September 11, 2023
You certainly know me by my scent.
What molecule am I?
Image of Camphor 3D Image of Camphor

Camphor is a naturally occurring terpene found in trees in the laurel family (Lauraceae), notably camphor laurel, or Cinnamomum camphora, that is native to east and south Asia and now grows worldwide. It has been used in folk medicine for centuries.

Camphor can exist in two enantiomers: (+)- or (R)-camphor (shown), the predominant natural isomer, and (–)-or (S)-camphor1, which occurs in sand sage (Artemisia filifolia), a flowering plant native to the western United States. Synthetic camphor is usually a racemic mixture2 of the two enantiomers.

Camphor, with its familiar, penetrating odor, has a wide range of uses, including as a plasticizer for modified celluloses; in lacquers, varnishes, and plastics; as a moth repellent alternative to p-dichlorobenzene; and as a preservative in cosmetics and embalming fluids. In medicine, it is an ingredient in topical creams and ointments to treat itching, irritation, and joint pain; and it is used internally to prevent or relieve gas in the gastrointestinal tract.

1. CAS Reg. No. 464-48-2.
2. CAS Reg. No. 76-22-2.

Camphor hazard information*

Hazard class**GHS code and hazard statement
Flammable solids, category 2H228—Flammable solidChemical Safety Warning
Acute toxicity, oral, category 4H302—Harmful if swallowedChemical Safety Warning
Skin corrosion/irritation, category 2H315—Causes skin irritationChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Acute toxicity, inhalation, category 4H332—Harmful if inhaledChemical Safety Warning
Specific target organ toxicity, single exposure, lungs, category 2H371—May cause damage to lungs if inhaledChemical Safety Warning
Short-term (acute) aquatic hazard, category 2H401—Toxic to aquatic life

*Compilation of multiple safety data sheets.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.

MOTW updates

Ammonia1 was the Molecule of the Week for February 8, 2021. A colorless, toxic gas, it is an important industrial and agricultural chemical and a starting material for making a host of other compounds. It was the topic of two literature reports in August.

The city of Beijing has chronically poor air quality. Yixin Guo, Lin Zhang, and coauthors at Peking University (Beijing) and other Chinese research institutions contend that the pollution may be even worse than previously thought. They found that summertime ammonia emissions are substantially underestimated in Beijing because the prevailing atmospheric models do not completely account for sources such as fertilizer, power plants, vehicle traffic, and residences.

In contrast, Ronny Neumann and collaborators at the Weizmann Institute of Science (Rehovot, Israel) and the University of Rovira i Virgili (Tarragona, Spain) developed a way to make ammonia from molecular nitrogen and water. This finding eliminates the coproduction of carbon dioxide, which occurs when ammonia is made from hydrogen derived from fossil fuel sources such as natural gas. The researchers’ electrolytic process is catalyzed by a tri-iron–substituted polyoxotungstate, {SiFe3W9}, in the presence of lithium or sodium cations. Water acts as both a proton and electron donor.

1. CAS Reg. No. 7664-41-7.

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Camphor fast facts

CAS Reg. No.464-49-3
SciFinder nomenclatureBicyclo[2.2.1]heptan-2-one, 1,7,7-trimethyl-, (1R,4R)-
Empirical formulaC10H16O
Molar mass152.23 g/mol
AppearanceWhite crystals
Melting point179 °C
Water solubility1.2 g/L (20 °C)
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