Hydroxide relaxers remove one atom of sulfur from a disulfide bond, converting it into which process?

• A. Lanthionization
• B. Desulfuration
• C. Sulfuration
• D. Hydrogenation

Answer: (A)

The process being described is lanthionization. In hydroxide relaxers, a strong base breaks the disulfide bond in hair and, instead of simply reducing it, one sulfur atom is removed from the bond. The remaining structure then forms a new sulfur-containing linkage with the neighboring part of the molecule, creating a lanthionine bond. This permanently alters the cross-links in the hair, reducing curl and giving a relaxed texture.

Desulfuration would imply removing sulfur entirely, which isn’t the typical result here. Sulfuration would add sulfur, which is the opposite of what happens. Hydrogenation would add hydrogen to bonds, not transform a disulfide into a lanthionine linkage.