JPS574957A - Preparation of phenylhydrazine - Google Patents

Abstract

PURPOSE: To obtain the titled compound useful as an intermediate for medicines, etc. without corroding an apparatus industrially and advantageously, by diazotizing aniline under specific conditions, reduing the diazonium compound, hydrolyzing the reduction product, in the order, basifying the hydrolysis producr, and extracting and separating the reaction product.

CONSTITUTION: Aniline fed from a line 1 is diazotized with a gas containing a nitrogen oxide in an NO_x concentration ≥8vol% fed from a line 3 at an atomic ratio between the N and the O of 0.6W0.75 in an aqueous solution of sulfuric acid fed from a line 2 at a molar ratio between the water and the sulfuric acid of 16W110 and a molar ratio between the sulfuric acid and the aniline of 0.5W1.5 in a reactor 100. The reaction product is then reduced with ammonium sulfite and ammonium hydrogensulfite in reactors 101 and 102 at a pH of 5.2W7.0 and a pressure ranging from the saturated pressure of the reaction mixture to 10kg/cm², and then hydrolyzed with sulfuric acid in a reactor 103. The reaction mixture is then basified with ammonia at pH≥9.0, and the reaction product is extracted in an extracting column 108 and separated in a separating column 109 to give the aimed compound.

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