Waxes represent a class of simple lipids defined as esters of long-chain fatty acids and long-chain monohydric alcohols, distinguishing them from glyceride-based fats and oils. These hydrophobic compounds serve primarily protective roles in nature, forming impermeable coatings on biological surfaces.
Chemical Structure
Waxes typically consist of a fatty acid (C12–C36, often saturated) esterified to a fatty alcohol (C12–C32, such as cetyl, stearyl, or myricyl alcohol), yielding neutral esters devoid of glycerol. Classic examples include cetyl palmitate (found in sperm whale head oil), myricyl palmitate (a major component of beeswax), and triacontyl palmitate (carnauba wax). Their general structure, R–COO–R’, highlights elongated nonpolar chains that minimize interaction with water.
Physical Properties
Solid at ambient temperatures with melting points ranging from 60–100°C, waxes exhibit low specific gravity (<1.0), high plasticity when warmed, and insolubility in water. However, they are soluble in nonpolar organic solvents such as chloroform and benzene. Their high melting behavior arises from straight-chain packing into stable β-crystals, while polymorphism can influence texture. For example, beeswax displays transitions from α (around 60°C) to β (62–64°C) crystalline forms.
