Sugar and Fat and All of That - Natural Products Chemistry: Sources, Separations, and Structures - page 51

5.10 FATS AND LIPIDS
Lipids constitute a group of naturally occurring molecules. They represent a large
number of important everyday products (e.g., fats, soaps, and waxes); mono-, di-, and
triglycerides; phospholipids; and fat-soluble vitamins A, D, E, and K (see Chapter 12).
The main biological functions of lipids include energy storage, signaling, and acting
as structural components of cell membranes.

5.11 SOAPS
Industrially, soaps are made from a mixture of the Na salts formed by adding
NaOH or sodium carbonate to natural fatty acids. The general reaction, called
saponification, requires heating up fats and oils with liquid alkali as represented in
the following reaction.

Fat + NaOH → Soap + Glycerol

5.12 DETERGENTS
Detergents are generally used as cleaning materials. They contain one or more sur-
factants, which reduce the surface tension of water. The detergent consists of a long
chain hydrocarbon and an ionic functional group.

• If the ion is an alkyl sulfate, the molecule is anionic.

• If the ionic group is cationic (e.g., an NH 4 group), these detergents are used

as a germicide and in shampoos.

• Neutral detergents may include the natural bile salts, which are produced in

the liver. Their main function, as derivatives of cholesterol in the body, is to
help the digestive process. The bile salts emulsify fats and oils in order that
the body's enzymes can further break down the fats.

5.13 WA XES
Waxes are water-resistant and form protective coatings on plants, fruits, and ani-
mal skins. Examples of waxlike materials include beeswax; Chinese wax used as a
polish; ear wax as a protective layer over the ear membrane; and lanolin found on
the skin and fur of animals, and used for rust prevention and cosmetics. Shellac is
used as a wood sealant. They differ from fats in that they have no triglyceride esters
(of three fatty acids). In fact, they are long chain nonpolar lipid esters, as shown in
Figure 5.10, and produced from an alcohol and a long chain fatty acid.

O

O

FIGURE 5.10 Structure of a wax ester formed from a long chain fatty acid and an alcohol.