Chemical of the Week 5 – DEET


This clever molecule is our weapon of choice against those airborne terrorists that seem determined to give us sleepless holiday nights plagued with swelling and scratching. Of course it is the dreaded mosquitos and thanks to research by the American army after WWII we have a molecule that offers some defence against their nasty bites. It should also be noted that in some parts of the world mosquitoes and other biting insects spread disease and cause widespread fatalities ( the WHO claim up to 1 million people die each year due to malaria). So it’s thanks to N,N-diethyl-3-methylbenzamide, also called DEET or diethyltoluamide, that we have a fighting chance.


Scientists are still not clear exactly how the molecule works – one school of thought is that the molecule interferes with the insect’s odorant receptors but it is looking most likely that mozzies just don’t like the smell. Products, such as sprays and creams, can contain DEET up to a concentration of 100% with the higher concentrations more effective for a longer periods of time. There is a lot of concern on the web about the safety of using DEET but if the recommended dosage is used and ingestion is avoided there are limited major health worries.

A quick look at DEET shows functional groups met at A2 level. This molecule would be a great starting point for some application questions eg. calculating molecular weight, reaction with bromine, acid/alkaline hydrolysis products …….


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