二甲苯砜加入法抑制甲苯磺化副反应

Sulfone Addition to Inhibit the Side Reaction in Toluene Sulfonation

对气相三氧化硫磺化甲苯过程中的副产物二甲苯砜的生成原因及抑制作用机理进行了分析,提出用磺化副产物二甲苯砜自身抑制的新方法。考察了二甲苯砜加入量和甲苯转化率对副反应的抑制作用。反应温度10℃,三氧化硫体积分数6％,甲苯转化率35％时,外加甲苯质量3.3％的二甲苯砜就能控制二甲苯砜含量不增加,且甲苯磺酸对位异构体质量分数由83.35％上升到88.39％,间位异构体质量分数由2.10％下降到1.01％。

The formation and inhibition mechanism of 4, 4'-dimethyl - diphenyl - sulfone, a byproduct of toluene sulfonation were studied. A new method that sulfone can act as self - inhibitor instead of other acid inhibitors was proposed and illustrated by addition of a preferable amount of sulfone to the reaction system under suitable reaction conditions.The suitable conditions were: 10℃ ,volume fraction 6% gaseous sulfur trioxide and especially at toluene conversion of 35% . Amount of sulfone added was 3.3% based on toluene mass. No further increment of sulfone was observed during reaction after the addition. Among the three toluene sulfonic acid isomers,the main P-isomer was up to 88.39% from 83.35% ,and m-isomer was down to 1.01% from 2.10% .