Final answer:
The addition of ammonia to thioglycolic acid creates ammonium thioglycolate, an alkaline substance that acts as the active reducing agent in alkaline hair permanents. It transforms the structure of hair by breaking disulfide bonds in keratin.
Step-by-step explanation:
The addition of ammonia to thioglycolic acid produces a new chemical called ammonium thioglycolate, which is alkaline and is the active ingredient or reducing agent in alkaline permanents. The primary reaction occurs when thioglycolate, a thiol, breaks the disulfide bonds in keratin through a reduction process. This action softens the hair, making it possible to reshape or curl the hair in the styling process known as a 'perm'. Ammonia acts to increase the pH of the thioglycolate solution, making it alkaline and more effective as a reducing agent.
Chemical depilatories often contain a related compound, calcium thioglycolate, to break down disulfide bonds in hair for easy removal. Other reagents like ammonium peroxydisulfate and hydrogen peroxide may be used as auxiliary oxidizing agents in cosmetic preparations.