Nonetheless, the reactivity of dibenzyl disulfide appears to be an exception; in general, spontaneous S-S metathesis of alkyl disulfides does not occur at room temperature in polar, aprotic solvents. The non-reactivity of tetrasulfides was also a surprise. The central S-S bond in the tetrasulfide is less than half the strength of the S-S bond of disulfides, as confirmed by high-level computations (S194-S195). Nevertheless, when di-n-propyl tetrasulfide and dibenzyl tetrasulfide were combined in an equimolar ratio in deuterated DMF, no reaction was observed by 1 H NMR spectroscopy for up to 12 hours (Figure ). Even heating this mixture to 80 ºC for 1 hour did not provoke a reaction. Reaction was only observed when the mixture was heated to 100 ºC, which is consistent with radical S-S exchange of tetrasulfides. A similar result was observed in the attempted metathesis of di-n-propyl tetrasulfide and bis(4-methoxybenzyl) tetrasulfide in DMF. In contrast, trisulfides exhibited very rapid metathesis in DMF at room temperature. Together, these results point to a unique reaction pathway of trisulfides that is not accessible to the corresponding di-or tetrasulfide substrates.