Coupling with Fast Blue Salt

Chohnesterase-inhibiting pesticides (e g., organophosphate and carbamate pesticides) are detected by dipping the developed chromatogram in a solution of the enzyme chohnesterase followed by incubation for a short period. Then the plate is dipped in a substrate solution, e.g., 1-naphthyl acetate/fast blue salt B. In the presence of the active enzyme, 1-naphthyl acetate is hydrolyzed to 1-naphthol and acetic acid, and the 1-naphthol is coupled with fast blue salt B to form a violet-blue azo dye. The enzyme is inhibited by the pesticide zones, so the enzyme-substrate reaction does not occur pesticides are, therefore, detected as colorless zones on a violet-blue background [36]. 

Performed on active carbon extracts of water, phenols coupled with Fast blue salt BB (Cl azoic diazo component 20)... 

Fast blue salt B couples best with phenols in alkaline medium, e.g. with 11-nor-d -THC-9-carboxylic acid to yield the following red-colored product ... 

Fast blue salt BB couples with phenols, preferably in alkaline medium, to yield intensely colored azo dyes. 

Tannins [8, 9] a- and y-Pyrone derivatives cr e.g. cumarins [10] H3CO pCHj N=N— ( -N=N 2-I- C - ZnClj Fast blue salt B couples best with phenols in alkaline medium, e.g. with 11-nor-d -THC-9-carboxylic acid to yield the following red-colored product ... 

Somewhat different chromogenic procedures have involved preliminary reaction of phenols with 4>(S-fluoro-2,4-dinitro-l-phenyIazo)-iV,iV-dimethylaniline (130) and coupling with 4-benzoylamine-2,5-diethoxyaniline (Fast Blue salt BB) (131) followed in each case by separation of the azocompounds produced. Diazotized 4-nitroaniline, or the preferred reagent, anthraquinone-l-diazonium chloride (Fast Red salt AL) (131), have been reacted with phenol, the isomeric methylphenols, and dimethyl-phenols, and the colored azo products separated on silica gel G impregnated with potassium carbonate (86). Using this technique separations otherwise impossible with the free phenols have been achieved. A wide scope exists for quantification procedures with greatly improved sensitivity. 4-(A Af-dimethyl-aminophenyl)-4 -azobenzoates of various phenols have also been used (132). 

Synthesis of the copper complex31 [167780-70-3] (H, Na salt) involves coupling of a diazonium compound with a hydrazone [54] 2-(3-amino-4-hydroxyphe-nylsulfonamido)chlorobenzene is dissolved in hot water, to which dilute NaOH solution is then added. After addition of sodium nitrite, the solution is cooled to -5 °C and then added to a well-stirred mixture of HC1, water, and ice. The diazonium salt suspension is neutralized with NaHC03 and combined with the weakly acidic solution of the hydrazone formed with 2-hydrazino-5-sulfobenzoic acid and benzaldehyde in water. The reaction mixture is kept at 0-10 °C, and at pH 10-12 by dropwise addition of diluted NaOH. When the coupling is complete, the pH of the formazan solution is reduced to 8 with HC1, a dilute aqueous solution of copper tetraaminosulfate is added and the solution is stirred for several hours. The copper complex 31 is precipitated at 85-90 °C with NaCl, then filtered and dried. The resulting powder colors wool in clear, fast blue tones. 

The introduction of a trifiuoromethyl group into the molecule of an aromatic amine gives improved light-fastness coupled with brightness of shade to the pigment, as demonstrated by Fast Scarlet VD Salt, (8). Derivatives of mono acetjdated paraphenylenediamine such as Fast Blue BB Base, (9), are particularly useful for blue shades. 

Polyamines as Coupling Components. Chrysoidines are obtained by coupling dia-zonium salts of aniline, toluidines, or mixtures thereof to polyamine coupling components such as 1,3-phenylenediamine, 2,4- or 2,6- toluylenediamine, or mixtures of these diamines. These dyes confer muted yellow to orange shades to paper, leather, and polyacrylonitrile fibers. When they are mixed with malachite green and fuchsin, medium-fast black shades are obtained on polyacrylonitriles. A mixture of chrysoidine with Crystal Violet or Victoria Pure Blue is used to adjust the color of nigrosine hectograph inks [1]. 

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