Naphthalene

NAFTHALENE, Naphthalinum, C₁₀H₈ (Ph. VII) (mol. wt. 128.1), hydrocarbon of the cyclic series, in the molecule of which two condensed benzene nuclei are present: сн си нс/\c/Чсн ! I! I нс\/c\^-сы сн сн Naphthalene is contained in significant quantities in fractions of coal tar boiling at t° 180-220°, and upon cooling of this distillate it is separated in the form of crystals; they are freed from liquid impurities by pressing and the resulting crude N. is purified by treatment with sulfuric acid, distillation and crystallization from alcohol. Pure N. appears as colorless, brilliant leaflets with a characteristic odor and burning taste. It melts at 80°, boils at 218°; is volatile at ordinary t°, insoluble in water, dissolves in hot alcohol, ether, chloroform, carbon disulfide; when ignited it burns with a luminous and smoky flame. By the action of sulfuric acid it is converted into sulfonic acids, by the action of nitric acid into nitro compounds. N. possesses antiseptic action, which however due to the insolubility of N. in water has only very limited application. The antiseptic property of N. also manifests itself in the vapor state; thus, air containing N. vapors formed during its evaporation inhibits the development of mold fungi and putrefactive bacteria and acts destructively on various insects; skin parasites (lice and mites) are also killed by N., for example when rubbed into the skin in the form of a solution. N. can be absorbed by the skin, subcutaneous tissue, gastrointestinal tract, as well as by the lungs when its vapors are inhaled. According to experiments by Fischer (Fischer), in humans and other warm-blooded animals, staying in an atmosphere with N. vapors causes no symptoms of poisoning (probably at low concentrations), whereas according to observations by other authors, an admixture of N. vapors to the air causes in humans headache, nausea, vomiting, skin diseases. When introduced into the body by other routes (per os, subcutaneously or intravenously), as shown by experiments on animals, differences in poisoning symptoms depend not on the route of administration but on the species of animal. Dogs prove to be more resistant, while cats are more sensitive. In dogs after administration of N. in doses of 2-5 g per 1 kg weight, only diarrhea, refusal of food and loss of body weight are observed without clear symptoms of poisoning from other organs. Cats after administration of 1-3 g per 1 kg weight die soon with symptoms of severe hemorrhagic nephritis. In rabbits, besides diarrhea, albuminuria and hemoglobinuria, N. can cause eye lesions in the form of persistent clouding of the lens and posterior surface of the cornea (naphthalene cataract). At the same time the retina is also affected, on which shiny white spots of various sizes appear; this process in some cases is characterized by vacuolar degeneration of all layers of the retina, in other cases an exudative inflammatory process is observed, ending in the death of retinal elements with their replacement by granulation tissue. After numerous investigations and mainly thanks to the experiments of van der Hoeve with the administration of D-naphthol to rabbits, confirmed by other authors, it can be considered that the poisonous effect on the eyes belongs to the oxidation products of naphthalene formed in the body, possibly β-naphthol, although its formation from N. in the body is not proven. In humans, symptoms of N. poisoning are the result of mainly damage to the gastrointestinal tract, kidneys and urinary tract, which manifests as diarrhea, pain in the kidney region, albuminuria, strangury. Eye lesions to the same extent as in animals are observed in humans in very rare cases, but various vision defects have been noted in cases of N. poisoning. Therapeutic use of N. began after in 1881 Fischer discovered its antiseptic and parasitotropic properties, and it came to be used to combat skin parasites, for disinfection of wounds, gastrointestinal tract and urinary tract. Soon however its poisonous action with the above-mentioned symptoms was discovered, as a result of which it was almost completely abandoned, and at present N. is rarely used for therapeutic purposes. N. is excreted from the body partly in unchanged form along with feces, and partly is absorbed and undergoes oxidation to naphthol and dioxynaphthalenes; these products are excreted through the kidneys in combination with glucuronic and sulfuric acids, the urine being colored by them dark red or olive-green and darkening on standing. Dosage: internally 0.1-0.5 several times a day in powders or pills for intestinal catarrhs and infectious intestinal diseases as a disinfectant; as an anthelmintic for oxyuris (children 0.1-0.4 four times a day, adults 0.5 per dose up to 3.0 pro die for two consecutive days with mandatory prior and subsequent administration of a non-fatty laxative). When taking N. internally, a fat-free diet must be observed and alcohol abstained from. Externally for scabies, favus, herpes tonsurans in the form of powder or ointment: 1:10; in 5-10% oil solution against pediculi capitis. Of the derivatives of N., nitro compounds are important, to which workers in the production of dyes and explosives are exposed. According to experiments by Kolsch, mononitro-N. and technical di-nitro-N. are significantly less poisonous than N.: the single lethal dose for a rabbit is 3-4 g per 1 kg weight. According to observations by authors who studied workers in the above-mentioned industries, occupational diseases in them are expressed mainly in clouding of the cornea and visual disturbances from the direct action of nitronaphthalene vapors on the eyes.