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 reaction in some case were studied. The results showed that only the benzyl group with p- methoxy substituent 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.

Key words: METHOXY GROUP, IODOMETHANE, SULFUR ETHER