Chapter 12. LIPIDS

12.1. CLASSIFICATION

Lipids are classified as either simple (two-component) or complex ones; the latter consist of three or more components (Table 12.1). Simple lipids represent esters in which carboxylic acids acylate trihydroxylic alcohol glycerol (as in fats and oils) or long-chain alcohols (as in waxes). Lipids of this group give only alcohols and carboxylic acids on hydrolysis.

Complex lipids may contain other components such as a substituted phosphate group (as in phosphatides) or carbohydrate units (as in glycolipids). Moreover, the amino alcohol sphingosine (instead of glycerol) is a constituent of the sphingolipid group.

Table 12.1. Classification of lipids

* Unstated R's are saturated or unsaturated long carbon chains.

¹ Note that this definition is based on a physical property (solubility) differing from that used for other classes. The latter were defined on the basis of their structures.