the nitrogen in the S-N bond of 2-hydroxysulfenanilides can oxidized to an imine species with sodium dichromate. Sulfenamides react with amino-azaheterocycles to form heterocyclic systems (often used as amino protecting groups in various other synthesis reactions). Chlorocarbonylsulfenyl chloride (ClCOSCl) also readily forms S-N bonds with 2-amino-azaheterocycles, but always of a cyclical nature. A novel variant of the Appel reaction has been noted for sulfenamides. Reaction of o-nitrobenzenesulfenamide with PPh3 and CCl4 leads the formation of o-nitro-N-(triphenylphosphorany1idene)-benzenesulfenamide. In this variant reaction the triphenyl phosphine forms a double bonded linkage with nitrogen in the sulfenamide instead of oxygen as is customary in the Appel reaction. Additionally in the traditional Apple reaction the R-OH bond is cleaved leaving oxygen attached to triphenylphosphine. In this variant the S-N bond is not cleaved. Applications Sulfenamides, e.g. cyclohexylthiophthalimide, are used extensively in the vulcanization of rubber. The sulfenamides are used to accelerate the process via the transient formation of labile S-N bonds. The substituents on the sulfenamides determine the point at which they will become active. Temperature dependent activation of sulfenamide accelerants is useful in the vulcanization process because the temperature at which the rubber polymerizes determines the length of the sulfur chains, and properties such as the elasticity of the final product. References Functional groups