Heterocyclic hansa yellow analogues: Synthesis of novel azodisperse dyes from 3-oxo-N-(pyrazol-4-yl) butanamide as possible dyes for polyester fibres

Different heterocyclic Hansa Yellow analogues were synthesized from 3-oxo-N-(pyrazol-4-yl)butanamide for possible use as azodisperse dyes for dyeing polyester fibres. The free energy relationship between the position of absorption of these dyes-λ-and substituent Hammett sigma constants was investigated.