Synthetic method ofphenylhydrazine

The invention discloses a synthetic method of phenylhydrazine. Aniline, hydrochloric acid, sodium nitrite, water, an ammonium bisulfite solution, 98% sulfuric acid, caustic soda liquid and caustic soda flakes are adopted as main raw materials, aniline, hydrochloric acid, sodium nitrite and tap water are converged through a metering pump and a flowmeter respectively and then pass through a tubularreactor (a miller-grid tube reactor) at a high speed to be subjected to diazotization reaction and diazonium salt liquid is obtained. The diazonium salt solution subjected to the pipeline reaction flows into a reduction tank to be subjected to a cold reduction reaction with an ammonium bisulfite solution, and heating is performed to perform a thermal reduction reaction. Concentrated sulfuric acidis added into the reduction solution and heated for hydrolysis. The hydrolysate is cooled and then filter pressing operation is performed, solid crystals are obtained after filtering, caustic soda liquid is added for dissolvin