GB754660A - New pyrazolones and process for their manufacture - Google Patents

Abstract

The invention comprises pyrazolones of the formula <FORM:0754660/IV(a)/1> where R is a benzene residue and X is the acyl residue of an organic sulphonic acid. These are prepared by condensing hydrazines H2N-NH-R-SO3-NH-X with suitable ring-closing agents, e.g. diketene or acetoacetic esters or amides. Preferably the reaction is carried out with methyl or ethyl acetoacetate in an aqueous alkaline medium at the boiling point. When acetoacetic amide is used, however, the medium is preferably neutral or weakly acid. An organic solvent may also be used. The hydrazines can be prepared from the corresponding amines by diazotization and reduction. Examples show the preparation of 3-hydrazino - benzenesulphon - (N - benzenesulphonyl)-amide and 4-hydrazino-benzenesulphon - (N - ethanesulphonyl) - amide, and ring closure with an acetoacetic ester to 1-phenyl-3-methyl - 5 - pyrazolone - 31 - sulphon - (N - benzenesulphonyl) - amide and - 41 - sulphon - (N-ethanesulphonyl) - amide respectively. Other products are mentioned in which R contains chlorine and methyl substituents, and X may also be chlorobenzenesulphonyl or dichlorobenzenesulphonyl. It is stated that in general the aromatic nuclei may contain non-solubilizing substituents such as alkyl, alkoxy, nitro or halogen.ALSO:Azo dyes are made from pyrozolones of the formula <FORM:0754660/IV(c)/1> where R is a benzene residue and X is the aryl radical of an organic sulphonic acid. Thus, diazotised aniline may be coupled with the compounds (1) R=m-phenylene, X=benzenesulphonyl, and (2) R=p-phenylene, X=ethanesulphonyl. Many other suitable pyrazolones are mentioned.