Nimesulide 5G. Nimesulide, A selective cyclooxygenase-2 (COX-2) inhibitor, CAS: 51803-78-2, MF: C13H12N2O5S, Molecular Weight: 308. 31, Purity: greater than or equal to 98%, Appearance: Yellow solid, Synonym: N-G(4-GNitro-G2-Gphenoxyphenyl)-Gmethanesulfonamide R805, Size: 5G