4-氯-3-氟甲苯和4-溴-3-氟甲苯的合成

SYNTHESIS OF 4-CHLORO-3-FLUOROTOLUENE AND 4-BROMO-3-FLUOROTOLUENE

以红色基GL(邻硝基对甲苯胺)为原料,采用“高温”重氮化反应分别经Sandmeyer反应、还原反应和Schiemann反应可制得纯度≥99．9%(GC)的4-氯-3-氟甲苯和纯度≥99．0%(GC)的4-溴-3-氟甲苯,总收率分别为33．8%和33．9%。其中重氮化氯代反应的最佳反应条件为:反应温度50℃,反应时间2．5h,n(红色基GL):n(CuCl)=1:0．55,保温温度70℃;重氮化溴代反应的最佳条件为:反应温度50℃,反应时间4h,n (红色基GL):n(CuBr)=1:0．60,保温温度60℃。产物经IR和GC-MS验证符合预期结构。此“高温”重氮化法可扩大至中试生产。

4-Chloro-3-fluorotoluene and 4-bromo-3-fluorotoluene were synthesized from o-nitro-p-toluidine（Fast Red Base GL） , through diazo reaction at high temperature, Sandmeyer reaction,reduction and Schiemann reaction. The purity of 4-chloro-3-fluorotoluene and 4-bromo-3-fluorotoluene were 99.9% （GC） and ≥99.0% （GC）, respectively, while the overall yield were 33.8% and 33. 9%, respectively. The optimal conditions for diazo-chlorination were： 50 ℃,reaction time 2.5 h, n（Fast Red Base GL ） ： n（cuprous chloride）=1 ： 0.55 and reaction temperature 70 ℃. The optimal conditions for diazo-bromization were： 50 ℃, reaction time 4 h, n（Fast Red Base GL ） ： n（cuprous bromide）=1 ： 0.60 and reaction temperature 60 ℃. The structures of the products were confirmed by IR and GC-MS. The high temperature diazo reaction could be scaled up.