Citronellol 95

• 📂 CAS N° 106-22-9

• ⚖️ MW — 156.26 g/mol

• 📝 Odor Type — floral (rosy)

• 📈 Odor Strength — Medium

• 👃🏼 Odor Profile — Floral leather waxy rosebud citrus. Floral, rosy, sweet, citrus with green fatty terpene nuances. Clean, rose-like. Has a rich, rosy geranium, citronella character.

• ⚗️ Uses — Very extensively used in perfume compositions, not only for rosy fragrance types but in general as a fresh-floral, chief ingredient of a multitude of soap fragrances, household product fragrances, low-cost perfumes, etc. It may be a major ingredient in low-cost Muguet types, and together with Geraniol, Phenylethyl alcohol, etc. form the basis of most Rose fragrances. Used in flavor compositions for imitation Berry, Citrus, Fruit, Floral, Rose, Raspberry, Strawberry and occasionally Peach.Widely used as a clean, rose note in fine fragrances. It can be used in tropical, lemon, lime, honey, cherry and raspberry flavors.

WHAT IS CITRONELLOL?

Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both enantiomers occur in nature. (+)-Citronellol, which is found in citronella oils, including Cymbopogon nardus (50%), is the more common isomer. (−)-Citronellol is found in the oils of rose (18–55%) and Pelargonium geraniums.[1]

Commercial CitronelIol usually contains measurable amounts of Geraniol and variable amounts of Dimethyl octanol (uP to 15%).

Colorless liquid. Very slightly soluble in water, soluble in alcohol, miscible with perfume and flavor oils. Soluble in Propylene glycol, but not in Glycerin. [14]

Discovery

It was not until quite recently that a pure citronellol was obtained, and characterized as a chemical compound. The chief difficulty was to separate it from geraniol since the two alcohols can not be separated by fractional distillation. Wallach and 2 Naschold obtained pure 1-citronellol by heating a mixture of this alcohol and geraniol with water in an autoclave at 250; by this treatment, geraniol is entirely decomposed into hydrocarbons, while citronellol remains unaltered. According to Tiemann and Schmidt, citronellol may be separated from geraniol by heating the mixture with phthalic anhydride at 200 for two hours; geraniol is thus converted into hydrocarbons, and the resulting liquid phthalic acid salt of citronellol is separated, washed and saponified. When phosphorus trichloride is allowed to act on a mixture of the two alcohols in ethereal solution, it converts geraniol into hydrocarbons and geranyl chloride; citronellol, however, gives rise to a chlorinated acid phosphoric acid ester, which dissolves in alkalis, and may thus be separated (Tiemann and Schmidt). Flatau and Labbe convert the mixture of the two alcohols into the acid phthalic esters; the geraniol derivative is crystalline (m. p. 47), while the citronellol compound is an oil.[16]

Natural Occurrence

Citronellol occurs in rose and geranium where the level can be up to 50% of the oil. The oil of the hedging rose, Rosa rugosa, contains about 60% citronellol. Levels of just under 10% can be found in ginger (Zingiber Officinale) and juniper berries (Juniperus communis) [15]

Other uses

Citronellol is used in perfumes and insect repellents,[4] and

References

Chirality & Odour Perception, John C. Leffingwell, Ph.D. – The Citronellols

Production

• Citronellol can be prepared by hydrogenation of geraniol or nerol.[2][3]

• from Citronella oil by hydrogenation of the Geraniol component. 

• from Pinene (in the synthesis of Hydroxy- citronellal). 

• from Citronellal by reduction (this yields a very pure Citronellol).[14]

Notes

The United States FDA considers citronellol as generally recognized as safe (GRAS) for food use.[5]
Citronellol is subject to restrictions on its use in perfumery,[9] as some people may become sensitized to it, but the degree to which citronellol can cause an allergic reaction in humans is disputed.[10][11]

H315 - Causes skin irritation
H317 - May cause an allergic skin reaction
H319 - Causes serious eye irritation
H401 - Toxic to aquatic life

P261 - Avoid breathing dust/fume/gas/mist/vapors/spray.
P264 - Wash skin thoroughly after handling.
P272 - Contaminated work clothing should not be allowed out of the workplace.
P273 - Avoid release to the environment.
P280 - Wear protective gloves/protective clothing/eye protection/face protection.
P302 + P352 - IF ON SKIN: wash with plenty of soap and water.
P305 + P351 + P338 - IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P333 + P313 - IF SKIN irritation or rash occurs: Get medical advice/attention.
P337 + P313 - IF eye irritation persists: Get medical advice/attention.
P362 - Take off contaminated clothing and wash before reuse.
P501 - Dispose of contents/ container to an approved waste disposal plant

Human Experience:
6 % solution: no irritation or sensitization.

Sources:

1. Lawless, J. (1995). The Illustrated Encyclopedia of Essential Oils. ISBN 978-1-85230-661-8.

2. Morris, Robert H. (2007). "Ruthenium and Osmium". In De Vries, J. G.; Elsevier, C. J. (eds.). The Handbook of Homogeneous Hydrogenation. Weinheim: Wiley-VCH. ISBN 978-3-527-31161-3.

3. Ait Ali, M.; Allaoud, S.; Karim, A.; Roucoux, A.; Mortreux, A. (1995). "Catalytic Synthesis of (R)- and (S)-citronellol by homogeneous hydrogenation over amidophosphinephosphinite and diaminodiphosphine rhodium complexes". Tetrahedron: Asymmetry. 6 (2): 369. doi:10.1016/0957-4166(95)00015-H.

4. Taylor, W. G.; Schreck, C. E. (1985). "Chiral-phase capillary gas chromatography and mosquito repellent activity of some oxazolidine derivatives of (+)- and (−)-citronellol". Journal of Pharmacological Science. 74 (5): 534–539. doi:10.1002/jps.2600740508. PMID 2862274.

5. "Redirect". epa.gov. Retrieved 29 July 2015.

6. ^ Revay, Edita E.; Kline, Daniel L.; Xue, Rui-De; Qualls, Whitney A.; Bernier, Ulrich R.; Kravchenko, Vasiliy D.; Ghattas, Nina; Pstygo, Irina; Müller, Günter C. (2013). "Reduction of mosquito biting-pressure: Spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel". Acta Tropica. 127 (1): 63–68. doi:10.1016/j.actatropica.2013.03.011. PMID 23545129.

7. ^ Songkro, Sarunyoo; Hayook, Narissara; Jaisawang, Jittarat; Maneenuan, Duangkhae; Chuchome, Thitima; Kaewnopparat, Nattha (2011). "Investigation of inclusion complexes of citronella oil, citronellal and citronellol with β-cyclodextrin for mosquito repellent". Journal of Inclusion Phenomena and Macrocyclic Chemistry. 72 (3–4): 339. doi:10.1007/s10847-011-9985-7.

8. ^ Alsters, Paul L.; Jary, Walther; Aubry, Jean-Marie (2010). ""Dark" Singlet Oxygenation of β-Citronellol: A Key Step in the Manufacture of Rose Oxide". Organic Process Research & Development. 14: 259–262.

9. "Archived copy". Archived from the original on 6 January 2012. Retrieved 19 July 2012.

10. Crop watch Report April 2008

11. Survey and health assessment of chemical substances in massage oils Archived 27 September 2007 at the Wayback Machine

12. Luebke, William tgsc, (1981)

13. Mosciano, Gerard P&F 16, No. 1, 31, (1991)

14. S.arctander – perfume and flavor materials

15. A fragrant introduction to terpenoid chemistry 

16. The chemistry of terpenes, F. Heusler Ph.D., (1902)

17. National Center for Biotechnology Information (2020). PubChem Compound Summary for CID 8842, Citronellol. Retrieved November 24, 2020 from https://pubchem.ncbi.nlm.nih.gov/compound/3_7-dimethyloct-6-en-1-ol.