Reaction Conditions

Reaction Steps

To the crude Citalopram (90 g, 0.28 mol) having desmethyl citalopram (7%, HPLC), formic acid (98%, 2.7 g) was added followed by aqueous formaldehyde (35%, 2.37 g). The reaction mass was heated at 85-95° C. for 30 min. HPLC indicated complete conversion of desmethyl impurity into Citalopram. The reaction mass was cooled to 30° C. and diluted with ethanol (900 ml). Oxalic acid dihydrate (41.94 g, 0.33 mol) was added and mass was heated to reflux. The obtained solution was cooled to 20-25° C. and stirring was continued for 2 hours at 20-25° C. The product thus obtained was filtered and crystallized from ethanol to provide highly pure 92 g of crystalline Citalopram oxalate having HPLC purity 99.7% and desmethyl citalopram impurity: Not Detected.

Provenance & Evidence