Abstract: A new method for synthesizing 4,6-diaminoresorcinol dihydrochloride(DAR·2HCl) was adopted by three steps, which will give DAR·2HCl without involving any nitro or halo compound but in high yields and high regioselectivity. In the first step, the resorcinol was reacted with acetic anhydride to give the 4,6-diacylresorcinol, then followed by the oximation of 4,6-diacylresorcinol to form the dioxime with the addition of hydroxylamine hydrochloride, finally, the dioxime was subject to producing DAR·2HCl by Beckmann rearrangement in the presence of polyphosphoric acid . The structures of these two intermediates and the final product(DAR·2HCl) were characterized and confirmed by FTIR, MS, elemental analysis, ¹H NMR and 13^C NMR etc ., the results show that all the products are very pure. Meanwhile, the salt of 4,6 diaminoresorcinol/terephthlate(TPA) was prepared with DAR·2HCl and terepthalic acid. By using TPA salt as the starting monomer, polybenzoxazole(PBO) with a high molecular weight was obtained in the polyphosphoric acid. The structure and thermal property of PBO were characterized by means of FTIR, solid state 13^C NMR and TGA.

Key words: 4,6-Diacetylresorcinol, Dioxime, 4,6-Diaminoresorcinol dihydrochloride(DAR·2HCl), TPA salt, Polybenzoxazole(PBO)