Rose oxide explained

Rose oxide^[1] is a fragrance chemical found in roses and rose oil. It also contributes to the flavor of some fruits, such as lychee, and wines, such as Gewürztraminer.

Chemistry

Rose oxide is an organic compound of the pyran class of monoterpenes. The compound has a cis- and a trans-isomer, each with a (+)- and (-)-stereoisomer, but only the (-)-cis isomer (odor threshold 0.5 ppb) is responsible for the typical rose (floral green) fragrance.^[2]

Production

Rose oxide can be produced industrially beginning with photooxygenation of citronellol to give the allyl hydroperoxide which is then reduced with sodium sulfite to provide the diol. Ring-closure with sulfuric acid forms both the cis- and trans-isomers in equal amounts.^[3]

Notes and References

1. Ghodsi Mohammadi Ziarani. Ghodsi. Mohammadi Ziarani. Fatemeh. Mohajer. Seyedh. Mahboobeh Jamali. Nader. Ale Ebrahim. 2020-11-30. Quantitative and Qualitative Bibliometric Scope Toward the Synthesis of Rose Oxide as a Natural Product in Perfumery. Current Organic Synthesis. en. 17. 8. 610–624. 10.2174/1872208314666200722161044. 32703138 . 220731373 .
2. Dieter Martinetz und Roland Hartwig: Taschenlehrbuch der Riechstoffe: ein Lexikon von A–Z. Verlag Harri Deutsch 1998; ; S. 330ff.
3. 10.1021/op900076g . "Dark" Singlet Oxygenation of β-Citronellol: A Key Step in the Manufacture of Rose Oxide . 2010 . Alsters . P. L. . Jary . W. . . Nardello-Rataj . V. . Aubry . J. M. . Organic Process Research & Development . 14 . 259–262 .