p-Menthane-3,8-diol
[CAS# 42822-86-6]

Identification

• Classification: Flavors and spices
• Name: p-Menthane-3,8-diol
• Synonyms: 2-Hydroxy-alpha,alpha,4-trimethylcyclohexanemethanol
• Molecular Formula: C₁₀H₂₀O₂
• Molecular Weight: 172.26
• CAS Registry Number: 42822-86-6
• EC Number: 255-953-7
• FEMA: 4053
• SMILES: CC1CCC(C(C1)O)C(C)(C)O

Properties

• Density: 1.0±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.487, Calc.^*
• Boiling Point: 267.6±8.0 ºC (760 mmHg), Calc.^*
• Flash Point: 120.7±13.0 ºC, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS02;GHS05 Danger
• Hazard Statements: H226-H318
• Precautionary Statements: P210-P233-P240-P241-P242-P243-P261-P264+P265-P271-P280-P303+P361+P353-P304+P340-P305+P354+P338-P317-P319-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Flammable liquids	Flam. Liq.	3	H226
Serious eye damage	Eye Dam.	1	H318
Skin sensitization	Skin Sens.	1	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319

Discovory and Applicatios

p-Menthane-3,8-diol (PMD) is a naturally occurring monoterpene diol found in the essential oil of the lemon eucalyptus tree (*Corymbia citriodora*). It was first identified as one of the active components responsible for the insect-repellent properties of lemon eucalyptus oil. PMD can also be synthesized through the hydration of para-menthane compounds.

PMD is best known for its application as an insect repellent. Studies have demonstrated its effectiveness in repelling mosquitoes, ticks, and other biting insects. It has been recognized as an alternative to synthetic repellents such as N,N-Diethyl-meta-toluamide (DEET), offering comparable protection in certain conditions. Due to its efficacy and favorable safety profile, PMD has been included in commercial insect-repellent formulations, often labeled as a natural or plant-based option.

Regulatory agencies, including the U.S. Environmental Protection Agency (EPA), have evaluated PMD for its safety and effectiveness. Approved formulations containing PMD are widely used in personal insect repellents and outdoor protection products. Unlike some synthetic repellents, PMD is biodegradable and has a relatively low environmental impact, contributing to its appeal for eco-conscious consumers.

Beyond insect repellency, PMD has been investigated for potential antimicrobial properties, though its primary application remains in the development of insect-repellent products. It is available in various formulations, including sprays, lotions, and wipes, often marketed for outdoor and travel use.

The extraction and production of PMD from *Corymbia citriodora* oil involve distillation and enrichment processes to increase the concentration of the active ingredient. Synthetic PMD is also produced to meet commercial demand and provide consistency in product formulations.

Overall, p-Menthane-3,8-diol is a well-established insect repellent derived from natural sources, widely used as an effective alternative to synthetic repellents. Its regulatory approval and demonstrated efficacy contribute to its continued application in personal and environmental protection against biting insects.

References

2009. Cyclization of citronellal to p-Menthane-3,8-diols in water and carbon dioxide. Green Chemistry, 11(8).
DOI: 10.1039/B823297K

2024. Repellent activity of essential oils to the Lone Star tick, Amblyomma americanum. Parasites & Vectors, 17.
DOI: 10.1186/s13071-024-06246-0

2024. Insect Repellents. Updates in Clinical Dermatology.
DOI: 10.1007/978-3-031-57836-6_33