The invention discloses a preparation method of 2,4-diamido-5-
nitroso-6-hydroxypyridine. The preparation method comprises the following steps: (1) in a
sodium methoxide methanol solution, carrying outa ring-closure reaction between methyl cyanoacetate and
guanidine salt; (2) adding recycled absolute
methanol to be diluted, filtering and recycling byproduct
sodium nitrate; (3) concentrating a filter liquor, and recycling absolute
methanol; (4) adding water to destroy excessive
sodium methoxide, concentrating and recycling water-containing methyl
alcohol; (5) in a diluted
methane acid solution,carrying out a
nitrosation reaction among an obtained concentrate,
sodium nitrite and a
nitrosation mother liquor; (6) after the reaction ends, carrying out cooling
crystallization, filtering, takinga filter liquor as the
nitrosation mother liquor to be used indiscriminately, and
drying an obtained
filter cake to obtain the 2,4-diamido-5-
nitroso-6-hydroxypyridine. According to the preparation method, indiscriminate use of the nitrosation
mother liquor and recycling of
sodium nitrate and methyl
alcohol are realized, and simultaneously the diluted
methane acid solution is used for replacing concentrated
sulfuric acid used, in the prior art, to carry out the nitrosation reaction, so that the recycling of a
solvent and a
reagent is facilitated, and the displacement of waste water is reduced.