Prepn. of 4,6-di:amino resorcinol, useful for the prepn. of poly:benzoxazole,

摘要

A method for the prepn. of 4,6-diamino resorcinol comprises the following steps: (A) 1,3-dichlorobenzene in anhydrous sulphuric acid contg. 0-10 wt.% free sulphur trioxide is reacted with an nitric acid/sulphuric acid mixt. contg. 0.7-1.5 (0.9-1.1) mols. sulphur trioxide per mol. nitric acid, at 0-40 deg C and in a nitric acid to 1,3-dichlorobenzene mol. ratio of 2-3; (B) the 1,3-dichloro-4,6/2,4-dinitrobenzene isomer mixt. contg. 0.1-60% 1,3-dichloro-2,4-dinitrobenzene wrt. the wt. of the isomer mixt., is reacted with 2-5 mols. benzyl alcohol and 2-5 equivs. strong base, in the presence of an inert solvent, during which the temp. is initially increased in stages from -15 to +15 deg C to give a working temp. of 20-40 deg C; and (C) the 1,3-dibenzyloxy-4,6-dinitrobenzene is reacted in an inert organic solvent at 20-100 deg C and 1-100 bar hydrogen pressure, in the presence of a noble metal contact, to form 4,6-diaminoresorcinol via a catalytic pump hydrogenation reaction.