2,6-二氯-3-甲基苯胺合成新工艺

Synthesis of 2,6-Dichloro-3-Methylaniline

通过N-乙酰化保护氨基,氯磺酸与氨水反应在氨基对位形成磺酰胺阻塞基团,再经脱乙酰基,氯化, 水解脱阻塞基团,合成2,6-二氯-3-甲基苯胺得到目标产物。与经典文献方法相比,用盐酸代替氢氧化钠脱除乙酰基,用氯酸钠和浓盐酸代替双氧水和浓盐酸或氯气的氯化方法,合成过程中省略了中间产物的分离步骤,以问甲苯胺计总摩尔收率从20％提高到了60．8％,产品纯度大于99．5％。

Synthesis process of 2,6-dichloro-3-methylaniline（Ⅶ） was investigated. 3-methylaniline was first N-acetylated with acetic anhydride, then treated with chlorosulphonic acid and ammonia yielding the 2-methyl-4-（N-acetyl）-benzenesulfonic amide, which was in turn deacetylated, chlorinated and hydrolyzed to the title compound. Hydrochloric acid was used instead of sodium hydroxide in deacetylation and sodium chlorate instead of hydrogen peroxide as oxidant in chlorination. Separation for 2-methyl-4-amino sulfanilamide intermediate was omitted. Then, high total molar yield was obtained, and based on 3-methylaniline, total molar yield of the product（Ⅶ） was 60. 8%. Steam distillation operation was employed to purify product （Ⅶ）, the purity was more than 99. 5 percent.