Hair dyeing

Bismarck brown, Basic Brown 1 Basic azo-dyestuff, dyes wool (reddish brown), used for cotton with tannin as mordant. Used as hair dye. 

It is used for hair dyeing, as a rubber accelerator and as a photographic developer. Derivatives are extensively used as developers in colour photography. 

For fluorine-free products, the labiUty of fluorine in fluoronitrobenzenes and other activated molecules permits it to serve as a handle in hair-dye manufacturing operations, high performance polymers such as polyetheretherketone (PEEK), production of dmgs such as diuretics, and fiber-reactive dyes. Labile fluorine has also been used in analytical appHcations and biological diagnostic reagents. 

Temporary hair dye products usually are formulated at a neutral or slightly acidic pH. Besides the dyes, the formulations may contain a small amount of a quaternary amine to neutralize the negative charge on the dyes, a fragrance, a small amount of a solvent or surfactant to solubilize the fragrance, and a preservative (Table 6). 

Permanent Hair Colorants. Permanent colorants produce hair coloration that lasts until the hair grows out. Color is formed inside the hair by hydrogen peroxide-induced coupling reactions of colorless dye precursors. A hiU range of shades can be obtained with this system and the permanent or oxidative hair colorants are considered to be the most important class of hair dyes. 

Amin ophen o1 has been used as a stabilizer of chlorine-containing thermoplastics (153), although its principal use is as an intermediate in the production of 4-aniino-2-hydroxybenzoic acid [65-49-6] a tuberculostat. This isomer is also employed as a hair colorant and as a coupler molecule in hair dyes (154,155). 

The dibydrochloride salt is used as a photographic developer. It also is employed as an intermediate in the manufacture of fur dyes, in hair dyeing, as a reagent in testing for ammonia and formaldehyde, and as an oxygen scavenger in water to prevent boiler corrosion (173). 

Its chief use is as a component in photographic developers. Because the free compound is unstable in air and light, it is usually marketed as the sulfate salt [55-55-0] Metol, mp 260°C (dec.). It also finds appHcation as an intermediate for fur and hair dyes and, under certain circumstances, as a corrosion inhibitor for steel. Prolonged exposure to 4-(/V-methy1amino)pheno1 has been associated with the development of dermatitis and allergies. 

The NF and reagent grades are employed in the pharmaceutical industry which makes use of benzyl alcohol s local anesthetic, antiseptic, and solvent properties (17—20). It also finds use in cough symps and drops ophthalmic solutions bum, dental (21), and insect repeUant solutions and ointments and dermatological aerosol sprays. It is used in nail lacquers and as a color developer in hair dyes by the cosmetics industry (22), and in acne treatment preparations (23). 

Hair colorants, the fourth class of color additives, may be used only to color scalp hair and may not be used in the area of the eye. Use of these colorants is exempt, that is, coal-tar hair dyes may be sold with cautionary labeling, directions for preliminary (patch) testing, and restrictions against use in or near the eye. The EDA diligently enforces the rules governing color additives and limits the use of, or even dehsts colorants deemed unsafe. The Hst of substances specifically prohibited for use in cosmetics is short. 

Table 17. Intermediates Used in Oxidation Hair Dyes ...

Benzophenone-4 is a water-soluble form used in cosmetics, hair-sprays, and hair dyes. 

Gennaro, M. C., Bertolo, P. L., and Marengo, E., Determination of aromatic amines at trace levels by ion interaction reagent reversed-phase high-performance liquid chromatography. Analysis of hair dyes and other water-soluble... 

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