羟基改性聚对亚苯基苯并二唑单体3,3′-二氨基-4,4′-二羟基联苯盐酸盐的合成

Synthesis of hydroxyl-modified PBO monomer 3,3′-diamino-4,4′-dihydroxybiphenyl hydrochloride

为改进聚对亚苯基苯并二唑(PBO)纤维复合黏结性能差等缺点,在苯环上引入极性基团羟基进行化学分子结构改性,3,3′-二氨基-4,4′-二羟基联苯盐酸盐(D ADHBP 2HCl)是羟基改性PBO的关键单体。以4,4′-二羟基联苯(D HBP)为原料经硝化、还原反应合成得到中间体3,3′-二硝基-4,4′-二羟基联苯(D NDHBP)和羟基改性PBO的单体DADHBP 2HCl,并对其反应条件进行了优化。结果表明:对于硝化反应,以甲苯、冰乙酸的混合液为反应溶剂,n(DHBP)∶n(HNO3)=1∶2,反应温度5℃,反应时间2.5h,收率81.39%,高效液相色谱(H PLC)纯度(质量分数)92.43%;还原反应,n(DNDHBP)∶n(FeSO47H2O)=1∶9,乙醇为溶剂,七水合硫酸亚铁为助剂,n(DNDHBP)∶n(N2H4 H2O)=1∶5.5,反应温度78℃,反应时间9h,热过滤,滤饼盐酸精制后得到DADHBP 2HCl,收率67.16%,HPLC纯度(质量分数)98.20%。中间体和产物结构经红外光谱、核磁氢谱和电喷雾质谱表征确认。

In order to improve the poor performance of PBO composite bonding,a polar group hydroxyl group is introduced into the benzene ring for structural modification,and 3,3′-diamino-4,4′-dihydroxybiphenyl hydrochloride(DADHBP·2HCl)is a key monomer for modification.The intermediate 3,3′-dinitro-4,4′-dihydroxybiphenyl(DNDHBP)and the hydroxyl-modified PBO monomer DADHBP·2HCl were synthesized by the nitration and reduction reaction of 4,4′-dihydroxybiphenyl,and the reaction conditions were optimized.The results showed that for the nitration reaction,the yield of 65%of DNDHBP with a HPLC purity 98.65%could be achieved under the conditions of reaction temperature 5℃,reaction time 2.5h and n(DHBP)∶n(HNO3)=1∶2 in the mixed solvent of toluene and glacial acetic acid.The catalytic reduction reaction was conducted in ethanol as solvent under the conditions of n(DNDHBP):n(N2H4·H2O)=1∶5.5,reaction temperature 78℃and reaction time 9h using ferrous sulfateheptahydrate as auxiliary[n(DNDHBP):n(FeSO4·7H2O)=1∶9].After the hot filtration of the reaction mixture,DADHBP·2HCl could be obtained with a yield of 67.16%and a HPLC purity of 98.20%through refined by hydrochloric acid.The intermediate and product structures were confirmed by FT-IR,1H-NMR and EI-MS.