Odoriferous Substances

organic compounds with characteristic pleasant odors used in the manufacture of various perfume and cosmetic goods, soaps, synthetic washing preparations, and food products. Odoriferous substances are abundant in nature. They form part of essential oils, aromatic resins, and other complex mixtures of organic substances extracted from animal and plant products.

Significant experimental data have been gathered about the connection between the odor of organic compounds and their structure; however, these data are not complete enough to reliably predict the odor of a newly synthesized substance on the basis of knowledge of all its structural features. Nevertheless, it is possible to establish some rules about the influence of an organic compound’s structural features on its odor. In particular, the size of the molecule and the degree of its branching greatly influence the odor. Compounds with a branched chain of carbon atoms in the molecule have stronger and often more pleasant odors than compounds with linear molecules. The odor is also influenced by the position of substitutes, the presence of multiple bonds, spatial factors, and molecular structure as a whole. Thus, of several valuable odoriferous substances used in industry, linalool (I) has the odor of lilies of the valley, citronellol (II) and beta-phenylethyl alcohol (III) have the odor of roses, citral (IV) has the odor of lemon, phenyl ether (V) that of geraniums, and diluted Ionone solutions, of violets.

The USSR produces thousands of tons of odoriferous substances yearly of more than 150 names. In industry odoriferous substances are synthesized from chemical raw materials and from products of the wood chemical industry (turpentines). Essential oils have also not lost their importance as sources of some odoriferous substances. It has become possible to synthesize many odoriferous substances that were formerly available only from natural raw materials as well as odoriferous substances not found in nature.