Oxidation of thiols to disulfides
Description: When treated with an oxidizing agent such as iodine or molecular oxygen, thiols can be converted to disulfides.
Notes: Other bases besides NaOH can be used here.
Mechanism: Deprotonation of thiol by base (Step 1, arrows A and B) leads to the more nucleophilic sulfide, which then attacks iodine (Step 2, arrows C and D). Now that there is a good leaving group on sulfur, a second equivalent of sulfide can attack the sulfur (Step 3, arrows E and F) giving the disulfide.