SYNTHESIS OF 2-BROMO-6-CHLOROTOLUENE BY SANDMEYER METHOD
Using the Sandmeyer method with 3-chloro-2-methylaniline as the raw material and sodium nitrite as diazotization reagent,diazonium salts were obtained at low temperature and acid environ-ment.Then,copper-based catalysts were used to decompose diazonium salts under-different tempera-ture conditions to obtain 2-chloro-6-bromotoluene.The optimal synthesis conditions are to dissolve the amine in 30％sulfuric acid(mass fraction),form the diazonium salt with a sulfuric acid solution of sodium nitrite,use hydrobromic acid as the bromine source,copper powder as the catalyst,and de-compose at 0℃.Among them,the amount of acid used is 5 times that of the raw material,n(3-Chlo-ro-2-methylaniline)∶n(sodium nitrite)∶n(copper)∶n(industrial hydrobromic acid)=1∶1.2∶0.1∶1.2,and the yield of 2-chloro-6-bromotoluene reaches 95％.
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