Synthesis of some 2-(5-methyl-4-phenylazo-2H-pyrazol-3-ylazo)-1,3-indandiones and investigation of visible absorption spectra

Diazonium salts were prepared with the use of o-,m-,p-substituted anilines and 3- amino-2-phenylazo-but-2-enenitrile was prepared by the coupling reaction of diazonium salts with 3-amino-but-2-enenitrile and finally 5-methyl-4-phenylazo- 2H-pyrazol-3-ylamine was obtained by the ring close of this compound with hydrazine monohydrate. The diazonium salts of these compounds were prepared again and 2-(5-methyl-4-phenylazo-2H-pyrazol-3-ylazo)-1,3-indanedione was prepared by the coupling of 1,3-indanedione at 2-position. The structures of the products synthesized were elucidated by H-NMR, MS and FT-IR spectra. The effects of solvent, concentration and acid-base on absorption spectra of the compounds were also investigated.