Citronellol is an oxygenated acyclic monoterpenoid alcohol produced by the secondary metabolism of plants and is present in flowers (Cymbopogon winterianu, Cymbopogon citratus.  Xylopia aromatica, Eupatorium cannabinum) citrus fruits, where it exerts various activities including anti-parasitic and growth-inhibiting.

Name breakdown and function of the components

• Citronellol - Derived from the term "citronella", the plant from which it was originally identified. It's a natural terpene and is part of the monoterpenic alcohols.

Description and function of the raw materials used in production

• Geranium or rose oil - These are the primary natural sources of citronellol. The oil is distilled from plants and flowers to obtain the compound.

Summary of the extraction process step by step

• Distillation - Essential oils containing citronellol, such as geranium or rose oil, undergo distillation to separate citronellol from other components.
• Refinement - Post-distillation, citronellol is further purified to remove impurities and achieve a high-quality product.
• Isolation - Finally, citronellol is separated and isolated as a pure compound.

Synthesised it appears as a colourless or slightly yellowish oily liquid with a pinkish odour and bitterish taste. Insoluble in water and glycerol, soluble in propylene glycol, ethanol and most non-volatile oils. Incompatible with oxidising agents.

What it is used for and where

Citronellol is an organic compound primarily used as a constituent in essential oils like rose and geranium. It has a characteristic scent similar to that of roses, which is why it's widely used in the cosmetic and fragrance industry. Additionally, it serves as an intermediate in the production of other chemical compounds.

Medical

Diabetes mellitus is a disease characterised by chronic hyperglycaemia with metabolic disturbances. This study showed that administration of citronellol attenuated hyperglycaemia in diabetic rats, improved key metabolic carbohydrate enzymes and could be developed as a functional and nutraceutical ingredient in the fight against diabetes mellitus (1). Citronellol may also exert an effective treatment, due to its anti-inflammatory and antioxidant effects, for allergic diseases (2) and may be considered as a potential drug against chronic dermatophytosis, due to its antimicrobial properties (3), properties that contribute to the preservation of food hygiene often compromised by the formation of biofilms against which citronellol prevented the formation of native microcolonies (4).

Cosmetics

It is a restricted ingredient as  III/86 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Substance or ingredient reported: Citronellol /+- 3,7-dimethyloct-6-en-1-ol

Perfuming. Unlike fragrance, which can also contain slightly less pleasant or characteristic odours, the term perfume indicates only very pleasant fragrances. Used for perfumes and aromatic raw materials.

Citronellol has shown good tolerability on the skin due to its low permeability and low skin penetration potential. It is added as a fragrance to liquid soaps, shampoos and other personal care products as a rose-scented cosmetic essence. As far as safety is concerned, the risk of sensitisation to this ingredient is possible, but very low (5).

Food

A food flavouring found in many confectionery products such as candies, baked goods and others. The function of citronellol in food is also as a preservative as it has been shown to destroy both the cell membrane and cell wall of the pathogenic fungus Aspergillus flavus, the main culprit of food mould, and against other fungi such as  Cladosporium spp., Cladosporium carrioni, C. cladosporioides, and C. oxysporum.  (6).

Other uses

Used in insecticides, insect repellents and for room scenting.

Perfumery: Given its pleasant fragrance, citronellol is often used in perfume-making.

Cosmetic and skincare products: Used as a fragrance component in a broad range of products such as lotions, creams, and bath gels.

Cleansing products: Citronellol can be found in soaps, cleansers, and other cleaning products due to its aromatic properties.

Insect repellents: Although different from citronella, citronellol may have some repelling properties.

Properties

Fragrance: It has a light floral scent that can vary slightly depending on its source.

Monoterpene alcohol: This chemical structure is what gives it its aromatic properties.

It's crucial to note that while citronellol is generally safe in the concentrations found in cosmetics and personal care products, some individuals may be sensitive or allergic to it. Always check product labels and conduct a patch test if you're unsure about sensitivities.

For more information:

Citronellol studies

Typical commercial product characteristics Citronellol

Appearance	Colourless or Yellowish oily liquid
Boiling Point	224.5±0.0°C at 760 mmHg
Melting Point	77-83°C
Flash Point	98.3±0.0°C
Density	0.8±0.1 g/cm3
Vapor Density	5.4
Vapor Pressure	0.0±0.9 mmHg at 25°C
Refraction Index	1,451
LogP	3.38
PSA	20.23000
Optical rotation	-0.3~+0.3°(D/20°C)
Shelf Life	24 months
Chemical Safety

• Molecular Formula    C₁₀H₂₀O
• Molecular Weight   156.26 g/mol
• Exact Mass    156.151413
• CAS  106-22-9  
• EC Number: 203-375-0  
• DSSTox Substance ID    DTXSID3026726   DTXSID20101583
• IUPAC  3,7-dimethyloct-6-en-1-ol
• InChl=1S/C10H20O/c1-9(2)5-4-6-10(3)7-8-11/h5,10-11H,4,6-8H2,1-3H3
• InChl Key      QMVPMAAFGQKVCJ-UHFFFAOYSA-N
• SMILES   CC(CCC=C(C)C)CCO
• MDL number  
• PubChem Substance ID    
• ChEBI  50462
• RTECS    RH3400000
• NCI    C65508
• FEMA     2309
• JECFA    1219
• NSC    8779

Synonyms:

• 2,6-DIMETHYL-2-OCTEN-8-OL
• 6-OCTEN-1-OL, 3,7-DIMETHYL
• 3,7-dimethyloct-6-en-1-ol
• Cephrol
• Elenol
• Rodinol

References_________________________________________________________________

(1) Srinivasan S, Muruganathan U. Antidiabetic efficacy of citronellol, a citrus monoterpene by ameliorating the hepatic key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats. Chem Biol Interact. 2016 Apr 25;250:38-46. doi: 10.1016/j.cbi.2016.02.020. 

(2) Kobayashi Y, Sato H, Yorita M, Nakayama H, Miyazato H, Sugimoto K, Jippo T. Inhibitory effects of geranium essential oil and its major component, citronellol, on degranulation and cytokine production by mast cells. Biosci Biotechnol Biochem. 2016 Jun;80(6):1172-8. doi: 10.1080/09168451.2016.1148573. 

(3) Pereira Fde O, Mendes JM, Lima IO, Mota KS, Oliveira WA, Lima Ede O. Antifungal activity of geraniol and citronellol, two monoterpenes alcohols, against Trichophyton rubrum involves inhibition of ergosterol biosynthesis. Pharm Biol. 2015 Feb;53(2):228-34. doi: 10.3109/13880209.2014.913299.

(4) Olszewska MA, Gędas A, Simões M. The Effects of Eugenol, Trans-Cinnamaldehyde, Citronellol, and Terpineol on Escherichia coli Biofilm Control as Assessed by Culture-Dependent and -Independent Methods. Molecules. 2020 Jun 6;25(11):2641. doi: 10.3390/molecules25112641.

(5) Lapczynski, A., Bhatia, S. P., Letizia, C. S., & Api, A. M. (2008). Fragrance material review on dl-citronellol. Food and chemical toxicology, 46(11), S103-S109.

(6) dos Santos, A. S., Silva, G. S., Silva, K. V. S., de Oliveira Lima, M. I., Arrua, J. M. M., de Oliveira Lima, E., & de Oliveira Pereira, F. (2017). Antifungal activity of geraniol and citronellol against food-relevant dematiaceous fungi Cladosporium spp. Revista Do Instituto Adolfo Lutz, 76, 1-8.