2,4-二氯氟苯合成工艺研究

Synthesis of 2,4-Dichlorofluorobenzene

由对二氯苯经三步反应合成了 2 ,4 二氯氟苯。用硝硫混酸硝化对二氯苯生成 2 ,5 二氯硝基苯 ,收率 98%以上。后者在环丁砜中与氟化钾反应 ,得 2 氟 5 氯硝基苯 ,收率 6 8% (由GC测定 )。 2 氟 5 氯硝基苯在偶氮二异丁腈存在下与氯气发生连续脱硝基氯化反应 ,得目标化合物 2 ,4 二氯氟苯 ,收率94%。该合成路线避免了氯苯路线以爆炸性的二硝基氯苯为中间体的缺陷 ,安全性较好。

Dichlorofluorobenzene was prepared from 1,4-dichlorobe nz ene via nitration,fluorination and denitrochlorination.1,4-Dichlorobenzene was nitrated with mixture of nitric acid and sulfuric acid to 2,5-dichloronitrobenz ene in over 98% isolated yield.Treatment of 2,5-dichloronitrobenzene with pota ssium fluoride in tetramethylene sulfone (sulfolane) gave 5-chloro-2-fluoroni trobenzene in 68% yield(by GC).The final product was obtained by continuous de nitrochlorination of 5-chloro-2-fluoronitrobenzene in the presence of a free radical initiating agent in over 94% yield.The drawback of the old method to us e the explosive intermediate 2,4-dinitrochlorobenzene was avoided.