| Popis: |
This paper concerns the effects of the position and the nature of substituents on the colour of azo dyes derived from 2-arainothiophens. Of primary interest is the colour shift from the red of phenylazo dyes to the greenish blue of the analogous 5-substituted 3-nitro-2-thienylazo dyes. The greenish blue of 2-amino-3-nitro-5-aeyl(or aroyl)thiophen dyes is in striking contrast with the violet—red of 2-amino-5-acylthiophen dyes and the violet of dyes from 2-amino-3:5-bismethylsulphonylthiophen. Even simple aniline coupling components afford blues to blue-greens with the 5-substituted 2-amino-3-nitrothiophens. However, progressively increased bathoehromic shifts to bluish green are obtained with the following coupler types— tetrahydroquinoline, benzomorpholine, and 2-alkoxy-5-acetamidoaniline. Dyes from 2-amino-3-nitro-5-acylthiophens, particularly, have excellent affinity for secondary cellulose acetate and give good exhaustion and level dyeing. They colour cellulose acetate deep, bright blues to greens. Dyed fabrics have superior gas-fume fastness, moderate light fastness, and good dischargeability. |
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