Polysubstituted pyrazoles. Part 2: Sulphonamidophenylhydrazone-2-pyrazolin-4-ones and sulphonamidophenylazopyrazoles...

The synthesis of some new derivatives of 1-[4-nitrophenyl]-5-[4-substituted sulphonamidophenylhydrazono]-2-pyrazolin-4-ones and 3,5-dimethyl-4-[4-substituted sulphonamidophenylazo]-pyrazoles is described. Bromination of ethyl 2-[nitrophenylhydrazono]-3-oxobutyrates in dry benzene afforded the 4-bromo derivatives which upon cyclization gave high yields of the 4-hydroxpyrazoles. Many other new intermediates were prepared and the results of the UV and IR spectral studies are discussed.