The Chemistry of Smellable Molecules → Volatility?
The chemistry of smellable molecules volatility? The chemical categories to which most odoriferous substances belong are : 1. Terpenes (= isoprenoides): e.g. Menthol, lemonene, thymol 2. Phenoles e.g. Coumarin, vanillin, heliotropin 3. Sulfuric compounds: e.g. Allyl isothiocyanate = volatile mustard oil 4. Amines e.g. Methylamine (dead fish) 5. Aldehydes e.g. Acetaldehyde (ripe fruits) benzaldehyde (bitter almond) 6. Esters & Lactones (cyclic esters) e.g. Allyl amyl glycolate (pineapple) 1. We smell only short molecules, large ones are no longer volatile and hence not odorous. 2. If molecule is very short, short is also its endurance, it will be a top note like e.g. dimethyl sulfide CSC – the transient smell of truffles 3. If a molecules carry a large net charges they will stick to each other and form hydrogen bonds. This prevents volatility. 4. Most olfactory molecules are made of C, H, O, N, S Perfumes – art, witchcraft or science? Perfumes are mixtures of raw materials: fragrant essential oils and other odorants, musk, fixatives, chemicals + solvents to give the human body, food, detergent, soap, juice, books etc pleasant smells. Why perfumes? Extracts from plants do not really smell like the real flowers but like a weak fake which might resemble but never match nature & original. The perfume maker therefore combines various raw materials to get something that resembles real flowers , or may even create some desirable fantasy smell The first perfume that used pure chemicals was in 1881Fougere Royal or Royal Fern by Parquet: it used lots of coumarin. Coumarin was used before but it was extracted from woodruff, vanilla leaf, & Tonka beans ($ 450/ kg), but not the pure, cheap chemical ($ 10/kg).
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