Study On The Synthesis Of[2,6-diimidazo(4,5-b:4’,5’-e)Pyridinylene-1,4(2,5-dihydroxy)Phenylene]

This paper mainly studies the synthesis of2,6-diimidazo(4,5-b:4’,5’-e) pyridiny-lene-1,4(2,5-dihydroxy)phenylene(PIPD), the best synthetic route was been adtopped after sdudied the preparation process of PIPD, the high purity polymerization monomers were been gotted after studied the purification process of the monomers of2,3,5,6-tetraaminopyri-dine (TAP) and2,5-dihydroxyterephthalic acid (DHTA). The intermediate and main products were been conducted a comprehensive characterization by the means of Infrared Spectroscopy(IR), NMR (1H-NMR、13C-NMR), Mass Spectrometry(MS), Differential scanning calorimetry(DSC) and thermogravimetric(TG). The structure of the product is correct after identified.2,6-diaminopyridine as the raw material, Oleum and fuming nitric acid as the super acid system, the2,6-diamino-3,5-dinitropyridine (DADNP) was synthesized by nitration. The effect of Oleum concentration, Molar ratio of fuming nitric acid with DAP, nitrification temperature and extraction methods to the reaction were been studied. The2,3,5,6-tetraaminopyridine were been gotted by use the catalytic hydrogenation technology after reduction the2,6-diamino-3,5-dinitropyridine.The effect of the kinds of catalysts, solvent, reduction temperature and the purity of raw materials to the reaction were been studied, the TAP’purification process was also been studied. After recrystallization the TAP’purity was up to99.9%Dimethyl-1,4-cyclohexanedione-2,5-dicarboxylate as raw material (DMSS), the intermediates2,5-dihydroxyl-terephthalate (DMDHT) was gotted after aromatization oxide. Then by esterification hydrolysis, after by dropping hydrochloric acid to control pH, the monomer DHTA was tained. The synthesis process was optimize after studied the factors of the type of solvent, oxidation and their’s dosage. Then after recrystallization the DHTA’purity was up to99.8%.With TAP and DHTA as the monomers, firstly they were prepared as2,3,5,6-tetraaminopyridine-2,5-dihydroxyterephthalic acid (TD salt), then by polymerization reaction, the high intrinsic viscosity PIPD was been prepared. After studied the effect of heating modes, the monomer’ molar ratio, antioxidants and Phosphorus pentoxide dosage to the reaction, the polymer’s viscosity was up to13.