P-Menthane-3,8-diol

p-Menthane-3,8-diol
IUPAC name 2-(1-Hydroxy-1-methylethyl)-5-methylcyclohexanol
Other names para-Menthane-3,8-diol; 2-Hydroxy-α,α,4-trimethylcyclohexanemethanol
Identifiers
CAS number	42822-86-6
ChemSpider	484204 Y
EC number	255–9537
ChEBI	CHEBI:48250 Y
Jmol-3D images	Image 1
SMILES OC(C1CCC(CC1O)C)(C)C
InChI InChI=1S/C10H20O2/c1-7-4-5-8(9(11)6-7)10(2,3)12/h7-9,11-12H,4-6H2,1-3H3 Y Key: LMXFTMYMHGYJEI-UHFFFAOYSA-N Y InChI=1/C10H20O2/c1-7-4-5-8(9(11)6-7)10(2,3)12/h7-9,11-12H,4-6H2,1-3H3 Key: LMXFTMYMHGYJEI-UHFFFAOYAL
Properties
Molecular formula	C10H20O2
Molar mass	172.26 g mol−1
Density	1.009 g/cm³
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

p-Menthane-3,8-diol, also known as para-menthane-3,8-diol, PMD, or Menthoglycol, is an active ingredient used in insect repellents. It smells similar to menthol and has a cooling feel.^[1] There are eight possible isomers of PMD,^[2] and the exact composition is rarely specified and is commonly assumed to be a complex mixture.

PMD is found in small quantities in the essential oil from the leaves of Eucalyptus citriodora. This tree is native to Australia, but is now cultivated in many warm places around the world.

E. citriodora oil, when refined to increase its PMD content for use in insect repellents, is known in the United States as oil of lemon eucalyptus (OLE) or by the tradename Citriodiol. Some commercial PMD products are not made from E. citriodora oil, but rather from synthetic citronellal. Pure PMD has proven to be significantly less efficacious in repelling mosquitoes than naturally derived PMD in the form of OLE.^[3]

Refined OLE contains approximately 64% PMD (a mixture of the cis and trans isomers of p-menthane-3,8-diol). OLE has been notified under the European Biocidal Products Directive (BPD) 98/8/EC (now BPR Regulation (EU) No. 528/212) under its generic name "PMD rich botanic oil" and is currently proceeding through the registration process with the Health and Safety Executive in the UK. It is also seeking registration with Canada's Pest Management Regulatory Agency under the generic name "PMD and related oil of lemon eucalyptus compounds". It is the only natural active ingredient that is permitted to be used an insect repellent in the United States and Europe.^{[citation needed]}

The Center for Disease Control has recognized OLE as the only effective naturally derived substance for deterring mosquitoes carrying West Nile Virus.^{[citation needed]} PMD can be synthetically manufactured; however, studies have found that repellents containing synthetic PMD mixtures are not as effective as those containing naturally derived PMD where the PMD content is in equivalent concentrations.^[4][5] This 2006 study also showed that naturally-derived PMD is as effective as DEET when used in like quantities. The 2011 study shows E. citriodora oil (which contains only 1-2% PMD and is therefore different from OLE as registered with the EPA min 64% PMD) has far less efficacy in repelling mosquitoes than OLE.

References

1. ↑ John C. Leffingwell. "Cool without menthol & cooler than menthol and cooling compounds as insect repellents". Leffingwell & Associates. 
2. ↑ PubChem Compound Search
3. ↑ Drapeau, Jeremy (2011). "Green synthesis of para-Menthane-3,8-diol from Eucalyptus citriodora: Application for repellent products". Comptes Rendus Chimie 14 (7-8): 629–635. doi:10.1016/j.crci.2011.02.008. 
4. ↑ Carroll, Scott P.; Loye, Jenella (2006). "PMD, a Registered Botanical Mosquito Repellent with Deet-Like Efficacy". Journal of the American Mosquito Control Association 22 (3): 507–13. doi:10.2987/8756-971X(2006)22[507:PARBMR]2.0.CO;2. PMID 17067054. 
5. ↑ Drapeau, Jeremy (2011). "Green synthesis of para-Menthane-3,8-diol from Eucalyptus citriodora: Application for repellent products". Comptes Rendus Chimie 14 (7-8): 629–635. doi:10.1016/j.crci.2011.02.008.