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CAMPHORS

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Originally appearing in Volume V05, Page 136 of the 1911 Encyclopedia Britannica.
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CAMPHORS , organic chemical compounds, the See also:

alcohols and See also:ketones of the See also:hydrocarbons known as See also:terpenes, occurring associated with volatile See also:oils in many See also:plants. They are extracted together with volatile oils by distilling certain plants with See also:steam, the volatile oils being subsequently separated by fractional See also:distillation. The See also:term " camphor " is generally applied to the solid products so obtained, and hence includes the " stearoptenes," or solid portions of the volatile oils. They are mostly See also:white crystalline solids, possessing a characteristic odour; theyare sparingly soluble in See also:water, but readily dissolve in See also:alcohol and See also:ether. Chemically, the camphors may be divided into two See also:main See also:groups, according to the nature of the corresponding See also:hydrocarbon or terpene. In this See also:article only the camphors of commercial importance will be treated; details as to the chemical structure, syntheses and relations will be found in the article TERPENES. Menthol, mentha or See also:peppermint camphor, C10H190H, 5-methyl-2-isopropyl hexahydrophenol, an oxyhexahydrocymene, occurs in the volatile oils of Mentha piperita and M. arvensis (See also:var. piperascens and glabrata), from which it is obtained by cooling and subsequently pressing the separated crystals; or by fractional distillation. It crystallizes in prisms, having the odour and See also:taste of peppermint; it melts at 42° and boils at 212°. It is very slightly soluble in water, but readily dissolves in alcohol and ether. It is optically active, being laevo-rotatory. Menthol is used in See also:medicine to relieve See also:pain, as in See also:rheumatism, See also:neuralgia, See also:throat affections and toothache. It acts also as a See also:local anaesthetic, vascular stimulant and disinfectant.

See also:

Thymol, See also:thyme camphor, C10H130H, 3-methyl-6-isopropyl phenol, an oxycymene, occurs in the volatile oil of Ajowan, Carum ajowan, See also:garden thyme, Thymus vulgaris, See also:wild thyme, T. Serpyllum and See also:horse See also:mint, Monarda punctata. Thymol crystallizes in large colourless plates which melt at 440 and See also:boil at 230°. It has the odour of thyme, is sparingly soluble in water, but very soluble in alcohol, ether and in alkaline solutions. In medicine it is used as an antiseptic, being more active than phenol. See also:Iodine and potash convert it into di-iodthymol, which has been introduced in See also:surgery under the names aristol and annidalin, as a substitute for See also:iodoform. Borneol, See also:Borneo camphor or camphol, also known as Malayan, Barus or Dryobalanops camphor, C1oH170H, occurs in fissures in the See also:wood of Dryobalanops aromatica, a majestic See also:tree flourishing in the See also:East Indies. This product is dextro-rotatory; the laevo and inactive modifications occur in the so-called baldrianic camphor. Borneol melts at 203° and boils at 212°. It is very similar to See also:common or See also:Japan camphor, but has a somewhat peppery odour. See also:Sodium and alcohol reduce common camphor to a mixture of d- and l-borneol. Common camphor, Japan or See also:Laurel camphor, C10H160, which constitutes the bulk of the camphor of See also:commerce, is the product of the camphor laurel, Cinnamonum camphora, a tree flourishing in Japan, See also:Formosa and central See also:China.

It also occurs in various volatile oils, e.g. See also:

lavender, See also:rosemary, See also:sage and spike. To ex-See also:tract the camphor, chips of the tree are steamed, and the mixed vapours of camphor, volatile oils and water are conducted to a condensing plant, where most of the camphor separates out. This is filtered, and the See also:remainder, about 20 % of the See also:total, which is retained in See also:solution, is extracted by fractional distillation and cooling the distillate. The crude camphor so obtained is exported from Japan in two grades—Samuel A and See also:Samuel B. It is purified by mixing with a little See also:charcoal, See also:sand, See also:iron filings or quicklime and subliming, by steam distillation or by See also:crystallization. Common camphor forms a translucent See also:mass of hexagonal prisms, melting at 175° and boiling at 204°. It sublimes very readily. In alcoholic solution it is dextro-rotatory; the laevo See also:form, Matricaria camphor, occurs in the oil of Matricaria parthenium and closely resembles the d form. Camphor is chiefly used in the celluloid See also:industry. The so-called " artificial camphor " is pinene hydrochloride (see TERPENES). Externally applied it acts medicinally as a See also:counter-irritant, and, in some degree, as a local anaesthetic, being also a definite antiseptic. It is, therefore, largely used in liniments for the See also:relief of myalgia, See also:sciatica, See also:lumbago, etc.

Combined with See also:

chloroform, thymol or carbolic See also:acid, it is a valuable local application for neuralgia and for toothache due to dental See also:caries. Taken internally, camphor is a See also:nerve stimulant, a diaphoretic and a feeble antipyretic. It is excreted by the kidneys as various substances, including campho-glycuric acid (Schmiedeberg). In large doses it causes marked See also:nervous symptoms, exhilaration being followed by abdominal pain, violent epileptiform See also:convulsions, See also:coma and See also:death. Its See also:internal uses are in See also:hysteria, and in such conditions as See also:diarrhoea, 'See also:dysentery and See also:cholera. It is a popular remedy for " See also:cold in the See also:head," but it is not to be relied upon as a prophylactic against infection either by an See also:ordinary cold or true See also:influenza.

End of Article: CAMPHORS

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