Thioterpineol

Structural formula
Simplified structural formula without stereochemistry
General
Surname	Thioterpineol
other names	p -Menth-1-en-8-thiol Menthenthiol TRIMETHYL-3-CYCLOHEXENE-1-METHANETHIOL ( INCI )
Molecular formula	C 10 H 18 S
External identifiers / databases
CAS number 71159-90-5 [( RS ) -thioterpineol] 83150-78-1 [( R ) -thioterpineol] EC number 275-223-1 ECHA InfoCard 100.068.364 PubChem 6427135 ChemSpider 4932553 Wikidata Q26220987
properties
Molar mass	170.31 g · mol -1
Physical state	liquid
density	0.948 g cm −3 (20 ° C) [( R ) form)]
boiling point	40 ° C (0.13 hPa )
Refractive index	1.503 (20 ° C)
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

The monoterpene thioterpineol ( p- menth-1-en-8-thiol) is a flavor component of grapefruit juice and the substance with the lowest known odor threshold .

Grapefruit (pink)

Already about 10 ⁻⁴ ppb of the racemate can be perceived in aqueous solution (see below for the differences in odor intensity).
Thioterpineol is one of the sulfur analogues of alcohols, the thiols .

Thioterpineol contains a stereocenter, so it is chiral . Thus, there are two mirror-image stereoisomers of thioterpineol: ( R ) -thioterpineol and ( S ) -thioterpineol. The racemate [1: 1 mixture of ( R ) -thioterpineol and ( S ) -thioterpineol] is called ( RS ) -thioterpineol.

( R ) -Thioterpineol (left) and ( S ) -Thioterpineol (right)

The enantiomers differ in terms of their odor threshold . For the ( S ) enantiomer it is 0.00008 ppb, for the ( R ) form it is only 0.00002 ppb. The odor qualities also differ: the ( S ) -enantiomer smells more fruity and less sulphurous than the ( R ) -enantiomer.

Individual evidence

1. ↑ Entry on TRIMETHYL-3-CYCLOHEXENE-1-METHANETHIOL in the CosIng database of the EU Commission, accessed on April 16, 2020.
2. ↑ ^{a b c d} Entry on p-menth-1-en-8-thiol. In: Römpp Online . Georg Thieme Verlag, accessed on March 26, 2016.
3. ↑ There is not yet a harmonized classification for this substance . A labeling of α, α, 4-trimethylcyclohex-3-ene-1-methanethiol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on July 29, 2019, is reproduced from a self-classification by the distributor .
4. ↑ Beyer-Walter: Textbook of organic chemistry
5. ^ John C. Leffingwell: Chirality & Odor Perception - The p-Menthen-8-thiols .