Antiseptics and Disinfectants

Among commonly used antiseptics, the chapter names inorganic examples -- iodine and boric acid -- alongside organic examples such as iodoform and a family of phenolic compounds. Tincture of iodine, a solution containing roughly 2-3 percent iodine dissolved in a mixture of alcohol and water, together with iodoform, serves as a powerful antiseptic and is applied directly to wounds. A dilute aqueous solution of boric acid, being comparatively weak, is used specifically as an antiseptic for the eyes. The largest family discussed is the phenol derivatives. Phenol itself, in a dilute aqueous solution, was historically known as carbolic acid and was one of the very first antiseptics used in medicine, in the late nineteenth century -- but it was found to be corrosive to tissue, which limited its usefulness. Chlorinated derivatives of phenol were subsequently developed as more potent antiseptics than phenol itself, and being more potent meant they could be used at much lower concentrations, which in turn reduced their corrosive effect on tissue. Two of the most widely used phenol-derivative antiseptics are 2,4,6-trichlorophenol (TCP), which carries three chlorine atoms on the ring, and chloroxylenol (para-chloro-meta-xylenol), which carries one chlorine atom and two methyl groups on the ring in addition to its -OH group; chloroxylenol is specifically the active ingredient, at a concentration of 4.8% w/v, in the popular antiseptic Dettol, whose other listed ingredients are isopropyl alcohol, pine oil, castor oil soap, caramel and water. Thymol, obtained from oil of thyme (a spice plant) and carrying a methyl group and an isopropyl group on its phe …