2-Amino-5-Nitrophenol → 1H-Pyrazol-5-ol, 3-methyl-1-phenyl-

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Reaction Steps

44.0 Parts of the 1:1 chromium complex (obtained by the known process and containing 1 atom of chromium for each molecule of monoazo dyestuff) of the azo dyestuff from diazotised 5-nitro-2-amino-1-hydroxybenzene and 1-phenyl-3-sulphomethyl-5-pyrazolone are stirred together in 1000 parts of hot water with 33.9 parts of the monoazo dyestuff obtained by the known process from diazotised 5-nitro-2-amino-1-hydroxybenzene and 1-phenyl-3-methyl-5-pyrazolone. The suspension is adjusted to a pH of 7 to 8 by addition of 20 parts by volume of concentrated sodium hydroxide solution and subsequently stirred at 90°-95° C. until both starting dyestuffs can no longer be detected. The unitary chromium mixed complex present in the clear solution is precipitated by addition of sodium chloride, isolated by filtration, washed with sodium chloride solution, and then dried in vacuo. After it has been ground, the dyestuff is in the form of a red, readily water-soluble powder and from a bath containing ammonium sulphate dyes wool or polyamide fibres in full red shades with good fastness properties. It has the following constitution: ##STR12##

Provenance & Evidence