Method for preparing 2,4-diaminolphenol or 2,4-diamonophenol

Abstract

A method for preparing 2,4-diaminophenol or 2,4-diaminophenol dihydrochloride comprising hydrogenation of 2,4-dinitrophenol on a membrane catalyst made of an alloy consisting of 90 to 98% by mass of palladium, 2 to 10% by mass of rhodium or ruthenium. Said hydrogenation of 2,4-dinitrophenol is effected by hydrogen diffusing through said membrane catalyst. The starting 2,4-dinitrophenol is used in a medium of water or a 4--37% aqueous solution of hydrochloric acid at a concentration of 2,4-dinitrophenol in said medium ranging from 2 to 50% by mass. The hydrogenation is effected at a temperature within the range of from 50.degree. to 150.degree. C. under a pressure of from 1 to 60 atm. The process is simple and performed on a simple equipment; it makes use of both pure and commercial hydrogen, enables elimination of the formation of waste waters and results in the desired products in a high yield: 2,4-diaminophenol--with a yield of up to 93%, 2,4-diaminophenol dihydrochloride--with a yield of up to 92% as calculated for the starting 2,4-dinitrophenol.