Drapeau, Jeremy and Rossano, Manon and Touraud, Didier and Kroecke, Ulla and Geier, Martin and Rose, Andreas and Kunz, Werner (2011) Green synthesis of para-Menthane-3,8-diol from Eucalyptus citriodora: Application for repellent products. Comptes Rendus Chimie 14 (7-8), pp. 629-635.
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A simple and efficient method was developed for the synthesis of para-Menthane-3,8-diol (PMD), a well-known repellent active against mosquitoes, from Eucalyptus citriodora essential oil by a treatment of citric acid in a biphasic medium (H2O/essential oil). The E. citriodora contains as main component (+)-citronellal (74% in the present case), which cyclises (Prins reaction) to form cis/trans PMD isomers. As an example, an emulsion contg. an aq. soln. of 7% citric acid and E. citriodora oil at 50°, conducted after 15 h stirring to 82% conversion of (+)-citronellal with a selectivity of 80% with the remaining presence of monoterpenes and sesquiterpenes in the medium. Investigations of lasting protection on human volunteers are carried out using a cage test bioassay protocol and Aedes aegypti mosquitoes. At 20% in iPrOH, the new reaction mixt. showed a complete protection of 303 min compared to 22 min with the pure essential oil. The modified oil was compared with N,N-diethyl-m-methylbenzamide (DEET), the most popular active used in repellent formulations. Thermogravimetric analyses (TGA) of E. citriodora, the modified oil, PMD, DEET, and (+)-citronellal were performed and showed a slow evapn. rate for PMD and DEET as well as for the modified oil, which may explain their long lasting protection action.
|Institutions:||Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Werner Kunz|
|Keywords:||green chem prepn menthanediol Eucalyptus oil mosquito repellent|
|Subjects:||500 Science > 540 Chemistry & allied sciences|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||11 May 2012 09:24|
|Last Modified:||11 May 2012 09:24|