5-硝基-6-羟基-2-(对甲氧羰基苯基)苯并噁唑的合成

研究了以关键中间体4-氨基-6-硝基间苯二酚盐酸盐（ANR·HCl）和对苯二甲酸单甲酯（MTA）为原料，分别经酰氯化、缩合、环合分步或原位合成AB型新单体前体--4-（5-硝基-6-羟基-2-苯并噁唑基）苯甲酸甲酯（MNB）的技术。 反应优化条件：在甲基异丁基酮溶剂中，n(ANR·HCl)∶n(MTA)=1.00∶1.03，115 ℃缩合反应2.5 h；m(ANR·HCl)∶m(PPA)=1.00∶3.25的多聚磷酸(PPA)，120 ℃环合8.5 h；MNB收率75.68%（以ANR·HCl计），HPLC测定ω(MNB)=96.32%。 产物结构经¹H NMR和IR确证。

Sythesis of Methyl 4-(5-nitro- 6-hydroxybenzoxazol-2-yl)benzoate

To achieve industrialization of the New AB-type poly (p-phenylene benzobizoxazole) (PBO)’s homogeneous polycondensation. The AB-type monomer precursor──methyl 4-(5-nitro- 6-hydroxybenzoxazol -2-yl)benzoate’s（MNB）synthesis process was studied , and MNB’s synthesis route using 4-amino-6-nitroresorcinol hydrochloride (ANR•HCl) and 4-(methoxycarbonyl)benzoic acid (MTA) as raw materials was developed by acyl chlorination、condensation and cyclization separately or one-pot synthesis. The optimum conditions were as follows: 4-methyl-2-pentanone as solvent, Feed ratio (mol ratio) of ANR•HCl / MTA was 1.00/1.03, condensation reaction at 115 ℃ for 2.5 h. Cyclization reaction at 120 ℃ for 8.5 h after adding PPA as dehydrating agent which the feed ratio (mass ratio) of ANR•HCl / PPA was 1.00/3.25, the product was obtained with a yield of 75.68% and the purity of MNB without further purification was 96.32% by HPLC method. Structures of the products were characterized by 1HNMR and IR.