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Disazo symmetrical stilbene dyes. Synthesis and colour evaluation.
1 , 2 , * 1
1  Institute of Chemistry Timisoara of Romanian Academy
2  University of Medicine and Pharmacy Victor Babeş Timişoara, Faculty of Pharmacy

Abstract: The synthesis of two new symmetrical disazo direct dyes containing 4,4'-diaminostilbene-2,2'disulphonic acid as middle component and 3-chlorosalicylanilide and 4-chlorosalicylanilide as coupling components are presented. The synthesized dyes were analyzed by thin layer chromatography (TLC), electronic spectra (VIS) and HPLC technique. Their structures were elucidated by FT/IR and 13C-NMR spectroscopy. The CIELAB (1976) colour space was used in all the colour measurements for the two disazo stilbene dyes under the CIE recommended illuminants: D65 (natural day light), A (tungsten light), F2 (fluorescent light) and the standard 10° observer respectively. The colour difference (ΔEab*) was calculated against one standard
Keywords: Azo-stilbene dyes, CIELAB uniform colour space