Process for preparing 4,6-diamino resorcinol hydrochloride

Abstract

The present invention discloses a preparation method of 4,6-diaminoresorcinol hydrochloride, including catalytioc hydrogenation step of 4,6-dinitro-2-chloro-1,3-dihydroxybenzene by using hydrogen in the organic solvent and in the presence of rare metal catalyst at normal pressure or middle pressure and normal temp. or under the condition of heating. Said catalyst is formed from carrier which is stable for organic solvent and rare metal loaded on the carrier, and the rare metal content is 0.1-10 wt% of total weight of said carrier. Said invention not only can continuously make multiple hydrogenation, and activity of said catalyst is not reduced, at the same time, but also can obtain high-yield and high-quality 4,6-diaminoresorbinol hydrochloride.

Description

technical field

[0001] The invention relates to a preparation method of 4,6-diaminoresorcinol hydrochloride, which is prepared by catalytic hydrogenation of 4,6-dinitro-2-chloro-1,3-dihydroxybenzene to 4 , 6-diaminoresorcinol hydrochloride. Background technique

[0002] 4,6-Diaminoresorcinol hydrochloride is an important structural unit of various macromolecules, especially polybenzoxazoles (cf. Wolf et al., "Macromolecules" 1981, 14:915).

[0003] Its structural formula is as follows:

[0004] US5399768 and US5371281 and US925358 describe the method for preparing 4,6-diaminoresorcinol through catalytic hydrogenation of 4,6-dinitro-2-chloro-1,3-dihydroxybenzene, an obvious one of said method The disadvantage is that the heterogeneous catalytic hydrogenation of 4,6-dinitro-2-chloro-1,3-dihydroxybenzene in batch hydrogenation over Pd / C catalysts does not enable the economical recycling of expensive rare metal catalysts . At the same time, due to the low stability of 4,6-...