Thioglycolic acid corresponding disulfide (2-[(carboxymethyl)disulfanyl]acetic acid or dithiodiglycolic acid): Thioglycolic acid, usually as its dianion, forms complexes with metal ions. Such complexes have been used for the detection of iron, molybdenum, silver, and tin. Thioglycolic acid reacts with diethyl acetylmalonate to form acetylmercaptoacetic acid and diethyl malonate, the reducing agent in conversion of Fe(III) to Fe(II). Scientist David R. Goddard, in the early 1930s, identified TGA as a useful reagent for reducing the disulfide bonds in proteins, including keratin (hair protein), while studying why protease enzymes could not easily digest hair, nails, feathers, and such. He realized that while the disulfide bonds,
Afro-textured hair (especially Black women) "had many Eurocentric features, including hairstyles." However, during the movement, the Black community endeavoured to define their own ideals and beauty standards, and hair became a central icon which was "promoted as a way of challenging mainstream standards regarding hair." At this time, an African-American person's "ability to conform to mainstream standards of beauty [was] tied to being successful." Thus, rejecting straightened hair symbolized a deeper act of rejecting the belief that straightening hair and other forms of grooming which were deemed 'socially acceptable' were the only means of looking presentable and attaining success in society. The