Wax

It is derived from the Anglo-Saxon word "weax" for beeswax, so a practical definition of a wax may therefore be " a substance similar in composition and physical properties to beeswax ". Technologists use the term for a variety of commercial products of mineral, marine, plant and insect origin that contain fatty materials of various kinds. Biochemists link waxes with the thin layer of fatty constituents that cover the leaves of plants or provide a surface coating for insects or the skin of animals. All of these tend to contain wax esters as major components, i.e. esters of long-chain fatty alcohols with long-chain fatty acids.

The nature of the other lipid constituents can vary greatly with the source of the waxy material, but they include hydrocarbons, sterol esters, aliphatic aldehydes, primary and secondary alcohols, diols, ketones, β-diketones, triacylglycerols, and many more.

Also, the chain-length and degree of unsaturation and branching of the aliphatic constituents will vary with the origin of the wax, but other than in some waxes of marine origin or from some higher animals, the aliphatic moieties tend to be saturated or monoenoic.

2. Commercial Waxes
A number of waxes are produced commercially in large amounts for use in cosmetics, lubricants, polishes, surface coatings, inks and many other applications. Some of these are of mineral origin (e.g. montan wax from brown coal/peat deposits), and only those from living organisms are discussed here. Amongst them are - Beeswax - Glands under the abdomen of bees secrete a wax, which they use to construct the honeycomb. The wax is recovered as a by-product when the honey is harvested and refined. It contains a high proportion of wax esters (35 to 80%). The hydrocarbon content is highly variable, and much may be "unnatural" as beekeepers may feed some to bees to improve the yield of honey. The wax esters consist of C40 to C46 molecular species, based on 16:0 and 18:0 fatty acids some with hydroxyl groups in the ω-2 and ω-3 positions. In addition, some diesters with up to 64 carbons may be present, together with triesters, hydroxy-polyesters and free acids (which are different in composition and nature from the esterified acids). Jojoba - The jojoba plant (//Simmondsia chinensis//), which grows in the semi-arid regions of Mexico and the U.S.A., is unique in producing wax esters rather than triacylglycerols in its seeds, and it has become a significant crop. It consists mainly of 18:1 (6%), 20:1 (35%) and 22:1 (7%) fatty acids linked to 20:1 (22%), 22:1 (21%) and 24:1 (4%) fatty alcohols. Therefore, it contains C38 to C44 esters with one double bond in each alkyl moiety. As methylene-interrupted double bonds are absent, the wax is relatively resistant to oxidation. Carnauba - The leaves of the carnauba palm, //Copernicia cerifera// that grows in Brazil, have a thick coating of wax, which can be harvested from the dried leaves. It contains mainly wax esters (85%), accompanied by small amounts of free acids and alcohols, hydrocarbons and resins. The wax esters constitute C16 to C20 fatty acids linked to C30 to C34 alcohols, giving C46 to C54 molecular species. Other vegetable "waxes" such as bayberry or Japan wax are better described as "tallows" as they consist mainly of high melting triacylglycerols. Wool wax (lanolin) - The grease obtained from the wool of sheep during the cleaning or refining process is rich in wax esters (of 1- and 2-alkanols, and 1,2-diols), sterol esters, triterpene alcohols, and free acids and sterols. The nature of the product varies with the degree and type of processing involved, but can contain up to 50% wax esters and 33% sterol esters. A high proportion of the sterol component is lanosterol. The fatty acid components are mainly saturated and //iso//- and //anteiso//-methyl-branched-chain.