Applications and Occurrences of Heterocycles in Everyday Life 191listed by the F&F suppliers, including many furans and pyrazines, together with thiazoles and some quinolines, indoles
and thiophenes.
Flavours have applications, not only in food products, but also in cosmetics and medicinal products (e.g. toothpastes,
cough syrups, lipsticks). Fragrances also have a range of uses: ‘fi ne’ perfumes and other cosmetics, and household
products such as detergents, soap, cleansing agents, washing powders and air fresheners. Many of the F&F components
occur naturally and the commercial materials can be natural, fully ‘artifi cial’ or ‘nature identical synthetics’. The natural
materials often contain trace components most of which are potent heterocyclics, which make them more ‘rounded’ or
‘fuller’. (The natural occurrence, formation and use of some of the heterocycles (particularly pyrazines and furans), in
relation to food, are discussed in the previous section.)
While most fragrance materials are not heterocyclic, the offi cial birth date of the synthetic fragrance industry is held
to be the development of a route to coumarin by W.H. Perkin in 1868, using a reaction that we now call the Perkin
condensation.
Some other signifi cant commercial heterocyclic F&F components are also shown below. Sulfurol occurs naturally (a
breakdown product of thiamine) and is used (meaty smell) in food products, and a number of its (non-natural) esters
have wider applications. Even skatole and indole, which in bulk have sickly faecal aromas, are used at very low con-
centrations in fragrances to give jasmine or ‘masculine/animalic’ notes. Indolall is a mixture of citronellal and indole,
which contains the bis-indolyl ‘aminal’ (it is also referred to as indole/hydroxycitronellal Schiff base). A number of
closely related quinolines are also used, particularly sec-butyl derivatives, and their iso-propyl and iso-butyl analogues,
which allow the fi ne-tuning of the basic leather/woody notes.
These F&F components are regulated by government agencies, such as the Food and Drug Administration (FDA) in
the USA. Safety testing is more limited and less onerous than that for new drugs, but the associated costs are high in
comparison to product value. Also, these regulations are being further tightened in some parts of the world, and this
represents a signifi cant threat to the industry. Most compounds are used only at low concentrations and this fact,