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Camphor

physical science Maturity 11-13 Next article →

Camphor is a waxy, colorless solid known for its intense, pungent aroma. Chemically, it is classified as a cyclic ketone and a terpenoid. This substance is highly significant because it can be easily purified from various natural sources. It has played a major role in history, ranging from ancient religious rituals to the development of the modern plastics industry.

Camphor Cubes
Camphor Cubes

In nature, camphor is found in several specific types of trees. The camphor laurel, or Cinnamomum camphora, is a large evergreen tree found in East Asia. Another source is the kapur tree, a tall timber tree from South East Asia. Other trees in the laurel family, such as Ocotea usambarensis, also contain the compound. Even common plants like rosemary contain small amounts, between 0.05% and 0.5%. Some plants, like camphorweed, contain much higher amounts, around 5%.

Camphor biosynthesis en
Camphor biosynthesis en

Camphor exists in two different forms called enantiomers. These are mirror images of each other, much like a left and right hand. The most common form found in nature is (+)-camphor, also known as (1R,4R)-bornan-2-one. Its mirror image, (−)-camphor, or (1S,4S)-bornan-2-one, is very rare in the natural world. While (+)-camphor is common in trees, the (−)-enantiomer occurs naturally in the essential oil of Matricaria plants.

10-CSA synthesis
10-CSA synthesis

Historically, camphor was produced by harvesting forest products. For centuries, people condensed camphor from the vapor produced by roasting woodchips. Later, they improved this by passing steam through pulverized wood to collect the vapors. By the early 19th century, many natural reserves were depleted. Large stands remained in Japan and Taiwan, making Taiwan a major producer. This resource was so valuable that it led to conflict. In 1868, a British naval force even bombarded the town of Anping to challenge a Chinese camphor monopoly.

Camphor-Camphor acid
Camphor-Camphor acid

As industrial demand grew, scientists developed ways to make camphor synthetically. This was necessary because the price of natural camphor rose sharply during World War I. In 1918, the price reached $3.75 per pound, compared to 50 cents earlier. To lower costs, chemists at DuPont began synthesizing camphor from turpentine. They used alpha-pinene, which comes from the oil of coniferous trees. This process involves converting alpha-pinene into isobornyl acetate using acetic anhydride and a strong acid catalyst. Through hydrolysis and oxidation, they could produce racemic camphor.

CamphorquinoneSynthesis
CamphorquinoneSynthesis

Camphor has many diverse applications in medicine and industry. In the early days of the plastics industry, it was used as a plasticizer to create celluloid from nitrocellulose. In medicine, it acts as a counterirritant when applied to the skin. It stimulates nerve endings to produce either a warm or cool sensation, which helps relieve itching or minor pain. It is also used in respiratory aerosols to help with nasal congestion. Beyond medicine, marksmen use the soot from burning camphor to blacken the sights on rifles.

Camphor-3-Brominecampher
Camphor-3-Brominecampher

Finally, camphor connects to many cultural and biological systems. In the ancient world, Egyptians used camphor oil during mummification. In religious practices, it is used in Hindu Aarti ceremonies and is mentioned in the Quran. Even in the culinary world, camphor has appeared in Tang dynasty ice cream and South Indian desserts like Payasam. Biologically, the substance is created through a complex pathway starting from geranyl pyrophosphate. This process involves the cyclisation of linaloyl pyrophosphate into bornyl pyrophosphate, which is then oxidized into camphor.

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🖼️ Images & Media (6)
File:10-CSA synthesis.png
10-CSA synthesis.png
File:Camphor-3-Brominecampher.png
Camphor-3-Brominecampher.png
File:CamphorquinoneSynthesis.svg
CamphorquinoneSynthesis.svg
File:Camphor-Camphor acid.png
Camphor-Camphor acid.png
File:Camphor_biosynthesis_en.svg
Camphor_biosynthesis_en.svg
File:Camphor Cubes.jpg
Camphor Cubes.jpg
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