N-(X-Chlorophenyl)-4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide (withX= 2 and 4)

The structures of N-(2-chloro­phenyl)-4-hydroxy-2-methyl-2H-1,2-benzo­thia­zine-3-carboxamide 1,1-dioxide and N-(4-chloro­phenyl)-4-hydroxy-2-methyl-2H-1,2-benzo­thia­zine-3-carboxamide 1,1-dioxide, both C16H13ClN2O4S, are stabilized by extensive intra­molecular hydrogen bonds. The 4-chloro derivative forms dimeric pairs of mol­ecules lying about inversion centres as a result of inter­molecular N—H⋯O hydrogen bonds, forming 14-membered rings representing an R22(14) motif; the 2-chloro derivative is devoid of any such inter­molecular hydrogen bonds. The heterocyclic thia­zine rings in both structures adopt half-chair conformations.