K. Hamada, M. Uchida, M. Mitsuishi
Jul 1, 1996
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Journal
Dyes and Pigments
Abstract
Abstract The syntheses of sodium 1-(2-trifluoromethylphenylazo)-2-hydroxy-5-benzenesulfonate, sodium 1-(3-trifluoromethylphenylazo)-2-hydroxy-5-benzenesulfonate, and sodium 1-(4-trifluoromethylphenylazo)-2-hydroxy-5-ben-zenesulfonate is reported and the solubility of these dyes in water was found to be dependent on the position of the trifluoromethyl group. Derivatives containing a methyl group could not be prepared, showing that the coupling reaction is affected by the substituent of the diazotized aniline derivatives. The extinction coefficients of the aqueous dye solutions did not change within the concentration range 1 × 10 −5 to 1 × 10 −3 mol dm −3 , which suggests that the dyes do not aggregate at these dye concentrations. The sorption behavior of the dyes by a nylon 6 film was investigated and compared with that of the fluorinated derivatives of sodium 1-phenylazo-2-hydroxy-6-naphthalenesulfonate. The intrinsic binding constants for the former dyes were found to be much smaller than those for the latter dyes.