Composition
Like many natural products, lanolin is complex and variable in composition. For example, a typical high purity grade of lanolin is composed predominantly of long chain waxy esters (circa 97% by weight) the remainder being lanolin alcohols, lanolin acids and lanolin hydrocarbons.
An estimated 8,000 to 20,000 different types of lanolin esters are present in lanolin, resulting from combinations between the 200 or so different lanolin acids and the 100 or so different lanolin alcohols identified so far.
Lanolin's complex composition of long chain esters, hydroxy esters, diesters, lanolin alcohols, and lanolin acids means in addition to it being a valuable product in its own right, it is also the starting point for the production of a whole spectrum of lanolin derivatives, which possess wide-ranging chemical and physical properties. The main derivatisation routes include hydrolysis, fractional solvent crystallisation, esterification, hydrogenation, and alkoxylation and quaternisation. Lanolin derivatives obtained from these processes are used widely in both high-value cosmetics and skin treatment products.
Hydrolysis of lanolin yields lanolin alcohols and lanolin acids. Lanolin alcohols are a rich source of cholesterol (an important skin lipid) and are powerful water-in-oil emulsifiers; they have been used extensively in skin care products for over 100 years. Interestingly, approximately 40% of the acids derived from lanolin are alpha hydroxy acids (AHAs). The use of AHAs in skin care products has attracted a great deal of attention in recent years. Details of the AHA’s isolated from lanolin can be seen in the table below.
| Type of lanolic acid | Carbon chain length | Number identified |
|---|---|---|
| Alpha hydroxy normal | C13–C24 | 12 |
| Alpha hydroxy iso | C13–C23 | 6 |
| Alpha hydroxy anteiso | C12–C24 | 7 |
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