硫醚中碳硫键室温选择性断裂反应的研究

本文研究了在四氟硼酸银存在下, 硫醚与碘甲烷室温下发生碳硫键选择性断裂反应。研究结果表明: 只有当二苄基硫醚的苯环对位连有强的供电子基团甲氧基时, 方可发生碳硫键的断裂。提出了一个离子型反应机理且碳硫键的断裂分三步完成。首先, 硫醚与甲基化试剂反应生成甲基锍盐; 继而, 此锍离子离解成由苄基碳正离子和硫醚组成的离子-偶极集合物; 最后, 甲基化试剂再进攻集合物中的硫醚, 从而导致碳硫键的断裂。

Study on the mechanism of selective carbon-sulfur bond cleavage in sulfide at room temperature

The reaction of various dibenzylsulfides with excess methyl iodide in the presence of excess silver tetrafluoroborate at room temperature and the carbon - sulfur bond selective cleavage reac-tion in some case were studied. The results showed that only the benzyl group with p - methoxy sub-stituent could undergo bond cleavage. The carbon - sulfur bond cleavage process might consist of three steps.The first, sulfide reacts with methylation agent to form methylsulfonium salt and the second, sulfonium ion undergoes dissociation to form an ion - dipole assemblage consisting of benzyl carbocation and sulfide. Finally, methylating agent attacks sulfide in assemblage to cleavage carbon - sulfur bond.