性质
2-溴-3-硝基吡啶在常温常压下呈现灰白色至奶油色结晶粉末状,属于吡啶类衍生物,具有吡啶环的通用性质。
用途
2-溴-3-硝基吡啶可用作医药化学和有机合成中间体。在合成过程中,吡啶环上的硝基可以被还原成氨基;受吡啶环缺电子特性和硝基强吸电子特性的影响,结构中的溴原子可被亲核试剂如烷基胺或氧负离子进攻,从而进一步衍生化。
合成方法
将25毫升二甲基亚砜中溶解的48%氢溴酸(2.31毫升,20毫摩尔)溶液滴加到含有2-氨基-3-硝基吡啶(0.986克,5毫摩尔)和25毫升二甲基亚砜以及10毫摩尔亚硝酸钾的混合体系中。反应物在35℃下搅拌后,转移到含5克碳酸钾的100毫升冰水溶液中。随后,将反应混合物溶解于乙醚中,并用水洗涤。使用无水硫酸镁干燥后,在减压条件下除去有机溶剂,得到粗品4-溴二苯甲酮。通过柱层析进一步纯化,最终获得2-溴-3-硝基吡啶。
合成路线
图 2-溴-3-硝基吡啶的合成路线
Halodimethylsulfonium halide 1, which is readily formed in situ from hydrohaloic acid and DMSO, is a good nucleophilic halide. This activated nucleophilic halide rapidly converts aryldiazonium salt prepared in situ by the same hydrohaloic acid and nitrite ion to aryl chlorides, bromides, or iodides in good yield. The combined action of nitrite ion and hydrohaloic acid in DMSO is required for the direct transformation of aromatic amines, which results in the production of aryl halides within 1 h. Substituted compounds with electron-donating or -withdrawing groups or sterically hindered aromatic amines are also smoothly transformed to the corresponding aromatic halides. The only observed by-product is the deaminated arene (usually <7%). The isolated aryldiazonium salts can also be converted to the corresponding aryl halides using 1. The present method offers a facile, one-step procedure for transforming aminoarenes to haloarenes and lacks the environmental pollutants that usually accompany the Sandmeyer reaction using copper halides. Key words: aminoarenes, haloarenes, halodimethylsulfonium halide, halogenation, amination.