α-Terpineol

December 25, 2017
I provide a forest-like aroma for the holidays.
What molecules are we?

α-Terpineol is a terpene alcohol that is found in natural oils such as pine oil and petitgrain (the oil from the bitter orange tree). It is the most common of four structural isomers; the others are β-, γ-, and 4-terpineol. It should not be confused with terpinol, the hydrate of terpin, a terpene diol.

α-Terpineol is a racemic mixture of (R)-(+)- and (S)-(–)-enantiomers. Both are found in nature; but the article of commerce, which is usually synthesized from α-pinene, is the racemate. In 1903, German chemists H. Waldbaum and O. Hüthig isolated the (+)-stereoisomer from petitgrain. Four years later, J. E. Teeple of New York City separated its enantiomer from long-leaf pine oil.

The lilac-like aroma of α-terpineol makes it a desirable ingredient for perfumes and cosmetics. This time of year, people burn α-terpineol-scented candles for their piney scent. Whatever your favorite aroma during the holidays, enjoy the season!

MOTW update

Fentanyl was the Molecule of the Week for December 11, 2017. The potent painkiller is one of the main culprits of the current opioid abuse epidemic in the United States. On December 13, as part of the effort to keep illicit fenanyl out of the country, US Customs Border Protection seized ≈35 kg of the drug at the San Ysidro, CA, port of entry. This quantity surpassed the previous record confiscation of ≈30 kg this past June.

α-Terpineol fast facts

CAS Reg. No. 98-55-5
Molar mass 154.25 g/mol
Formula C10H18O
Appearance Colorless liquid
Boiling point ≈217–219 ºC
Water solubility 2.4 g/L
Chemical Abstract Service - a division of ACS

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