1911 Encyclopædia Britannica/Thymol

THYMOL, C₁₀H₁₄O or C₆H₃(OH) (CH₃) (C₃H₇) [ 1:3:6 ], a methylisopropylphenol isomeric with carvacrol (q.v.), is an aromatic substance found with the hydrocarbons cymene, C₁₀H₁₄, and thymene, C₁₀H₁₆, in oil of thyme (from Thymus vulgaris) and in other essential oils, e.g. Carum copticum, from which it may be extracted by shaking with potassium hydroxide, filtering and precipitating the phenol with hydrochloric acid. It can be prepared from dibrom-menthone (obtained by brominating menthone in chloroform solution) by eliminating two molecules of hydrobromic acid. Thymol crystallizes in large colourless plates, which melt at 44° and boil at 230°. On distillation with phosphorus sulphide it gives cymene.

Thymol has a strong odour of thyme and a pungent taste, and is freely soluble in alcohol, ether, chloroform or olive oil, but almost insoluble in cold water. It is a more powerful antiseptic than carbolic acid, but its insolubility prevents its being used for the same purposes. A saturated solution (1 in 1000 of warm water), thymol gauze and an ointment are used. Externally it is antiparasitic, and is used in certain stages of eczema and psoriasis, and the alcoholic solution has been used in ringworm; internally it has been employed as an intestinal antiseptic in typhoid fever. Its chief use is as an anthelmintic to destroy the Ankylostoma duodenale. Thymol may colour the urine green. Thymol iodide, official in the United States, is a compound of iodine and thymol; it is also known as aristol or annidalin. It was introduced as a substitute for iodoform and is stated to be less toxic. Glycothymolin is a proprietary preparation, used in the treatment of catarrhal conditions of mucous membranes, while a mixture of naphthalene, camphor and thymol is sold under the name of thymolin.