3.4: Lipid Molecules - Waxes
- Describe the roles played by waxes
Waxes
Waxes are a type of long chain nonpolar lipid. Natural waxes are typically esters of fatty acids and long chain alcohols. Waxes are synthesized by many animals and plants. Animal wax esters are typically derived from a variety of carboxylic acids and fatty alcohols. The composition of a wax depends not only on the species, but also on the geographic location of the organism. The best known animal wax is beeswax, but other insects secrete waxes as well. A major component of beeswax is the ester myricyl palmitate, which bees use for constructing honeycombs. Spermaceti is also a wax that occurs in large amounts in the oil of a sperm whale’s head. One of its main constituents is cetyl palmitate, an ester of a fatty acid and fatty alcohol. Plant waxes are derived from mixtures of long-chain hydrocarbons containing functional groups such as alkanes, fatty acids, alcohols, diols, ketones, and aldehydes. Plants also use waxes as a protective coating to control evaporation and hydration and to prevent them from drying out. Waxes are valuable to both plants and animals because of their hydrophobic nature. This makes them water resistant, which prevents water from sticking on surfaces.
Unlike most natural waxes, which are esters, synthetic waxes consist of long-chain hydrocarbons lacking functional groups. Paraffin wax is a type of synthetic wax derived from petroleum and refined by vacuum distillation. Synthetic waxes may also be obtained from polyethylene. Millions of of these waxes are produced annually, and they are used in adhesives, cosmetics, sealants and lubricants, insecticides, and UV protection. They are also used in foods like chewing gum.
Key Points
- Natural waxes are typically esters of fatty acids and long chain alcohols.
- Animal wax esters are derived from a variety of carboxylic acids and fatty alcohols.
- Plant waxes are derived from mixtures of long-chain hydrocarbons containing functional groups.
- Because of their hydrophobic nature, waxes prevent water from sticking on plants and animals.
- Synthetic waxes are derived from petroleum or polyethylene and consist of long-chain hydrocarbons that lack functional groups.
- Synthetic and waxes are used in adhesives, cosmetics, food, and many other commercial products.
Key Terms
- paraffin wax : A waxy white solid hydrocarbon mixture used to make candles, wax paper, lubricants, and sealing materials.
- polyethylene : A polymer consisting of many ethylene monomers bonded together; used for kitchenware, containers etc.