Determination of organic pharmaceuticals with N-bromosuccinimide. Part I. Some pyrazolidinedione derivatives

Abstract

Phenylbutazone (4-butyl-1,2-diphenylpyrazolidine-3,5-dione), oxyphenbutazone [4-butyl-2-(4-hydroxyphenyl)-1-phenylpyrazolidine-3,5-dione], sulphinpyrazone [1,2-diphenyl-4-(2-phenylsulphinylethyl)pyrazolidine-3,5-dione] and monophenylbutazone (4-butyl-1-phenylpyrazolidine-3,5-dione) are determined by direct titration with N-bromosuccinimide in acetic acid medium. With the exception of monophenylbutazone, the concentration of acetic acid at the end of the titration should not fall below 10 N. With monophenylbutazone the acetic acid concentration at the end-point should be at least 6 N.

The pyrazolidinedione derivatives are brominated readily and quantitatively by N-bromosuccinimide to the 4-bromo derivatives. This has been proved by calculating the molar ratio of the reaction, and also by elemental microanalysis of the 4-bromo derivative of phenylbutazone isolated by a microsynthetic procedure similar to the analytical determination.