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A solution containing ammonium thioglycolate contains a lot of

  • Ammonium thioglycolate, also known as perm salt, is the chemical compound with the formula HSCH2CO2NH4.

    Being the salt of a weak acid and weak base, ammonium thioglycolic acid exists in solution as an equilibrium mixture of the salt itself as well as the free carboxylic acid thioglycolic acid (HSCH2CO2H) and ammonia:

    HSCH2COO− + NH4+ ⇌ HSCH2COOH + NH3
    A solution containing ammonium thioglycolate contains a lot of free ammonia, which swells hair, rendering it permeable. The thioglycolic acid in the perm solution reduces the disulfide cystine bonds in the cortex of the hair. In a sense, the thioglycolate removes crosslinks. After washing, the hair is treated with a mild solution of hydrogen peroxide, which oxidizes the cysteines back to cystine. These new chemical bonds impart the structural rigidity necessary for a successful perm. The rigidification process is akin to the vulcanization of rubber, where commonly polysulfide linkages are used to crosslink the polymer chains. However, not as many disulfide bonds are reformed as there were before the permanent. As a result, the hair is weaker than before the permanent was applied and repeated applications over the same spot may eventually cause strand breakage.
    In the 2001 film Legally Blonde, law student Elle Woods wins her first case by her knowledge of the chemistry of ammonium thioglycolate (which she pronounces "ammonium thyglocolate"), something she claims "any Cosmo girl would have known."
    Solutions containing ammonium thioglycolate contain a lot of free ammonia, which swells the hair and makes it permeable. Thioglycolic acid contained in the perm solution reduces disulfide cystine bonds in the cortex. In a sense, thioglycolic acid removes cross-links. After washing, hair is treated with a mild solution of hydrogen peroxide to oxidize cysteine ​​to cystine. These new chemical bonds give the structural rigidity needed for a successful perm. The curing process is similar to vulcanization of rubber and generally uses polysulfide bonds to crosslink the polymer chains. However, it does not reform as many disulfide bonds as it did before permanent bonds. As a result, your hair will be weaker than it was before the perm, and repeated perms in the same spot can eventually break your hair. Since polar molecules are less volatile than non-polar ones, the glycolic acid substituent makes the thiols non-volatile and reduces odor. A further advantage is that glycolate confers some degree of water solubility. Perming with HSCH3 and ammonia is almost certainly possible, but it can seriously affect your sense of smell.
    In the 2001 film Legally Blonde, the main character, law student Elle Woods, wins her first lawsuit by proving that a witness who had a perm on the day of the murder could not have been in the shower at the time of the murder. To do. The first rule of perm maintenance is not to get your hair wet for at least 24 hours after perming, as this may cause the ammonium thioglycolate to become inactive. ”
    An ammonium thioglycolate solution contains a lot of free ammonia that swells up the hair and makes it more permeable. Thioglycolic acid in perm solutions reduces disulphide cysteine bonds in the hair cortex. After washing, hair is treated with a delicate hydrogen peroxide solution, which oxidises cysteine residues and turns them into cystine. It is these chemical bonds that create the structural rigidity that is needed for a good perm.