同分异构体2,4-及2,6-二甲基硝基苯分离

STUDY ON SEPARATION OF 2,4-DIMETHYLNITROBENZENE FROM 2,6DIMETHYLNITROBENZENE ISOMER

同分异构体２，４及２，６二甲基硝基苯的分离是由间二甲苯制２，４及２，６二甲基胺的关键过程，间二甲苯经硝化反应生成的硝化混合液中，含有２，４及２，６二甲基硝基苯和少量的２，３及２，５二甲基硝基苯等杂质。为了硝基苯加氢的顺利进行，必须将这些物质进行分离。研究结果表明，采用新型复合塔件，塔板数４０块，回流比５～６，真空（６６６６Ｐａ）可得到纯的２，６二甲基硝基苯和２，４二甲基硝基苯。

Separation of 2,4-dimethylnitrobenzene from 2,6-dimethylnitrobenzene is the key process during the preparation of 2,4 and 2,6-dimethylaniline from m-dimethylbenzene. m-Dimethylbenzene is nitrated to form a mixture of 2,4 and 2,6- dimethylnitrobenzene accompanied with small amounts of 2,3 and 2,5-dimethylnitrobenzene as mixture. These must be separated before hydrogenation of dimethylnitrobenzene. In this research, a new type of packing tower was used. The result showed that pure 2,4 and 2,6-dimethylnitrobenzene were obtained under the following conditions: plate number about 40; reflux ratio 6; pressure (vaccum) 6666Pa.