Camphor

Camphor (/ˈkæmfər/) is a waxy, flammable, transparent solid with a strong aroma. It is a terpenoid with the chemical formula C10H16O. It is found in the wood of the camphor laurel (Cinnamomum camphora), a large evergreen tree found in Asia (particularly in Sumatra and Borneo islands, Indonesia) and also of the unrelated kapur tree, a tall timber tree from the same region. It also occurs in some other related trees in the laurel family, notably Ocotea usambarensis. The oil in rosemary leaves (Rosmarinus officinalis), in the mint family, contains 10 to 20% camphor, while camphorweed (Heterotheca) only contains some 5%. Camphor can also be synthetically produced from oil of turpentine. It is used for its scent, as an ingredient in cooking (mainly in India), as an embalming fluid, for medicinal purposes, and in religious ceremonies. A major source of camphor in Asia is camphor basil (the parent of African blue basil). Camphor (/ˈkæmfər/) is a waxy, flammable, transparent solid with a strong aroma. It is a terpenoid with the chemical formula C10H16O. It is found in the wood of the camphor laurel (Cinnamomum camphora), a large evergreen tree found in Asia (particularly in Sumatra and Borneo islands, Indonesia) and also of the unrelated kapur tree, a tall timber tree from the same region. It also occurs in some other related trees in the laurel family, notably Ocotea usambarensis. The oil in rosemary leaves (Rosmarinus officinalis), in the mint family, contains 10 to 20% camphor, while camphorweed (Heterotheca) only contains some 5%. Camphor can also be synthetically produced from oil of turpentine. It is used for its scent, as an ingredient in cooking (mainly in India), as an embalming fluid, for medicinal purposes, and in religious ceremonies. A major source of camphor in Asia is camphor basil (the parent of African blue basil). The molecule has two possible enantiomers as shown in the structural diagrams. The structure on the left is the naturally occurring (R)-form, while its mirror image shown on the right is the (S)-form. The word camphor derives from the French word camphre, itself from Medieval Latin camfora, from Arabic kāfūr, from Tamil karuppūram (கருப்பூரம்), from Austroasiatic languages - Khmer kāpōr / kapū, Mon khapuiw, ultimately from an Austronesian source - Malay kapur. Camphor was used in India from ancient time when religions like Buddhism and Jainism flourished. However, Suśruta and later kāvya literature mention this word. In Old Malay it is known as kapur Barus, which means 'the chalk of Barus'. Barus was the name of an ancient port located near modern Sibolga city on the western coast of Sumatra island. This port traded in camphor extracted from laurel trees (Cinnamonum camphora) that were abundant in the region. Even now, the local tribespeople and Indonesians in general refer to aromatic naphthalene balls and moth balls as kapur Barus. Camphor has been produced as a forest product for centuries, condensed from the vapor given off by the roasting of wood chips cut from the relevant trees, and later by passing steam through the pulverized wood and condensing the vapors. When its use in the nascent chemical industries (discussed below) greatly increased the volume of demand in the late 19th century, potential for changes in supply and in price followed. In 1911 Robert Kennedy Duncan, an industrial chemist and educator, related that the Imperial Japanese government had recently (1907–1908) tried to monopolize the production of natural camphor as a forest product in Asia but that the monopoly was prevented by the development of the total synthesis alternatives, which began in 'purely academic and wholly uncommercial' form with Gustav Komppa's first report 'but it sealed the fate of the Japanese monopoly For no sooner was it accomplished than it excited the attention of a new army of investigators—the industrial chemists. The patent offices of the world were soon crowded with alleged commercial syntheses of camphor, and of the favored processes companies were formed to exploit them, factories resulted, and in the incredibly short time of two years after its academic synthesis artificial camphor, every whit as good as the natural product, entered the markets of the world .':133–134 '...And yet artificial camphor does not—and cannot—displace the natural product to an extent sufficient to ruin the camphor-growing industry. Its sole present and probable future function is to act as a permanent check to monopolization, to act as a balance-wheel to regulate prices within reasonable limits.' This ongoing check on price growth was confirmed in 1942 in a monograph on DuPont's history, where William S. Dutton said, 'Indispensable in the manufacture of pyroxylin plastics, natural camphor imported from Formosa and selling normally for about 50 cents a pound, reached the high price of $3.75 in 1918 . The organic chemists at replied by synthesizing camphor from the turpentine of Southern pine stumps, with the result that the price of industrial camphor sold in carload lots in 1939 was between 32 cents and 35 cents a pound.':293 The background of Gustaf Komppa's synthesis was as follows. In the 19th century, it was known that nitric acid oxidizes camphor into camphoric acid. Haller and Blanc published a semisynthesis of camphor from camphoric acid. Although they demonstrated its structure, they were unable to prove it. The first complete total synthesis of camphoric acid was published by Komppa in 1903. Its inputs were diethyl oxalate and 3,3-dimethylpentanoic acid, which reacted by Claisen condensation to yield diketocamphoric acid. Methylation with methyl iodide and a complicated reduction procedure produced camphoric acid. William Perkin published another synthesis a short time later. Previously, some organic compounds (such as urea) had been synthesized in the laboratory as a proof of concept, but camphor was a scarce natural product with a worldwide demand. Komppa realized this. He began industrial production of camphor in Tainionkoski, Finland, in 1907 (with plenty of competition, as Kennedy Duncan reported). Camphor can be produced from alpha-pinene, which is abundant in the oils of coniferous trees and can be distilled from turpentine produced as a side product of chemical pulping. With acetic acid as the solvent and with catalysis by a strong acid, alpha-pinene readily rearranges into camphene, which in turn undergoes Wagner-Meerwein rearrangement into the isobornyl cation, which is captured by acetate to give isobornyl acetate. Hydrolysis into isoborneol followed by oxidation gives racemic camphor. By contrast, camphor occurs naturally as D-camphor, the (R)-enantiomer. In biosynthesis, camphor is produced from geranyl pyrophosphate, via cyclisation of linaloyl pyrophosphate to bornyl pyrophosphate, followed by hydrolysis to borneol and oxidation to camphor.