Resorcinol

RESORCINOL, Resorcinum (Pharmacopoeia VII), meta-dihydroxybenzene, a dihydric phenol, a derivative of benzene, C₆H₄(OH)₂. Colorless prismatic crystals, specific gravity 1.27, with a sweetish, stinging, and then bitter taste, and a peculiar, very faint odor. When perfectly pure, it melts at 118° (the pharmacopoeia allows a melting point of 110–112°). It boils at 276° and volatilizes (sublimes) at a significantly lower temperature. In the presence of air and light, resorcinol acquires a reddish color. 1 part of resorcinol dissolves in 0.9 parts of water and the same amount of alcohol; resorcinol is easily soluble in glycerin and ether, less so in benzene, and almost insoluble in chloroform. Resorcinol is an energetic reducing agent, especially in the presence of alkalis: it reduces Fehling's solution and solutions of silver and mercury salts, with the corresponding metals being precipitated. When heated with a double amount of phthalic anhydride, it yields easily identifiable fluorescein. Nitric acid converts resorcinol into trinitroresorcinol (OH)₂C₆H(NO₂)₃, which is soluble in water with an intensely yellow color. A solution of resorcinol with ferric chloride gives an intensely violet coloration. Aqueous solutions of resorcinol are colored intensely red when heated with concentrated sulfuric acid in the presence of tartaric acid. Resorcinol is stored in a dark glass bottle in a dry and cool place. According to its physiological action, resorcinol is close to phenol, possessing an antiseptic effect approximately three times weaker than a phenol solution of the same concentration. Resorcinol precipitates protein even at high dilution. Locally, resorcinol acts as a cauterizing agent, without causing pain or the formation of scars. When large doses of resorcinol are taken orally by humans, redness of the face, dizziness, tinnitus, and acceleration of breathing and pulse are observed. About 4.0 grams can cause collapse and loss of consciousness. Larger doses (10.0 grams and more) cause cooling of the extremities, epileptoid convulsions, opisthotonus, and death with symptoms of collapse. In the body, resorcinol combines with sulfuric or glucuronic acids and is excreted in this form through the kidneys, while part of it undergoes further oxidation, which is detected by the olive-greenish coloration of the urine. Starkenstein described a case of fatal poisoning of a 3-week-old infant by 5% resorcinol vaseline. The picture at autopsy generally resembles phenol poisoning, but the symptoms are less sharply defined; the blood is dark brownish-red. In forensic chemical analysis, resorcinol is extracted from the object with benzene after acidification with tartaric acid, by distillation with water vapor, and the described reactions are performed with the distillate. Microchemically, resorcinol is identified in the form of resorcin-quinhydrone (rectangular plates with yellow-red dichroism), which is obtained by adding quinone to an alcohol-benzene solution of resorcinol, and in the form of tribromoresorcinol (long needles and rods).

Therapeutic use of resorcinol is found mainly in dermatology. In concentrations of 1–2%, resorcinol is used as an anti-pruritic and antiseptic agent for urticaria and other inflammatory processes of the epidermis; in a 3–4% solution, it acts as an antiseptic and possesses a weak keratolytic effect. For furunculosis, a 2% solution of resorcinol in 50% alcohol is used as compresses at the very beginning of the process; in ophthalmic practice, a 1–2% ointment is used; in gynecology, 1–2% solutions are used for leukorrhea, itching of the external genitalia, and colpitis; for gonorrhea, a 0.25–2% solution is used for douching. Internally, resorcinol is prescribed rarely, mainly for gastritis. Doses: internally 0.1–0.5 per dose for an adult; for children, less, according to age, in solution. Externally, in ointments; resorcinol is mixed into the ointment base in the form of a very fine, dust-like powder (do not dissolve in water, as a general effect is possible): 5–10% in vaseline or with lanolin aa. Avoid simultaneous prescription of resorcinol with alkalis and salts of heavy metals due to the possibility of reduction of the latter. In case of resorcinol poisoning: gastric lavage with lime water heavily sweetened with sugar, then Glauber's salt, egg white diluted with water by half; energetic symptomatic treatment!

Resopyrin—white, water-insoluble crystals, obtained by mixing aqueous solutions of resorcinol and antipyrine.