citronellol

Rose otto is mostly wax and unremarkable alcohol by weight, and citronellol, C₁₀H₂₀O, is typically the largest single odorous component of that oil. It sits alongside geraniol and its cis-isomer nerol, C₁₀H₁₈O, genuinely rosy compounds that, smelled alone, you would readily place as rose. In this library citronellol appears only from rose buds, traced across five teas, where crushing the dried buds releases it as the tea's floral top note.

It is a monoterpene alcohol, a ten-carbon chain carrying a single hydroxyl group, plain in structure next to the wax it shares a bottle with. Rose buds carry it at 21.5 percent of the essential oil, one of the two alcohols doing most of the carrying; steam distillation and solvent extraction of the same petals give noticeably different results overall, mostly because phenylethyl alcohol, a different and more water-soluble compound, partitions away into the distillation water rather than staying in the oil.

None of that, on its own, is the smell of a rose. Citronellol, geraniol and nerol are the body of the fragrance rather than its signature: abundant, correctly floral, and still not enough by themselves to convince a nose the flower is in the room. The trace compound that manages that, beta-damascenone, sits at around a tenth of a percent of the oil and is not one of this library's traced compounds. In the five rose teas here, citronellol is what a crushed bud gives up into the cup: the floral crown recipes describe as soft, rosy, or refined rather than medicinal.