Acid dyes bisazo

The complete reaction scheme is shown in Fig. 5.3-7, while Fig. 5.4-51 gives a simplified representation. 1-naphthol (A) is primarily coupled with diazotized sulphanilic acid (B) to form monoazo dyes coupled in para and ortho positions (p-R and o-R, respectively). This reaction is first order in both A and B. Each of the primary products can react with diazotized sulphanilic acid to form bisazo dye (5). Rate constants at 298 K and pH 10 are ku = 10600 m mof s k2i = 1 22 = 1.7 m mor s (see Fig. 5-4-51). 

According to the works by Bourne et al. [162, 163], the azo coupling reactions between a-naphthol (A) and diazotized sulfanilic acid (B) to produce monoazo dye (R) and bisazo dye (S) are used as the competitive-consecutive (series-parallel) reaction scheme for the determination of micromixing, for which the rate constants have been determined [163], and their values at 298 K are... 

Azo dyes based on the aromatic intermediate benzidine were invented in 1884. These were the first synthetic dyes that adhered to cotton fabrics without the need for a fixing agent (mordant). For this reason they were known as direct or substantive dyes. The first member was discovered by Paul Bottiger, at Bayer. From benzidine (25) and naphthionic acid (20) he obtained a red bisazo dyestuff (26)41 see Scheme 9. 

Fragmentation of bisazo species of formula Ar1—N=N—C10H6—N=N—Ar2 occurred at both azo linkages, thus yielding valuable structural information. The FAB method has also been applied to sulfonated azo dyes incorporating a phosphonic acid... 

J. B. Lloyd, F. Beck, A. Griffiths, and L. M. Parry, The mechanism of action of acid bisazo dyes, in The Interaction of Drugs and Subcellular Components in Animal Cells (P. N. Campbell, ed.), pp. 171-203, Little, Brown, Boston (1968). 

H chemical shifts were measured of dyes prepared by diazoniiun salt coupling with 2,2, 4,4 -tetrahydroxybenzophenone (mono and bisazo compounds), 3-amino-5-nitro[2,l]benzisothiazole, basic dyes derived from 3-(acetoacetamido)- pyridine, 5-sulfonylpiperidino- and morpholino-8-hydro-xyquinoline, 5,6-dichloro- and 6,7-dichloro-2-aminobenzothiazoles, H-acid, 1 -butyl-3-cyano-6-hydroxy-5-methyl-2( 1 //)pyndone, ethyl-2-hydro-... 

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